Antelope
The term antelope refers to numerous extant or recently extinct species of the ruminant artiodactyl family Bovidae that are indigenous to most of Africa, India, the Middle East, Central Asia, and a small area of Russia. Antelopes do not form a monophyletic group, as some antelopes are more closely related to other bovid groups, such as bovines, goats, and sheep, than to other antelopes.
A stricter grouping, known as the true antelopes, includes only the genera Gazella, Nanger, Eudorcas, and Antilope. One North American mammal, the pronghorn or "pronghorn antelope", is colloquially referred to as the "American antelope", despite the fact that it belongs to a completely different family than the true Old-World antelopes; pronghorn are the sole extant member of a lineage that once included many species which went extinct in the prehistoric period.
Although antelopes are sometimes misidentified as "deer", the groups are only distantly related. While antelopes are found in abundance in Africa, there is only one living African deer species: the Barbary stag of North Africa. By comparison, numerous deer species are found in regions of the world with few or no antelope species present, such as throughout Southeast Asia, Europe and all of the Americas. This is likely due to competition over shared resources, as deer and antelope fill a virtually identical ecological niche in their respective habitats. Countries like India, however, have large populations of endemic deer and antelope, with the different species generally keeping to their own "niches" with minimal overlap.
Unlike deer, in which males of most species sport bone antlers that are shed and regrown annually, antelope horns are bone encased in keratin and grow steadily, never falling off. If a horn is broken, it will either remain broken or take years to partially regenerate, depending on the species.
Etymology
The English word "antelope" first appeared in 1417 and is derived from the Old French antelop, itself derived from Medieval Latin antalopus, which in turn comes from the Byzantine Greek word ἀνθόλοψ, anthólops, first attested in Eustathius of Antioch, according to whom it was a fabulous animal "haunting the banks of the Euphrates, very savage, hard to catch and having long, saw-like horns capable of cutting down trees". It perhaps derives from Greek ἀνθος, anthos and ώψ, ops, perhaps meaning "beautiful eye" or alluding to the animals' long eyelashes. This, however, may be a folk etymology in Greek based on some earlier root. The word talopus and calopus, from Latin, came to be used in heraldry. In 1607, it was first used for living, cervine animals.Species
There are 91 antelope species, most of which are native to Africa, in about 30 genera. The classification of tribes or subfamilies within Bovoidea is still a matter of debate, with several alternative systems proposed.Antelope are not a cladistic or taxonomically defined group. The term is used to describe all members of the family Bovidae that do not fall under the category of sheep, cattle, or goats. Usually, all species of the Antilopinae, Hippotraginae, Reduncinae, Cephalophinae, many Bovinae, the grey rhebok, and the impala are called antelope.
Distribution and habitat
More species of antelope are native to Africa than to any other continent, almost exclusively in savannahs, with 25-40 species co-occurring over much of East Africa. Because savannah habitat in Africa has expanded and contracted five times over the last three million years, and the fossil record indicates this is when most extant species evolved, it is believed that isolation in refugia during contractions was a major driver of this diversification. Other species occur in Asia: the Arabian Peninsula is home to the Arabian oryx and Dorcas gazelle. South Asia is home to the nilgai, chinkara, blackbuck, Tibetan antelope, and four-horned antelope, while Russia and Central Asia have the Tibetan antelope and saiga.File:Blue Duiker skeleton.jpg|thumb|Blue duiker '' skeleton on display at the Museum of Osteology
No antelope species is native to Australasia or Antarctica, nor do any extant species occur in the Americas, though the nominate saiga subspecies occurred in North America during the Pleistocene. North America is currently home to the native pronghorn, which taxonomists do not consider a member of the antelope group, but which is often locally referred to as such. In Europe, several extinct species occur in the fossil record, and the saiga was found widely during the Pleistocene but did not persist into the later Holocene, except in Russian Kalmykia and Astrakhan Oblast.
Many species of antelope have been imported to other parts of the world, especially the United States, for exotic game hunting. With some species possessing spectacular leaping and evasive skills, individuals may escape. Texas in particular has many game ranches, as well as habitats and climates that are very hospitable to African and Asian plains antelope species. Accordingly, wild populations of blackbuck antelope, gemsbok, and nilgai may be found in Texas.
Antelope live in a wide range of habitats. Most live in the African savannahs. However, many species are more secluded, such as the forest antelope, as well as the extreme cold-living saiga, the desert-adapted Arabian oryx, the rocky koppie-living klipspringer, and semiaquatic sitatunga.
Species living in forests, woodland, or bush tend to be sedentary, but many of the plains species undertake long migrations. These enable grass-eating species to follow the rains and thereby their food supply. The gnus and gazelles of East Africa perform some of the most impressive mass migratory circuits of all mammals.
Morphology
Body and covering
Antelope vary greatly in size. For example, a male common eland can measure at the shoulder and weigh almost, whereas an adult royal antelope may stand only at the shoulder and weigh a mere.Antelope have a wide variety of coverings, though most have a dense coat of short fur. In most species, the coat is some variation of a brown colour, often with white or pale underbodies. Exceptions include the zebra-marked zebra duiker, the grey, black, and white Jentink's duiker, and the black lechwe. Most of the "spiral-horned" antelope have pale, vertical stripes on their backs. Many desert and semidesert species are particularly pale, some almost silvery or whitish ; the beisa and southern oryxes have gray and black pelages with vivid black-and-white faces. Common features of various gazelles are white rumps, which flash a warning to others when they run from danger, and dark stripes midbody. The springbok also has a pouch of white, brushlike hairs running along its back, which opens up when the animal senses danger, causing the dorsal hairs to stand on end.
Many antelope are sexually dimorphic. In most species, both sexes have horns, but those of males tend to be larger. Males tend to be larger than the females, but exceptions in which the females tend to be heavier than the males include the bush duiker, dwarf antelope, Cape grysbok, and oribi, all rather small species. A number of species have hornless females. In some species, the males and females have differently coloured pelages.
Many wild antelopes are characterized by high running and jumping abilities. Their main defence against predators is to try to escape.
Species such as black wildebeest, springbok, blesbok, mountain reedbuck, greater kudu as well the European fallow deer have high concentrations of glycolitic fast twitch type IIx muscle fibers; smaller species naturally have higher concentrations of type IIx fibers than larger species. Although their concentration of type IIx fibers is still lower than that of the wild cheetah, other running-adapted mammal; wild cheetah vastus lateralis muscle have a concentration of 76% of type IIx fibers, compared to 58% of springbok, 57% of mountain reedbuck, 55% of blesbok, 48% of European fallow deer, 43% of greater kudu and 30% black wildebeest. The concentration of type IIx muscle fibers in human vastus lateralis muscle is 7%.
The activity of the anaerobic enzyme LDH, an indicator of a principally anaerobic muscle metabolism, is around 4 times more higher than that of humans, a level of activity comparable to that of the lion, but lower than that of the wild caracal and especially that of the wild cheetah; LDH activity is 6 times higher than that of the humans in caracal and 9 times higher in the wild cheetah.
Activity of aerobic enzymes CS and 3HAD is higher than that of the felids in general and is comparable to that of human endurance runners. This indicates muscles capable of both high speed and high endurance.
Impala muscles, on the other hand, have a high concentrations of oxidative-glycolitic fast twitch type IIa muscle fibers.
Both impala and reindeer have a CS level activity comparable to that of the human endurance runners and their muscle metabolism appears to be principally aerobic, indicating muscles capable of high endurance.
In the impala, hindlimbs muscles form 17.5% of their body mass while forelimbs muscles form 11.3%. Compared to the reindeer in which hind and forelimb muscles form 14.8% and 10.9% of their body mass, respectively.
Antelopes tend to have very long limbs for their body masses; a 60 kg Peter's gazelle have a shoulder height of 90 cm, whereas a cheetah and a leopard of the same body mass have a shoulder height of 79 cm and 64 cm, respectively. Pronghorns and Old World antelopes have greater elongation and weight reduction in the distal parts of their limbs, than the cheetah, the fastest land animal, indicating that longer limbs with more elongated and lighter distal parts are not as necessary for reaching the highest speeds for short periods of time, but are more necessary for maintaining higher speeds for longer periods of time.
A maximum running speed of 63.7 km/h for the impala and 54 km/h for the blue wildebeest has been estimated by GPS-IMU collars. A top speed of 65.2 km/h is obtained by calculating the distance and time it takes a Thomson's gazelle to escape from an approaching human. Film analysis of lion hunts gives maximum speeds of 90–97 km/h for the Thomson's gazelle. By speedometer reading when an animal runs alongside a car on a straight course, a maximum speed of up to 70 km/h has been estimated for the eland and the topi, and up to 80 km/h for the hartebeest, blue wildebeest, Grant's gazelle and Thomson's gazelle. Pronghorns are capable of running as fast as Old World antelopes, reaching speeds of 80 km/h commonly, and 97 km/h in favourable conditions such as running on flat dry lake beds. The speeds of the pronghorn were determined by reading the speedometer when the animals ran parallel to a moving vehicle.
Red forest duikers can jump cleanly over fences 1.6 m high, an impressive feat considering their shoulder height of 30 cm. Impalas can jump highs of 2.4 m. Common elands can jump cleanly over 2.7 m fences.
Female Thomson's gazelles have been reported to be faster and more agile than males. This is in line with the fact that female springboks, another antilopine, have higher concentrations of type IIx fibres and thus probably a higher amount of muscle glycogen than males. Meanwhile, the concentration of muscle glycogen in cheetahs is very similar between males and females.