Data from: Transitions between phases of genomic differentiation during stick-insect speciation

Speciation can involve a transition from a few genetic loci that are resistant to gene flow to genome-wide differentiation. However, only limited data exist concerning this transition and the factors promoting it. Here, we study phases of speciation using data from >100 populations of 11 species of Timema stick insects. Consistent with early phases of genic speciation, adaptive colour-pattern loci reside in localized genetic regions of accentuated differentiation between populations experiencing gene flow. Transitions to genome-wide differentiation are also observed with gene flow, in association with differentiation in polygenic chemical traits affecting mate choice. Thus, intermediate phases of speciation are associated with genome-wide differentiation and mate choice, but not growth of a few genomic islands. We also find a gap in genomic differentiation between sympatric taxa that still exchange genes and those that do not, highlighting the association between differentiation and complete reproductive isolation. Our results suggest that substantial progress towards speciation may involve the alignment of multi-faceted aspects of differentiation.

物种形成（speciation）可涉及从少数抗基因流（gene flow）的遗传位点（genetic loci）到全基因组分化（genome-wide differentiation）的转变过程。然而，目前关于这一转变及其驱动因素的相关数据仍较为匮乏。本研究基于11个物种的100余个Timema属竹节虫（Timema stick insects）种群的数据，对物种形成的不同阶段展开研究。研究结果与基因物种形成（genic speciation）的早期阶段相符：在存在基因流的种群间，适应性体色图案位点位于分化程度加剧的局部遗传区域内。在存在基因流的情况下，本研究同样观测到向全基因组分化的转变，这一转变与影响配偶选择的多基因化学性状的分化相关联。由此可见，物种形成的中间阶段与全基因组分化及配偶选择相关联，而非少数基因组岛（genomic islands）的扩张。本研究还发现，仍存在基因交流的同域类群（sympatric taxa）与不存在基因交流的同域类群之间，存在基因组分化的差异，这凸显了分化与完全生殖隔离（reproductive isolation）之间的关联。本研究结果表明，物种形成过程中取得实质性进展，可能需要多维度分化特征的协同整合。