Hybrid Breakdown and Cellular-DNA Content in a Contact Zone between Two Species of Pocket Gophers (Geomys)

Abstract

DNA content and coefficients of variation surrounding mean values were examined in 35 individuals from a contact zone between Geomys bursarius major and G. knoxjonesi in New Mexico. Three classes of individuals (parental types and hybrids) from the contact zone were compared to reference samples from outside the contact zone. No significant differences were found in either DNA content or in individual coefficients of variation among any of the five classes examined. Comparison of data from Peromyscus leucopus and pocket gophers documents that hybrid breakdown in cellular-DNA content is not correlated with magnitude of chromosomal, allozymic, and mitochondrial-DNA, or ribosomal-DNA differentiation that distinguishes parental types. Mechanisms that maintain the integrity of the respective gene pools of G. b. major and G. knoxjonesi are not associated with differences in mean DNA content or with variation in quantity of DNA among cells of an individual.