Systematics and phylogeography of North American <italic>Myotis</italic> (Chiroptera: Vespertilionidae).

Abstract

The bat genus <italic>Myotis</italic> is the most diverse mammalian genus. With over 100 species worldwide, <italic>Myotis</italic> represents 10% of total bat species richness. Much remains to be understood about this important group of bats, despite their species richness in northern temperate regions and extensive research on aspects of the ecology of a few <italic> Myotis</italic> species. The goals of this research are to better understand the evolutionary history of a group of <italic>Myotis</italic> species, from a continent-wide study of relationships and cryptic variation among North American <italic>Myotis</italic>, to the dynamics of intraspecific population structure in a habitat specialist, <italic>M. evotis</italic>. Lack of morphological diversity in <italic>Myotis</italic> means that molecular data are especially important for testing historical relationships. Mitochondrial data are used in both phylogenetic and population genetic frameworks to test patterns of relationship among species and to test for expected population genetic patterns resulting from historical demographic changes. Dense intra-specific sampling makes it possible to critically test (1) the alpha taxonomy of North American species, and (2) intra-specific genetic patterns across a large and varied landscape, western North America. Results indicate that morphological similarity among <italic>Myotis</italic> species is not a reliable indicator of relatedness. The dynamism of <italic> Myotis</italic> evolutionary history is under-appreciated because of extensive morphological similarities among species. Within the western long-eared <italic> Myotis</italic> group, however, including their close relatives, three cryptic lineages of <italic>M. lucifugus</italic> (<italic>M. l. alascensis, M. l. carissima</italic>, and <italic>M. l. relictus</italic>), there is also evidence of the potential for rapid morphological change. This group represents a recent, rapid divergence into three distinct morphologies specialized for exploiting different ecological spaces. Finally, the habitat specialization and widespread western distribution of <italic>M. evotis</italic>, coupled with their relatively low levels of vagility, result in patterns of population differentiation that are both predicted by previous work in other taxa, and unexpected. Functional constraints evident in morphological evolution in <italic>Myotis</italic>, and patterns of population structure in western North American <italic>Myotis </italic>, serve as models for study in other groups with similar constraints or distributions.