Data from: Chemical communication, sexual selection, and introgression in wall lizards

Divergence in communication systems should influence the likelihood that individuals from different lineages interbreed, and consequently shape the direction and rate of hybridization. Here, we studied the role of chemical communication in hybridization, and its contribution to asymmetric and sexually selected introgression, between two lineages of the common wall lizard (Podarcis muralis). Males of the two lineages differed in the chemical composition of their femoral secretions. Chemical profiles provided information regarding male secondary sexual characters, but the associations were variable and inconsistent between lineages. In experimental contact zones, chemical composition was weakly associated with male reproductive success, and did not predict the likelihood of hybridization. Consistent with these results, introgression of chemical profiles in a natural hybrid zone resembled that of neutral nuclear genetic markers overall, but one compound in particular (tocopherol methyl ether) matched closely the introgression of visual sexual characters. These results imply that associations between male chemical profiles, sexual characters and reproductive success largely reflect transient and environmentally driven effects, and that genetic divergence in chemical composition is largely neutral. We therefore suggest that femoral secretions in wall lizards primarily provide information about residency and individual identity rather than function as sexual signals.

通讯系统的分化会影响不同谱系个体间杂交繁殖的可能性，并进而塑造杂交的方向与速率。本研究以普通壁蜥（Podarcis muralis）的两个谱系为研究对象，探讨了化学通讯（chemical communication）在杂交中的作用，及其对不对称且受性选择的基因渐渗（introgression）的贡献。两个谱系的雄性个体在股腺分泌物的化学成分上存在差异。化学特征谱能够反映雄性第二性征的相关信息，但这类关联在不同谱系间存在变异且并不一致。在实验接触区中，化学成分仅与雄性繁殖成功率存在微弱关联，且无法预测杂交发生的可能性。与上述结果相符，自然杂交带中化学特征谱的基因渐渗整体上与中性核遗传标记（neutral nuclear genetic markers）的渐渗模式相似，但其中一种特定化合物——生育酚甲基醚（tocopherol methyl ether）的渐渗情况与视觉性征的渐渗高度匹配。上述结果表明，雄性化学特征谱、性征与繁殖成功率之间的关联，在很大程度上反映了短暂且受环境驱动的效应，而化学成分的遗传分化整体上多呈中性。因此我们认为，壁蜥的股腺分泌物主要用于传递领地归属与个体身份信息，而非作为性信号发挥功能。