Genetic and demographic responses of mosquitofish (Gambusia holbrooki) populations exposed to mercury for multiple generations
Genetic and demographic responses of mosquitofish were examined after multiple generations of exposure to mercury. Previous studies of acute lethal exposures of mosquitofish to either mercury or arsenic demonstrated a consistent correlation between time to death and genotype at the glucosephosphate isomerase-2 (Gpi-2) locus. A mesocosm study involving mosquitofish populations exposed to mercury for 111 d showed significant female sexual selection and fecundity selection at the Gpi-2 locus. Here the mesocosm study was extended to populations exposed to mercury for several (approx. four) generations. After 2 years, control and mercury-exposed populations met Hardy-Weinberg expectations and showed no evidence of genetic bottlenecks. The mean number of heterozygous loci did not differ significantly between the mercury-exposed and control populations. Significant differences in allele frequencies at the Gpi-2 locus were observed between the mercury-exposed and control populations. Relative to the initial and control allele frequencies, the GPI-2{sup 100} allele frequency was lower, the Gpi-2{sup 66} allele frequency increased, but the Gpi-2{sup 38} allele frequency did not change in mercury-exposed populations. No significant differences were found in standard length, weight, sex ratio, or age class ratio between the control and mercury-exposed populations. Allele frequency changes at the Gpi-2 locus suggest population-level response to chronic mercury exposure. Changes in allele frequency may be useful as indicators of population response to contaminants, provided that the population in question is well understood.
- Research Organization:
- Univ. of Georgia, Savannah River Ecology Lab., Aiken, SC (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FC09-96SR18546
- OSTI ID:
- 20012781
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 18, Issue 12; Other Information: PBD: Dec 1999; ISSN 0730-7268
- Country of Publication:
- United States
- Language:
- English
Similar Records
Allozyme genotype in mosquitofish, Gambusia holbrooki, during mercury exposure: Temporal stability, concentration effects and field verification
Allozyme genotypic indicators of adaptive responses in contaminant-exposed populations: Consistency among fish species and contaminants