|SREL Reprint #1964|
GENETIC AND DEMOGRAPHIC RESPONSES OF
MOSQUITOFISH (GAMBUSIA HOLBROOKI GIRARD
1859) POPULATIONS STRESSED BY MERCURY
Abstract - Genetic and demographic changes in mosquitofish populations are
reported after chronic (111 d) exposure to mercury. Sex ratios, normally
female-biased in field populations, were also female-biased in control mesocosms.
However, the sex ratio was male-biased in the mercury treatments. Frequencies of
glucosephosphate isomerase-2 (Gpi-2) allozymes for fish exposed to mercury
differed from initial frequencies and from those of control fish. In a
selection-component analysis, female sexual selection was statistically significant
for the mercury-treated fish; the proportion of females that were gravid differed
among Gpi-2 genotypes. The number of developing embryos per female also
differed among Gpi-2 genotypes. Mercury had genotype-specific effects on
mosquitofish reproduction in addition to genotype-specific effects on mortality
reported earlier. These effects may reflect metabolic qualities of the Gpi-2
genotypes or loci closely linked to the Gpi-2 locus.
SREL Reprint #1964
Mulvey, M., M.C. Newman, A. Chazal, M.G. Heagler, and L.S. Hales Jr. 1995. Genetic and demographic responses of mosquitofish (Gambusia holbrooki Girard 1859) populations stressed by mercury. Environmental Toxicology and Chemistry 14:1411-1418.