Data from: Does population size affect genetic diversity? A test with sympatric lizard species

Genetic diversity is a fundamental requirement for evolution and
adaptation. Nonetheless, the forces that maintain patterns of genetic
variation in wild populations are not completely understood. Neutral
theory posits that genetic diversity will increase with a larger effective
population size and the decreasing effects of drift. However, the lack of
compelling evidence for a relationship between genetic diversity and
population size in comparative studies has generated some skepticism over
the degree that neutral sequence evolution drives overall patterns of
diversity. The goal of this study was to measure genetic diversity among
sympatric populations of related lizard species that differ in population
size and other ecological factors. By sampling related species from a
single geographic location, we aimed to reduce nuisance variance in
genetic diversity owing to species differences, for example, in mutation
rates or historical biogeography. We compared populations of zebra-tailed
lizards and western banded geckos, which are abundant and short-lived, to
chuckwallas and desert iguanas, which are less common and long-lived. We
assessed population genetic diversity at three protein-coding loci for
each species. Our results were consistent with the predictions of neutral
theory, as the abundant species almost always had higher levels of
haplotype diversity than the less common species. Higher population
genetic diversity in the abundant species is likely due to a combination
of demographic factors, including larger local population sizes (and
presumably effective population sizes), faster generation times and high
rates of gene flow with other populations.