Isolating barriers and microevolution in sympatric populations of the blackcap (Sylvia atricapilla)

物种形成是进化生物学的核心课题，但导致种群间生殖隔离的机制往往是未知的，因为它们必须在回顾性中确定。因此，同域种群的初期持续隔离为评估不同隔离屏障的相对重要性提供了一个独特的窗口。黑帽（Sylvia atricapilla）是一个理想的模式系统，因为它在过去60年里发展了一种已知遗传基础的迁徙。我们发现具有不同迁徙路线的同域种群在遗传上存在差异。我们将研究这些种群的遗传和表型特征，以分析本地适应和推断选择模式。我们使用中性遗传标记来解释遗传漂移，并分析鸟类时钟基因来评估遗传适应。我们结合春季到来和求偶的遗传和行为分析来评估生殖隔离进化的其他假设。这种方法可以评估早期的生殖隔离是否是非选择性选型交配的副产品，还是由杂交不育导致的早熟行为隔离或交配后隔离所驱动的适应性隔离。因此，我们可以量化60年前发生的迁徙行为转变的进化意义。

Speciation is the core topic of evolutionary biology, but the mechanisms leading to reproductive isolation between populations are often unknown as they have to be identified in retrospective. Incipient ongoing isolation in sympatric populations thus offers a unique window to evaluate the relative importance of different isolating barriers. The blackcap [Sylvia atricapilla) is an ideal model system because it developed a migratory shiff with a known genetic basis in the last 60 years. We found that sympatric populations with distinct migratory routes differ genetically. We will study genetic and phenotypic characters of these populations to analyse local adaptation and infer the mode of selection. We account for genetic driff using neutral genetic markers and assess genetic adaptation analysing an avian clock gene. We combine genetic with behavioural analyses of spring arrival and courtship to assess alternative hypotheses on the evolution of reproductive isolation. This approach allows to evaluate whether incipient reproductive isolation is a by-product of non-selective assortative mating or whether it is adaptive driven by premating behavioural isolation or postmating isolation owing to hybrid inviability. We can thus quantify the evolutionary significance of the shift in migratory behaviour that occurred 60 years ago.