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DEVELOPMENT OF A DNA ARCHIVE FOR GENETIC MONITORING OF FISH POPULATIONS
Citation:
Bagley, M J., S E. Franson, T K. Wessendarp, S A. Christ, J M. Lazorchak, G P. Toth, AND M K. Smith. DEVELOPMENT OF A DNA ARCHIVE FOR GENETIC MONITORING OF FISH POPULATIONS. Presented at Society of Environmental Toxicology and Chemistry, Nashville, TN, November 12-16, 2000.
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:
Analysis of intraspecific genetic diversity provides a potentially powerful tool to estimate the impacts of environmental stressors on populations. Genetic responses of populations to novel stressors include dramatic shifts in genotype frequencies at loci under selection (i.e. adaptation) as well as large reductions in genetic diversity within populations at both neutral and selected loci (due to reduced effective population sizes). Typically inferences of genetic change are made through comparison of contemporaneous samples taken from spatially separated populations, some of which are treated as stressor-exposed "test" populations while others are treated as unexposed "reference" populations. In effect, these "genetic snapshots" are surrogates for more costly and logistically difficult temporal or spatio-temporal studies. The difficulty with the genetic snapshot approach is that the degree of genetic and ecological independence between test and reference populations, including the levels and types of past exposures, is rarely known with any accuracy. We believe that studies that directly measure genetic change within populations over time are critical to effective utilization of genetic markers and that the associated cost and logistical difficulties can be overcome if the proper infrastructure is provided. To aid in providing the necessary baseline, the USEPA created and maintains a DNA and fin-tissue archive for freshwater and estuarine fish. Access to the archive is open, and deposits by non-EPA investigators and institutions are encouraged. Current plans include creation of a web-accessible database of DNA collections cross-referenced to available phenotypic, enviornmental, and genetic data. Anticipated benefits of the archive include facilitation of some of the first studies designed to assess the evolutionary responses of populations to local, regional and global environmental change.