"Pathogens, mate choice and gene flow in songbirds"

寄生虫占所有已知物种的近一半，对寄主个体的适合度有重要影响。这项研究计划的一个主要目标是了解血源性寄生虫如何影响其鸣禽宿主种群的进化潜力。由于遗传多样性(“异交”)宿主被认为比近亲繁殖的个体能够抵抗更广泛的传染病，一种可能性(“寄生虫作为连接器”的假说)是寄生虫促进了基因流动和近亲繁殖的避免，从而维持了宿主高度的遗传多样性。或者，另一种可能性(“寄生虫为楔形”假说)是宿主对当地寄生虫的适应减少了种群间的基因流动，促进了近亲繁殖，导致宿主遗传多样性的丧失。为了区分这些选择，我的研究结合了对野生繁殖鸣禽行为和生态的密集和长期实地研究，以及遗传分析和免疫挑战。第二个相辅相成的研究重点是习得的鸟鸣在连接或隔离种群方面的作用。在鸣禽中，歌声是在生命早期学会的，因此可能反映了鸣禽的起源种群。这为近亲交配或近亲交配提供了潜在的行为线索。随着人类活动日益破坏自然栖息地和孤立自然种群，识别和了解保护或侵蚀野生遗传多样性的因素变得至关重要。鉴于与气候变化相关的新出现的传染病，预测寄生虫如何影响宿主进化尤为重要。

Parasites represent nearly half of all known species and have important effects on the fitness of host individuals. A major goal of this research program is to understand how bloodborne parasites affect the evolutionary potential of their songbird host populations. Because genetically diverse ("outbred") hosts are thought to be able to resist a broader array of infectious disease than are more inbred individuals, one possibility (the "parasites-as-connectors" hypothesis) is that parasites promote gene flow and inbreeding avoidance, and thereby maintain high levels of host genetic diversity. Alternatively, another possibility (the "parasites-as-wedges" hypothesis) is that host adaptations to local parasites reduce gene flow between populations and promote inbreeding, resulting in the loss of host genetic diversity. To distinguish between these alternatives, my research combines intensive and long-term field study of the behaviour and ecology of wild-breeding songbirds with genetic analyses and immune challenges. A second, complementary, line of research focuses on the role of learned birdsong in connecting or in isolating populations. In songbirds, song is learned during early life and may thus reflect the singer's population of origin. This provides a potential behavioural cue for inbreeding or outbreeding. With human activities increasingly fragmenting natural habitats and isolating natural populations, it has become critical to identify and understand the factors that protect or erode genetic diversity in the wild. Predicting how parasites influence host evolution is particularly important in light of newly emerging infectious diseases associated with a changing climate.