物种形成过程中的分化基因组岛及其形成机制

理解物种形成机制是生态和进化领域的重要任务。得益于测序技术的快速发展, 越来越多研究发现分化种群(亚种、物种)间的基因组常呈现异质性分化景观, 存在分化基因组岛, 这被认为是基因流存在下的歧化选择引起的, 支持基因流存在下的成种假说。然而, 基因渐渗、祖先多态性的差异分选、连锁选择等其他进化过程也可导致分化基因组岛的形成。现有实证研究在解析分化基因组岛的形成机制时, 往往忽略了上述其他进化过程的作用。为此, 本文在辨析分化基因组岛相关概念的基础上, 总结了利用种群基因组数据鉴定分化基因组岛的方法, 对比了不同进化过程形成分化基因组岛的特征, 指出在区分不同机制时联用基因渐渗程度、绝对分化指数(d_XY)、相对节点深度(RND)、重组率等多个指标的必要性, 归纳了物种形成过程中分化基因组岛形成机制解析的研究思路, 并对未来在生殖隔离机制上的深入探索以及实证研究的整合分析等方面进行了展望。

Genomic island of divergence during speciation and its underlying mechanisms

Background & Aims Understanding the mechanisms underlying the formation of species is a major task of ecological and evolutionary studies. Aided by the rapid development of sequencing technologies during the last two decades, a growing body of research has revealed a heterogeneous genomic landscape of divergence with the existence of genomic islands of divergence between closely related taxa. This pattern was interpreted as evidence for the speciation-with-gene-flow model, and genomic islands in divergence landscape were hypothesized to be caused by divergent selection in the face of gene flow. However, genomic islands can also arise from other evolutionary processes, such as introgression, divergent sorting of ancient polymorphisms, and linked selection. Previous empirical studies often focused on part of evolutionary processes when discerning the mechanism governing the formation of genomic islands. Therefore, this paper aims to clarify genomic island of divergence and related concepts, summarize the pros and cons of different methods of identifying genomic islands, compare the predicted properties of genomic islands of divergence under different evolutionary processes, and propose a research route for discerning the mechanism contributing to genomic islands during speciation. This paper may provide a guide for future studies on genomic islands and their underlying mechanisms.