Empirical data that identify contemporary mechanisms of divergence shed light on how species could multiply. In this study, we measured population genetic structure, song syllable diversity and response to simulated intruder song in Darwin's small tree finch (Camarhynchus parvulus) on Santa Cruz and Floreana Islands, Galápagos archipelago. Our aim was to test whether the magnitude of contemporary behavioural response in resident birds was consistent with patterns of genetic or cultural differences between populations. We analysed genetic structure and the occurrence of song syllable types, and experimentally measured the response of resident birds to intruder bird song from different geographical origin (i.e., island) or syllable type. We discovered a weak signal of population genetic structure between Santa Cruz and Floreana Islands. Although some song syllables occurred on both islands, others were unique to each island; Santa Cruz Island males used more unique syllables than Floreana Island males. Both Santa Cruz and Floreana resident males discriminated their response towards a simulated intruder song based on the geographical origin of the intruder song, but not on the syllable type sung by the intruder. We conclude that the populations are diverging in genetic and cultural traits and identified a signal of contemporary behavioural response that could maintain divergence upon secondary contact.

中文翻译：

---

加拉帕戈斯群岛达尔文小树雀的遗传差异异域种群对歌曲的行为反应。

确定当代分化机制的经验数据揭示了物种如何繁殖。在这项研究中，我们测量了加拉帕戈斯群岛圣克鲁斯岛和弗洛里阿纳群岛的达尔文小树雀（Camarhynchus parvulus）的种群遗传结构、歌曲音节多样性以及对模拟入侵者歌曲的反应。我们的目的是测试留鸟当代行为反应的程度是否与种群之间的遗传或文化差异模式一致。我们分析了遗传结构和歌曲音节类型的出现，并通过实验测量了留鸟对来自不同地理来源（即岛屿）或音节类型的入侵者鸟类歌曲的反应。我们发现圣克鲁斯岛和弗洛雷纳群岛之间的种群遗传结构存在微弱信号。尽管一些歌曲音节出现在两个岛屿上，但其他音节是每个岛屿所独有的。圣克鲁斯岛男性比弗洛里纳岛男性使用更多独特的音节。圣克鲁斯和弗洛里纳的男性居民都会根据入侵者歌曲的地理起源来区分他们对模拟入侵者歌曲的反应，而不是根据入侵者所唱的音节类型。我们得出的结论是，人群在遗传和文化特征上存在差异，并确定了当代行为反应的信号，该信号可能在二次接触时保持差异。