Snag (ecology)
In forest ecology, a snag refers to a standing, dead or dying tree missing a top or most of the smaller branches. In freshwater ecology it refers to trees and other pieces of occurring wood found sunken in rivers and streams; when used in manufacturing in Scandinavia, they are called "dead wood" and in Finland "kelo wood". Snags are an important structural component in forest communities, making up 10–20% of all trees present in old-growth tropical and boreal forests. Snags and downed coarse woody debris represent a large portion of the woody biomass in a healthy forest. In temperate forests, snags provide critical habitat for more than 100 species of bird and mammal, snags are called'wildlife trees' by foresters. Dead, decaying wood supports a rich community of decomposers like bacteria and fungi and other invertebrates; these organisms and their consumers, along with the structural complexity of cavities and broken tops make snags important habitat for birds and small mammals, which in turn feed larger mammalian predators.
Snags are optimal habitat for primary cavity nesters such as woodpeckers which create the majority of cavities used by secondary cavity users in forest ecosystems. Woodpeckers excavate cavities for more than 80 other species and the health of their populations relies on snags. Most snag-dependent birds and mammals are insectivorous and represent a major portion of the insectivorous forest fauna, are important factors in controlling forest insect populations. There are many instances in which birds reduced outbreak populations of forest insects, such as woodpeckers affecting outbreaks of southern hardwood borers and Engelmann spruce beetles. Snag creation occurs as trees die due to old age, drought, or wildfire. A snag undergoes a series of changes from the time the tree dies until final collapse, each stage in the decay process has particular value to certain wildlife species. Snag persistence depends on two factors, the size of the stem, the durability of the wood of the species concerned; the snags of some large conifers, such as Giant Sequoia and Coast Redwood on the Pacific Coast of North America, the Alerce of Patagonia, can remain intact for 100 years or more, becoming progressively shorter with age, while other snags with decaying wood, such as aspen and birch, break up and collapse in 2–10 years.
Snag Forests, or Complex Early Seral Forests, are ecosystems that occupy forested sites after a stand-replacement disturbance and before re-establishment of a closed-forest canopy. They are generated by natural disturbances such as wildfire or insect outbreaks that reset ecological succession processes and follow a pathway, influenced by biological legacies that were not removed during the initial disturbance. Water hunting birds like the osprey or kingfishers can be found near water, perched in a snag tree, or feeding upon their fish catch. In freshwater ecology in Australia and the United States, the term snag is used to refer to the trees and other pieces of occurring wood found in a sunken form in rivers and streams; such snags have been identified as being critical for shelter and as spawning sites for fish, are one of the few hard substrates available for biofilm growth supporting aquatic invertebrates in lowland rivers flowing through alluvial flood plains. Snags are important as sites for biofilm growth and for shelter and feeding of aquatic invertebrates in both lowland and upland rivers and streams.
In Australia, the role of freshwater snags has been ignored until and more than one million snags have been removed from the Murray-Darling basin. Large tracts of the lowland reaches of the Murray-Darling system are now devoid of the snags that native fish like Murray cod require for shelter and breeding; the damage such wholesale snag removal has caused is enormous but difficult to quantify, however some quantification attempts have been made.. Most snags in these systems are river red gum snags; as the dense wood of river red gum is impervious to rot it is thought that some of the river red gum snags removed in past decades may have been several thousand years old. Known as deadheads submerged snags posed hazards to early riverboat navigation and commerce. If hit, snags punctured the wooden hulls used in early 20th century. Snags were, in fact, the most encountered hazard in the early years of steamboat travel. In the United States, the U. S. Army Corps of Engineers operated "snagboats" such as the W. T.
Preston in the Puget Sound of Washington State and the Montgomery in the rivers of Alabama to pull out and clear snags. Starting in 1824, there were successful efforts to remove snags from the Mississippi and its tributaries. By 1835, a lieutenant reported to the Chief of Engineers that steamboat travel had become much safer, but by the mid-1840s the appropriations for snag removal dried up and snags re-accumulated until after the Civil War. In Scandinavia and Finland snags, invariably pine trees, known in Finnish as kelo and in Swedish as torraka, are collected for the production of different objects, from furniture to entire log houses. Commercial enterprises market them abroad as "dead wood" or in Finland as "kelo wood", they have been prized for their silver-grey weathered surface in the manufacture of vernacular or national romantic products. The suppliers of "dead wood" emphasise its age: the wood has developed with dehydration in the dry coldness of the subarctic zones, the tree having stopped growing after some 300–400 years, a
William John Swainson
William John Swainson FLS, FRS, was an English ornithologist, conchologist and artist. Swainson was born in Dover Place, St Mary Newington, the eldest son of John Timothy Swainson the Second, an original fellow of the Linnean Society, he was cousin of the amateur botanist Isaac Swainson. His father's family originated in Lancashire, both grandfather and father held high posts in Her Majesty's Customs, the father becoming Collector at Liverpool. William, whose formal education was curtailed because of an impediment in his speech, joined the Liverpool Customs as a junior clerk at the age of 14, he joined the Army Commissariat and toured Malta and Sicily He studied the ichthyology of western Sicily and in 1815, was forced by ill health to return to England where he subsequently retired on half pay. William followed in his father's footsteps to become a fellow of the Linnean Society in 1815. In 1806 he accompanied the English explorer Henry Koster to Brazil. Koster had become famous for his book Travels in Brazil.
There he met Dr Grigori Ivanovitch Langsdorff an explorer of Brazil, Russian Consul General. They did not spend a long time on shore because of a revolution, but Swainson returned to England in 1818 in his words "a bee loaded with honey", with a collection of over 20,000 insects, 1,200 species of plants, drawings of 120 species of fish, about 760 bird skins; as with many Victorian scientists, Swainson was a member of many learned societies, including the Wernerian Society of Edinburgh. He was elected a fellow of the Royal Society after his return from Brazil on 14 December 1820, married his first wife Mary Parkes in 1823, with whom he had four sons and a daughter, his wife Mary died in 1835. Swainson remarried in 1840 to Ann Grasby, emigrated to New Zealand in 1841, their daughter, Edith Stanway Swainson, married Arthur Halcombe in 1863. Swainson was involved in property management and natural history-related publications from 1841 to 1855, forestry-related investigations in Tasmania, New South Wales, Victoria from 1851 to 1853.
Swainson died at Fern Grove, Lower Hutt, New Zealand, on 6 December 1855. Swainson was at times quite critical of the works of others and in life, others in turn became quite critical of him. Apart from the common and scientific names of many species, it is for the quality of his illustrations that he is best remembered, his friend William Elford Leach, head of zoology at the British Museum, encouraged him to experiment with lithography for his book Zoological Illustrations. Swainson became the first illustrator and naturalist to use lithography, a cheap means of reproduction and did not require an engraver, he began publishing many illustrated works serially. Subscribers received and paid for fascicles, small sections of the books, as they came out, so that the cash flow was constant and could be reinvested in the preparation of subsequent parts; as book orders arrived, the monochrome lithographs were hand-coloured, according to colour reference images, known as ‘pattern plates’, which were produced by Swainson himself.
It was his early adoption of this new technology and his natural skill of illustration that in large part led to his fame. When in March 1822 Leach was forced to resign from the British Museum due to ill health, Swainson applied to replace him, but the post was given to John George Children. Soon after his first marriage in 1823, Swainson visited Paris and formed friendships with Georges Cuvier, Étienne Geoffroy Saint-Hilaire, other eminent French naturalists. Upon his return to London, he was employed by Messrs. Longman as editor for the natural history departments of Lardner's Cabinet Cyclopedia. Swainson continued with his writing, the most influential of, the second volume of Fauna Boreali-Americana, which he wrote with John Richardson; this series was the first illustrated zoological study to be funded in part by the British government. He produced a second series of Zoological Illustrations, three volumes of William Jardine's Naturalist's Library, eleven volumes of Lardner's Cabinet Cyclopedia.
In 1819 William Sharp Macleay had published his ideas of the Quinarian system of biological classification, Swainson soon became a noted and outspoken proponent. The Quinarian System fell out of favour, giving way to the rising popularity of the geographical theory of Hugh Edwin Strickland. Swainson was overworked by Dionysius Lardner, the publisher of the Cabinet Cyclopaedia and both Swainson and Macleay were derided for their support of the Quinarian system. Both proponents left Britain. An American visiting Australasia in the 1850s heard to his surprise that both Macleay and Swainson were living there, imagined that they had been exiled to the Antipodes'for the great crime of burdening zoology with a false though much laboured theory which has thrown so much confusion into the subject of its classification and philosophical study'. In 1839 he became a member of the committee of the New Zealand Company and of the Church of England committee for the appointment of a bishop to New Zealand, bought land in Wellington, gave up scientific literary work.
He married his second wife, Anne Grasby, in 1840. He was the first Fellow of the Royal Society to move to New Zealand, he was made an honorary Fellow of the Royal Society of Tasmania. Together with most of his chi
Animal
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
Arizona
Arizona is a state in the southwestern region of the United States. It is part of the Western and the Mountain states, it is the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona shares the Four Corners region with Utah and New Mexico. Arizona is the 48th state and last of the contiguous states to be admitted to the Union, achieving statehood on February 14, 1912, coinciding with Valentine's Day. Part of the territory of Alta California in New Spain, it became part of independent Mexico in 1821. After being defeated in the Mexican–American War, Mexico ceded much of this territory to the United States in 1848; the southernmost portion of the state was acquired in 1853 through the Gadsden Purchase. Southern Arizona is known for its desert climate, with hot summers and mild winters. Northern Arizona features forests of pine, Douglas fir, spruce trees. There are ski resorts in the areas of Flagstaff and Tucson. In addition to the Grand Canyon National Park, there are several national forests, national parks, national monuments.
About one-quarter of the state is made up of Indian reservations that serve as the home of 27 federally recognized Native American tribes, including the Navajo Nation, the largest in the state and the United States, with more than 300,000 citizens. Although federal law gave all Native Americans the right to vote in 1924, Arizona excluded those living on reservations in the state from voting until the state Supreme Court ruled in favor of Native American plaintiffs in Trujillo v. Garley; the state's name appears to originate from an earlier Spanish name, derived from the O'odham name alĭ ṣonak, meaning "small spring", which applied only to an area near the silver mining camp of Planchas de Plata, Sonora. To the European settlers, their pronunciation sounded like "Arissona"; the area is still known as alĭ ṣonak in the O'odham language. Another possible origin is the Basque phrase haritz ona, as there were numerous Basque sheepherders in the area. A native Mexican of Basque heritage established the ranchería of Arizona between 1734 and 1736 in the current Mexican state of Sonora, which became notable after a significant discovery of silver there, c.
1737. There is a misconception. For thousands of years before the modern era, Arizona was home to numerous Native American tribes. Hohokam and Ancestral Puebloan cultures were among the many that flourished throughout the state. Many of their pueblos, cliffside dwellings, rock paintings and other prehistoric treasures have survived, attracting thousands of tourists each year; the first European contact by native peoples was with Marcos de Niza, a Spanish Franciscan, in 1539. He explored parts of the present state and made contact with native inhabitants the Sobaipuri; the expedition of Spanish explorer Coronado entered the area in 1540–1542 during its search for Cíbola. Few Spanish settlers migrated to Arizona. One of the first settlers in Arizona was José Romo de Vivar. Father Kino was the next European in the region. A member of the Society of Jesus, he led the development of a chain of missions in the region, he converted many of the Indians to Christianity in the Pimería Alta in the 1690s and early 18th century.
Spain founded presidios at Tubac in 1752 and Tucson in 1775. When Mexico achieved its independence from the Kingdom of Spain and its Spanish Empire in 1821, what is now Arizona became part of its Territory of Nueva California known as Alta California. Descendants of ethnic Spanish and mestizo settlers from the colonial years still lived in the area at the time of the arrival of European-American migrants from the United States. During the Mexican–American War, the U. S. Army occupied the national capital of Mexico City and pursued its claim to much of northern Mexico, including what became Arizona Territory in 1863 and the State of Arizona in 1912; the Treaty of Guadalupe Hidalgo specified that, in addition to language and cultural rights of the existing inhabitants of former Mexican citizens being considered as inviolable, the sum of US$15 million dollars in compensation be paid to the Republic of Mexico. In 1853, the U. S. acquired the land south below the Gila River from Mexico in the Gadsden Purchase along the southern border area as encompassing the best future southern route for a transcontinental railway.
What is now known as the state of Arizona was administered by the United States government as part of the Territory of New Mexico until the southern part of that region seceded from the Union to form the Territory of Arizona. This newly established territory was formally organized by the Confederate States government on Saturday, January 18, 1862, when President Jefferson Davis approved and signed An Act to Organize the Territory of Arizona, marking the first official use of the name "Territory of Arizona"; the Southern territory supplied the Confederate government with men and equipment. Formed in 1862, Arizona scout companies served with the Confederate States Army duri
Binomial nomenclature
Binomial nomenclature called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomen, binominal name or a scientific name; the first part of the name – the generic name – identifies the genus to which the species belongs, while the second part – the specific name or specific epithet – identifies the species within the genus. For example, humans belong within this genus to the species Homo sapiens. Tyrannosaurus rex is the most known binomial; the formal introduction of this system of naming species is credited to Carl Linnaeus beginning with his work Species Plantarum in 1753. 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; the application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature for animals and the International Code of Nomenclature for algae and plants.
Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in the terminology they use and in their precise rules. In modern usage, the first letter of the first part of the name, the genus, is always capitalized in writing, while that of the second part is not when derived from a proper noun such as the name of a person or place. 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 binomial name is given, at least when it is first mentioned, the date of publication may be specified. In zoology "Patella vulgata Linnaeus, 1758"; the name "Linnaeus" tells the reader who it was that first published a description and name for this species of limpet. "Passer domesticus". The original name given by Linnaeus was Fringilla domestica; 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, although nomenclatorial catalogs include such information.
In botany "Amaranthus retroflexus L." – "L." is the standard abbreviation used in botany for "Linnaeus". "Hyacinthoides italica Rothm. – Linnaeus first named this bluebell species Scilla italica. The name is composed of two word-forming elements: "bi", a Latin prefix for two, "-nomial", relating to a term or terms; the word "binomium" was used in Medieval Latin to mean a two-term expression in mathematics. Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name, from one to several words long. Together they formed a system of polynomial nomenclature; these names had two separate functions. First, to designate or label the species, second, to be a diagnosis or description. In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; such "polynomial names" may sometimes look like binomials, but are different. For example, Gerard's herbal describes various kinds of spiderwort: "The first is called Phalangium ramosum, Branched Spiderwort.
The other... 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, more known by his Latinized name Carl Linnaeus, 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 specific name; the Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word. Linnaeus's trivial names introduced an important new idea, namely that the function of a name could be to give a species a unique label; this meant. Thus Gerard's Phalangium ephemerum virginianum became Tradescantia virgi
Sap
Sap is a fluid transported in xylem cells or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is distinct from resin, or cell sap. Saps may be broadly divided into two types: xylem sap and phloem sap. Xylem sap consists of a watery solution of hormones, mineral elements and other nutrients. Transport of sap in xylem is characterized by movement from the roots toward the leaves. Over the past century, there has been some controversy regarding the mechanism of xylem sap transport. Xylem sap transport can be disrupted by cavitation—an "abrupt phase change from liquid to vapor"—resulting in air-filled xylem conduits. In addition to being a fundamental physical limit on tree height, two environmental stresses can disrupt xylem transport by cavitation: "increasingly negative xylem pressures associated with water stress, freeze-thaw cycles in temperate climates. Phloem sap consists of sugars and mineral elements dissolved in water, it flows from where carbohydrates are stored to where they are used.
The pressure flow hypothesis proposes a mechanism for phloem sap transport. Although other hypotheses have been proposed. Phloem sap is thought to play a role in sending informational signals throughout vascular plants. "Loading and unloading patterns are determined by the conductivity and number of plasmodesmata and the position-dependent function of solute-specific, plasma membrane transport proteins. Recent evidence indicates that mobile proteins and RNA are part of the plant's long-distance communication signaling system. Evidence exists for the directed transport and sorting of macromolecules as they pass through plasmodesmata." A large number of insects of the order Hemiptera, feed directly on phloem sap, make it the primary component of their diet. Phloem sap is "nutrient-rich compared with many other plant products and lacking in toxins and feeding deterrents, it is consumed as the dominant or sole diet by a restricted range of animals"; this apparent paradox is explained by the fact that phloem sap is physiologically extreme in terms of animal digestion, it is hypothesized that few animals take direct advantage of this because they lack two adaptations that are necessary to enable direct use by animals.
These include the existence of a high ratio of non-essential/essential amino acids in phloem sap for which these adapted Hemiptera insects contain symbiotic microorganisms which can provide them with essential amino acids. A much larger set of animals do however consume phloem sap by proxy, either "through feeding on the honeydew of phloem-feeding hemipterans. Honeydew is physiologically less extreme than phloem sap, with a higher essential:non-essential amino acid ratio and lower osmotic pressure," or by feeding on the biomass of insects that have grown on more direct ingestion of phloem sap. Maple syrup is made from reduced sugar maple xylem sap; the sap is harvested from the Sugar Maple, Acer saccharum. In some countries harvesting the early spring sap of birch trees for human consumption is common practice. Certain palm tree sap can be used to make palm syrup. In the Canary Islands they use the Canary Island Date Palm while in Chile they use the Chilean Wine Palm to make their syrup called miel de palma.
Latex Resin
Mexico
Mexico the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States. Covering 2,000,000 square kilometres, the nation is the fifth largest country in the Americas by total area and the 13th largest independent state in the world. With an estimated population of over 120 million people, the country is the eleventh most populous state and the most populous Spanish-speaking state in the world, while being the second most populous nation in Latin America after Brazil. Mexico is a federation comprising 31 states and Mexico City, a special federal entity, the capital city and its most populous city. Other metropolises in the state include Guadalajara, Puebla, Tijuana and León. Pre-Columbian Mexico dates to about 8000 BC and is identified as one of five cradles of civilization and was home to many advanced Mesoamerican civilizations such as the Olmec, Teotihuacan, Zapotec and Aztec before first contact with Europeans. In 1521, the Spanish Empire conquered and colonized the territory from its politically powerful base in Mexico-Tenochtitlan, administered as the viceroyalty of New Spain.
Three centuries the territory became a nation state following its recognition in 1821 after the Mexican War of Independence. The post-independence period was tumultuous, characterized by economic inequality and many contrasting political changes; the Mexican–American War led to a territorial cession of the extant northern territories to the United States. The Pastry War, the Franco-Mexican War, a civil war, two empires, the Porfiriato occurred in the 19th century; the Porfiriato was ended by the start of the Mexican Revolution in 1910, which culminated with the promulgation of the 1917 Constitution and the emergence of the country's current political system as a federal, democratic republic. Mexico has the 11th largest by purchasing power parity; the Mexican economy is linked to those of its 1994 North American Free Trade Agreement partners the United States. In 1994, Mexico became the first Latin American member of the Organisation for Economic Co-operation and Development, it is classified as an upper-middle income country by the World Bank and a newly industrialized country by several analysts.
The country is considered both a regional power and a middle power, is identified as an emerging global power. Due to its rich culture and history, Mexico ranks first in the Americas and seventh in the world for number of UNESCO World Heritage Sites. Mexico is an ecologically megadiverse country, ranking fourth in the world for its biodiversity. Mexico receives a huge number of tourists every year: in 2018, it was the sixth most-visited country in the world, with 39 million international arrivals. Mexico is a member of the United Nations, the World Trade Organization, the G8+5, the G20, the Uniting for Consensus group of the UN, the Pacific Alliance trade bloc. Mēxihco is the Nahuatl term for the heartland of the Aztec Empire, namely the Valley of Mexico and surrounding territories, with its people being known as the Mexica, it is believed to be a toponym for the valley which became the primary ethnonym for the Aztec Triple Alliance as a result, although it could have been the other way around.
In the colonial era, back when Mexico was called New Spain this territory became the Intendency of Mexico and after New Spain achieved independence from the Spanish Empire it came to be known as the State of Mexico with the new country being named after its capital: the City of Mexico, which itself was founded in 1524 on top of the ancient Mexica capital of Mexico-Tenochtitlan. Traditionally, the name Tenochtitlan was thought to come from Nahuatl tetl and nōchtli and is thought to mean "Among the prickly pears rocks". However, one attestation in the late 16th-century manuscript known as "the Bancroft dialogues" suggests the second vowel was short, so that the true etymology remains uncertain; the suffix -co is the Nahuatl locative, making the word a place name. Beyond that, the etymology is uncertain, it has been suggested that it is derived from Mextli or Mēxihtli, a secret name for the god of war and patron of the Mexica, Huitzilopochtli, in which case Mēxihco means "place where Huitzilopochtli lives".
Another hypothesis suggests that Mēxihco derives from a portmanteau of the Nahuatl words for "moon" and navel. This meaning might refer to Tenochtitlan's position in the middle of Lake Texcoco; the system of interconnected lakes, of which Texcoco formed the center, had the form of a rabbit, which the Mesoamericans pareidolically associated with the moon rabbit. Still another hypothesis suggests that the word is derived from Mēctli, the name of the goddess of maguey; the name of the city-state was transliterated to Spanish as México with the phonetic value of the letter x in Medieval Spanish, which represented the voiceless postalveolar fricative. This sound, as well as the voiced postalveolar fricative, represented by a j, evolved into a voiceless velar fricative during the 16th century; this led to the use of the variant Méjico in many publications in Spanish, most notably in Spain, whereas in Mexico and most other Spanish–speaking countries, México was the preferred spelling. In recent years, the Real Academia Española, which regulates the Spanish l
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