J.D. Ballou | USGS Science

USGS2008

Identification of kin structure among Guam rail founders: A comparison of pedigrees and DNA profiles

Kin structure among founders can have a significant effect on subsequent population structure. Here we use the correlation between DNA profile similarity and relatedness calculated from pedigrees to test hypotheses regarding kin structure among founders to the captive Guam rail ( Rallus owstoni ) population. Five different pedigrees were generated under the following hypotheses: (i) founders are unrelated; (ii) founders are unrelated except for same-nest chicks; (iii) founders from the same major site are siblings; (iv) founders from the same local site are siblings; and (v) founders are related as defined by a UPGMA cluster analysis of DNA similarity data. Relatedness values from pedigrees 1, 2 and 5 had the highest correlation with DNA similarity but the correlation between relatedness and similarity were not significantly different among pedigrees. Pedigree 5 resulted in the highest correlation overall when using only relatedness values that changed as a result of different founder hypotheses. Thus, founders were assigned relatedness based on pedigree 5 because it had the highest correlations with DNA similarity, was the most conservative approach, and incorporated all field data. The analyses indicated that estimating relatedness using DNA profiles remains problematic, therefore we compared mean kinship , a measure of genetic importance, with mean DNA profile similarity to determine if genetic importance among individuals could be determined via use of DNA profiles alone. The significant correlation suggests this method may provide more information about population structure than was previously thought. Thus, DNA profiles can provide a reasonable explanation for founder relatedness and mean DNA profile similarity may be helpful in determining relative genetic importance of individuals when detailed pedigrees are absent.

Guam↗

USGS2003

Genetic variation in natural and translocated populations of the endangered Delmarva fox squirrel (Sciurus niger cinereus)

The Delmarva fox squirrel, Sciurus niger cinereus , is a federally listed endangered subspecies whose range has been reduced by 90%. In an attempt to increase both population size and range, translocation sites were established beginning in the 1960's by moving squirrels from the natural range to sites outside the current range. Although translocations have served as the primary component of the DFS recovery program, there has been very little post-release examination of the genetics of the translocation sites. In this study, we developed ten microsatellite loci, screened the three polymorphic loci, and sequenced a 330 bp fragment of the mitochondrial control region in order to assess levels of genetic variation in natural and translocated regions of Delmarva fox squirrels and to compare them to Southeastern fox squirrels ( S. n. niger ). Although we found low levels of microsatellite polymorphism, there were no differences in heterozygosity between natural and translocated regions, or between Delmarva and Southeastern fox squirrels. We found high levels of polymorphism in the mitochondrial control region. Our patterns of haplotype diversity suggest incomplete lineage sorting of the two subspecies. In general, our data suggest that the current levels of genetic variation in the translocated sites are representative of those found in the natural population, and we encourage the continued use of translocations as a major component of Delmarva fox squirrel recovery.

Conservation Genetics↗