Phylogeography and genetic structure of northern populations of the yellowwarbler (Dendroica petechia)

Phylogeographic patterns of intraspecific variation can provide insights in to the population-level processes responsible for speciation and yield info rmation useful for conservation purposes. To examine phylogeography and pop ulation structure in a migratory passerine bird at both continental and reg ional geographical scales, we analysed 344 bp of mitochondrial DNA (mtDNA) control region sequence from 155 yellow warblers (Dendroica petechia) colle cted from seven locations across Canada and from Alaska. There is a major s ubdivision between eastern (Manitoba to Newfoundland) and western (Alaska a nd British Columbia) populations which appears to have developed during the recent Pleistocene. Some localities within these two regions also differ s ignificantly in their genetic composition, suggesting further subdivision o n a regional geographical scale. Eastern and western birds form distinct ph ylogeographic entities and the clustering of all western haplotypes with tw o eastern haplotypes suggests that the western haplotypes may be derived fr om an eastern lineage. Analyses based on coalescent models support this exp lanation for the origin of western haplotypes. These results are consistent with important features of Mengel's model of warbler diversification. From a conservation perspective they also suggest that individual populations o f migrant birds may form demographically isolated management units on a sma ller scale than previously appreciated.