鲟类系统发育基因组学及其生活史特征演化研究

The reconstruction of the branching patterns of the Tree of Life (ToL) has become the research hotspot on biological community worldwide. The Tree of Life related projects have already made substantial contributions to establishing the major branches of the tree of life; this project will focus on a special branch of the ray-finned fishes, sturgeons (Actinopterygii, Acipenseriformes, Acipenseridae). Sturgeons form a small group that is thought to have split off from other fishes early in the evolutionary history of ray-finned fishes. The 25 extant species of sturgeons are distinctive fishes; their unique benthic specializations and conserved morphology, their evolutionary age, the variation in their basic diadromous life history, their polyploid genomes, and the large public interest due to their near extinction or critically endangered status, make sturgeons highly interesting groups for molecular evolutionary, conservation biological, and genomic studies. Despite their importance in these aspects of researches, the phylogenetic branching order of sturgeons has remained controversial in spite of several molecular and morphological studies, and key questions remain regarding the interrelationships among the genera and species.. .This project will conduct the first ever analysis of evolutionary relationships of sturgeons based on a near-complete species sampling and over 100 molecular markers employed (more than 50 kb in total) using phylogenomic approaches. The goals of this project are to reconstruct the evolutionary relationships among sturgeon species and then use these results to produce a reliable or well-resolved sturgeon systematics and to understand evolutionary patterns of migration and other life- history traits, and also to explore the correlation between the evolutionary rate differences and the life-history trait differences of different sturgeon species. Results from this project will be used to further evolutionary genomic studies and to inform conservation decisions and management strategies. As such, results from this proposal will have both theoretical and applied implications for sturgeon conservation, evolution, and genome biology.

本项目瞄准重建"生命之树"这一国际关注的热点问题，在我们前期研究工作的基础上，选择有"活化石"之称的鲟形目鲟科鱼类（sturgeons）进行研究。鲟类因其在鱼类演化历史过程中的重要性和特殊性以及现实的濒危状况，现已成为进化生物学、保护生物学以及基因组学研究的热点类群。然而此前研究存在取样不全以及分子标记少等局限，其系统发育关系还亟待阐明。本研究采用系统发育基因组学（phylogenomics）的原理和方法，在基因组水平上进行鲟类分子系统发育关系研究，以期获得一个鲟类最为可靠的系统发育关系假说。在此基础上，结合鲟类生活史特征数据，采用比较系统发育分析方法，研究其生活史特征演化规律；同时通过系统发育独立对比分析方法，探讨鲟类分子进化速率差异与其生活史差异间的相关关系，以期为鲟类进化基因组学和保护生物学研究的深入开展奠定基础。

有“活化石”之称的鲟形目鱼类因其在鱼类演化历史过程中的重要性和特殊性以及现实的濒危状况，是进化生物学、保护生物学以及基因组学研究的热点类群。本项目以鲟形目鲟科鱼类（sturgeons）为研究对象，采集了16种鲟科鱼类样品，采用常规sanger测序和下一代高通量测序技术，运用生物信息学分析方法，结合已公布的鲟类转录组以及相关物种全基因组序列数据，我们在达氏鲟基因组中开发了大量微卫星分子标记并成功筛选出八个具有多态性的微卫星座位，这为达氏鲟及其近缘物种的保护遗传学研究打下了坚实基础；同时我们成功开发了16个匿名分子标记以及8个单拷贝直系同源核基因分子标记，这为后续鲟类系统发育关系的全面解析奠定了坚实的基础。由于存在样品获取非常困难以及在多倍体物种中分离单拷贝直系同源基因非常困难等因素，目前项目部分目标还未实现，但本项目所涉及的研究工作还在深入的开展之中。

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