Into Tibet: An Early Pliocene Dispersal of Fossil Zokor (Rodentia: Spalacidae) from Mongolian Plateau to the Hinterland of Tibetan Plateau

Genomic insights into zokors' phylogeny and speciation in China

SignificancePhylogenies are the basis of many ecological and evolutionary studies. However, zokor phylogeny and speciation patterns are heavily debated. This study disentangled the phylogeny and speciation of zokors genomically. Six species of the Eospalax were separated into high-altitude E. baileyi and E. smithi and the rest four low-altitude species by recent Qinghai-Tibet Plateau uplift 3.6 million y ago. E. rothschildi and E. smithi speciated south of the Qinling-Huaihe Line, where refuges were supplied during glaciation. Introgression and incomplete lineage sorting led to the complex phylogeny of zokors. Genomic islands were formed due to ancient polymorphisms and divergence hitchhiking. This study concluded that climatic, geological, and tectonic events shaped the phylogeny and speciation of zokors in China.

Qurliqnoria (Mammalia: Bovidae) fossils from Qaidam Basin, Tibetan Plateau and deep-time endemism of the Tibetan antelope lineage

The Tibetan antelope (Pantholops hodgsonii) is an endemic bovid of the Tibetan Plateau, which was, until recently, considered an endangered species. Researchers have long speculated on the evolutionary origin of Pantholops, suggesting a connection to the rare fossil bovid Qurliqnoria. However, the lack of adequate fossil samples has prevented the testing of this deep-time endemism hypothesis for eight decades. Here, we report new fossils of Qurliqnoria cheni from the northern Tibetan Plateau, substantially increasing the amount of morphological data that can be brought to bear on the question of Tibetan antelope evolution. Phylogenetic analysis supports a Pantholops–Qurliqnoria clade and suggests that this lineage has been endemic to the Plateau for 11 Myr. Recent morphological and molecular studies that support the outgroup position of Pantholops relative to caprins (goats and relatives) and the fossil record of stem bovids from Europe together suggest that the Qurliqnoria–Pantholops lineage is likely to have dispersed to the Tibetan Plateau 15–11 Mya. Furthermore, the harsh environmental conditions to which Pantholops has adapted are likely to extend back to the time of its evolutionary origin. These findings provide an important new context for conservation management and research into the near-threatened Tibetan antelope, as the longest-living endemic member of the Tibetan Plateau fauna.

"Into and Out of" the Qinghai-Tibet Plateau and the Himalayas: Centers of origin and diversification across five clades of Eurasian montane and alpine passerine birds

Encompassing some of the major hotspots of biodiversity on Earth, large mountain systems have long held the attention of evolutionary biologists. The region of the Qinghai-Tibet Plateau (QTP) is considered a biogeographic source for multiple colonization events into adjacent areas including the northern Palearctic. The faunal exchange between the QTP and adjacent regions could thus represent a one-way street ("out of" the QTP). However, immigration into the QTP region has so far received only little attention, despite its potential to shape faunal and floral communities of the QTP. In this study, we investigated centers of origin and dispersal routes between the QTP, its forested margins and adjacent regions for five clades of alpine and montane birds of the passerine superfamily Passeroidea. We performed an ancestral area reconstruction using BioGeoBEARS and inferred a time-calibrated backbone phylogeny for 279 taxa of Passeroidea. The oldest endemic species of the QTP was dated to the early Miocene (ca. 20 Ma). Several additional QTP endemics evolved in the mid to late Miocene (12-7 Ma). The inferred centers of origin and diversification for some of our target clades matched the "out of Tibet hypothesis' or the "out of Himalayas hypothesis" for others they matched the "into Tibet hypothesis." Three radiations included multiple independent Pleistocene colonization events to regions as distant as the Western Palearctic and the Nearctic. We conclude that faunal exchange between the QTP and adjacent regions was bidirectional through time, and the QTP region has thus harbored both centers of diversification and centers of immigration.

Evolutionary history of zoogeographical regions surrounding the Tibetan Plateau

The Tibetan Plateau (TP) and surrounding regions have one of the most complex biotas on Earth. However, the evolutionary history of these regions in deep time is poorly understood. Here, we quantify the temporal changes in beta dissimilarities among zoogeographical regions during the Cenozoic using 4,966 extant terrestrial vertebrates and 1,278 extinct mammal genera. We identify ten present-day zoogeographical regions and find that they underwent a striking change over time. Specifically, the fauna on the TP was close to the Oriental realm in deep time but became more similar to the Palearctic realms more recently. The present-day zoogeographical regions generally emerged during the Miocene/Pliocene boundary (ca. 5 Ma). These results indicate that geological events such as the Indo-Asian Collision, the TP uplift, and the aridification of the Asian interior underpinned the evolutionary history of the zoogeographical regions surrounding the TP over different time periods.