[Animals] Giraffe - Description - Information

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The giraffe is a large African hoofed mammal belonging to the genus Giraffa. It is the tallest living terrestrial animal and the largest ruminant on Earth. Traditionally, giraffes have been thought of as one species, Giraffa camelopardalis, with nine subspecies. Most recently, researchers proposed dividing them into up to eight extant species due to new research into their mitochondrial and nuclear DNA, and individual species can be distinguished by their fur coat patterns. Seven other extinct species of Giraffa are known from the fossil record. The giraffe's chief distinguishing characteristics are its extremely long neck and legs, its horn-like ossicones, and its spotted coat patterns. It is classified under the family Giraffidae, along with its closest extant relative, the okapi. Its scattered range extends from Chad in the north to South Africa in the south, and from Niger in the west to Somalia in the east. Giraffes usually inhabit savannahs and woodlands. Their food source is leaves, fruits, and flowers of woody plants, primarily acacia species, which they browse at heights most other herbivores cannot reach. Lions, leopards, spotted hyenas, and African wild dogs may prey upon giraffes. Giraffes live in herds of related females and their offspring or bachelor herds of unrelated adult males, but are gregarious and may gather in large aggregations. Males establish social hierarchies through "necking", combat bouts where the neck is used as a weapon. Dominant males gain mating access to females, which bear sole responsibility for rearing the young. The giraffe has intrigued various ancient and modern cultures for its peculiar appearance, and has often been featured in paintings, books, and cartoons. It is classified by the International Union for Conservation of Nature (IUCN) as vulnerable to extinction and has been extirpated from many parts of its former range. Giraffes are still found in numerous national parks and game reserves, but estimates as of 2016 indicate there are approximately 97,500 members of Giraffa in the wild. More than 1,600 were kept in zoos in 2010. Etymology The name "giraffe" has its earliest known origins in the Arabic word zarāfah (زرافة),[2] ultimately from Persian زُرنَاپَا‎ (zurnāpā), a compound of زُرنَا‎ (zurnā, "flute, zurna") and پَا‎ (pā, "leg").[3][4] In early Modern English the spellings jarraf and ziraph were used, probably directly from the Arabic,[5] and in Middle English jarraf and ziraph, gerfauntz. The Italian form giraffa arose in the 1590s. The modern English form developed around 1600 from the French girafe.[2] "Camelopard" /kəˈmɛləˌpɑːrd/ is an archaic English name for the giraffe; it derives from the Ancient Greek καμηλοπάρδαλις (kamēlopárdalis), from κάμηλος (kámēlos), "camel", and πάρδαλις (párdalis), "leopard", referring to its camel-like shape and leopard-like colouration.[6][7] Taxonomy Evolution The giraffe is one of only two living genera of the family Giraffidae in the order Artiodactyla, the other being the okapi.[8] They are ruminants of the clade Pecora, along with Antilocapridae (pronghorns),

Cervidae (deer), Bovidae (cattle, antelope, goats and sheep) and Moschidae (musk deer). A 2019 genome study (cladogram below) finds that Giraffidae are a sister taxon to Antilocapridae, with an estimated split of over 20 million years ago.[9] Ruminantia Tragulina Tragulidae Pecora Antilocapridae Giraffidae Cervidae Bovidae Moschidae The family Giraffidae was once much more extensive, with over 10 fossil genera described.[8] The elongation of the neck appears to have started early in the giraffe lineage. Comparisons between giraffes and their ancient relatives suggest vertebrae close to the skull lengthened earlier, followed by lengthening of vertebrae further down.[10] One early giraffid ancestor was Canthumeryx, which has been dated variously to have lived 25 to 20 million years ago, 17–15 mya or 18–14.3 mya and whose deposits have been found in Libya. This animal resembled an antelope and had a medium-sized, lightly built body. Giraffokeryx appeared 15–12 mya on the Indian subcontinent and resembled an okapi or a small giraffe, and had a longer neck and similar ossicones.[8] Giraffokeryx may have shared a clade with more massively built giraffids like Sivatherium and Bramatherium.[10] The extinct giraffid Samotherium (middle) in comparison with the okapi (below) and giraffe. The anatomy of Samotherium appears to have shown a transition to a giraffe-like neck.[11] Giraffids like Palaeotragus, Shansitherium and Samotherium appeared 14 mya and lived throughout Africa and Eurasia. These animals had broader skulls with reduced frontal cavities.[8][10] Paleotragus resembled the okapi and may have been its ancestor.[8] Others find that the okapi lineage diverged earlier, before Giraffokeryx.[10] Samotherium was a particularly important transitional fossil in the giraffe lineage, as the length and structure of its cervical vertebrae were between those of a modern giraffe and an okapi, and its neck posture was likely similar to the former's.[11] Bohlinia, which first appeared in southeastern Europe and lived 9–7 mya, was likely a direct ancestor of the giraffe. Bohlinia closely resembled modern giraffes, having a long neck and legs and similar ossicones and dentition.[8] Bohlinia colonised China and northern India and produced the Giraffa, which, around 7 million years ago, reached Africa. Climate changes led to the extinction of the Asian giraffes, while the African giraffes survived and radiated into new species. Living giraffes appear to have arisen around 1 million years ago in eastern Africa during the Pleistocene.[8] Some biologists suggest the modern giraffes descended from G. jumae;[12] others find G. gracilis a more likely candidate. G. jumae was larger and more robust, while G. gracilis was smaller and more slender.[8] The changes from extensive forests to more open habitats, which began 8 mya, are believed to be the main driver for the evolution of giraffes.[8] During this time, tropical plants disappeared and were replaced by arid C4 plants, and a dry savannah emerged across eastern and northern Africa and western India.[13][14] Some researchers have hypothesised that this new habitat, coupled with a different diet, including acacia species, may have exposed giraffe ancestors to toxins that caused higher mutation rates and a higher rate of evolution.[15] The coat patterns of modern giraffes may also have coincided with these habitat changes. Asian giraffes are hypothesised to have had more okapi-like colourations.[8] The giraffe genome is around 2.9 billion base pairs in length, compared to the 3.3 billion base pairs of the okapi. Of the proteins in giraffe and okapi genes, 19.4% are identical. The divergence of giraffe and okapi lineages dates to around 11.5 mya. A small group of regulatory genes in the giraffe appear to be responsible for the animal's height and associated circulatory adaptations.[16][17] Species and subspecies Approximate geographic ranges, fur patterns, and phylogenetic relationships between some giraffe subspecies Map showing "Approximate geographic ranges, fur patterns, and phylogenetic relationships between some giraffe subspecies based on mitochondrial DNA sequences. Colored dots on the map represent sampling localities. The phylogenetic tree is a maximum-likelihood phylogram based on samples from 266 giraffes. Asterisks along branches correspond to node values of more than 90% bootstrap support. Stars at branch tips identify paraphyletic haplotypes found in Maasai and reticulated giraffes".[18] The International Union for Conservation of Nature (IUCN) currently recognises only one species of giraffe with nine subspecies.[1] Carl Linnaeus originally classified living giraffes as one species in 1758. He gave it the binomial name Cervus camelopardalis. Mathurin Jacques Brisson coined the generic name Giraffa in 1762.[19] During the 1900s, various taxonomies with two or three species were proposed.[20] A 2007 study on the genetics of giraffes using mitochondrial DNA suggested at least six lineages could be recognised as species.[18] A 2011 study using detailed analyses of the morphology of giraffes, and application of the phylogenetic species concept, described eight species of living giraffes.[21] A 2016 study also concluded that living giraffes consist of multiple species. The researchers suggested the existence of four species, which have not exchanged genetic information between each other for 1 to 2 million years.[22] A 2020 study showed that depending on the method chosen, different taxonomic hypotheses recognizing from two to six species can be considered for the genus Giraffa. That study also found that multi-species coalescent methods can lead to taxonomic over-splitting, as those methods delimit geographic structures rather than species. The three-species hypothesis, which recognises G. camelopardalis, G. giraffa, and G. tippelskirchi, is highly supported by phylogenetic analyses and also corroborated by most po[CENSORED]tion genetic and multi-species coalescent analyses.[23] A 2021 whole genome sequencing study suggests the existence of four distinct species and seven subspecies.[24] A 2024 study found a higher amount of ancient gene flow than expected between po[CENSORED]tions.[25] The cladogram below shows the phylogenetic relationship between the four proposed species and seven subspecies based on a 2021 genome analysis.[24] Note the eight lineages correspond to eight of the traditional subspecies in the one species hypothesis. The Rothschild giraffe is subsumed into G. camelopardalis camelopardalis.

https://en.wikipedia.org/wiki/Giraffe