ABSTRACT
Abstract. Hybridization between some pairs of closely related taxa is increasing due to anthropogenic factors such as habitat destruction and fragmentation, as well as an introduction of exotics. Outcomes of hybridization vary according to the species involved. With the advancement in molecular techniques in recent years, it is now possible to examine hybridization with far greater precision and to more fully understand hybridization systems and relationships between species. A better understanding of patterns and process can be used to inform appropriate conservation actions. Hybridization between Golden-winged Warblers (Vermivora chrysoptera) and Blue-winged Warblers (V. cyanoptera) has been ongoing for at least the past 140 years and is thought to be a primary cause of recent declines of Golden-winged Warblers in populations throughout their breeding
distribution. Here, we summarize the current knowledge of the genetics of this hybridization system. Specically, recent analyses demonstrated extensive introgression in populations of Goldenwinged Warblers throughout their breeding distribution, and bidirectional gene ow in almost all surveyed populations. To date, the use of mitochondrial genetic markers has provided the best resolution for understanding the warbler hybridization system, and a need for informative nuclear markers remains. We conclude with suggested avenues for future genetic research to increase understanding of hybridization, and to guide conservation management for Golden-winged Warblers.
