Hl. Gibbs et Pj. Weatherhead, Insights into population ecology and sexual selection in snakes through the application of DNA-based genetic markers, J HEREDITY, 92(2), 2001, pp. 173-179
Hypervariable genetic markers have revolutionized studies of kinship, behav
ioral ecology, and population biology in vertebrate groups such as birds, b
ut their use in snakes remains limited. To illustrate the value of such mar
kers in snakes, we review studies that have used microsatellite DNA loci to
analyze local population differentiation and parentage in snakes. Four eco
logically distinct species of snakes all show evidence for differentiation
at small spatial scales (2-15 km), but with substantial differences among s
pecies. This result highlights how genetic analysis can reveal hidden aspec
ts of the natural history of difficult-to-observe taxa, and it raises impor
tant questions about the ecological factors that may contribute to restrict
ed gene flow. A 3-year study of genetic parentage in marked populations of
the northern water snake showed that (1) participation in mating aggregatio
ns was a poor predictor of genetic-based measures of reproductive success;
(2) multiple paternity was high, yet there was no detectable fitness advant
age to multiple mating by females; and (3) the opportunity for selection wa
s far higher in males than in females due to a larger variance in male repr
oductive success, and yet this resulted in no detectable selection on morph
ological variation in males. Thus genetic markers have provided accurate me
asures of individual reproductive success in this species, an important ste
p toward resolving the adaptive significance of key features including mult
iple paternity and reversed sexual size dimorphism, Overall these studies i
llustrate how genetic analyses of snakes provide previously unobtainable in
formation of long-standing interest to behavioral ecologists.