Review of DNA-based census and effective population size estimators

The detection of reductions in effective population size (N-e) or census size (N-c) is essential for conservation. Recent developments allow wildlife researchers to obtain genetic material via non-invasive sampling techniques that may provide the large sample sizes necessary for precise estimates of N-e and N-c. Population genetic theory provides several methods to estimate N-e from allele frequency data: including temporal change in allele frequencies, gametic disequilibrium and heterozygote excess methods. Modification of capture-mark-recapture methods for use with multi-locus genotype data provides new means for estimating N-c. The combination of new DNA sampling techniques, polymerase chain reaction-based DNA markers and analytical methods may provide unprecedented power to detect reductions in N-e and N-c of endangered populations. However, these genetic methods are largely untested in the field. We review some relatively unexplored, but promising ways that multi-locus genetic data can be used to provide important genetic and demographic information and suggest avenues for further research in this area.