Evolution is change in the heritable characteristics of biological populations over successive generations. Evolutionary processes give rise to biodiversity at every level of organisation, including the levels of species, individual organisms. In July 2016, scientists reported identifying a set of 355 genes from the LUCA of all living on Earth. The fossil record includes a progression from early biogenic graphite, to microbial mat fossils, existing patterns of biodiversity have been shaped both by speciation and by extinction. More than 99 percent of all species that lived on Earth are estimated to be extinct. Estimates of Earths current species range from 10 to 14 million, more recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described. In the mid-19th century, Charles Darwin formulated the theory of evolution by natural selection. This teleonomy is the quality whereby the process of natural selection creates and preserves traits that are fitted for the functional roles they perform.
The processes by which the changes occur, from one generation to another, are called evolutionary processes or mechanisms, the four most widely recognized evolutionary processes are natural selection, genetic drift and gene migration. Natural selection and genetic drift sort variation and gene migration create variation, consequences of selection can include meiotic drive, nonrandom mating and genetic hitchhiking. In the early 20th century the modern evolutionary synthesis integrated classical genetics with Darwins theory of evolution by natural selection through the discipline of population genetics, the importance of natural selection as a cause of evolution was accepted into other branches of biology. Moreover, previously held notions about evolution, such as orthogenesis, evolutionary computation, a sub-field of artificial intelligence, involves the application of Darwinian principles to problems in computer science. The proposal that one type of organism could descend from another type goes back to some of the first pre-Socratic Greek philosophers, such as Anaximander, such proposals survived into Roman times.
The poet and philosopher Lucretius followed Empedocles in his masterwork De rerum natura, in contrast to these materialistic views, Aristotelianism considered all natural things as actualisations of fixed natural possibilities, known as forms. This was part of a teleological understanding of nature in which all things have an intended role to play in a divine cosmic order. In the 17th century, the new method of modern science rejected the Aristotelian approach, this new approach was slow to take root in the biological sciences, the last bastion of the concept of fixed natural types. The biological classification introduced by Carl Linnaeus in 1735 explicitly recognized the nature of species relationships. Other naturalists of this time speculated on the change of species over time according to natural laws
Genomics is an interdisciplinary field of science focusing on genomes. A genome is a set of DNA within a single cell of an organism, and as such genomics is a branch of molecular biology concerned with the structure, evolution. Genomics aims at the collective characterization and quantification of genes, which direct the production of proteins with the assistance of enzymes, proteins in turn make up body structures like organs and tissues as well as control chemical reactions and carry signals between cells. If a cells DNA is mutated, a protein may be produced. Advances in genomics have triggered a revolution in discovery-based research to understand even the most complex systems such as the brain. The field includes efforts to determine the entire DNA sequence of organisms, the field includes studies of intragenomic phenomena such as heterosis, epistasis and other interactions between loci and alleles within the genome. From the Greek ΓΕΝ gen, gene meaning become, creation, following Rosalind Franklins confirmation of the helical structure of DNA, James D.
In 1964, Robert W. Holley and colleagues published the first nucleic acid sequence ever determined, extending this work, Marshall Nirenberg and Philip Leder revealed the triplet nature of the genetic code and were able to determine the sequences of 54 out of 64 codons in their experiments. In 1972, Walter Fiers and his team at the Laboratory of Molecular Biology of the University of Ghent were the first to determine the sequence of a gene, the gene for Bacteriophage MS2 coat protein. Fiers group expanded on their MS2 coat protein work, determining the complete nucleotide-sequence of bacteriophage MS2-RNA and Simian virus 40 in 1976 and 1978, in 1975, he and Alan Coulson published a sequencing procedure using DNA polymerase with radiolabelled nucleotides that he called the Plus and Minus technique. This involved two closely related methods that generated short oligonucleotides with defined 3 termini and these could be fractionated by electrophoresis on a polyacrylamide gel and visualised using autoradiography.
The procedure could sequence up to 80 nucleotides in one go and was a big improvement, nevertheless, in 1977 his group was able to sequence most of the 5,386 nucleotides of the single-stranded bacteriophage φX174, completing the first fully sequenced DNA-based genome. For their groundbreaking work in the sequencing of nucleic acids, the advent of these technologies resulted in a rapid intensification in the scope and speed of completion of genome sequencing projects. The first complete genome sequence of an organelle, the human mitochondrion, was reported in 1981. In 1992, the first eukaryotic chromosome, chromosome III of brewers yeast Saccharomyces cerevisiae was sequenced, the first free-living organism to be sequenced was that of Haemophilus influenzae in 1995. As of October 2011, the sequences are available for,2,719 viruses,1,115 archaea and bacteria. Of the other sequenced species, most were chosen because they were well-studied model organisms or promised to become good models, yeast has long been an important model organism for the eukaryotic cell, while the fruit fly Drosophila melanogaster has been a very important tool.
The worm Caenorhabditis elegans is an often used model for multicellular organisms
Emil Hans Willi Hennig was a German biologist who is considered the founder of phylogenetic systematics, known as cladistics. In 1945 as a prisoner of war, Hennig began work on his theory of cladistics, with his works on evolution and systematics he revolutionised the view of the natural order of beings. As a taxonomist, he specialised in dipterans, Hennig was born in Dürrhennersdorf, Upper Lusatia. His mother Marie Emma, née Groß, worked as a maid and, and his father Karl Ernst Emil Hennig was a rail worker. Willi had two brothers, Fritz Rudolf Hennig, who became a minister, and Karl Herbert, who went missing at Stalingrad in 1943, in the spring of 1919, Willi Hennig started school in Dürrhennersdorf, and subsequently was at school in Taubenheim an der Spree and Oppach. Rudolf Hennig described the family as calm, his father possessed an even temperament, as of 1927, Willi Hennig continued his education at the Realgymnasium and boarding school in Klotzsche near Dresden. Here he met his first mentor M.
Rost, a science teacher, Rost had an interest in insects and introduced Hennig to Wilhelm Meise, who worked as a scientist at the Dresdener Museum für Tierkunde. In 1930, Hennig skipped a year, and graduated on February 26,1932, as early as 1931, Willi Hennig composed an essay entitled Die Stellung der Systematik in der Zoologie as part of his school work, published posthumously in 1978. It showed his interest as well as his treatment of systematic problems. From the summer semester of 1932 onwards, Hennig read zoology, botany and he would continue to visit the Museum in Dresden. There, he met the curator of the collection, the Dipteran expert Fritz Isidor van Emden. Hennig saw him regularly until van Emden was expelled from National Socialist Germany for having a Jewish mother, Hennig developed a deep friendship with Emdens successor, Klaus Günther. Hennig concluded his studies with a dissertation entitled, Beiträge zur Kenntnis des Kopulationsapparates der cyclorrhaphen Dipteren, by this time, Hennig had published eight scientific papers.
Besides his 300-page revision of the Tylidae, there were papers on Diptera. After his studies, Hennig was Volontär at the State Museum for Zoology in Dresden, on January 1,1937, he obtained a scholarship from the Deutsche Forschungsgemeinschaft to work at the German Entomological Institute of the Kaiser-Wilhelm-Gesellschaft in Berlin-Dahlem. On May 13,1939, Hennig married his fellow student Irma Wehnert. By 1945, they had three sons, Wolfgang and Gerd, Willi Hennig was drafted in 1938 to train for the infantry and concluded this course in 1939. As of the start of World War II, he was deployed in the infantry in Poland, France and Russia
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 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 and cytology.
He further excludes phylogenetic reconstruction from alpha taxonomy, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is 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
Horizontal gene transfer
Horizontal gene transfer or lateral gene transfer is the movement of genetic material between unicellular and/or multicellular organisms other than by the transmission of DNA from parent to offspring. HGT is an important factor in the evolution of many organisms and it often involves temperate bacteriophages and plasmids. Most thinking in genetics has focused upon vertical transfer, but horizontal gene transfer is important, artificial horizontal gene transfer is a form of genetic engineering. Inter-bacterial gene transfer was first described in Japan in a 1959 publication that demonstrated the transfer of resistance between different species of bacteria. In the mid-1980s, Syvanen predicted that lateral gene transfer existed, had biological significance, as Jian and Lake put it, studies of genes and genomes are indicating that considerable horizontal transfer has occurred between prokaryotes. The phenomenon appears to have had significance for unicellular eukaryotes as well. As Bapteste et al. observe, additional evidence suggests that gene transfer might be an important evolutionary mechanism in protist evolution, there is some evidence that even higher plants and animals have been affected and this has raised concerns for safety.
Grafting of one plant to another can transfer chloroplasts, mitochondrial DNA, some Lepidoptera have been genetically modified by horizontal gene transfer from the wasp bracovirus. Bites from the insect Reduviidae can, via a parasite, infect humans with the trypanosomal Chagas disease and it has been suggested that lateral gene transfer to humans from bacteria may play a role in cancer. Richardson and Palmer state, Horizontal gene transfer has played a role in bacterial evolution and is fairly common in certain unicellular eukaryotes. However, the prevalence and importance of HGT in the evolution of multicellular eukaryotes remain unclear, some have argued that the process may be a hidden hazard of genetic engineering as it could allow transgenic DNA to spread from species to species. There are several mechanisms for horizontal gene transfer, the alteration of a cell resulting from the introduction, uptake. This process is common in bacteria, but less so in eukaryotes. Transformation is often used in laboratories to insert genes into bacteria for experiments or for industrial or medical applications.
See molecular biology and biotechnology, the process in which bacterial DNA is moved from one bacterium to another by a virus. Bacterial conjugation, a process involves the transfer of DNA via a plasmid from a donor cell to a recombinant recipient cell during cell-to-cell contact. Gene transfer agents, virus-like elements encoded by the host that are found in the alphaproteobacteria order Rhodobacterales. A transposon is a segment of DNA that can sometimes pick up a resistance gene and insert it into a plasmid or chromosome
Nucleic acid sequence
A nucleic acid sequence is a succession of letters that indicate the order of nucleotides within a DNA or RNA molecule. By convention, sequences are presented from the 5 end to the 3 end. For DNA, the strand is used. Because nucleic acids are linear polymers, specifying the sequence is equivalent to defining the covalent structure of the entire molecule. For this reason, the nucleic acid sequence is termed the primary structure, the sequence has capacity to represent information. Biological deoxyribonucleic acid represents the information which directs the functions of a living thing, nucleic acids have a secondary structure and tertiary structure. Primary structure is sometimes referred to as primary sequence. Conversely, there is no concept of secondary or tertiary sequence. Nucleic acids consist of a chain of linked units called nucleotides, each nucleotide consists of three subunits, a phosphate group and a sugar make up the backbone of the nucleic acid strand, and attached to the sugar is one of a set of nucleobases.
The nucleobases are important in base pairing of strands to form secondary and tertiary structure such as the famed double helix. The possible letters are A, C, G, and T, in the typical case, the sequences are printed abutting one another without gaps, as in the sequence AAAGTCTGAC, read left to right in the 5 to 3 direction. With regards to transcription, a sequence is on the strand if it has the same order as the transcribed RNA. One sequence can be complementary to sequence, meaning that they have the base on each position in the complementary. For example, the sequence to TTAC is GTAA. If one strand of the double-stranded DNA is considered the sense strand, the other strand, considered the antisense strand, will have the complementary sequence to the sense strand. Apart from adenine, guanine and uracil, in DNA, the most common modified base is 5-methylcytidine. In RNA, there are many modified bases, including pseudouridine, inosine, ribothymidine and 7-methylguanosine and xanthine are two of the many bases created through mutagen presence, both of them through deamination.
Hypoxanthine is produced from adenine, xanthine from guanine, deamination of cytosine results in uracil
A songbird is a bird belonging to the clade Passeri of the perching birds. Another name that is seen as a scientific or vernacular name is Oscines, from Latin oscen. This group contains some 4,000 species found all over the world, in which the vocal organ typically is developed in such a way as to produce a diverse and elaborate bird song. Songbirds form one of the two lineages of extant perching birds, the other being the Tyranni which are most diverse in the Neotropics. These have a simpler syrinx musculature, and while their vocalizations are often just as complex and striking as those of songbirds, there is a third perching bird lineage, the Acanthisitti from New Zealand, of which only two species remain alive today. The song in this clade is essentially territorial in that it communicates the identity and whereabouts of an individual to other birds, sexual selection among songbirds is highly based on mimetic vocalization. Female preference has shown in some populations to be based on the extent of a males song repertoire, the larger a males repertoire, the more females a male individual attracts.
It is not to be confused with bird calls which are used for alarms, while almost all living birds give calls of some sort, well-developed songs are only given by a few lineages outside the songbirds. Other birds sometimes have songs to attract mates or hold territory, the monotonous repetition of the common cuckoo or little crake can be contrasted with the variety of a nightingale or marsh warbler. On the other hand, although many songbirds have songs which are pleasant to the human ear, many members of the crow family communicate with croaks or screeches which sound harsh to humans. Even these, have a song of sorts, a softer twitter which is given between courting partners, sexual selection can be broken down into several different studies regarding different aspects of a bird’s song. As a result, song can vary even within a single species, many believe that song repertoire and cognition have a direct relationship. However, a study published in 2013 has shown that all cognitive ability may not be related to the song repertoire of a songbird.
Specifically, spatial learning is said to have a relationship with song repertoire. So for example, this would be an individual who does not migrate as far as others in the species and this suggests an evolutionary trade-off between possible alleles. With natural selection choosing traits best fit for reproductive success there could be a trade off in either direction depending on which trait would produce a higher fitness at that time period, Song repertoire can be attributed to male songbirds as it is one of the main mechanisms of courtship. Song repertoires differ from individual to male individual and species to species. Some species may typically have large repertoires while others may have smaller ones
Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups, the cladistic term for the same phenomenon is homoplasy. The recurrent evolution of flight is an example, as flying insects, birds. Functionally similar features that have arisen through convergent evolution are analogous, whereas homologous structures or traits have a common origin, bird and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different traits, convergent evolution is similar to but different from parallel evolution. Many instances of convergent evolution are known in plants, including the development of C4 photosynthesis, seed dispersal by fleshy fruits adapted to be eaten by animals.
In morphology, analogous traits arise when different species live in similar ways and/or a similar environment, when occupying similar ecological niches similar problems can lead to similar solutions. The British anatomist Richard Owen was the first to identify the difference between analogies and homologies. In biochemistry and chemical constraints on mechanisms have caused some active site arrangements such as the triad to evolve independently in separate enzyme superfamilies. In his 1989 book Wonderful Life, Stephen Jay Gould argued that if one could rewind the tape of life the same conditions were encountered again, evolution could take a very different course. In cladistics, a homoplasy is a trait shared by two or more taxa for any other than that they share a common ancestry. Taxa which do share ancestry are part of the same clade, homoplastic traits caused by convergence are therefore, from the point of view of cladistics, confounding factors which could lead to an incorrect analysis.
In some cases, it is difficult to tell whether a trait has been lost and re-evolved convergently, or whether a gene has simply been switched off, such a re-emerged trait is called an atavism. From a mathematical standpoint, a gene has a steadily decreasing probability of retaining potential functionality over time. When two species are similar in a character, evolution is defined as parallel if the ancestors were similar. When the ancestral forms are unspecified or unknown, or the range of traits considered is not clearly specified, the enzymology of proteases provides some of the clearest examples of convergent evolution. These examples reflect the intrinsic chemical constraints on enzymes, leading evolution to converge on equivalent solutions independently and repeatedly and cysteine proteases use different amino acid functional groups as a nucleophile. In order to activate that nucleophile, they orient an acidic, the chemical and physical constraints on enzyme catalysis have caused identical triad arrangements to evolve independently more than 20 times in different enzyme superfamilies
Field research or fieldwork is the collection of information outside a laboratory, library or workplace setting. The approaches and methods used in field research vary across disciplines, although the method generally is characterized as qualitative research, it may include quantitative dimensions. Field research has a long history, cultural anthropologists have long used field research to study other cultures. In Fields that is, circumscribed areas of study which have been the subject of social research, Fields could be education, industrial settings, or Amazonian rain forests. Field research may be conducted by zoologists such as Jane Goodall, radcliff-Brown and Malinowski were early cultural anthropologists who set the models for future work. Business use of Field research is a form of anthropology and is as likely to be advised by sociologists or statisticians in the case of surveys. Consumer marketing field research is the marketing technique used by businesses to research their target market.
The quality of results obtained from field research depends on the data gathered in the field. The data in turn, depend upon the worker, his or her level of involvement. The more open researchers are to new ideas and things which they may not have seen in their own culture, the better will be the absorption of those ideas. Better grasping of such material means better understanding of the forces of culture operating in the area, Social scientists have always been taught to be free from ethnocentrism, when conducting any type of field research. Participant observation, data collection, and survey research are examples of research methods. When conducting field research, keeping a record is essential to the process. Field notes are a key part of the ethnographic record, the process of field notes begin as the researcher participates in local scenes and experiences in order to make observations that will be written up. The field researcher tries first to take notes of certain details in order that they be written down later.
Field Note Chart The first writing that is done typically consists of jotted or condensed notes, key words or phrases are written down while the researcher is in or very close to the field. Some researchers jot field notes openly in the presence of those being studied, adopting this practice early on enables some researchers to find that they can establish a note-taker role that will be accepted or at least tolerated by those being studied. However, some find that people develop expectations of what should be recorded and what should not
Passerida is, under the Sibley-Ahlquist taxonomy, one of two parvorders contained within the suborder Passeri. While more recent research suggests that its sister parvorder, Corvida, is not a monophyletic grouping, the Passerida quite certainly consist of the 3 major subclades outlined by Sibley & Ahlquist. However, their content has been much revised, in addition, it has turned out that not all passeridan lineages neatly fit into this arrangement. The kinglets are so distinct that they might form a separate infraorder. See Jønsson & Fjeldså for details on phylogeny, Mostly insectivores, distribution centered on the Indo-Pacific region. Alaudidae, larks Hirundinidae and martins Phylloscopidae, leaf-warblers, long-tailed tits Cettiidae, ground-warblers and allies. Pycnonotidae, bulbuls Cisticolidae and allies Sylviidae, true/sylviid warblers, sylvioidea incertae sedis African warblers, A proposed clade, but monophyly needs confirmation. Tentatively placed here, possibly closest to Megaluridae, tentatively placed here, formerly in Pycnonotidae.
Tentatively placed here, formerly in Paradoxornithidae, Mostly insectivores, near-global distribution centered on Old World tropics. One family is endemic to the Americas, dippers Muscicapidae, Old World flycatchers and chats. Sturnidae and possibly Philippine creepers, placement of latter in Muscicapoidea seems good, but inclusion in Sturnidae requires confirmation, possibly distinct family Rhabdornithidae. Mimidae and thrashers Mostly herbivores, near-global distribution centered on Palearctic, true sparrows Prunellidae, accentors Motacillidae and pipits Urocynchramidae, Przewalskis finch. Recently split from Fringillidae, tentatively placed here, certain members of Ploceidae, such as the long-tailed widowbird are well known for their elaborate sexual ornaments. Viduidae and whydahs Nine-primaried oscines Peucedramidae, olive warbler Fringillidae, family invalid or not monotypic, reallocation pending. Rather basal Passerida, most of which seem to constitute several small, most occur in Asia and North America.
Possible superfamily Paroidea – titmice and allies Paridae, tits and titmice Remizidae, a newly assembled family, sometimes included in Paridae. Possible superfamily Sittoidea or Certhioidea – wrens and allies, tentatively placed here, might belong into Certhidae. Troglodytidae, wrens Polioptilidae, gnatcatchers Possible monotypic superfamily N. N, sugarbirds Possible monotypic superfamily N. N
Linnaean taxonomy can mean either of two related concepts, the particular form of biological classification set up by Carl Linnaeus, as set forth in his Systema Naturae and subsequent works. In the taxonomy of Linnaeus there are three kingdoms, divided into classes, and they, in turn, into orders, genera, a term for rank-based classification of organisms, in general. That is, taxonomy in the sense of the word. This term is used as opposed to cladistic systematics, which groups organisms into clades. It is attributed to Linnaeus, although he neither invented the concept of ranked classification nor gave it its present form, in his Imperium Naturae, Linnaeus established three kingdoms, namely Regnum Animale, Regnum Vegetabile and Regnum Lapideum. This approach, the Animal and Mineral Kingdoms, survives today in the mind, notably in the form of the parlour game question, Is it animal. The work of Linnaeus had a impact on science, it was indispensable as a foundation for biological nomenclature.
However, the impact he had on science was not because of the value of his taxonomy and his classes and orders of plants, according to his Systema Sexuale, were never intended to represent natural groups but only for use in identification. They were used for that purpose well into the nineteenth century, within each class were several orders. The Linnaean classes for plants, in the Sexual System, monandria, flowers with 1 stamen Classis 2. Diandria, flowers with 2 stamens Classis 3, flowers with 3 stamens Classis 4. Tetrandria, flowers with 4 stamens Classis 5, flowers with 5 stamens Classis 6. Hexandria, flowers with 6 stamens Hexandria monogynia pp. 285–352 Hexandria polygynia pp. 342–343 Classis 7, flowers with 7 stamens Classis 8. Octandria, flowers with 8 stamens Classis 9, flowers with 9 stamens Classis 10. Decandria, flowers with 10 stamens Classis 11, flowers with 12 stamens Classis 12. Icosandria, flowers with 20 stamens, perigynous Classis 13, flowers with many stamens, inserted on the receptacle Classis 14.
Didynamia, flowers with 4 stamens,2 long and 2 short Classis 15, flowers with 6 stamens,4 long and 2 short Classis 16. Monadelphia, flowers with the separate, but the filaments united
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty, the goal of science is to form taxa to biological taxa whose affinity is known. Form taxa are groupings that are based on common overall forms, early attempts at classification of labyrinthodonts was based on skull shape. The amount of convergent evolution in the groups lead to a number of polyphyletic taxa. Such groups are united by a mode of life, often one that is generalist. Ediacaran biota — whether they are the precursors of the Cambrian explosion of the fossil record, other examples include the seabirds and the Graculavidae. A parataxon, or sciotaxon, is a based on incomplete data, for instance. It reflects a paucity of data that makes biological classification impossible, a term morphotaxa allows for differences in preservational state. These three terms have been replaced as of 2011 by provisions for fossil-taxa that are similar to the provisions for other types of plants.
Names given to organ genera could only be applied to the organs in question, fossil-taxon names can cover several parts of an organism, or several preservational states, but do not compete for priority with any names for the same organism that are based on a non-fossil type. Well-known form taxa of this kind include ducks, fish and worms