Genetic Variation and Differentiation in the Spotted Owl (Strix occidentalis)

Abstract

We used starch-gel electrophoresis to investigate genetic variability at 23 loci in 107 individuals from seven populations of the Spotted Owl (Strix occidentalis). These populations sample all three currently recognized subspecies. No genetic variation was found in six populations from Oregon and California. Average heterozygosity in owls from New Mexico was 0.022. The low level of genetic variability will make it more difficult to monitor the genetics of this threatened species; the paucity of variation is possibly due to a small overall effective population size or bottlenecks in the past. At one locus there was a major allelic frequency difference between the Pacific Coast populations (S. o. caurina and S. o. occidentalis) and the allopatric taxon (S. o. lucida) found in New Mexico; our estimate of F_ST is 0.55. We believe the two allopatric populations have long been isolated, and it is probable that they represent two species. The data do not help elucidate the subspecific status of S. o. caurina.