Effective number of breeding adults in Oregon spotted frogs (Rana pretiosa): genetic estimates at two life stages
2010
Phillipsen, Ivan C | Bowerman, Jay | Blouin, Michael
We used genetic methods to estimate the effective number of breeders (N b) in a population of Rana pretiosa, an imperiled amphibian in western North America. Microsatellite data was gathered from large samples of adults, eggs, and juveniles collected in 2006. We wished to determine where in the life cycle the greatest reductions in N b occur, and to compare genetic estimates of N b to an egg mass count estimate of the number of breeding adults. We predicted that N b estimated at the metamorph stage would be reduced by increased variance in family size due to egg mass mortality. Contrary to our prediction, estimates of N b at the egg and metamorph stages were similar. Thus, we found no evidence of inflated variance in family size between the two stages. If our results for this population are typical for R. pretiosa, then increased variance in family size during the egg to metamorph stage may not be a strong factor in reducing the effective population sizes (N e) relative to the census sizes (N) in this species.
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