Abstract. If phylogeographic studies are to be broadly used for assessing population-level processes relevant to speciation and systematics, the ability to identify and incorporate instances of hybridization into the analytical framework is essential. Here, we examine the evolutionary history of two chipmunk species, Tamias ruficaudus and Tamias amoenus, in the northern Rocky Mountains by integrating multivariate morphometrics of bacular (os penis) variation, phylogenetic estimation, and nested clade analysis with regional biogeography. Our results indicate multiple examples of mitochondrial DNA introgression layered within the evolutionary history of these nonsister species. Three of these events are most consistent with recent and/or ongoing asymmetric introgression of mitochondrial DNA across morphologically defined secondary contact zones. In addition, we find preliminary evidence where a fourth instance of nonconcordant characters may represent complete fixation of introgressed mitochondrial DNA via a more ancient hybridization event, although alternative explanations of convergence or incomplete sorting of ancestral polymorphisms cannot be dismissed with these data. The demonstration of hybridization among chipmunks with strongly differentiated bacular morphology contradicts long-standing assumptions that variation within this character is diagnostic of complete reproductive isolation within Tamias. Our results illustrate the utility of phylogeographic analyses for detecting instances of reticulate evolution and for incorporating this and other information in the inference of the evolutionary history of species.

If phylogeographic studies are to be broadly used for assessing population-level processes relevant to speciation and systematics, the ability to identify and incorporate instances of hybridization into the analytical framework is essential. Here, we examine the evolutionary history of two chipmunk species, Tamias ruficaudus and Tamias amoenus, in the northern Rocky Mountains by integrating multivariate morphometrics of bacular (os penis) variation, phylogenetic estimation, and nested clade analysis with regional biogeography. Our results indicate multiple examples of mitochondrial DNA introgression layered within the evolutionary history of these nonsister species. Three of these events are most consistent with recent and/or ongoing asymmetric introgression of mitochondrial DNA across morphologically defined secondary contact zones. In addition, we find preliminary evidence where a fourth instance of nonconcordant characters may represent complete fixation of introgressed mitochondrial DNA via a more ancient hybridization event, although alternative explanations of convergence or incomplete sorting of ancestral polymorphisms cannot be dismissed with these data. The demonstration of hybridization among chipmunks with strongly differentiated bacular morphology contradicts long-standing assumptions that variation within this character is diagnostic of complete reproductive isolation within Tamias. Our results illustrate the utility of phylogeographic analyses for detecting instances of reticulate evolution and for incorporating this and other information in the inference of the evolutionary history of species.

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Karyotypes of 15 species of African Chiroptera (Epomops jranqueti, Epornophorus crypturus, E. gambianus, E. wahlbergi, Nycteris thebaica, Hipposideros caffer, Rhinolophus hildebrandti, R. darlingi, R. denti, Pipistrellus nanus, Eptesicus hottentotus, E. capensis, Scotophilus nigrita, Tadarida bivittata, and T. fulminans) were studied. An XO male sex chromosome system was discovered in E. crypturus and E. gambianus. Distinctive marker chromosomes occurred in 14 species. [Karyotypes; Chiroptera; Africa; Kenya; Rhodesia] Introduction-Data on chiropteran karyotypes were reviewed by Baker (1970) and Capanna and Civitelli (1970). Nonetheless, karyotypic data for African Chiroptera are few. Our purpose here is to describe the chromosomes of 15 species of African bats representing six families and briefly to compare results with known karyotypic data of related species (Table 1). The karyological material was obtained by the senior author during field studies in Kenya and Rhodesia in 1972. Materials and Methods-Slides of somatic chromosomes were prepared using the in vivo bone marrow technique described by Baker (1970). Although some slides were stained in the field, most were stained in the laboratory. Metaphase spreads were photographed with Kodak High Contrast Copy film 5069 using a Reichert Zetopan photomicroscope at a magnification of 630 x under oil immersion. To determine the diploid number (2N), a minimum of 12 spreads was counted for each specimen. Nomenclature for chromosomal morphology is that of Patton (1967). Fundamental number (FN) is defined as the number of autosomal arms. Metacentric, submetacentric, and subtelocentric chromosomes are assigned a value of two, and acrocentrics a value of one. Because chromosome morphology may vary in metaphase spreads as a result of different degrees of chromosome contraction, karyotypes presented in the figures may not correspond exactly to descriptions in the text. The descriptions of karyotypes and fundamental number of each species were based on photographs of a minimum of four but

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