Data from: Using genomic data to revisit a classic example of reproductive character displacement in Haitian Anolis lizards

The pattern of reproductive character displacement (RCD)—in which traits associated with reproductive isolation are more different where two species occur together than where they occur in isolation—is frequently attributed to reinforcement, a process during which natural selection acting against maladaptive mating events leads to enhanced prezygotic isolation between species or incipient species. One of the first studies of RCD to include molecular genetic data was described 40 years ago in a complex of Haitian trunk anole lizards using a small number of allozyme loci. In this example, Anolis caudalis appears to experience divergence in the color and pattern of an extensible throat fan, or dewlap, in areas of contact with closely related species at the northern and southern limits of its range. However, this case study has been largely overlooked for decades; meanwhile, explanations for geographic variation in dewlap color and pattern have focused primarily on adaptation to local signalling environments. We reinvestigate this example using amplified fragment length polymorphism (AFLP) genome scans, mtDNA sequence data, information on dewlap phenotypes and GIS data on environmental variation to test the hypothesis of RCD generated by reinforcement in Haitian trunk anoles. Together, our phenotypic and genetic results are consistent with RCD at the southern and northern limits of the range of A. caudalis. We evaluate the evidence for reinforcement as the explanation for RCD in Haitian trunk anoles, consider alternative explanations and provide suggestions for future work on the relationship between dewlap variation and speciation in Haitian trunk anoles.

生殖性状置换（reproductive character displacement, RCD）指两类物种同域分布时，与生殖隔离相关的性状差异程度显著高于各自异域分布时的情况，该现象通常被归因于强化作用（reinforcement）——即自然选择针对不适应性交配事件发挥作用，进而提升物种或初期分化物种间的合子前生殖隔离水平。40年前，学界针对海地树栖安乐蜥类群开展的一项研究首次将分子遗传数据纳入RCD分析，该研究仅使用了少量同工酶座位（allozyme loci）。在此案例中，尾安乐蜥（Anolis caudalis）在其分布范围南北两端与近缘物种接触的区域，其可伸展喉扇（dewlap）的颜色与图案呈现出分化特征。然而这一案例在数十年来几乎被学界忽视；与此同时，针对喉扇颜色与图案的地理变异的相关解释，主要聚焦于对局部信号传递环境的适应性演化。本研究重新审视该案例，通过扩增片段长度多态性（amplified fragment length polymorphism, AFLP）基因组扫描、线粒体DNA（mitochondrial DNA, mtDNA）序列数据、喉扇表型信息以及环境变异的地理信息系统（Geographic Information System, GIS）数据，验证"强化作用驱动海地树栖安乐蜥产生RCD"这一假说。综合表型与遗传分析结果，我们的研究支持尾安乐蜥分布范围南北两端存在RCD现象。我们评估了将强化作用作为海地树栖安乐蜥RCD成因的相关证据，同时探讨了其他替代性解释，并为未来研究海地树栖安乐蜥喉扇变异与物种形成间的关联提供了建议。