The Relationship Between Genome Size and Genetic Variation

Abstract

A strong negative relationship is demonstrated between the amount of variation in structural genes and the amount of nuclear DNA in salamanders. Significant correlations are seen in a group of 14 species of salamanders from seven families and among 15 species from a single genus. The limited evidence available suggests that this relationship may exist in other organisms. In salamanders, interspecific differences in amount of DNA appear to be due primarily to differences in amounts of repetitive DNA. One possible explanation for this phenomenon is that as potential for diversity at regulatory genes increases, selection for variation in structural genes decreases, leading to a negative correlation between genome size and variation in structural genes.