Animal Ecology, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden.
Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 100101, Beijing, People's Republic of China.
BMC Ecol Evol. 2021 Oct 24;21(1):194. doi: 10.1186/s12862-021-01921-7.
The boreal forest is one of the largest biomes on earth, supporting thousands of species. The global climate fluctuations in the Quaternary, especially the ice ages, had a significant influence on the distribution of boreal forest, as well as the divergence and evolution of species inhabiting this biome. To understand the possible effects of on-going and future climate change it would be useful to reconstruct past population size changes and relate such to climatic events in the past. We sequenced the genomes of 32 individuals from two forest inhabiting bird species, Hazel Grouse (Tetrastes bonasia) and Chinese Grouse (T. sewerzowi) and three representatives of two outgroup species from Europe and China.
We estimated the divergence time of Chinese Grouse and Hazel Grouse to 1.76 (0.46-3.37) MYA. The demographic history of different populations in these two sibling species was reconstructed, and showed that peaks and bottlenecks of effective population size occurred at different times for the two species. The northern Qilian population of Chinese Grouse became separated from the rest of the species residing in the south approximately 250,000 years ago and have since then showed consistently lower effective population size than the southern population. The Chinese Hazel Grouse population had a higher effective population size at the peak of the Last Glacial Period (approx. 300,000 years ago) than the European population. Both species have decreased recently and now have low effective population sizes.
Combined with the uplift history and reconstructed climate change during the Quaternary, our results support that cold-adapted grouse species diverged in response to changes in the distribution of palaeo-boreal forest and the formation of the Loess Plateau. The combined effects of climate change and an increased human pressure impose major threats to the survival and conservation of both species.
北方森林是地球上最大的生态系统之一，支持着成千上万的物种。第四纪的全球气候波动，尤其是冰河时代，对北方森林的分布以及栖息在这个生态系统中的物种的分化和进化产生了重大影响。为了了解正在发生和未来的气候变化的可能影响，重建过去的种群大小变化，并将其与过去的气候事件联系起来将是有用的。我们对来自两种森林鸟类——榛鸡（Tetrastes bonasia）和中国雉鸡（T. sewerzowi）的 32 个个体以及来自欧洲和中国的两个外群物种的三个代表进行了基因组测序。
我们估计中国雉鸡和榛鸡的分化时间为 1.76（0.46-3.37）MYA。重建了这两个姊妹物种不同种群的种群历史，结果表明，两个物种的有效种群大小峰值和瓶颈出现在不同的时间。中国雉鸡的祁连山北部种群与分布在南部的其余种群大约在 25 万年前就已经分开，此后，该种群的有效种群规模一直低于南部种群。中国榛鸡的种群在末次冰期高峰时的有效种群规模（约 30 万年前）高于欧洲种群。这两个物种最近都有所减少，现在的有效种群规模都很低。
结合第四纪的隆升历史和重建的气候变化，我们的结果支持冷适应松鸡物种是为了应对古北方森林分布的变化和黄土高原的形成而分化的。气候变化和人类压力增加的综合影响对这两个物种的生存和保护构成了重大威胁。
