1.
Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
2.
Animal
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Animals are multicellular, eukaryotic organisms of the kingdom Animalia. The animal kingdom emerged as a clade within Apoikozoa as the group to the choanoflagellates. Animals are motile, meaning they can move spontaneously and independently at some point in their lives and their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later in their lives. All animals are heterotrophs, they must ingest other organisms or their products for sustenance, most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago. Animals can be divided broadly into vertebrates and invertebrates, vertebrates have a backbone or spine, and amount to less than five percent of all described animal species. They include fish, amphibians, reptiles, birds and mammals, the remaining animals are the invertebrates, which lack a backbone. These include molluscs, arthropods, annelids, nematodes, flatworms, cnidarians, ctenophores, the study of animals is called zoology. The word animal comes from the Latin animalis, meaning having breath, the biological definition of the word refers to all members of the kingdom Animalia, encompassing creatures as diverse as sponges, jellyfish, insects, and humans. Aristotle divided the world between animals and plants, and this was followed by Carl Linnaeus, in the first hierarchical classification. In Linnaeuss original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, in 1874, Ernst Haeckel divided the animal kingdom into two subkingdoms, Metazoa and Protozoa. The protozoa were later moved to the kingdom Protista, leaving only the metazoa, thus Metazoa is now considered a synonym of Animalia. Animals have several characteristics that set apart from other living things. Animals are eukaryotic and multicellular, which separates them from bacteria and they are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. All animals are motile, if only at life stages. In most animals, embryos pass through a stage, which is a characteristic exclusive to animals. With a few exceptions, most notably the sponges and Placozoa and these include muscles, which are able to contract and control locomotion, and nerve tissues, which send and process signals
3.
Arthropod
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An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and jointed appendages. Arthropods form the phylum Arthropoda, which includes the insects, arachnids, myriapods, arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages, the rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Their versatility has enabled them to become the most species-rich members of all guilds in most environments. They have over a million described species, making up more than 80% of all described living species, some of which. Arthropods range in size from the microscopic crustacean Stygotantulus up to the Japanese spider crab, arthropods primary internal cavity is a hemocoel, which accommodates their internal organs, and through which their haemolymph – analogue of blood – circulates, they have open circulatory systems. Like their exteriors, the organs of arthropods are generally built of repeated segments. Their nervous system is ladder-like, with paired ventral nerve cords running through all segments and their heads are formed by fusion of varying numbers of segments, and their brains are formed by fusion of the ganglia of these segments and encircle the esophagus. The respiratory and excretory systems of arthropods vary, depending as much on their environment as on the subphylum to which they belong, arthropods also have a wide range of chemical and mechanical sensors, mostly based on modifications of the many setae that project through their cuticles. Aquatic species use internal or external fertilization. Almost all arthropods lay eggs, but scorpions give birth to live young after the eggs have hatched inside the mother, arthropod hatchlings vary from miniature adults to grubs and caterpillars that lack jointed limbs and eventually undergo a total metamorphosis to produce the adult form. The level of care for hatchlings varies from nonexistent to the prolonged care provided by scorpions. The evolutionary ancestry of arthropods dates back to the Cambrian period, the group is generally regarded as monophyletic, and many analyses support the placement of arthropods with cycloneuralians in a superphylum Ecdysozoa. Overall however, the relationships of Metazoa are not yet well resolved. Likewise, the relationships between various groups are still actively debated. Arthropods contribute to the food supply both directly as food, and more importantly indirectly as pollinators of crops. Some species are known to spread disease to humans, livestock. The word arthropod comes from the Greek ἄρθρον árthron, joint, and πούς pous, i. e. foot or leg, arthropods are invertebrates with segmented bodies and jointed limbs
4.
Insect
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Insects are a class of hexapod invertebrates within the arthropod phylum that have a chitinous exoskeleton, a three-part body, three pairs of jointed legs, compound eyes and one pair of antennae. They are the most diverse group of animals on the planet, including more than a million described species, the number of extant species is estimated at between six and ten million, and potentially represent over 90% of the differing animal life forms on Earth. Insects may be found in all environments, although only a small number of species reside in the oceans. The life cycles of insects vary but most hatch from eggs, insect growth is constrained by the inelastic exoskeleton and development involves a series of molts. The immature stages can differ from the adults in structure, habit and habitat, Insects that undergo 3-stage metamorphosis lack a pupal stage and adults develop through a series of nymphal stages. The higher level relationship of the Hexapoda is unclear, fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonflies with wingspans of 55 to 70 cm. The most diverse insect groups appear to have coevolved with flowering plants, adult insects typically move about by walking, flying or sometimes swimming. As it allows for rapid yet stable movement, many insects adopt a tripedal gait in which they walk with their legs touching the ground in alternating triangles, Insects are the only invertebrates to have evolved flight. Many insects spend at least part of their lives under water, with adaptations that include gills. Some species, such as water striders, are capable of walking on the surface of water, Insects are mostly solitary, but some, such as certain bees, ants and termites, are social and live in large, well-organized colonies. Some insects, such as earwigs, show maternal care, guarding their eggs, Insects can communicate with each other in a variety of ways. Male moths can sense the pheromones of female moths over great distances, other species communicate with sounds, crickets stridulate, or rub their wings together, to attract a mate and repel other males. Lampyridae in the beetle order communicate with light, humans regard certain insects as pests, and attempt to control them using insecticides and a host of other techniques. Some insects damage crops by feeding on sap, leaves or fruits, a few parasitic species are pathogenic. Some insects perform complex ecological roles, blow-flies, for example, help consume carrion, Many other insects are considered ecologically beneficial as predators and a few provide direct economic benefit. Silkworms and bees have been used extensively by humans for the production of silk and honey, in some cultures, people eat the larvae or adults of certain insects. Insect first appears documented in English in 1601 in Hollands translation of Pliny, translations of Aristotles term also form the usual word for insect in Welsh, Serbo-Croatian, Russian, etc. The evolutionary relationship of insects to other animal groups remains unclear, in the Pancrustacea theory, insects, together with Entognatha, Remipedia, and Cephalocarida, make up a natural clade labeled Miracrustacea
5.
Fly
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True flies are insects of the order Diptera, the name being derived from the Greek di = two, and ptera = wings. Insects of this use only a single pair of wings to fly. Diptera is an order containing an estimated 1,000,000 species including horse-flies, crane flies, hoverflies and others. Flies have a head, with a pair of large compound eyes. Their wing arrangement gives them great manoeuvrability in flight, and claws, Flies undergo complete metamorphosis, the eggs are laid on the larval food-source and the larvae, which lack true limbs, develop in a protected environment, often inside their source of their food. The pupa is a capsule from which the adult emerges when ready to do so. Diptera is one of the insect orders and are of considerable ecological. Flies are important pollinators, second only to the bees and their Hymenopteran relatives, Flies may have been among the evolutionarily earliest pollinators responsible for early plant pollination. Flies can be annoyances especially in parts of the world where they can occur in large numbers. Larger flies such as flies and screwworms cause significant economic harm to cattle. Blowfly larvae, known as gentles, and other larvae, known more generally as maggots, are used as fishing bait. They are also used in medicine in debridement to clean wounds, dipterans are endopterygotes, insects that undergo radical metamorphosis. They belong to the Mecopterida, alongside the Mecoptera, Siphonaptera, Lepidoptera and Trichoptera, the possession of a single pair of wings distinguishes most true flies from other insects with fly in their names. However, some true flies such as Hippoboscidae have become secondarily wingless and this cladogram represents the current consensus view. The first true dipterans known are from the Middle Triassic, and they became widespread during the Middle, modern flowering plants did not appear until the Cretaceous, so the original dipterans must have had a different source of nutrition other than nectar. The basal clades in the Diptera include the Deuterophlebiidae and the enigmatic Nymphomyiidae, three episodes of evolutionary radiation are thought to have occurred based on the fossil record. Many new species of lower Diptera developed in the Triassic, about 220 million years ago, many lower Brachycera appeared in the Jurassic, some 180 million years ago. A third radiation took place among the Schizophora at the start of the Paleogene,66 million years ago, the phylogenetic position of Diptera has been controversial
6.
Drosophilidae
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The Drosophilidae are a diverse, cosmopolitan family of flies, which includes fruit flies. Another unrelated family of flies, Tephritidae, also includes species known as fruit flies and this fruit fly is mostly composed of post-mitotic cells, has a very short lifespan, and shows gradual aging. As in other species, temperature influences the life history of the animal, several genes have been identified that can be manipulated to extend the lifespan of these insects. Generally, drosophilids are considered to be nuisance flies rather than pests, zaprionus indianus Gupta is unusual among Drosophilidae species in being a serious, primary pest of at least one commercial fruit, figs in Brazil. Another species, Drosophila suzukii, infests thin-skinned fruit such as raspberries and cherries, Drosophila repleta larvae inhabit drains and spread bacteria. Fruit flies in general are considered as a vector in propagating acetic acid bacteria in nature. This often ruins the alcohol fermentation process and can ruin beer or wine by turning it into vinegar, doing so protects the flies from becoming host to the larvae, as the wasps have a low alcohol tolerance. This oviposition behavior change only occurs upon seeing the female wasp larva, the family contains more than 4,000 species classified under 75 genera. Recently, a phylogenetic classification of the genera based on both molecular and morphological characters has been published. info photo gallery Family Drosophilidae at EOL images
7.
Drosophila
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One species of Drosophila in particular, D. melanogaster, has been heavily used in research in genetics and is a common model organism in developmental biology. The terms fruit fly and Drosophila are often used synonymously with D. melanogaster in modern biological literature, the entire genus, however, contains more than 1,500 species and is very diverse in appearance, behavior, and breeding habitat. The term Drosophila, meaning dew-loving, is a modern scientific Latin adaptation from Greek words δρόσος, drósos, dew, Drosophila species are small flies, typically pale yellow to reddish brown to black, with red eyes. Many species, including the noted Hawaiian picture-wings, have distinct black patterns on the wings, the plumose arista, bristling of the head and thorax, and wing venation are characters used to diagnose the family. Most are small, about 2–4 mm long, but some, Drosophila species are found all around the world, with more species in the tropical regions. They can be found in deserts, tropical rainforest, cities, swamps, most species breed in various kinds of decaying plant and fungal material, including fruit, bark, slime fluxes, flowers, and mushrooms. The larvae of at least one species, D. suzukii, can feed in fresh fruit. A few species have switched to being parasites or predators, many species can be attracted to baits of fermented bananas or mushrooms, but others are not attracted to any kind of baits. Males may congregate at patches of suitable breeding substrate to compete for the females, or form leks, several Drosophila species, including D. melanogaster, D. immigrans, and D. simulans, are closely associated with humans, and are often referred to as domestic species. These and other species have been introduced around the world by human activities such as fruit transports. Males of this genus are known to have the longest sperm cells of any studied organism on Earth, including one species, Drosophila bifurca, the cells are mostly tail, and are delivered to the females in tangled coils. The other members of the genus Drosophila also make relatively few giant sperm cells, D. melanogaster sperm cells are a more modest 1.8 mm long, although this is still about 35 times longer than a human sperm. Several species in the D. melanogaster species group are known to mate by traumatic insemination, Drosophila species vary widely in their reproductive capacity. Those such as D. melanogaster that breed in large, relatively rare resources have ovaries that mature 10–20 eggs at a time, others that breed in more-abundant but less nutritious substrates, such as leaves, may only lay one egg per day. The eggs have one or more respiratory filaments near the anterior end, larvae feed not on the vegetable matter itself, but on the yeasts and microorganisms present on the decaying breeding substrate. Development time varies widely between species and depends on the factors such as temperature, breeding substrate, and crowding. Numerous studies have shown that fruit flies lay eggs using an environmental circle, if fruit flies laid eggs at nighttime during which the environmental conditions were advantageous, the eggs could not be susceptible to desiccation from parasites. As a result, the offspring reproduced from these eggs would have greater fitness compared to offspring that were reproduced from eggs laid during the day, since eggs are laid with a biological clock, D. melanogaster became adaptive to their environmental cycles, which showed a major advantage
8.
Binomial nomenclature
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Such a name is called a binomial name, a binomen, binominal name or a scientific name, more informally it is also called a Latin name. The first part of the name identifies the genus to which the species belongs, for example, humans belong to the genus Homo and within this genus to the species Homo sapiens. The formal introduction of system of naming species is credited to Carl Linnaeus. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus. Although the general principles underlying binomial nomenclature are common to these two codes, there are differences, both in the terminology they use and in their precise rules. Similarly, both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a name is usually given, at least when it is first mentioned. In zoology Patella vulgata Linnaeus,1758, the original name given by Linnaeus was Fringilla domestica, the parentheses indicate that the species is now considered to belong in a different genus. The ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, in botany Amaranthus retroflexus L. – L. is the standard abbreviation used in botany for Linnaeus. – Linnaeus first named this bluebell species Scilla italica, Rothmaler transferred it to the genus Hyacinthoides, the ICN does not require that the dates of either publication be specified. Prior to the adoption of the binomial system of naming species. Together they formed a system of polynomial nomenclature and these names had two separate functions. First, to designate or label the species, and second, to be a diagnosis or description, such polynomial names may sometimes look like binomials, but are significantly different. For example, Gerards herbal describes various kinds of spiderwort, The first is called Phalangium ramosum, Branched Spiderwort, is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia. The Latin phrases are short descriptions, rather than identifying labels, the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné. It was in his 1753 Species Plantarum that he first began using a one-word trivial name together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as an epithet or specific name
9.
Johann Wilhelm Meigen
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Johann Wilhelm Meigen was a German entomologist famous for his pioneering work on Diptera. Meigen was born in Solingen, the fifth of eight children of Johann Clemens Meigen and his parents, though not poor, were not wealthy either. They ran a shop in Solingen. His paternal grandparents however owned an estate and hamlet with twenty houses, adding to the rental income, Meigen’s grandfather was a farmer and a guild mastercutler in Solingen. Two years after Meigen was born his grandparents died and his parents moved to the family estate and this was already heavily indebted by the Seven Years War, then bad crops and rash speculations forced sale and the family moved back to Solingen. Meigen attended the school but only for a short time. Fortunately he had learned to read and write on his grandfather’s estate, a lodger in the household, a state surveyor named Stamm gave Meigen instruction in mathematics. Another family friend a Reformed Church organist and teacher called Berger, gave him lessons from his 10th year on in piano, orthography, later on, in 1776, he also taught him French. Meigen became Bergers assistant, going to Mülheim, with him, there he saw for the first time a systematic collection of butterflies, and here he also learnt how to collect and prepare insects. In the Autumn of 1779 he returned to Solingen to help his parents, at first by giving lessons in French. During his few hours in this period he studied history from Charles Rollins 15 volume Roman History. The only entomological work in his possession at this time was Moders Caterpillar Calendar, later in 1784 he was recommended to Pelzer, a tradesman in Aachen, for the position of resident tutor. On taking up the post, he was treated as a family member, Pelzer had a cousin in Aachen by the name of Mathias Baumhauer, a wool merchants son, who was a very able entomologist. Baumhauer had a collection including about 1200 species as well as numbers of insects of all other orders. He soon made his first discovery, the Linnean genera were too inclusive and a better classification could be arrived at using wing venation. This conclusion had already occurred to both Moses Harris in England and Louis Jurine in Geneva but at the time Meigen was unaware of this, sensing an important step forward he secured the works of Fabricius and from that time concentrated on Diptera. In 1786 the Solingen organist, a brother of his former teacher Berger died in Solingen. That position, with a French school connected with it, was offered to Meigen, there he became closely acquainted with a man called Weniger, who shared his interests in botany and entomology
10.
Charles W. Woodworth
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Charles William Woodworth was an American entomologist. He published extensively in entomology and founded the Entomology Department at the University of California and he was the first person to breed the model organism Drosophila melanogaster in captivity and to suggest to early genetic researchers at Harvard its use for scientific research. He spent four years at the University of Nanking, China and he drafted and lobbied for Californias first insecticide law and administered the law for 12 years. The Pacific Branch of the Entomological Society of America named its annual career achievement award the C. W. Woodworth Award and he was born in Champaign, Illinois on April 28,1865 to Alvin Oakley Woodworth and Mary Celina Woodworth. His father was a merchant but died when Charles was four, some years later, his mother married Alvins older brother Stephen Elias Woodworth to help raise Charles and his older brother Howard. Stephen had earlier been a resident of Seneca Falls, New York and was a signatory of the 1848 Seneca Falls Declaration of Sentiments, Charles graduated with a BS in 1885 and an MS in 1886 from the University of Illinois at Urbana-Champaign. The funds received from the judgment in the 1884 U. S. Supreme Court Case, New England Mutual Life Ins. Co. v. Woodworth, during the period of 1884–1886, he was assistant to S. A. Forbes. From 1886 to 1888 he studied at Harvard University under Hermann August Hagen and he returned between 1900 and 1901 and worked under William E. Castle. In 1888, he was appointed entomologist and botanist at the University of Arkansass Arkansas Agricultural Experiment Station, on September 4,1889, he married Leonora Stern in Rolla, Missouri, the city where her parents, Edward Stern and Lizzie Hardin Evans Stern, lived. Charles suffered from attacks of malaria while in Arkansas. He left there in 1891 to become assistant in entomology at the University of California where he founded and he also participated in the development of the Agricultural Experiment Station, now known as UC Davis, and is also considered the founder of the Entomology Department there. At Berkeley, he rose to be Assistant Professor in 1891, Associate Professor in 1904, Professor in 1913, Woodworth is credited with first breeding Drosophila in quantity while he was at Harvard. Thomas Hunt Morgans Nobel Prize biography says that Woodworth suggested to William E, Castle that Drosophila might be used for genetical work. While on sabbatical leave in 1918, he was a lecturer at the University of Nanking and honorary professor of entomology at the National Southeastern University at Nanking, during his year there he effected a practical control of mosquitoes for the first time in that citys history. He returned for a period in 1921-1924. During this period he organized the Kiangsu Provincial Bureau of Entomology as well as other things. In the words of the president of the University of Nanking and his publications were very extensive and included nearly every field of entomology. A few of his most outstanding works are, A List of the Insects of California, The Wing Veins of Insects, Guide to California Insects and he was the first editor and first contributor to the University of California Publications in Entomology
11.
Model organism
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Model organisms are in vivo models and are widely used to research human disease when human experimentation would be unfeasible or unethical. This strategy is made possible by the descent of all living organisms. Studying model organisms can be informative, but care must be taken when extrapolating from one organism to another, in researching human disease, model organisms allow for better understanding the disease process without the added risk of harming an actual human. The species chosen will usually meet a determined taxonomic equivalency to humans, although biological activity in a model organism does not ensure an effect in humans, many drugs, treatments and cures for human diseases are developed in part with the guidance of animal models. There are three types of disease models, homologous, isomorphic and predictive. Homologous animals have the same causes, symptoms and treatment options as would humans who have the same disease, isomorphic animals share the same symptoms and treatments. Predictive models are similar to a human disease in only a couple of aspects. The use of animals in research dates back to ancient Greece, with Aristotle, research using animal models has been central to most of the achievements of modern medicine. It has contributed most of the knowledge in fields such as human physiology and biochemistry. For example, the results have included the near-eradication of polio and the development of organ transplantation, from 1910 to 1927, Thomas Hunt Morgans work with the fruit fly Drosophila melanogaster identified chromosomes as the vector of inheritance for genes. Drosophila became one of the first, and for some time the most widely used, model organisms, D. melanogaster remains one of the most widely used eukaryotic model organisms. The mouse has since been used extensively as an organism and is associated with many important biological discoveries of the 20th. In the late 19th century, Emil von Behring isolated the diphtheria toxin and he went on to develop an antitoxin against diphtheria in animals and then in humans, which resulted in the modern methods of immunization and largely ended diphtheria as a threatening disease. The diphtheria antitoxin is famously commemorated in the Iditarod race, which is modeled after the delivery of antitoxin in the 1925 serum run to Nome. The success of animal studies in producing the diphtheria antitoxin has also attributed as a cause for the decline of the early 20th-century opposition to animal research in the United States. This led to the 1922 discovery of insulin and its use in treating diabetes, modern general anaesthetics, such as halothane and related compounds, were also developed through studies on model organisms, and are necessary for modern, complex surgical operations. In the 1940s, Jonas Salk used rhesus monkey studies to isolate the most virulent forms of the polio virus, the vaccine, which was made publicly available in 1955, reduced the incidence of polio 15-fold in the United States over the following five years. It has been estimated that developing and producing the vaccines required the use of 100,000 rhesus monkeys, models are those organisms with a wealth of biological data that make them attractive to study as examples for other species and/or natural phenomena that are more difficult to study directly
12.
Genetics
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Genetics is the study of genes, genetic variation, and heredity in living organisms. It is generally considered a field of biology, but intersects frequently with other life sciences and is strongly linked with the study of information systems. The father of genetics is Gregor Mendel, a late 19th-century scientist, Mendel studied trait inheritance, patterns in the way traits are handed down from parents to offspring. He observed that organisms inherit traits by way of discrete units of inheritance and this term, still used today, is a somewhat ambiguous definition of what is referred to as a gene. Gene structure and function, variation, and distribution are studied within the context of the cell, the organism, genetics has given rise to a number of subfields, including epigenetics and population genetics. Organisms studied within the broad field span the domain of life, including bacteria, plants, animals, genetic processes work in combination with an organisms environment and experiences to influence development and behavior, often referred to as nature versus nurture. The intracellular or extracellular environment of a cell or organism may switch gene transcription on or off, a classic example is two seeds of genetically identical corn, one placed in a temperate climate and one in an arid climate. The word genetics stems from the ancient Greek γενετικός genetikos meaning genitive/generative, the observation that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding. The modern science of genetics, seeking to understand this process, prior to Mendel, Imre Festetics, a Hungarian noble, who lived in Kőszeg before Mendel, was the first who used the word genetics. He described several rules of inheritance in his work The genetic law of the Nature. His second law is the same as what Mendel published, in his third law, he developed the basic principles of mutation. Other theories of inheritance preceded his work, a popular theory during Mendels time was the concept of blending inheritance, the idea that individuals inherit a smooth blend of traits from their parents. Mendels work provided examples where traits were not blended after hybridization. Blending of traits in the progeny is now explained by the action of genes with quantitative effects. Another theory that had some support at that time was the inheritance of acquired characteristics, other theories included the pangenesis of Charles Darwin and Francis Galtons reformulation of pangenesis as both particulate and inherited. Modern genetics started with Gregor Johann Mendel, a scientist and Augustinian friar who studied the nature of inheritance in plants, the importance of Mendels work did not gain wide understanding until the 1890s, after his death, when other scientists working on similar problems re-discovered his research. William Bateson, a proponent of Mendels work, coined the word genetics in 1905, Bateson popularized the usage of the word genetics to describe the study of inheritance in his inaugural address to the Third International Conference on Plant Hybridization in London in 1906. After the rediscovery of Mendels work, scientists tried to determine which molecules in the cell were responsible for inheritance, in 1911, Thomas Hunt Morgan argued that genes are on chromosomes, based on observations of a sex-linked white eye mutation in fruit flies
13.
Physiology
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Physiology is the scientific study of normal mechanisms, and their interactions, which operate within a living system. A sub-discipline of biology, its focus is in how organisms, organ systems, organs, cells, and biomolecules carry out the chemical or physical functions that exist in a living system. Given the size of the field, it is divided into, among others, animal physiology, plant physiology, cellular physiology, microbial physiology, bacterial physiology, and viral physiology. The Nobel Prize in Physiology or Medicine is awarded to those who make significant achievements in this discipline by the Royal Swedish Academy of Sciences. In medicine, a state is one occurring from normal body function, rather than pathologically. Physiological studies date back to the ancient civilizations of India and Egypt alongside anatomical studies, the study of human physiology as a medical field dates back to at least 420 BC to the time of Hippocrates, also known as the father of medicine. Hippocrates incorporated his belief called the theory of humours, which consisted of four basic substance, earth, water, air. Each substance is known for having a corresponding humour, black bile, phlegm, blood and yellow bile, Hippocrates also noted some emotional connections to the four humours, which Claudis Galenus would later expand on. The critical thinking of Aristotle and his emphasis on the relationship between structure and function marked the beginning of physiology in Ancient Greece. Like Hippocrates, Aristotle took to the theory of disease. Claudius Galenus, known as Galen of Pergamum, was the first to use experiments to probe the functions of the body, unlike Hippocrates though, Galen argued that humoral imbalances can be located in specific organs, including the entire body. His modification of this theory better equipped doctors to more precise diagnoses. Galen was also the founder of experimental physiology, and for the next 1,400 years, Galenic physiology was a powerful and influential tool in medicine. Jean Fernel, a French physician, introduced the term physiology, inspired in the work of Adam Smith, Milne-Edwards wrote that the body of all living beings, whether animal or plant, resembles a factory. Where the organs, comparable to workers, work incessantly to produce the phenomena that constitute the life of the individual, in more differentiated organisms, the functional labor could be apportioned between different instruments or systems. In 1858, Joseph Lister studied the cause of blood coagulation and inflammation that resulted after previous injuries and he later discovered and implemented antiseptics in the operating room, and as a result decreases death rate from surgery by a substantial amount. The Physiological Society was founded in London in 1876 as a dining club, the American Physiological Society is a nonprofit organization that was founded in 1887. The Society is, devoted to fostering education, scientific research, in 1891, Ivan Pavlov performed research on conditional reflexes that involved dogs saliva production in response to a plethora of sounds and visual stimuli
14.
Nobel Prize
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The Nobel Prize is a set of annual international awards bestowed in a number of categories by Swedish and Norwegian institutions in recognition of academic, cultural, or scientific advances. The will of the Swedish inventor Alfred Nobel established the prizes in 1895, the prizes in Chemistry, Literature, Peace, Physics, and Physiology or Medicine were first awarded in 1901. Medals made before 1980 were struck in 23 carat gold, between 1901 and 2016, the Nobel Prizes and the Prize in Economic Sciences were awarded 579 times to 911 people and organisations. With some receiving the Nobel Prize more than once, this makes a total of 23 organisations, the prize ceremonies take place annually in Stockholm, Sweden. Each recipient, or laureate, receives a medal, a diploma. The Nobel Prize is widely regarded as the most prestigious award available in the fields of literature, medicine, physics, chemistry, peace, and economics. The prize is not awarded posthumously, however, if a person is awarded a prize and dies before receiving it, though the average number of laureates per prize increased substantially during the 20th century, a prize may not be shared among more than three people. Alfred Nobel was born on 21 October 1833 in Stockholm, Sweden and he was a chemist, engineer, and inventor. In 1894, Nobel purchased the Bofors iron and steel mill and this invention was a precursor to many smokeless military explosives, especially the British smokeless powder cordite. As a consequence of his patent claims, Nobel was eventually involved in a patent infringement lawsuit over cordite, Nobel amassed a fortune during his lifetime, with most of his wealth from his 355 inventions, of which dynamite is the most famous. In 1888, Nobel was astonished to read his own obituary, titled The merchant of death is dead, as it was Alfreds brother Ludvig who had died, the obituary was eight years premature. The article disconcerted Nobel and made him apprehensive about how he would be remembered and this inspired him to change his will. On 10 December 1896, Alfred Nobel died in his villa in San Remo, Italy, Nobel wrote several wills during his lifetime. He composed the last over a year before he died, signing it at the Swedish–Norwegian Club in Paris on 27 November 1895, Nobel bequeathed 94% of his total assets,31 million SEK, to establish the five Nobel Prizes. Because of skepticism surrounding the will, it was not until 26 April 1897 that it was approved by the Storting in Norway. The executors of Nobels will, Ragnar Sohlman and Rudolf Lilljequist, formed the Nobel Foundation to take care of Nobels fortune, Nobels instructions named a Norwegian Nobel Committee to award the Peace Prize, the members of whom were appointed shortly after the will was approved in April 1897. Soon thereafter, the other prize-awarding organisations were designated or established and these were Karolinska Institutet on 7 June, the Swedish Academy on 9 June, and the Royal Swedish Academy of Sciences on 11 June. The Nobel Foundation reached an agreement on guidelines for how the prizes should be awarded, and, in 1900, in 1905, the personal union between Sweden and Norway was dissolved
15.
Chromosome
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A chromosome is a DNA molecule with part or all of the genetic material of an organism. Prokaryotes usually have one single circular chromosome, whereas most eukaryotes are diploid, chromosomes in eukaryotes are composed of chromatin fiber. Chromatin fiber is made of nucleosomes, a nucleosome is a histone octamer with part of a longer DNA strand attached to and wrapped around it. Chromatin fiber, together with associated proteins is known as chromatin, chromatin is present in most cells, with a few exceptions, for example, red blood cells. Occurring only in the nucleus of cells, chromatin contains the vast majority of DNA, except for a small amount inherited maternally. Chromosomes are normally visible under a microscope only when the cell is undergoing the metaphase of cell division. Before this happens every chromosome is copied once, and the copy is joined to the original by a centromere resulting in an X-shaped structure, the original chromosome and the copy are now called sister chromatids. During metaphase, when a chromosome is in its most condensed state, in this highly condensed form chromosomes are easiest to distinguish and study. In prokaryotic cells, chromatin occurs free-floating in cytoplasm, as these cells lack organelles, the main information-carrying macromolecule is a single piece of coiled double-helix DNA, containing many genes, regulatory elements and other noncoding DNA. The DNA-bound macromolecules are proteins that serve to package the DNA, chromosomes vary widely between different organisms. Some species such as certain bacteria also contain plasmids or other extrachromosomal DNA and these are circular structures in the cytoplasm that contain cellular DNA and play a role in horizontal gene transfer. Chromosomal recombination during meiosis and subsequent sexual reproduction plays a significant role in genetic diversity. In prokaryotes and viruses, the DNA is often densely packed and organized, in the case of archaea, by homologs to eukaryotic histones, small circular genomes called plasmids are often found in bacteria and also in mitochondria and chloroplasts, reflecting their bacterial origins. Some use the term chromosome in a sense, to refer to the individualized portions of chromatin in cells. However, others use the concept in a sense, to refer to the individualized portions of chromatin during cell division. The word chromosome comes from the Greek χρῶμα and σῶμα, describing their strong staining by particular dyes, schleiden, Virchow and Bütschli were among the first scientists who recognized the structures now so familiar to everyone as chromosomes. The term was coined by von Waldeyer-Hartz, referring to the term chromatin, in a series of experiments beginning in the mid-1880s, Theodor Boveri gave the definitive demonstration that chromosomes are the vectors of heredity. His two principles were the continuity of chromosomes and the individuality of chromosomes and it is the second of these principles that was so original
16.
Tephritidae
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The Tephritidae are one of two fly families referred to as fruit flies, the other family being the Drosophilidae. The Tephritidae family does not include the model organisms of the genus Drosophila. Nearly 5,000 described species of fruit fly are categorized in almost 500 genera of the Tephritidae. Description, recategorization, and genetic analyses are constantly changing the taxonomy of this family, to distinguish them from the Drosophilidae, the Tephritidae are sometimes called peacock flies, in reference to their elaborate and colorful markings. The name comes from the Greek τεφρος, tephros, meaning ash grey and they are found in all the ecozones. The head is hemispherical and usually short, the face is vertical or retreating and the frons is broad. Ocelli and cellar bristles are present, the postvertical bristles are parallel to divergent. Two to eight pairs of bristles are seen. In some species, the bristles are inserted on a raised tubercle. Interfrontal setulae are usually absent or represented by one or two tiny setulae near the lunula, true vibrissae are absent, but several genera have strong bristles near the vibrissal angle. The wings usually have yellow, brown, or black markings or are dark-coloured with lighter markings, in a few species, the wings are clear. The costa has both a humeral and a subcostal break, the apical part of the subcostal is usually indistinct or even transparent and at about a right angle with respect to the basal part. Crossvein BM-Cu is present, the cup is closed and nearly always narrowing to an acute angle. It is closed by a geniculated vein, the CuA2 vein is rarely straight or convex. The tibiae lack a dorsal preapical bristle, the body varies from white to yellowish or brown. The posterior end of pale-coloured species is sometimes black, the body tapers at the anterior. The two mandibles sometimes have teeth along the ventral margin, the antennomaxillary lobes at each side of the mandibles have several transverse oral ridges or short laminae directed posteriorly. The anterior spiracles end bluntly and are not elongated, each has at least three openings or up to 50 arranged transversely in one to three groups or irregularly
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Australia
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Australia, officially the Commonwealth of Australia, is a country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. It is the worlds sixth-largest country by total area, the neighbouring countries are Papua New Guinea, Indonesia and East Timor to the north, the Solomon Islands and Vanuatu to the north-east, and New Zealand to the south-east. Australias capital is Canberra, and its largest urban area is Sydney, for about 50,000 years before the first British settlement in the late 18th century, Australia was inhabited by indigenous Australians, who spoke languages classifiable into roughly 250 groups. The population grew steadily in subsequent decades, and by the 1850s most of the continent had been explored, on 1 January 1901, the six colonies federated, forming the Commonwealth of Australia. Australia has since maintained a liberal democratic political system that functions as a federal parliamentary constitutional monarchy comprising six states. The population of 24 million is highly urbanised and heavily concentrated on the eastern seaboard, Australia has the worlds 13th-largest economy and ninth-highest per capita income. With the second-highest human development index globally, the country highly in quality of life, health, education, economic freedom. The name Australia is derived from the Latin Terra Australis a name used for putative lands in the southern hemisphere since ancient times, the Dutch adjectival form Australische was used in a Dutch book in Batavia in 1638, to refer to the newly discovered lands to the south. On 12 December 1817, Macquarie recommended to the Colonial Office that it be formally adopted, in 1824, the Admiralty agreed that the continent should be known officially as Australia. The first official published use of the term Australia came with the 1830 publication of The Australia Directory and these first inhabitants may have been ancestors of modern Indigenous Australians. The Torres Strait Islanders, ethnically Melanesian, were originally horticulturists, the northern coasts and waters of Australia were visited sporadically by fishermen from Maritime Southeast Asia. The first recorded European sighting of the Australian mainland, and the first recorded European landfall on the Australian continent, are attributed to the Dutch. The first ship and crew to chart the Australian coast and meet with Aboriginal people was the Duyfken captained by Dutch navigator, Willem Janszoon. He sighted the coast of Cape York Peninsula in early 1606, the Dutch charted the whole of the western and northern coastlines and named the island continent New Holland during the 17th century, but made no attempt at settlement. William Dampier, an English explorer and privateer, landed on the north-west coast of New Holland in 1688, in 1770, James Cook sailed along and mapped the east coast, which he named New South Wales and claimed for Great Britain. The first settlement led to the foundation of Sydney, and the exploration, a British settlement was established in Van Diemens Land, now known as Tasmania, in 1803, and it became a separate colony in 1825. The United Kingdom formally claimed the part of Western Australia in 1828. Separate colonies were carved from parts of New South Wales, South Australia in 1836, Victoria in 1851, the Northern Territory was founded in 1911 when it was excised from South Australia
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South Africa
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South Africa, officially the Republic of South Africa, is the southernmost country in Africa. South Africa is the 25th-largest country in the world by land area and it is the southernmost country on the mainland of the Old World or the Eastern Hemisphere. About 80 percent of South Africans are of Sub-Saharan African ancestry, divided among a variety of ethnic groups speaking different Bantu languages, the remaining population consists of Africas largest communities of European, Asian, and multiracial ancestry. South Africa is a multiethnic society encompassing a variety of cultures, languages. Its pluralistic makeup is reflected in the recognition of 11 official languages. The country is one of the few in Africa never to have had a coup détat, however, the vast majority of black South Africans were not enfranchised until 1994. During the 20th century, the black majority sought to recover its rights from the dominant white minority, with this struggle playing a role in the countrys recent history. The National Party imposed apartheid in 1948, institutionalising previous racial segregation, since 1994, all ethnic and linguistic groups have held political representation in the countrys democracy, which comprises a parliamentary republic and nine provinces. South Africa is often referred to as the Rainbow Nation to describe the multicultural diversity. The World Bank classifies South Africa as an economy. Its economy is the second-largest in Africa, and the 34th-largest in the world, in terms of purchasing power parity, South Africa has the seventh-highest per capita income in Africa. However, poverty and inequality remain widespread, with about a quarter of the population unemployed, nevertheless, South Africa has been identified as a middle power in international affairs, and maintains significant regional influence. The name South Africa is derived from the geographic location at the southern tip of Africa. Upon formation the country was named the Union of South Africa in English, since 1961 the long form name in English has been the Republic of South Africa. In Dutch the country was named Republiek van Zuid-Afrika, replaced in 1983 by the Afrikaans Republiek van Suid-Afrika, since 1994 the Republic has had an official name in each of its 11 official languages. Mzansi, derived from the Xhosa noun umzantsi meaning south, is a name for South Africa. South Africa contains some of the oldest archaeological and human fossil sites in the world, extensive fossil remains have been recovered from a series of caves in Gauteng Province. The area is a UNESCO World Heritage site and has termed the Cradle of Humankind
19.
Ceratitis capitata
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Ceratitis capitata, the Mediterranean fruit fly, or medfly for short, is a species of fruit fly capable of causing extensive damage to a wide range of fruit crops. It is native to the Mediterranean area, but has spread invasively to many parts of the world, including Australasia, adult medflies lay their eggs under the skins of fruit, particularly where the skin is already broken. The eggs hatch within three days, and the larvae develop inside the fruit, maggots may stay from 5 to 10 days. Depending on temperature adult emergence may occur in as short as 7 days, the adults have a limited ability to disperse, but the global fruit trade can transport infected fruit over thousands of miles. Sex determination in C. capitata is by the familiar XY system, unusually for a dipteran and for a frugivore, medflies do not have an opsin gene for blue light perception as shown from the whole-genome sequencing project completed in September 2016. The Geographic Distribution Map of Ceratitis capitata and this updated map provides information on the distribution of the Mediterranean fruit fly, Ceratitis capitata, throughout the world. The information is based on available Mediterranean fruit fly national surveillance reports. Therefore, the map displays assessments of the presence of this pest at the national level, in the United States, C. capitata has invaded four states, but has been eradicated from all but Hawaii. Reintroduced populations of the medfly have been spotted in California as recently as mid September 2009, requiring additional eradication and it has also been eradicated from New Zealand and Chile. Much research has been dedicated to means of controlling the medfly, in particular, use of the sterile insect technique has allowed the species to be eradicated from several areas. In 1981, California Governor Jerry Brown, who had established a reputation as a strong environmentalist, was confronted with a serious medfly infestation in the San Francisco Bay Area. He was advised by the agricultural industry, and the US Department of Agricultures Animal and Plant Health Inspection service. Initially, in accordance with his environmental protection stance, he chose to authorize ground-level spraying only, unfortunately, the infestation spread as the medfly reproductive cycle out-paced the spraying. After more than a month, millions of dollars of crops had been destroyed, Governor Brown then authorized a massive response to the infestation. Fleets of helicopters sprayed malathion at night, and the California National Guard set up highway checkpoints, in the final stage of the campaign, entomologists released millions of sterile male medflies in an attempt to disrupt the insects reproductive cycle. Ultimately the infestation was eradicated, but both the Governors delay and the scale of the action has remained ever since. Some people claimed that malathion was toxic to humans, as well as insects, in response to such concerns, Browns chief of staff, B. T. Collins, staged a news conference during which he publicly drank a small glass of malathion. Many people complained that, while the malathion may not have been toxic to humans
20.
Ectotherm
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An ectotherm, is an organism in which internal physiological sources of heat are of relatively small or quite negligible importance in controlling body temperature. Such organisms rely on environmental heat sources, which permit them to operate at very economical metabolic rates, colloquially, some refer to these organisms as cold blooded though such a term is not technically correct, as the blood temperature of the organism varies with ambient environmental temperature. Some of these live in environments where temperatures are practically constant. In contrast to ectotherms, endotherms rely largely, even predominantly, in ectotherms, fluctuating ambient temperatures may affect the body temperature. Such variation in temperature is called poikilothermy, though the concept is not widely satisfactory. Ectotherms can also display the features of homeothermy, especially within aquatic organisms, various patterns of behavior enable certain ectotherms to regulate body temperature to a useful extent. To warm up, reptiles and many insects find sunny places and adopt positions that maximise their exposure, in cold weather, honey bees huddle together to retain heat. Butterflies and moths may orient their wings to maximize exposure to radiation in order to build up heat before take-off. Gregarious caterpillars, such as the Forest Tent caterpillar, benefit from basking in groups for thermoregulation. Many flying insects, such as bees and bumble bees, also raise their internal temperatures endothermally prior to flight. Such endothermal activity is an example of the difficulty of consistent application of such as poikilothermy and homiothermy. In addition to adaptations, physiological adaptations help ectotherms regulate temperature. The skin of bullfrogs secretes more mucus when it is hot, during periods of cold, some ectotherms enter a state of torpor, in which their metabolism slows or, in some cases, such as the wood frog, effectively stops. The torpor might last overnight or last for a season, or even for years, ectotherms rely largely on external heat sources such as sunlight to achieve their optimal body temperature for various bodily activities. Accordingly, they depend on ambient conditions to reach operational body temperatures, also, as a rule, ectotherms have lower metabolic rates than endotherms at a given body mass. As a consequence, endotherms generally rely on food consumption. Such requirements may limit the capacity of a given environment for endotherms as compared to its carrying capacity for ectotherms. Because ectotherms depend on conditions for body temperature regulation, as a rule, they are more sluggish at night
21.
Mushroom
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A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. These gills produce microscopic spores that help the fungus spread across the ground or its occupant surface, by extension, the term mushroom can also designate the entire fungus when in culture, the thallus of species forming the fruiting bodies called mushrooms, or the species itself. Identifying mushrooms requires an understanding of their macroscopic structure. Their spores, called basidiospores, are produced on the gills, at the microscopic level the basidiospores are shot off basidia and then fall between the gills in the dead air space. As a result, for most mushrooms, if the cap is cut off and placed gill-side-down overnight, the color of the powdery print, called a spore print, is used to help classify mushrooms and can help to identify them. Spore print colors include white, brown, black, purple-brown, pink, yellow, and creamy, but almost never blue, green, or red. The presence of juices upon breaking, bruising reactions, odors, tastes, shades of color, habitat, habit, tasting and smelling mushrooms carries its own hazards because of poisons and allergens. Chemical tests are used for some genera. In general, identification to genus can often be accomplished in the using a local mushroom guide. However, over-mature specimens lose features and cease producing spores, many novices have mistaken humid water marks on paper for white spore prints, or discolored paper from oozing liquids on lamella edges for colored spored prints. Typical mushrooms are the bodies of members of the order Agaricales, whose type genus is Agaricus and type species is the field mushroom. Other mushrooms are not gilled, so the mushroom is loosely used. Some have pores underneath, others have spines, such as the mushroom and other tooth fungi. Mushroom has been used for polypores, puffballs, jelly fungi, coral fungi, bracket fungi, stinkhorns, thus, the term is more one of common application to macroscopic fungal fruiting bodies than one having precise taxonomic meaning. Approximately 14,000 species of mushrooms are described, the terms mushroom and toadstool go back centuries and were never precisely defined, nor was there consensus on application. Between 1400 and 1600 AD, the terms mushrom, mushrum, muscheron, mousheroms, mussheron, the term mushroom and its variations may have been derived from the French word mousseron in reference to moss. However, delineation between edible and poisonous fungi is not clear-cut, so a mushroom may be edible, poisonous, cultural or social phobias of mushrooms and fungi may be related. The term fungophobia was coined by William Delisle Hay of England, the word toadstool has apparent analogies in Dutch paddestoel and German Krötenschwamm
22.
Slime flux
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Slime flux is a bacterial disease of certain trees, primarily elm, cottonwood, poplar, boxelder, ash, aspen, fruitless mulberry and oak. A wound to the bark, caused by pruning, insects, poor branch angles or natural cracks and splits, bacteria may infect this sap causing it to darken and stain the bark, eventually taking on a foamy appearance and unpleasant odor. This slimy ooze becomes toxic to the bark and eats into the tree, additionally, the fermented sap attracts insects like flies, ants, and maggots. There is no cure, but the bark of a tree is like skin, the wound should be disinfected with rubbing alcohol or a household bleach solution of one part bleach to nine parts water. The excess sap should be wiped from the tree to discourage hungry insects, with prompt and continuous treatment, the tree should survive. In the forest, practices that minimize wounding will reduce the spread of this disease, for urban trees, maintaining vigorous, healthy growing conditions and avoiding wounds will reduce the probability that trees will be affected by this disease. Removing bark from the area will reduce damage to an individual tree. Slime flux or more known as Wet wood is a seepage of the wood that is unseen by the human eye. The seepage is typically a sour smell that comes from the trunk of the tree, the slime flux disease causes a constant odor, Bleeding Cankers on the base of the tree. Slime flux will not kill a tree but is merely a sign that there has been an earlier injury, in some cases as the outer wound calluses over and the internal methane production decreases, the slime flux may stop in a year or two. In other cases slime flux may reoccur year after year
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Larva
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A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a phase of their life cycle. The larvas appearance is very different from the adult form. A larva often has unique structures and organs that do not occur in the adult form and their diet may also be considerably different. Larvae are frequently adapted to separate from adults. For example, some such as tadpoles live almost exclusively in aquatic environments. By living in an environment, larvae may be given shelter from predators. Animals in the stage will consume food to fuel their transition into the adult form. In some species like barnacles, adults are immobile but their larvae are mobile, some larvae are dependent on adults to feed them. In many eusocial Hymenoptera species, the larvae are fed by female workers, in Ropalidia marginata the males are also capable of feeding larvae but they are much less efficient, spending more time and getting less food to the larvae. The larvae of species can become pubescent and do not develop further into the adult form. This is a type of neoteny and it is a misunderstanding that the larval form always reflects the groups evolutionary history. This could be the case, but often the stage has evolved secondarily. In these cases the form may differ more than the adult form from the groups common origin. Within Insects, only Endopterygotes show different types of larvae, several classifications have been suggested by many entomologists, and following classification is based on Antonio Berlese classification in 1913. There are four types of endopterygote larvae types, Apodous larvae - no legs at all and are poorly sclerotized. Based on sclerotization, three forms are recognized. Eucephalous - with well sclerotized head capsule, found in Nematocera, Buprestidae and Cerambycidae families
24.
Ecdysis
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Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa. Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth, the remnants of the old, empty exoskeleton are called exuviae. After moulting, an arthropod is described as teneral, a callow, it is fresh, pale, within one or two hours, the cuticle hardens and darkens following a tanning process analogous to the production of leather. During this short phase the animal expands, since growth is constrained by the rigidity of the exoskeleton. Growth of the limbs and other parts normally covered by hard exoskeleton is achieved by transfer of fluids from soft parts before the new skin hardens. A spider with a small abdomen may be undernourished but more probably has recently undergone ecdysis, some arthropods, especially large insects with tracheal respiration, expand their new exoskeleton by swallowing or otherwise taking in air. Ecdysis allows damaged tissue and missing limbs to be regenerated or substantially re-formed, complete regeneration may require a series of moults, the stump becoming a little larger with each moult until it is a normal, or near normal, size. The term ecdysis comes from Ancient Greek, ἐκδύω, to take off, in preparation for ecdysis, the arthropod becomes inactive for a period of time, undergoing apolysis or separation of the old exoskeleton from the underlying epidermal cells. Once the old cuticle has separated from the epidermis, a fluid is secreted into the space between them. However, this fluid remains inactive until the part of the new cuticle has been formed. Then, by crawling movements, the organism pushes forward in the old integumentary shell, while the old cuticle is being digested, the new layer is secreted. All cuticular structures are shed at ecdysis, including the parts of the exoskeleton. Endopterygota tend to have four or five instars. Endopterygotes have more alternatives to moulting, such as expansion of the cuticle, the process of moulting in insects begins with the separation of the cuticle from the underlying epidermal cells and ends with the shedding of the old cuticle. In many species it is initiated by an increase in the hormone ecdysone, moulting fluid is then secreted into the exuvial space between the old cuticle and the epidermis, this contains inactive enzymes which are activated only after the new epicuticle is secreted. This prevents the new procuticle from getting digested as it is laid down, the lower regions of the old cuticle, the endocuticle and mesocuticle, are then digested by the enzymes and subsequently absorbed. The exocuticle and epicuticle resist digestion and are shed at ecdysis. Spiders generally change their skin for the first time while still inside the egg sac, the number of moults varies, both between species and genders, but generally will be between five times and nine times before the spider reaches maturity
25.
Microorganism
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A microorganism or microbe is a microscopic organism, which may be single-celled or multicellular. The study of microorganisms is called microbiology, a subject that began with the discovery of microorganisms in 1674 by Antonie van Leeuwenhoek, microorganisms are very diverse and include all bacteria, archaea and most protozoa. This group also contains some fungi, algae, and some such as rotifers. Many macroscopic animals and plants have microscopic juvenile stages, some microbiologists classify viruses and viroids as microorganisms, but others consider these as nonliving. In July 2016, scientists identified a set of 355 genes from the last universal ancestor of all life, including microorganisms. Microorganisms, under certain test conditions, have observed to thrive in the vacuum of outer space. Microorganisms likely far outweigh all other living things combined, the mass of prokaryote microorganisms including the bacteria and archaea may be as much as 0.8 trillion tons of carbon, out of the total biomass of between 1 and 4 trillion tons. Microorganisms appear to thrive in the Mariana Trench, the deepest spot in the Earths oceans, in August 2014, scientists confirmed the existence of microorganisms living 800 m below the ice of Antarctica. According to one researcher, You can find microbes everywhere — theyre extremely adaptable to conditions, microorganisms are crucial to nutrient recycling in ecosystems as they act as decomposers. As some microorganisms can fix nitrogen, they are a part of the nitrogen cycle. Microorganisms are also exploited in biotechnology, both in food and beverage preparation, and in modern technologies based on genetic engineering. A small proportion of microorganisms are pathogenic, causing disease and even death in plants, Robert Hooke coined the term cell after viewing plant cells under his microscope. Antonie Van Leeuwenhoek was one of the first people to observe microorganisms in 1673, later, in the 19th century, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In 1876 Robert Koch discovered that microorganisms cause diseases, single-celled microorganisms were the first forms of life to develop on Earth, approximately 3–4 billion years ago. Further evolution was slow, and for about 3 billion years in the Precambrian eon, so, for most of the history of life on Earth, the only forms of life were microorganisms. Bacteria, algae and fungi have been identified in amber that is 220 million years old, microorganisms tend to have a relatively fast rate of evolution. Most microorganisms can reproduce rapidly, and bacteria are able to freely exchange genes through conjugation, transformation and transduction. This rapid evolution is important in medicine, as it has led to the development of multidrug resistant pathogenic bacteria, superbugs, the possible existence of microorganisms was discussed for many centuries before their discovery in the 17th century
26.
Pupa
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A pupa is the life stage of some insects undergoing transformation. The pupal stage is only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages, embryo, larva, pupa. The pupae of different groups of insects have different names such as chrysalis for the pupae of butterflies, pupae may further be enclosed in other structures such as cocoons, nests or shells. In the life of an insect the pupal stage follows the larval stage and it is during the time of pupation that the adult structures of the insect are formed while the larval structures are broken down. The adult structures, imaginal discs, then grow to become the adult structures, pupae are inactive, and usually sessile. However, the pupae may be exarate or obtect and they have a hard protective coating and often use camouflage to evade potential predators. Pupation may last weeks, months or even years, for example, it is two weeks in monarch butterflies. The pupa may enter dormancy or diapause until the season for the adult insect. In temperate climates pupae usually stay dormant during winter, while in the tropics pupae usually do so during the dry season, anise swallowtails sometimes emerge after years as a chrysalis. Insects emerge from pupae by splitting the pupal case, and the process of pupation is controlled by the insects hormones. Most butterflies emerge in the morning, in mosquitoes the emergence is in the evening or night. In fleas the process is triggered by vibrations that indicate the presence of a suitable host. Prior to emergence, the adult inside the exoskeleton is termed pharate. Once the pharate adult has eclosed from the pupa, the empty pupal exoskeleton is called an exuvia, in most hymenopterans the exuvia is so thin, pupae are usually immobile and are largely defenseless. To overcome this, a feature is concealed placement. There are some species of Lycaenid butterflies who are protected in their pupal stage by ants, another means of defense by pupae of other species is the capability of making sounds or vibrations to scare potential predators. A few species use chemical defenses including toxic secretions, the pupae of social hymenopterans are protected by adult members of the hive. Examples are pupae of the orders Neuroptera, Mecoptera, Trichoptera, adecticous pupa - pupae without articulated mandibles
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Metamorphosis
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Metamorphosis is iodothyronine-induced and an ancestral feature of all chordates. Some insects, fishes, amphibians, mollusks, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis, animals that go through metamorphosis are called metamorphoses. Animals can be divided into species that undergo metamorphosis, incomplete metamorphosis. Scientific usage of the term is technically precise, and it is not applied to general aspects of cell growth, the word metamorphosis derives from Greek μεταμόρφωσις, transformation, transforming, from μετα-, change and μορφή, form. Metamorphosis is iodothyronine-induced and a feature of all chordates. In insects growth and metamorphosis are controlled by hormones synthesized by endocrine glands near the front of the body, neurosecretory cells in an insects brain secrete a hormone, the prothoracicotropic hormone that activates prothoracic glands, which secrete a second hormone, usually ecdysone, that induces ecdysis. PTTH also stimulates the corpora allata, an organ, to produce juvenile hormone. Experiments on firebugs have shown how juvenile hormone can affect the number of nymph instar stages in hemimetabolous insects, All three categories can be found in the diversity of insects, including no metamorphosis, incomplete or partial metamorphosis, and complete metamorphosis. In hemimetabolous insects, immature stages are called nymphs, development proceeds in repeated stages of growth and ecdysis, these stages are called instars. The juvenile forms closely resemble adults, but are smaller and lack features such as wings. The size and morphological differences between nymphs in different instars are small, often just differences in proportions and the number of segments, in later instars. In holometabolous insects, immature stages are called larvae, and differ markedly from adults, insects which undergo holometabolism pass through a larval stage, then enter an inactive state called pupa, and finally emerge as adults. The earliest insect forms showed direct development, and the evolution of metamorphosis in insects is thought to have fuelled their dramatic radiation, some early ametabolous true insects are still present today, such as bristletails and silverfish. Hemimetabolous insects include cockroaches, grasshoppers, dragonflies, and true bugs, phylogenetically, all insects in the Pterygota undergo a marked change in form, texture and physical appearance from immature stage to adult. According to research from 2008, adult Manduca sexta is able to retain behavior learned as a caterpillar, many observations have indicated that programmed cell death plays a considerable role during physiological processes of multicellular organisms, particularly during embryogenesis and metamorphosis. Sequence illustrating complete metamorphosis in the white butterfly, Pieris rapae In typical amphibian development, eggs are laid in water. Frogs, toads, and newts all hatch from the eggs as larvae with external gills, afterwards, newt larvae start a predatory lifestyle, while tadpoles mostly scrape food off surfaces with their horny tooth ridges. Metamorphosis in amphibians is regulated by thyroxin concentration in the blood, which stimulates metamorphosis, and prolactin, specific events are dependent on threshold values for different tissues
28.
Sperm
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Sperm is the male reproductive cell and is derived from the Greek word sperma. In the types of reproduction known as anisogamy and its subtype oogamy. A uniflagellar sperm cell that is motile is referred to as a spermatozoon, Sperm cells cannot divide and have a limited life span, but after fusion with egg cells during fertilization, a new organism begins developing, starting as a totipotent zygote. The human sperm cell is haploid, so that its 23 chromosomes can join the 23 chromosomes of the egg to form a diploid cell. In mammals, sperm develops in the testicles and is released from the penis, the mammalian sperm cell consists of a head, neck, a midpiece and a tail. The head contains the nucleus with densely coiled chromatin fibres, surrounded anteriorly by an acrosome, the neck contains the sperm centriole. The midpiece has a central core with many mitochondria spiralled around it, used for ATP production for the journey through the female cervix, uterus. The tail or flagellum executes the lashing movements that propel the spermatocyte, although semen contains millions of sperm, the egg will admit only one. The other ones will die and be absorbed. The spermatozoa of animals are produced through spermatogenesis inside the gonads via meiotic division. The initial spermatozoon process takes around 70 days to complete, the spermatid stage is where the sperm develops the familiar tail. The next stage where it becomes fully mature takes around 60 days when it is called a spermatozoan, Sperm cells are carried out of the male body in a fluid known as semen. Human sperm cells can survive within the reproductive tract for more than 5 days post coitus. Semen is produced in the vesicles, prostate gland and urethral glands. In 2016 scientists at Nanjing Medical University claimed they had produced cells resembling mouse spermatids artificially from stem cells and they injected these spermatids into mouse eggs and produced pups. Sperm quantity and quality are the parameters in semen quality. Thus, in humans, it is a measure of fertility in a man, the genetic quality of sperm, as well as its volume and motility, all typically decrease with age. Human sperm cells are vulnerable to free radical attack and the generation of oxidative DNA damage
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Female sperm storage
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Female sperm storage is an integral stage in the reproductive process for many animals with internal fertilization. Enabling mating, ovulation and/or fertilization to occur at different times or in different environments, supporting prolonged and sustained female fertility. Having a role influencing offspring sex ratios among some insects possessing a haplodiploid sex-determination system, one important advantage female insects that store sperm gain is increased genetic diversity in their offspring. There are many ways that females can alter offspring genetics to increase their success, an example of how this can be accomplished is in female Scathophaga that preferentially fertilize eggs to survive in different environments. Since many environments require different traits for success, females are able to match sperm that have the best genes for whichever environment in which they will develop. Many of the different properties of the environment, including temperature, studies have also shown that ovipositing is nonrandom and females lay eggs with varying PGM genotypes in different environments in order to optimize offspring success. Females are acutely aware to their environment and manipulate the genetic diversity of their offspring in appropriate ways to ensure their success, another way sperm-storing females can alter the diversity of their offspring is controlling the relatedness to the males that provide them with sperm. Inbreeding depression can have a impact on populations of organisms and is due to mating of closely related individuals. To combat this effect, female insects appear to be able to out the sperm of relatives from the sperm of non-relatives to choose the best option to fertilize their eggs. Female crickets are able to store sperm of multiple unrelated males to that of their siblings. Females possess remarkable abilities to select sperm to store and to fertilize their eggs that will make their offspring diverse. Though it has shown that a majority of female insect species can store sperm, specific examples that have been studied could include field crickets, dung flies. Females largely benefit from this mechanism, but males often can experience low fitness because their paternity is not secure, sperm stored often determines which male ends up fertilizing the most eggs. An example of this is seen in Red Flour Beetles, where most of the sperm is stored in the first mating, another male can remove previously stored sperm to better chances of successful mating. This has been compared to a race between sexes. In many cases, male mating behavior is detrimental to the females fitness, for example, when insects reproduce by means of traumatic insemination, it is very disadvantageous to the females health. During mating, males try to inseminate as many females as possible. However, the times a females abdomen is punctured, the less likely she is to survive
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Spermatheca
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The spermatheca, also called receptaculum seminis, is an organ of the female reproductive tract in insects, e. g. bees, some molluscs, oligochaeta worms and certain other invertebrates and vertebrates. Its purpose is to receive and store sperm from the male or, in the case of hermaphrodites, spermathecae can sometimes be the site of fertilization when the oocytes are sufficiently developed. Some species of animal have multiple spermathecae, for example, certain species of earthworms have four pairs of spermathecae—one pair each in the 6th, 7th, 8th, and 9th segments. The spermathecae receive and store the spermatozoa of another earthworm during copulation and they are lined with epithelium and are variable in shape, some are thin, heavily coiled tubes, while others are vague outpocketings from the main reproductive tract. It is one of the variations in sexual reproduction. The nematode Caenorhabditis elegans has two spermathecae, one at the end of each gonad, the C. elegans spermatheca is made up of 24 smooth muscle-like cells that form a stretchable tubular structure. Actin filaments line the spermatheca in a circumferential manner, the C. elegans spermatheca is used as a model to study mechanotransduction. An apiculturist may examine the spermatheca of a queen bee to find out whether it had received sperm from a male. The haplo-diploid system of sex determination makes it possible for the queen to choose the sex of the egg, reproductive system of gastropods Female sperm storage Cyphopods, sperm receptacles in female millipedes
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Fertilisation
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The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms the haploid male gamete combines with two polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation. In 1784, Spallanzani established the need of interaction between the females ovum and males sperm to form a zygote, oscar Hertwig, in Germany, described the fusion of nuclei of spermatozoa and of ova from sea urchin. In flowering plants there are two sperm from each pollen grain, in seed plants, after pollination, a pollen grain germinates, and a pollen tube grows and penetrates the ovule through a tiny pore called a micropyle. The sperm are transferred from the pollen through the pollen tube, bryophyte is a traditional name used to refer to all embryophytes that do not have true vascular tissue and are therefore called non-vascular plants. Some bryophytes do have specialised tissues for the transport of water, however, since these do not contain lignin, a fern is a member of a group of roughly 12,000 species of vascular plants that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular and they have stems and leaves, like other vascular plants. Most ferns have what are called fiddleheads that expand into fronds, the gymnosperms are a group of seed-producing plants that includes conifers, Cycads, Ginkgo, and Gnetales. The term gymnosperm comes from the Greek composite word γυμνόσπερμος, meaning naked seeds and their naked condition stands in contrast to the seeds and ovules of flowering plants, which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, often modified to form cones, the pollen tube does not directly reach the ovary in a straight line. It travels near the skin of the style and curls to the bottom of the ovary, then near the receptacle, it breaks through the ovule through the micropyle, after being fertilised, the ovary starts to swell and develop into the fruit. With multi-seeded fruits, multiple grains of pollen are necessary for syngamy with each ovule, the growth of the pollen tube is controlled by the vegetative cytoplasm. The sperms are interconnected and dimorphic, the one, in a number of plants, is also linked to the tube nucleus and the interconnected sperm. Double fertilisation is the process in angiosperms in which two sperm from each pollen tube fertilise two cells in a gametophyte that is inside an ovule. After the pollen tube enters the gametophyte, the tube nucleus disintegrates. This is the point when fertilisation actually occurs, pollination and fertilisation are two separate processes, the nucleus of the other sperm cell fuses with two haploid polar nuclei in the centre of the gametophyte. This triploid cell divides through mitosis and forms the endosperm, a nutrient-rich tissue, the two central-cell maternal nuclei that contribute to the endosperm arise by mitosis from the single meiotic product that also gave rise to the egg. Therefore, maternal contribution to the constitution of the triploid endosperm is double that of the embryo
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Peptide
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Peptides are biologically occurring short chains of amino acid monomers linked by peptide bonds. The covalent chemical bonds are formed when the group of one amino acid reacts with the amine group of another. The shortest peptides are dipeptides, consisting of 2 amino acids joined by a peptide bond, followed by tripeptides, tetrapeptides. A polypeptide is a long, continuous, and unbranched peptide chain, hence, peptides fall under the broad chemical classes of biological oligomers and polymers, alongside nucleic acids, oligosaccharides and polysaccharides, etc. Peptides are distinguished from proteins on the basis of size, all peptides except cyclic peptides have an N-terminal and C-terminal residue at the end of the peptide. Ribosomal peptides Ribosomal peptides are synthesized by translation of mRNA and they are often subjected to proteolysis to generate the mature form. These function, typically in higher organisms, as hormones and signaling molecules, some organisms produce peptides as antibiotics, such as microcins. Since they are translated, the amino acid residues involved are restricted to those utilized by the ribosome, however, these peptides frequently have posttranslational modifications such as phosphorylation, hydroxylation, sulfonation, palmitoylation, glycosylation and disulfide formation. In general, they are linear, although lariat structures have been observed, more exotic manipulations do occur, such as racemization of L-amino acids to D-amino acids in platypus venom. Nonribosomal peptides Nonribosomal peptides are assembled by enzymes that are specific to each peptide, the most common non-ribosomal peptide is glutathione, which is a component of the antioxidant defenses of most aerobic organisms. Other nonribosomal peptides are most common in organisms, plants. These complexes are often out in a similar fashion. These peptides are often cyclic and can have highly complex cyclic structures, since the system is closely related to the machinery for building fatty acids and polyketides, hybrid compounds are often found. The presence of oxazoles or thiazoles often indicates that the compound was synthesized in this fashion, Peptones See also Tryptone Peptones are derived from animal milk or meat digested by proteolysis. In addition to containing small peptides, the material includes fats, metals, salts, vitamins. Peptones are used in nutrient media for growing bacteria and fungi, Peptide fragments Peptide fragments refer to fragments of proteins that are used to identify or quantify the source protein. Peptides received prominence in molecular biology for several reasons, the first is that peptides allow the creation of peptide antibodies in animals without the need of purifying the protein of interest. This involves synthesizing antigenic peptides of sections of the protein of interest and these will then be used to make antibodies in a rabbit or mouse against the protein
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Gene
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A gene is a locus of DNA which is made up of nucleotides and is the molecular unit of heredity. The transmission of genes to an offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes, genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes as well as gene–environment interactions, genes can acquire mutations in their sequence, leading to different variants, known as alleles, in the population. These alleles encode slightly different versions of a protein, which cause different phenotypical traits, usage of the term having a gene typically refers to containing a different allele of the same, shared gene. Genes evolve due to natural selection or survival of the fittest of the alleles, the concept of a gene continues to be refined as new phenomena are discovered. For example, regulatory regions of a gene can be far removed from its coding regions, some viruses store their genome in RNA instead of DNA and some gene products are functional non-coding RNAs. The existence of discrete inheritable units was first suggested by Gregor Mendel, from 1857 to 1864, in Brno, he studied inheritance patterns in 8000 common edible pea plants, tracking distinct traits from parent to offspring. He described these mathematically as 2n combinations where n is the number of differing characteristics in the original peas, although he did not use the term gene, he explained his results in terms of discrete inherited units that give rise to observable physical characteristics. This description prefigured the distinction between genotype and phenotype, charles Darwin developed a theory of inheritance he termed pangenesis, from Greek pan and genesis / genos. Darwin used the term gemmule to describe hypothetical particles that would mix during reproduction, de Vries called these units pangenes, after Darwins 1868 pangenesis theory. In 1909 the Danish botanist Wilhelm Johannsen shortened the name to gene, advances in understanding genes and inheritance continued throughout the 20th century. Deoxyribonucleic acid was shown to be the repository of genetic information by experiments in the 1940s to 1950s. In the early 1950s the prevailing view was that the genes in a chromosome acted like discrete entities, indivisible by recombination, collectively, this body of research established the central dogma of molecular biology, which states that proteins are translated from RNA, which is transcribed from DNA. This dogma has since shown to have exceptions, such as reverse transcription in retroviruses. The modern study of genetics at the level of DNA is known as molecular genetics, in 1972, Walter Fiers and his team at the University of Ghent were the first to determine the sequence of a gene, the gene for Bacteriophage MS2 coat protein. The subsequent development of chain-termination DNA sequencing in 1977 by Frederick Sanger improved the efficiency of sequencing, an automated version of the Sanger method was used in early phases of the Human Genome Project. The theories developed in the 1930s and 1940s to integrate molecular genetics with Darwinian evolution are called the evolutionary synthesis
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Mutation
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In biology, a mutation is the permanent alteration of the nucleotide sequence of the genome of an organism, virus, or extrachromosomal DNA or other genetic elements. Mutations may also result from insertion or deletion of segments of DNA due to mobile genetic elements, mutations may or may not produce discernible changes in the observable characteristics of an organism. Mutations play a part in normal and abnormal biological processes including, evolution, cancer, and the development of the immune system. The genomes of RNA viruses are based on RNA rather than DNA, the RNA viral genome can be double stranded or single stranded. In some of these viruses replication occurs quickly and there are no mechanisms to check the genome for accuracy and this error-prone process often results in mutations. Mutation can result in different types of change in sequences. Mutations in genes can either have no effect, alter the product of a gene, mutations can also occur in nongenic regions. Mutations can involve the duplication of large sections of DNA, usually through genetic recombination and these duplications are a major source of raw material for evolving new genes, with tens to hundreds of genes duplicated in animal genomes every million years. Most genes belong to larger families of shared ancestry, known as homology. Here, protein domains act as modules, each with a particular and independent function, that can be mixed together to produce genes encoding new proteins with novel properties. For example, the eye uses four genes to make structures that sense light. Another advantage of duplicating a gene is that this increases engineering redundancy, other types of mutation occasionally create new genes from previously noncoding DNA. Changes in chromosome number may involve even larger mutations, where segments of the DNA within chromosomes break and then rearrange. For example, in the Homininae, two fused to produce human chromosome 2, this fusion did not occur in the lineage of the other apes. Sequences of DNA that can move about the genome, such as transposons, make up a fraction of the genetic material of plants and animals. For example, more than a million copies of the Alu sequence are present in the genome. Another effect of these mobile DNA sequences is that when they move within a genome, they can mutate or delete existing genes, nonlethal mutations accumulate within the gene pool and increase the amount of genetic variation. The abundance of some changes within the gene pool can be reduced by natural selection, while other more favorable mutations may accumulate
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Pheromone
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A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the individual to impact the behavior of the receiving individuals. There are alarm pheromones, food trail pheromones, sex pheromones, Pheromones are used from basic unicellular prokaryotes to complex multicellular eukaryotes. Their use among insects has been well documented. In addition, some vertebrates, plants and ciliates communicate by using pheromones, the portmanteau word pheromone was coined by Peter Karlson and Martin Lüscher in 1959, based on the Greek φερω pheroo and ὁρμων hormon. Pheromones are also classified as ecto-hormones. For this reason, bacteria are too small to use pheromones as sex attractants on an individual basis, however, they do use them to determine the local population density of similar organisms and control behaviors that take more time to execute. Aggregation pheromones function in mate selection, overcoming host resistance by mass attack, a group of individuals at one location is referred to as an aggregation, whether consisting of one sex or both sexes. Most sex pheromones are produced by the females, only a percentage of sex attractants are produced by males. Aggregation pheromones have been found in members of the Coleoptera, Diptera, Hemiptera, Dictyoptera, aggregation pheromones are among the most ecologically selective pest suppression methods. They are nontoxic and effective at low concentrations. Some species release a volatile substance when attacked by a predator that can trigger flight or aggression in members of the same species, for example, Vespula squamosa use alarm pheromones to alert others to a threat. In Polistes exclamans, alarm pheromones are used as an alert to incoming predators. Pheromones also exist in plants, Certain plants emit alarm pheromones when grazed upon and these tannins make the plants less appetizing for the herbivore. Epideictic pheromones are different from territory pheromones, when it comes to insects, releaser pheromones are pheromones that cause an alteration in the behavior of the recipient. For example, some organisms use powerful attractant molecules to attract mates from a distance of two miles or more, in general, this type of pheromone elicits a rapid response, but is quickly degraded. In contrast, a primer pheromone has an onset and a longer duration. For example, rabbit release mammary pheromones that trigger immediate nursing behavior by their babies, signal pheromones cause short-term changes, such as the neurotransmitter release that activates a response
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Courtship
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Courtship is the period in a couples relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. During courtship, a couple get to each other and decide if there will be an engagement or other such agreement. A courtship may be an informal and private matter between two people or may be an affair, or a formal arrangement with family approval. The average duration of courtship varies considerably throughout the world, furthermore, there is vast individual variation between couples. Courtship may be omitted, as in cases of some arranged marriages where the couple do not meet before the wedding. Regarding duration between proposal and wedding, the UK poll above gave an average of 2 years and 3 months, while the date is fairly casual in most European-influenced cultures, in some traditional societies, courtship is a highly structured activity, with very specific formal rules. In some societies, the parents or community propose potential partners, in Japan, there is a such type of courtship called Omiai, with similar practices called Xiangqin in the Greater China Area. Parents will hire a matchmaker to provide pictures and résumés of potential mates, the matchmaker and parents will often exert pressure on the couple to decide whether they want to marry or not after a few dates. Courtship in the Philippines is one known form of courtship. Unlike what is seen in other societies, it takes a far more subdued. It is complex in that it involves stages, and it is considered normal for courtship to last a year or longer and it is common to see the male showing off by sending love letters and love poems, singing romantic songs and buying gifts for the female. The parents are seen as part of the courtship practice, as their approval is commonly needed before courtship may begin. In more closed societies, courtship is virtually eliminated altogether by the practice of arranged marriages, in the earlier 1800s, young adults were expected to court with the intention of finding a marriage partner, rather than for social reasons. She further states that with courtship, commitment happens before intimacy, in America, in the 1820s, the phrase date was most closely associated with prostitution. However, by the Jazz Age of the 1920s, dating for fun was becoming a cultural expectation and this form of dating, though, was usually more chaste than is seen today, since premarital sex was not considered the norm. The concept of dating was initially seen as frustrating and mocked the moralistic values of traditional courtship. One of the reasons there was this disagreement was that they did not want their children growing up doing what many did during the revolution in the 60’s. The act of dating is seen to be temporary, with such acts seeming as if they are “on one day”
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Copulation
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Sexual intercourse, or coitus or copulation, is principally the insertion and thrusting of the penis, usually when erect, into the vagina for sexual pleasure, reproduction, or both. This is also known as vaginal intercourse or vaginal sex, other forms of penetrative sexual intercourse include anal sex, oral sex, fingering, and penetration by use of a dildo. These activities involve physical intimacy between two or more individuals and are used among humans solely for physical or emotional pleasure. A variety of views concern what constitutes sexual intercourse or other sexual activity and it is usually defined by sexual penetration, while non-penetrative sex acts, such as non-penetrative forms of cunnilingus or mutual masturbation, have been termed outercourse. Non-penetrative sex acts, however, may additionally be considered sexual intercourse, the term sex, often a shorthand for sexual intercourse, can mean any form of sexual activity. Religious beliefs also play a role in decisions about sexual intercourse or other sexual activity, such as decisions about virginity, or legal. Religious views on sexuality vary significantly between different religions and sects of the religion, though there are common themes, such as prohibition of adultery. For most non-human mammals, mating and copulation occur at the point of estrus, however, bonobos, dolphins and chimpanzees are known to engage in sexual intercourse regardless of whether or not the female is in estrus, and to engage in sex acts with same-sex partners. Sexual intercourse may be defined by different words, including coitus, copulation, coition and this is often termed vaginal intercourse or vaginal sex. The term vaginal sex, and less often vaginal intercourse, may refer to any vaginal sexual activity, particularly if penetrative. The World Health Organization states that non-English languages and cultures use different terms for sexual activity, various vulgar or slang words and euphemisms are also used to describe sexual intercourse or other sexual activity, such as the term fuck, shag, and the phrase sleep together. Penetration of the vagina by the penis is additionally known as intromission. Vaginal, anal and oral sex are recognized as sexual intercourse more often than other sexual behaviors, lesbians may define oral sex or fingering as sexual intercourse and subsequently an act of virginity loss, or tribadism as a primary form of sexual activity. Researchers commonly define sexual intercourse as penile–vaginal intercourse while using terms, such as anal sex or oral sex. Scholars Richard M. Lerner and Laurence Steinberg state that researchers also rarely disclose how they define sex or even whether they resolved potential discrepancies in definitions of sex. This focus can also relegate other forms of sexual activity to foreplay or contribute to them not being regarded as real sex. Studies regarding the definition of sexual intercourse sometimes conflict, a 1999 study by the Kinsey Institute examined the definition of sex based on a 1991 random sample of 599 college students from 29 U. S. The specificity of questions concerning sexual activity can additionally affect definitions of sexual intercourse or other sexual behaviors, another study by the Kinsey Institute sampled 484 people, ranging in ages 18–96
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Natural selection
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Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in heritable traits of a population over time, Charles Darwin popularised the term natural selection, and compared it with artificial selection. Variation exists within all populations of organisms and this occurs partly because random mutations arise in the genome of an individual organism, and offspring can inherit such mutations. Throughout the lives of the individuals, their genomes interact with their environments to cause variations in traits, the environment of a genome includes the molecular biology in the cell, other cells, other individuals, populations, species, as well as the abiotic environment. Individuals with certain variants of the trait may survive and reproduce more than individuals with other, less successful, variants, therefore, factors that affect reproductive success are also important, including sexual selection and fecundity selection. Over time, this process can result in populations that specialise for particular ecological niches, in other words, natural selection is a key process in the evolution of a population. Natural selection can be contrasted with artificial selection, in which humans intentionally choose specific traits, Natural selection is one of the cornerstones of modern biology. The concept of natural selection originally developed in the absence of a theory of heredity, at the time of Darwins writing. The union of traditional Darwinian evolution with subsequent discoveries in classical genetics formed the synthesis of the mid-20th century. The addition of molecular genetics has led to developmental biology. While genotypes can slowly change by random genetic drift, natural selection remains the primary explanation for adaptive evolution, empedocles idea that organisms arose entirely by the incidental workings of causes such as heat and cold was criticised by Aristotle in Book II of Physics. He posited natural teleology in its place, and believed that form was achieved for a purpose, nevertheless, he accepted in his biology that new types of animals, monstrosities, can occur in very rare instances. And in like manner as to the parts in which there appears to exist an adaptation to an end. Yet it is impossible that this should be the true view, for teeth and all other natural things either invariably or normally come about in a given way, but of not one of the results of chance or spontaneity is this true. We do not ascribe to chance or mere coincidence the frequency of rain in winter, but frequent rain in summer we do, nor heat in the dog-days, therefore action for an end is present in things which come to be and are by nature. The struggle for existence was later described by the Islamic writer Al-Jahiz in the 9th century, the classical arguments were reintroduced in the 18th century by Pierre Louis Maupertuis and others, including Darwins grandfather, Erasmus Darwin. Until the early 19th century, the view in Western societies was that differences between individuals of a species were uninteresting departures from their Platonic ideals of created kinds. However, the theory of uniformitarianism in geology promoted the idea that simple and this theory, Lamarckism, was an influence on the Soviet biologist Trofim Lysenkos antagonism to mainstream genetic theory as late as the mid 20th century
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Polygamy
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Polygamy involves marriage with more than one spouse. When a man is married to more than one wife at a time, when a woman is married to more than one husband at a time, it is called polyandry. If a marriage includes multiple husbands and wives, it can be called a group marriage, in contrast, monogamy is marriage consisting of only two parties. Like monogamy, the term polygamy is often used in a de facto sense, in sociobiology and zoology, researchers use polygamy in a broad sense to mean any form of multiple mating. Polygamy is widely accepted among different societies worldwide, according to the Ethnographic Atlas, of 1,231 societies noted,588 had frequent polygyny,453 had occasional polygyny,186 were monogamous and 4 had polyandry. Polygamy is also common among animals, such as the common fruit-fly. Polygyny is the practice wherein a man has more than one wife at the same time, the vast majority of polygamous marriages are polygynous. Polygyny is legally accepted in many Muslim majority countries and some countries with a sizeable Muslim minority, in some of the sparsely populated regions where shifting cultivation takes place in Africa, women do much of the work. This favours polygamous marriages in which men sought to monopolize the production of women who are valued both as workers and as child bearers, goody however, observes that the correlation is imperfect and varied. Senior wives can benefit as well when their work load is lightened by the addition of junior wives to the family. Wives, especially wives, status in the community can be increased by the addition of other wives. For such reasons, senior wives sometimes work hard or contribute from their own resources to enable their husbands to accumulate the bride price for a second wife, Polygyny may also result from the practice of levirate marriage. In such cases, the deceased mans heir may inherit his assets and wife, or, more usually and this provides support for the widow and her children and maintains the tie between the husband and wives kin groups. The sororate is like the levirate, in that a widower must marry the sister of his dead wife, the wifes family, in other words, must provide a replacement for her thus maintaining the ties between them. Both levirate and sororate may result in a man having multiple wives and this is a form of de facto polygyny that is referred to as concubinage. In many polygynous marriages the husbands wives may live in separate households often at a great distance and they can thus be described as a series of linked nuclear families with a father in common. Polyandry is the practice wherein a woman has more than one husband at the same time, polyandry is much less popular than polygyny and is illegal in virtually every state in the world. It occurs only in remote communities, polyandry is believed to be more likely in societies with scarce environmental resources, as it is believed to limit human population growth and enhance child survival
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