Interpreting the genomic landscape of speciation: a road map for finding barriers to gene flow

Speciation, the evolution of reproductive isolation amongst populations, is continuous, complex, and involves multiple, interacting barriers. Until it is complete, the effects of this process vary along the genome and can lead to a heterogeneous genomic landscape with peaks and troughs of differentiation and divergence. When gene flow occurs during speciation, barriers restricting migration locally in the genome lead to patterns of heterogeneity. However, genomic heterogeneity can also be produced or modified by variation in factors such as background selection and selective sweeps, recombination- and mutation-rate variation, and heterogeneous gene density. Extracting the effects of gene flow, divergent selection and reproductive isolation from such modifying factors presents a major challenge to speciation genomics. We argue one of the principal aims of the field is to identify the barrier loci involved in limiting gene flow. We first summarise the expected signatures of selection at b...

物种形成（speciation）指种群间生殖隔离（reproductive isolation）的演化过程，其兼具连续性与复杂性，涉及多重相互作用的生殖障碍。在生殖隔离完全形成前，该过程对基因组的影响沿基因组区域存在差异，可造就分化与趋异峰谷错落的异质性基因组景观（genomic landscape）。若物种形成过程中存在基因流（gene flow），基因组局部区域的迁移限制障碍会催生此类异质性模式。然而，基因组异质性也可由其他因素的变异产生或修饰，例如背景选择（background selection）、选择性清除（selective sweeps）、重组率与突变率的变异，以及基因密度（gene density）的异质性。从这类修饰因子中剥离基因流、趋异选择与生殖隔离的效应，是物种形成基因组学面临的重大挑战。我们认为该领域的核心目标之一，是鉴定参与限制基因流的障碍位点（barrier loci）。我们首先总结了在b……处的预期选择特征。