Gene flow in Anna's Hummingbird (Calypte anna)

Anthropogenic changes have altered the historical distributions of many North American taxa. As environments shift, ecological and evolutionary processes can combine in complex ways to either stimulate or inhibit range expansion. Here we examine the role of evolution in a rapid range expansion whose ecological context has been well-documented, Anna's Hummingbird (Calypte anna). We examine the role of gene flow and adaptation during range expansion from their native California breeding range, north into Canada and east into New Mexico and Texas, USA. Contemporary shifts in species' ranges provide an opportunity to examine the factors defining range limits in real time.

人为活动改变了诸多北美类群的历史分布格局。随着环境不断变迁，生态过程与演化过程可通过复杂的组合方式，对物种的分布范围扩张起到促进或抑制作用。本研究以安氏蜂鸟（*Calypte anna*）为研究对象，该物种的快速分布范围扩张事件的生态背景已被充分记录，我们在此探讨演化在该过程中所发挥的作用。具体而言，我们将解析该物种从原生繁殖地加利福尼亚出发，向北扩散至加拿大、向东扩散至美国新墨西哥州与得克萨斯州的范围扩张过程中，基因流与适应性演化所起到的关键作用。当前的物种分布范围变迁，为我们实时探究界定物种分布边界的核心影响因素提供了绝佳的研究契机。