The Northern Flicker Hybrid Zone

北极光是研究物种形成进化过程的一个模型。两个相当不同的亚种的活动范围在大平原西部重叠，在那里它们形成了一个广泛的杂交带。尽管这两个亚种进行了广泛的杂交，但亚种的独特性仍然保持着。先前的研究强烈表明，选择是在杂交区维持两个亚种特征的主要力量。目前的研究旨在确定自然选择和性选择哪个更重要。自然选择将以与杂交区相关的生态变量的形式出现，而性选择将反映亚种在其原生范围之外建立繁殖区域的能力。解决这些问题将促进我们对物种形成过程的理解，以及如此多的物种多样性是如何在如此短的时间内进化的。

The Northern Flicker serves as a model for studies on the evolutionary process of speciation. The ranges of two rather distinct subspecies overlap on the western Great Plains where they form an extensive hybrid zone. The distinctness of the subspecies is maintained even though the two hybridize extensively. Previous work strongly suggests that selection is a major force in maintaining the characteristics of the two subspecies across the hybrid zone. Current research is designed to determine whether natural selection or sexual selection is most important. Natural selection would be in the form of ecological variables associated with the hybrid zone whereas sexual selection would reflect the ability of the subspecies to establish breeding territories outside of their native ranges. Resolving these questions will advance our understanding of how speciation occurs and how so much diversity evolves in such a short time.