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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

An Evaluation of Population Differentiation for Two Anurans (Rana luteiventris and Hyla regilla): The Limits of Genetic Inference

EPA Grant Number: U914713
Title: An Evaluation of Population Differentiation for Two Anurans (Rana luteiventris and Hyla regilla): The Limits of Genetic Inference
Investigators: Call, Douglas R.
Institution: Washington State University
EPA Project Officer: Broadway, Virginia
Project Period: January 1, 1995 through January 1, 1997
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1995)
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology

Description:

Objective:

The main objectives of this research project were to: (1) develop seven microsatellite markers; and (2) study their frequency distributions in eight Rana luteiventris (three loci) and three Hyla regilla (four loci) populations.

Approach:

Allele sizes appeared to conform to a stepwise mutation model, except 11 percent of allele differences probably resulted from larger mutations. Most loci were in Hardy-Weinberg equilibrium, although there was evidence of null alleles for three R. luteiventris loci. Significant regressions of M on geographic distance (P < 0.001) suggested a neighborhood size of 19 to 274 frogs for R. luteiventris populations. Using these estimates with models for effective population size, the mutation rate was estimated to be near 10-3. New statistics derived specifically for microsatellite data appear to have higher variances than estimators based on an infinite allele model.

A multilocus detection method for measuring microsatellite variation simultaneously at many loci was investigated. This technique reveals a series of alleles within a restriction fragment profile, but potential measurement errors require grouping alleles of similar size into bins. Mean band sharing and heterozygosity were highly correlated (r = -0.99), and the former increased continuously with increasing bin width. Replicate gels were used to calibrate a binning algorithm and significant differentiation between R. luteiventris (n = 5) and H. regilla (n = 2) populations (P less than or equal to 0.008) was found, which was consistent with results from single-locus markers. Contrary to published findings, band-sharing statistics do not exhibit excessive levels of covariance.

Supplemental Keywords:

fellowship, microsatellite markers, band sharing, bin width, frequency distributions, single-locus markers, microsatellite variation., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Monitoring/Modeling, Environmental Monitoring, Ecology and Ecosystems, monitoring, biomarkers, allele model, genotypes, population models, amphibian population

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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