You are here:
NO REDUCTION IN GENETIC DIVERSITY DESPITE RAPID ADAPTATION IN PCB POLLUTION: IMPLICATIONS FOR CONSERVATION OF LARGE ESTUARINE POPULATIONS
Citation:
McMillan, A., M J. Bagley, D Nacci, AND S A. Christ. NO REDUCTION IN GENETIC DIVERSITY DESPITE RAPID ADAPTATION IN PCB POLLUTION: IMPLICATIONS FOR CONSERVATION OF LARGE ESTUARINE POPULATIONS. Presented at Society for Conservation Biology, Duluth, MN, June 28-July 2, 2003.
Impact/Purpose:
The objective of this task is to develop molecular indicators to evaluate the integrity and sustainability of aquatic fish, invertebrate, and plant communities (GPRA goal 4.5.2). Specifically, this subtask aims to evaluate methods for the measurement of:
fish and invertebrate community composition, especially for morphologically indistinct (cryptic) species
population genetic structure of aquatic indicator species and its relationship to landscape determinants of population structure (to aid in defining natural assessment units and to allow correlation of population substructure with regional stressor coverages)
genetic diversity within populations of aquatic indicator species, as an indicator of vulnerability to further exposure and as an indicator of cumulative exposure
patterns of temporal change in genetic diversity of aquatic indicator species, as a monitoring tool for establishing long-term population trends.
Description:
Anthropogenic stressors can have negative fitness impacts on populations by reducing population size through direct mortality or reduced reproduction. Evolutionary consequences of pollutants are inevitable if genetic diversity and structure are changed as a result of these impacts. We evaluated the genetic structure and diversity of Fundulus heteroclitus, a non-migratory fish found in abundance in estuaries along the east coast of the U.S., including a PCB-contaminated superfund site in New Bedford Harbor (NBH), MA. Laboratory challenge experiments showed F. heteroclitus from NBH are adapted to high PCB levels while fish from uncontaminated sites are not. These results suggest that strong divergence has occurred in response to recent anthropogenic changes and has been maintained among populations with potentially high gene flow. We used AFLP analysis to determine whether genetic variability of tolerant F. heteroclitus populations in NBH is reduced relative to populations residing in less contaminated sites and to estimate the degree of genetic differentiation between populations with different sensitivities to PCBs. F. heteroclitus populations were differentiated at local scales but genetic diversity was not reduced in PCB adapted populations. Demographic factors, including large population sizes and high fecundity rates, appear to be the primary causes for these results.