Relationships between Genetic Variability and Niche Dimensions among Coexisting Species of Peromyscus

Abstract

Genic heterozygosity values in the four species of Peromyscus (Rodentia: Cricetidae) in this study span the range in variability known for the genus. Heterozygosity is high in populations of P. maniculatus (H̄ = 0.11 to 0.15) and low in P. boylii and P. truei (H̄ < 0.05). Peromyscus californicus is strongly differentiated at several polymorphic loci between geographically northern and southern population groups. In this species heterozygosity values vary geographically from 0.03 to 0.12, with the higher values found in the zone of contact and in southern populations. Genetic variability measured by variability in epigenetic characters is significantly correlated with the electrophoretic measure of variability. Habitat niche width was chosen as the most appropriate measure of environmental heterogeneity in these species. Neither the electrophoretic nor the epigenetic measure of genetic variability is significantly correlated with species niche width. The potential impact of geographic differentiation within a species, population patterns, and reproductive potential on levels of variability is discussed.