Trachypithecus obscurus

Aifat, Nor Rahman, Abdul-Latiff, Muhammad Abu Bakar, Roos, Christian & Md-Zain, Badrul Munir, 2020, Oxynoemacheilus persa, Zoological Studies 59 (64), pp. 1-11 : 9

Biogeography of T. obscurus in Peninsular

Malaysia

Roos et al. (2011) suggested that the primitive ancestor of the Asian Colobinae migrated to Asia via a land route connecting Africa and the Arabian Peninsula during the late Miocene (Stewart and Disotell 1998; Whybrow 1992). This is supported by the discovery of Colobinae primate fossils dated to the last days of the Miocene, which were found in the Tibetan plateau via the northern road of the Himalayas ( Davies and Oates 1994). The Hengduan Mountain, which is now a border area between Myanmar and China, is said to be the hotspot of this genetic diversity ( Peng et al. 1993; Thinh et al. 2010). The rise in wide river waters in Southeast Asia such as the Mekong River, Salween River, and Yangtze River caused Trachypithecus to migrate south of the Asia mainland, which includes Thailand and Peninsular Malaysia (Hallet and Mollnar 2001).

According to Abdul-Latiff (2015), species diversification from this genus formed four groups of species: those in South Asia, center of Southeast Asia, southern Southeast Asia, and northern Southeast Asia. This situation illustrates that the ancestors of extant species are likely to survive in these four separate groups. The cool climate during the Pliocene led to declines in the area of evergreen forest ( Batchelor 1979; Morley 2000) and caused these four groups to separate ( Wang 1994). In this study, we proposed that T. obscurus invaded Peninsular Malaysia around 0.25 MYA. This process caused the species to separate into north-east and south populations. Separation of T. obscurus occurred in the mainland before the species were distributed in the archipelago area around Peninsular Malaysia. Trachypithecus o. styx diverged after separation from the Perlis population T. o. flavicauda. The molecular clock results showed that the hypothesis of Groves (2001) is acceptable.