Department of Biology, Lund University, Lund, 223 62, Sweden.
Department of Earth and Environmental Sciences, University of Pavia, Pavia, 27100, Italy.
Evolution. 2020 Jul;74(7):1289-1300. doi: 10.1111/evo.14001. Epub 2020 May 24.
Hybrid zones provide insights into the evolution of reproductive isolation. Sexual selection can contribute to the evolution of reproductive barriers, but it remains poorly understood how sexual traits impact gene flow in secondary contact. Here, we show that a recently evolved suite of sexual traits that function in male-male competition mediates gene flow between two lineages of wall lizards (Podarcis muralis). Gene flow was relatively low and asymmetric in the presence of exaggerated male morphology and coloration compared to when the lineages share the ancestral phenotype. Putative barrier loci were enriched in genomic regions that were highly differentiated between the two lineages and showed low concordance between the transects. The exception was a consistently low genetic exchange around ATXN1, a gene that modulates social behavior. We suggest that this gene may contribute to the male mate preferences that are known to cause lineage-assortative mating in this species. Although female choice modulates the degree of reproductive isolation in a variety of taxa, wall lizards demonstrate that both male-male competition and male mate choice can contribute to the extent of gene flow between lineages.
杂种区为研究生殖隔离的演化提供了线索。性选择可能有助于生殖障碍的演化，但性特征如何影响二次接触中的基因流仍知之甚少。在这里，我们发现，最近演化出的一套雄性间竞争的性特征，调节了壁蜥（Podarcis muralis）两个谱系间的基因流。与谱系共享祖先表型相比，在雄性形态和颜色夸张的情况下，基因流相对较低且不对称。假定的障碍基因座在两个谱系之间高度分化的基因组区域中富集，并在横截面上显示出低一致性。一个例外是 ATXN1 周围的遗传交换始终较低，ATXN1 是一个调节社会行为的基因。我们认为，这个基因可能有助于雄性配偶偏好，已知这种偏好会导致该物种的谱系交配。虽然雌性选择在多种分类群中调节生殖隔离的程度，但壁蜥表明，雄性间竞争和雄性配偶选择都可以影响谱系间的基因流程度。
