Re: Mac Os X 10.5 Tiger Download
Jhuls Morgan
The tiger (Panthera tigris) is the largest living cat species and a member of the genus Panthera. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on ungulates, such as deer and wild boar. It is territorial and generally a solitary but social predator, requiring large contiguous areas of habitat to support its requirements for prey and rearing of its offspring. Tiger cubs stay with their mother for about two years and then become independent, leaving their mother's home range to establish their own.
The tiger was first scientifically described in 1758. It once ranged widely from the Eastern Anatolia Region in the west to the Amur River basin in the east, and in the south from the foothills of the Himalayas to Bali in the Sunda Islands. Since the early 20th century, tiger populations have lost at least 93% of their historic range and have been extirpated from Western and Central Asia, the islands of Java and Bali, and in large areas of Southeast and South Asia and China. What remains of the range where tigers still roam free is fragmented, stretching in spots from Siberian temperate forests to subtropical and tropical forests on the Indian subcontinent, Indochina and a single Indonesian island, Sumatra.
The tiger is among the most recognisable and popular of the world's charismatic megafauna. It featured prominently in the ancient mythology and folklore of cultures throughout its historic range and continues to be depicted in modern films and literature, appearing on many flags, coats of arms and as mascots for sporting teams. The tiger is the national animal of India, Bangladesh, Malaysia and South Korea.
The Middle English tigre and Old English tigras derive from Old French tigre, from Latin tigris. This was a borrowing of Classical Greek τίγρις 'tigris', a foreign borrowing of unknown origin meaning 'tiger' and the river Tigris.[6] The origin may have been the Persian word tigra ('pointed or sharp') and the Avestan word tigrhi ('arrow'), perhaps referring to the speed of the tiger's leap, although these words are not known to have any meanings associated with tigers.[7]
In 1758, Carl Linnaeus described the tiger in his work Systema Naturae and gave it the scientific name Felis tigris.[2] In 1929, the British taxonomist Reginald Innes Pocock subordinated the species under the genus Panthera using the scientific name Panthera tigris.[9][10]
Following Linnaeus's first descriptions of the species, several tiger specimens were described and proposed as subspecies.[12] The validity of several tiger subspecies was questioned in 1999. Most putative subspecies described in the 19th and 20th centuries were distinguished on basis of fur length and colouration, striping patterns and body size, hence characteristics that vary widely within populations. Morphologically, tigers from different regions vary little, and gene flow between populations in those regions is considered to have been possible during the Pleistocene. Therefore, it was proposed to recognize only two tiger subspecies as valid, namely P. t. tigris in mainland Asia, and P. t. sondaica in the Greater Sunda Islands.[13]
This two-subspecies proposal was reaffirmed in 2015 by a comprehensive analysis of morphological, ecological and molecular traits of all putative tiger subspecies using a combined approach. The authors proposed recognition of only two subspecies, namely P. t. tigris comprising the Bengal, Malayan, Indochinese, South Chinese, Siberian and Caspian tiger populations of continental Asia, and P. t. sondaica comprising the Javan, Bali and Sumatran tiger populations of the Sunda Islands. The continental nominate subspecies P. t. tigris constitutes two clades: a northern clade composed of the Siberian and Caspian tiger populations, and a southern clade composed of all other mainland populations.[14]
The authors of the 2015 study noted that this two-subspecies reclassification will affect tiger conservation management.[14] It would make captive breeding programs and future re-wilding of zoo-born tigers easier, as one tiger population could then be used to bolster the population of another population. However, there is the risk that the loss of subspecies uniqueness could negatively impact protection efforts for specific populations.[15]
In 2017, the Cat Classification Task Force of the IUCN Cat Specialist Group revised felid taxonomy in accordance with the two-subspecies proposal of the comprehensive 2015 study, and recognized the tiger populations in continental Asia as P. t. tigris, and those in the Sunda Islands as P. t. sondaica.[16]
This two-subspecies view is still disputed by researchers, since the currently recognized nine subspecies can be distinguished genetically.[15] Results of a 2018 whole-genome sequencing of 32 specimens support six monophyletic tiger clades corresponding with the living subspecies and indicate that the most recent common ancestor lived about 110,000 years ago.[17]
Panthera zdanskyi is considered to be a sister taxon of the modern tiger. It lived at the beginning of the Pleistocene about two million years ago, its fossil remains were excavated in Gansu Province, northwestern China. It was smaller and more "primitive", but functionally and ecologically similar to the modern tiger. It is disputed as to whether it had the striping pattern. Northwestern China is thought to be the origin of the tiger lineage. Tigers grew in size, possibly in response to adaptive radiations of prey species like deer and bovids, which may have occurred in Southeast Asia during the Early Pleistocene.[35]
Panthera tigris trinilensis lived about 1.2 million years ago and is known from fossils excavated near Trinil in Java.[36] The Wanhsien, Ngandong, Trinil, and Japanese tigers became extinct in prehistoric times.[37] Tigers reached India and northern Asia in the late Pleistocene, reaching eastern Beringia, Japan, and Sakhalin. Some fossil skulls are morphologically distinct from lion skulls, which could indicate tiger presence in Alaska during the last glacial period, about 100,000 years ago.[38]
Fossil teeth and bones found in Borneo were attributed to the Bornean tiger and date to about 13,745 to 3,000 years ago. It may have accessed Borneo, when the sea level was low during a glaciation period, and may have survived until about 200 years ago.[39][40]In the Ille Cave on the island of Palawan, two articulated phalanx bones were found amidst an assemblage of other animal bones and stone tools. They were smaller than mainland tiger fossils, possibly due to insular dwarfism.[41] It has been speculated that the tiger parts were either imported from elsewhere, or that the tiger colonised Palawan from Borneo before the Holocene.[42][43] Fossil remains of tigers were also excavated in Sri Lanka, China, Japan and Sarawak dating to the Late Pliocene, Pleistocene and Early Holocene.[38][39]
Results of a phylogeographic study indicate that all living tigers had a common ancestor 108,000 to 72,000 years ago.[25] The potential tiger range during the late Pleistocene and Holocene was predicted applying ecological niche modelling based on more than 500 tiger locality records combined with bioclimatic data. The resulting model shows a contiguous tiger range at the Last Glacial Maximum, indicating gene flow between tiger populations in mainland Asia. The Caspian tiger population was likely connected to the Bengal tiger population through corridors below elevations of 4,000 m (13,000 ft) in the Hindu Kush. The tiger populations on the Sunda Islands and mainland Asia were possibly separated during interglacial periods.[44]
Captive tigers were bred with lions to create hybrids called liger and tigon. They share physical and behavioural qualities of both parent species. Breeding hybrids is now discouraged due to the emphasis on conservation.[46] The liger is a cross between a male lion and a tigress. Ligers are typically between 3 and 3.5 m (10 and 12 ft) in length, and weigh between 350 and 450 kg (800 and 1,000 lb) or more.[47] Because the lion sire passes on a growth-promoting gene, but the corresponding growth-inhibiting gene from the female tiger is absent, ligers grow far larger than either parent species.[48]
The less common tigon is a cross between a lioness and a male tiger.[46] Because the male tiger does not pass on a growth-promoting gene and the lioness passes on a growth inhibiting gene, tigons are around the same size as their parents.[48] Some females are fertile and have occasionally given birth to litigons when mated to a male Asiatic lion.[49]
The tiger has a muscular body with strong forelimbs, a large head and a tail that is about half the length of its body. Its pelage colouration comes in shades of orange and brown with a white underside and distinctive mostly vertical black or dark brown stripes; the patterns of which are unique in each individual.[50][23] Stripes are likely advantageous for camouflage in vegetation such as long grass with strong vertical patterns of light and shade.[51][52] The tiger is one of only a few striped cat species; it is not known why spotted patterns and rosettes are the more common camouflage pattern among felids.[53] The orange colour may also aid in camouflage as the tiger's prey are dichromats, and thus may perceive the cat as green and blended in with the vegetation.[54]
A tiger's coat pattern is still visible when it is shaved. This is not due to skin pigmentation, but to the stubble and hair follicles embedded in the skin.[55] It has a mane-like heavy growth of fur around the neck and jaws and long whiskers, especially in males. The pupils are circular with yellow irises. The small, rounded ears have a prominent white spot on the back, surrounded by black.[23] These spots are thought to play an important role in intraspecific communication.[56]
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