Asymmetric song recognition does not influence gene flow in an emergent songbird hybrid zone

Hybrid zones can be used to examine the mechanisms affecting reproductive isolation and speciation, like song. Song has equivocal support as a driver of speciation; we did not find song to cause reproductive isolation. We examined an emerging secondary contact zone between White-crowned Sparrow subspecies pugetensis and gambelii by measuring song variation, song recognition, plumage, morphology and mtDNA. Plumage and morphological characters provided evidence of hybridization in the contact zone, with some birds possessing plumage and song characteristics intermediate between the subspecies. Playback experiments revealed asymmetric song recognition: male pugetensis displayed greater response to their own song than gambelii song, whereas gambelii did not discriminate significantly. If female choice operates similarly to male song discrimination, we predicted asymmetric gene flow, resulting in a greater number of hybrids with gambelii mitochondrial DNA (mtDNA). Contrary to our prediction,...杂交带（hybrid zone）可用于探究影响生殖隔离与物种形成的相关机制，鸣声（song）便是这类机制之一。然而鸣声作为物种形成驱动力的相关证据尚存争议，本研究未发现鸣声能够引发生殖隔离。本研究针对白冠麻雀（White-crowned Sparrow）亚种pugetensis与gambelii之间的新兴次生接触带展开研究，通过测定鸣声变异、鸣声识别、羽色、形态特征以及线粒体DNA（mtDNA）开展相关分析。羽色与形态特征的检测结果为该接触带的杂交现象提供了证据，部分个体的羽色与鸣声特征介于两个亚种之间。鸣声回放实验显示存在不对称的鸣声识别模式：雄性pugetensis对自身鸣声的响应强度显著高于对gambelii鸣声的响应，而雄性gambelii未表现出显著的鸣声辨别能力。若雌性配偶选择机制与雄性的鸣声辨别模式一致，则我们预测会出现不对称的基因流，最终导致携带gambelii线粒体DNA的杂交个体数量更多。但本研究结果与该预测相悖……