PARENT SESSION
Ecological Risk Assessment Poster Session.
Monday, November 13, 2000
1:20 PM to 5:20 PM
CC West/Center Exhibit Hall
(PMP047) Comparison of genetic diversity and its role in survival of mosquitofish acutely exposed to copper.
Schlueter, Mark A.1, 1
ABSTRACT- Several studies have examined the role of a specific toxicants on the differential survival and genetic diversity of populations. However, few studies have compared and contrasted the patterns of differential survival, genetic diversity, and resistant/sensitive genotypes among different wild populations when exposed to a toxicant. In the present study, mosquitofish (Gambusia affinis) were collected from four different sites varying in water quality. These four different populations were then simultaneously exposed to 4 mg/ml of copper over a 96 hour period. This resulted in a mortality rate of over 90% for each population. Horizontal starch gel electrophoresis was used to determine the genotypes at several enzyme loci. Six enzymes (GPI-1*, GPI-2*, IDHP-1*, IDHP-2*, MDH-1*, MDH-2*, and PGM-2*) were found to be variable. Significant differences in population genetic structure were detected among populations. In particular, GPI-1*, GPI-2*, and MDH-2* differed significantly. Statistical analyses were used to evaluate the relationships between genetic data and weight, length, and time-to-death (TTD) of fish using an accelerated failure time regression model (LIFEREG). MDH-2* and PGM-2* were found to be significantly related to TTD. Larger fish had a longer TTD and a greater chance of survival. Similar patterns of survival related to genotypes were observed among populations. The results of this study indicate that differential survival to copper is genetically related. Different populations have different genetic structures which may affect their ability to survive to future environmental contaminants. Similar survivorship patterns of resistant and sensitive genotypes of several enzymes existed in these populations. These enzymes may serve as an effective biomarker of past or current toxicant stress.
Key words: Allozyme electrophoresis, Gambusia affinis, Regression model, Weight effects