Tim L. King — Page 3 | USGS Science

USGS2003

Estimating black bear population density and genetic diversity at Tensas River, Louisiana using microsatellite DNA markers

The Recovery Plan for the federally threatened Louisiana black bear ( Ursus americanus luteolus ) mandates that remnant populations be estimated and monitored. In 1999 we obtained genetic material with barbed-wire hair traps to estimate bear population size and genetic diversity at the 329-km 2 Tensas River Tract, Louisiana. We constructed and monitored 122 hair traps, which produced 1,939 hair samples. Of those, we randomly selected 116 subsamples for genetic analysis and used up to 12 microsatellite DNA markers to obtain multilocus genotypes for 58 individuals. We used Program CAPTURE to compute estimates of population size using multiple mark-recapture models. The area of study was almost entirely circumscribed by agricultural land, thus the population was geographically closed. Also, study-area boundaries were biologically discreet, enabling us to accurately estimate population density. Using model Chao M h to account for possible effects of individual heterogeneity in capture probabilities, we estimated the population size to be 119 (SE=29.4) bears, or 0.36 bears/km 2 . We were forced to examine a substantial number of loci to differentiate between some individuals because of low genetic variation. Despite the probable introduction of genes from Minnesota bears in the 1960s, the isolated population at Tensas exhibited characteristics consistent with inbreeding and genetic drift. Consequently, the effective population size at Tensas may be as few as 32, which warrants continued monitoring or possibly genetic augmentation.

Louisiana↗

USGS1999

Targeted stock identification using multilocus genotype 'familyprinting'

We present an approach to stock identification of small, targeted populations that uses multilocus microsatellite genotypes of individual mating adults to uniquely identify first- and second-generation offspring in a mixture. We call the approach ‘familyprinting’; unlike DNA fingerprinting where tissue samples of individuals are matched, offspring from various families are assigned to pairs of parents or sets of four grandparents with known genotypes. The basic unit of identification is the family, but families can be nested within a variety of stock units ranging from naturally reproducing groups of fish in a small tributary or pond from which mating adults can be sampled to large or small collections of families produced in hatcheries and stocked in specific locations. We show that, with as few as seven alleles per locus using four loci without error, first-generation offspring can be uniquely assigned to the correct family. For second-generation applications in a hatchery more alleles per locus (10) and loci (10) are required for correct assignment of all offspring to the correct set of grandparents. Using microsatellite DNA variation from an Atlantic salmon ( Salmo solar ) restoration river (Connecticut River, USA), we also show that this population contains sufficient genetic diversity in sea-run returns for 100% correct first-generation assignment and 97% correct second-generation assignment using 14 loci. We are currently using first- and second-generation familyprinting in this population with the ultimate goal of identifying stocking tributary. In addition to within-river familyprinting, there also appears to be sufficient genetic diversity within and between Atlantic salmon populations for identification of ‘familyprinted’ fish in a mixture of multiple populations. We also suggest that second-generation familyprinting with multiple populations may also provide a tool for examining stock structure. Familyprinting with microsatellite DNA markers is a viable method for identification of offspring of randomly mating adults from small, targeted stocks and should provide a useful addition to current mixed stock analyses with genetic markers.

Fisheries Research↗