a few days ago, by the institute of zoology, Chinese academy of sciences, shenzhen bgi cooperation unit such as the panda population evolution and adaptive correlation results in the journal nature & middot; genetics published online. The study by the methods of genomics and population genetics depicts the panda complete evolution profile.
the panda evolutionary lineage history can be traced back to 8 million years ago, in the past for millions of years, the panda was once prosperous, but now only a genus & ndash; & ndash; Giant pandas are endangered. Recent survey shows that only distributed in six mountains in the western area of China: qinling, minshan, qionglai mountains, big ridge, the small ridge and liangshan, wild pandas existing about 1600.
in this study, the researchers on the basis of genomic information to determine the six pandas can be divided into the qinling mountain systems, minshan, qionglai mountain ridge – size phase – liangshan three genetic system, by building a giant panda from origin to today’s historical evolution, reveal the meantime twice experienced by the population expansion, two bottlenecks and population differentiation phenomenon.
around 3 million years ago, original panda’s diet structure from meat to feed on bamboo, and other Dwarf type & throughout; The giant panda. When warm, humid environment suitable for the growth of the bamboo forest, giant panda population appeared for the first time to expand. About 700000 years ago, the giant panda population began to decline, to about 300000 years ago, the bottleneck for the first time. This is because during this period, China’s large pleistocene glaciation appeared twice, cold climate change leads to large size pap panda replaced & other; Dwarf type & throughout; The giant panda. After second from bottom in the ice age, giant panda population was made between the second expansion, and the peak of 50000 to 30000 years ago, in the great lakes period of warm climate may have contributed significantly to the prosperity of the giant panda, alpine coniferous and this period is suitable for the panda habitat environment. In the last ice age to the stage, because of the serious mountain glaciers, cold weather, the loess deposition, resulting in a large number of panda habitat loss, which caused the population bottleneck for the second time.
around 300000 years ago, the panda population differentiation become the qinling and qinling two. And the simulation results show that in 40000 years ago, the qinling population expanded by a factor of three, while the qinling group decreased by 80%. Since then, the qinling population gradually reduce, whereas qinling population stabilises. About 2800 years ago, the qinling group split into two branches, namely the minshan pandas and qionglai mountain ridge – liangshan panda – size, form the three genetic system such as the current stable.
in the further analysis of the qinling pandas, compared to the natural environment, the researchers noted that the impact of human activities on the more serious. Change from the spring and autumn period of agriculture in our country and the clearing of the han and tang dynasties period of panda deforestation built palace and entertainment and diplomatic strategy, which caused serious influence on its habitat and species.