两栖爬行动物 z-bo 2020-11-04 399

　　Based on long-term investigations and studies on the Himalayas, Che Jing’s team, a researcher from the Kunming Institute of Zoology, Chinese Academy of Sciences, reconstructed the temporal and spatial evolutionary history of most of the existing amphibians and reptiles in the area, and discussed important geological and historical events such as the uplift of the Himalayas and the development of the South Asian monsoon The hypothesis reveals the impact of these events on biological differentiation and migration.

　　The evolution history of amphibians and reptiles in the Himalayas

　　The Himalayas are located in the southern part of the Qinghai-Tibet Plateau. They are the highest mountain range in the world. There are 10 peaks above 8000 meters. Among them, Mount Everest is the highest peak in the world with an altitude of 88.843 meters. The Himalayas is also one of the 34 biodiversity hotspots in the world. Its special environment, huge altitude difference, bred rich vegetation gradients and unique animal groups.

　　Based on the first-hand data collected by the team and the integration of the species sequence data published on GenBank, the multi-gene sequence fragment data of 1628 amphibians and reptiles in 14 families were collected, involving 182 species in the Himalayas, accounting for the total number of recorded species in the region. Around 60%. The study explores the temporal and spatial dynamic evolution pattern of amphibians and reptiles distributed in the Himalayas by constructing a species evolution tree, combining time correction points and species distribution information.

　　The diversity of living amphibians and reptiles in the Himalayas has been accumulated since the Paleocene. In general, the changing trends of in-situ seeding events and inter-regional spreading events are basically the same, and they are relatively slow in the early stage, but in the late Oligocene (Oligocene) to the early Miocene (Miocene), the rate of species accumulation accelerated. Around the middle of the Miocene, about 15 million years ago, the species accumulation rate in the Himalayas reached the highest peak and then began to show a downward trend.

　　Animal evolution supports the "progressive uplift hypothesis"

　　As the youngest and tallest mountain range on earth, the Himalayas are formed by the collision of the Indian subcontinent and the Eurasian plate. However, there are still controversies regarding the history and mechanism of the uplift of the Himalayas. Early studies put the Himalayas and the plateau as a whole, and put forward the "Himalayan early uplift hypothesis", that is, the Himalayas were formed in the early Cenozoic. However, considering the obvious difference between the plateau surface and the Himalayas in the history of geological uplift, the current geological evidence has generally rejected this hypothesis.

　　At present, there are two hypotheses about the history of the uplift of the Himalayas: One is the Late Orogeny Hypothesis, which is supported by hydrological and thermal evidence, and it is believed that the Himalayas did not reach the present until the mid-Pliocene. There are heights; the second is the Stepwise Hypothesis, which believes that the Himalayas had already started to uplift in the late Paleocene, but the uplift in the early stage was relatively slow, and it was not until the Miocene that it began to uplift quickly and then Reach the current height.

　　The evolution of a region's biota is closely related to geological and climate changes. During the uplift of a mountain range, the increased heterogeneity of the topography will produce a large number of opportunities for geographical isolation and niche differentiation, thereby promoting the formation of a large number of local species. Corresponding to these two geological hypotheses, two completely different biological evolution patterns can be predicted: (1) If the recent uplift hypothesis is established, the cumulative acceleration time of amphibians and reptile species in the Himalayas will occur in the mid-Pliocene or after. (2) If the gradual uplift hypothesis is established, the accumulation of local species will begin in the late Paleocene and accelerate in the Miocene.

　　The evolutionary dynamic model of amphibians and reptiles in the Himalayan area reconstructed by this study supports the "progressive uplift hypothesis". The study is the first to integrate and analyze the evolutionary history of amphibians and reptiles in the Himalayas, and explore different geological hypotheses. From the perspective of biodiversity conservation, this research is of great significance, and its results support that the Himalayas are important species formation and differentiation cradles. The Himalayas have concentrated so many endemic species in such a small area and are a world-class biological gene treasure house. The protection of the ecological environment and habitat of the region should be strengthened to protect these precious and unique biological resources.