Phylogeography of chestnut-backed chickadees in western North America

Abstract

This chapter assesses the biogeography of chestnut-backed chickadees using microsatellite analysis, providing alternative scenarios for the glacial refugia and dispersal patterns that could explain the present distribution of distinct, genetic populations. This chapter also considers the potential for hybridization within the brown-capped chickadees to contribute to differentiation among disjunct populations within the chestnut-backed chickadees of northwestern Canada and Alaska. The factors influencing contemporary patterns of population structure in chestnut-backed chickadees are considered, including historical range expansion and geographic distribution, while potential barriers to dispersal are discussed. The patterns found in this western North American species are compared to those of other North American and Eurasian Parids. The population structure of chestnut-backed chickadees, and that of other Parids, appears to be complex and influenced by a variety of factors, most notably postglacial colonization and distribution. Many of the factors limiting dispersal in chestnut-backed chickadees seem to be common in other Parids. These include isolation of peripheral populations, and limited dispersal over large water barriers or other areas of unsuitable habitat.