中科院动物所在MBE发文揭示反刍动物气候适应性遗传机制

绵羊作为人类驯养的动物之一，是人类的重要食物来源。其广泛分布于世界不同的区域特异性气候环境中。经过数以千百年的自然与人工选择，形成了适应于区域气候环境且具有独特表型的地方品种。

本研究利用绵羊全基因组的约5万个单核苷酸多态性位点(SNPs)和分布于全世界的32个地方绵羊品种，以及9个气候环境因素(包括105个参数)，通过遗传数据与气候环境参数的结合，进行全基因组水平的选择性检验分析。最终检测到230个与气候环境因素变异显著相关的SNPs，这些位点与气候因素的自然选择作用显著相关。

进一步，通过这230个snps，在绵羊基因组上发现了17个与能量代谢、内分泌调节及自身免疫相关候选基因。其中，候选基因TBC1D12在全球范围内呈现出显著的频率变异模式，这一模式表明对于赤道气候区域分布的绵羊的有害变异可能对于分布在寒冷气候区域的绵羊是有益突变。进一步的分析表明，光照、降水等气候因子对绵羊的区域适应性的作用主要通过影响牧草生长，进而间接的影响到绵羊的摄食以及其他的相关生理代谢活动。

本研究结果对于基因组信息，尤其是第二代或第三代高通量测序技术产生的大量基因组数据，在绵羊育种以及反刍动物的气候适应性研究方面的应用具有重要意义。例如，当今世界全球气候变化将可能影响到植被类型的生长，进一步有利于更多木本植物的生长。而本研究的结果显示，我们可以鉴定和选择独特的具有良好地方气候适应性的品种或利用分子辅助育种方法培育出独特的适应某一特定气候环境的品种，这些品种将具有适应未来气候变化的独特遗传特性。

以上研究成果于9月23日在线发表于molecular Biology and Evolution。吕锋骅博士论文的第一作者，李孟华研究员为通讯作者。该研究得到了中国科学院“百人计划”和国家自然科学基金的资助。芬兰、瑞士、澳大利亚、意大利和埃及的科学家参加了该项目的研究。Science Daily等新闻媒体对该工作进行了报道。

原文摘要：

Adaptations to Climate-Mediated Selective Pressures in Sheep

Feng-Hua Lv, Saif Agha, Juha Kantanen, Licia Colli, Sylvie Stucki,James W. Kijas, Stéphane Joost, Meng-Hua Li, and Paolo Ajmone Marsan

Following domestication, sheep (Ovis aries) have become an essential farmed animals across the world through adaptation to a diverse range of environments and varied production systems. Climate-mediated selective pressure has shaped phenotypic variation and has left genetic “footprints” in the genome of breeds raised in different agro-ecological zones. Unlike numerous studies that have searched for evidence of selection using only population genetics data, here, we conducted an integrated co-analysis of environmental data with SNP variation. By examining 49,034 SNPs from 32 old, autochthonous sheep breeds that are adapted to a spectrum of different regional climates, we identified 230 SNPs with evidence for selection that is likely due to climate-mediated pressure. Among them, 189 (82%) showed significant correlation (P ≤ 0.05) between allele frequency and climatic variables in a larger set of native populations from a worldwide range of geographic areas and climates. Gene ontology analysis of genes co-located with significant SNPs identified 17 candidates related to GTPase regulator and peptide receptor activities in the biological processes of energy metabolism and endocrine and autoimmune regulation. We also observed high linkage disequilibrium and significant extended haplotype homozygosity (EHH) for the core haplotype TBC1D12-CH1 of TBC1D12. The global frequency distribution of the core haplotype and allele OAR22_18929579-A showed an apparent geographic pattern and significant (P ≤ 0.05) correlations with climatic variation. Our results imply that adaptations to local climates have shaped the spatial distribution of some variants and they are candidates to underpin adaptive variation in sheep.

作者：动物所