Genetic monitoring reveals loss of microsatellite diversity in a breeding population of the endangered Alabama red-bellied turtle

Genetic monitoring is becoming an increasingly effective tool for determining population stability in endangered species. Evaluating trends in genetic diversity allows conservation managers to identify serious declines and possible extinction risks for threatened populations. Here we used microsatellite analyses to assess the stability of one of the largest known breeding populations of the endangered Alabama red-bellied turtle Pseudemys alabamensis. A total of 238 hatchling specimens were collected over a 9 yr period and analyzed using 6 microsatellite loci. We found no indication of genetic structure within the sample group, indicating that these specimens represent the reproductive output of a single turtle population over 9 consecutive breeding seasons. Measures of genetic diversity, including FST values, expected heterozygosity, allelic richness, private allelic richness, and level of inbreeding, were calculated in order to assess the stability of the population over the 9 yr study period. We detected the impacts of genetic drift within the population as a significant change in allele frequencies (FST) over the study period. We also observed a significant level of inbreeding within this population. We estimated the average effective number of breeders over the study period as Nb = 25, indicating a low number of mature adults contributing to reproductive output each year. Results signal a possible decline in population numbers of Alabama red-bellied turtles and may be critical in assessing current and future conservation measures for this endangered species.