Karyotypic variation in populations of deer mice (Peromyscus maniculatus) from the northeastern United States and eastern Canada

Abstract

Karyotypic analyses are provided for five previously uncharacterized subspecies of deer mice (Peromyscus maniculatus) from the northeastern United States and eastern Canada. Nondifferentially-stained, G-banded and C-banded karyotypes were analyzed in order to determine the karyotypic variation within and among these populations. All individuals had a diploid number of 48, but variation in the number of autosomal arms ranged from 80 to 86. These differences are due to pericentric inversions (chromosomes 8 and 19) and/or the presence of heterochromatic chromosomal arms (chromosomes 8, 10, 12 and 19). Among deer mice for which data on chromosomal homology are available, the populations in this study are unique in being characterized by the plesiomorphic condition of chromosome 10. All previous chromosome-banding studies of P[ ] maniculatus report data for geographically central or western populations and indicate the pericentric inversion-derived and biarmed condition of chromosome 10. As the plesiomorphic condition of chromosome 10 appears to be restricted to northeastern populations of P. maniculatus, the morphology of chromosome 10 potentially represents a simple and discrete character for resolving the historically problematic question of the specific status of the grassland-and forest-dwering morophotypes of the northeastern deer mice.