title: Introgression and dispersal among spotted owl (Strix occidentalis) subspecies.
abstract: Population genetics plays an increasingly important role in the conservation and management of declining species, particularly for defining taxonomic units. Subspecies are recognized by several conservation organizations and countries and receive legal protection under the US Endangered Species Act (ESA). Two subspecies of spotted owls, northern (Strix occidentalis caurina) and Mexican (S. o. lucida) spotted owls, are ESA-listed as threatened, but the California (S. o. occidentalis) spotted owl is not listed. Thus, determining the boundaries of these subspecies is critical for effective enforcement of the ESA. We tested the validity of previously recognized spotted owl subspecies by analysing 394 spotted owls at 10 microsatellite loci. We also tested whether northern and California spotted owls hybridize as suggested by previous mitochondrial DNA studies. Our results supported current recognition of three subspecies. We also found bi-directional hybridization and dispersal between northern and California spotted owls centered in southern Oregon and northern California. Surprisingly, we also detected introgression of Mexican spotted owls into the range of northern spotted owls, primarily in the northern part of the subspecies' range in Washington, indicating long-distance dispersal of Mexican spotted owls. We conclude with a discussion of the conservation implications of our study.
authors.affiliation: US Geological Survey, Forest and Rangeland Ecosystem Science Center Corvallis, OR, USA.
authors.forename: W Chris
authors.initials: WC
authors.lastname: Funk
authors.affiliation: USDA Forest Service, Pacific Northwest Research Station Corvallis, OR, USA.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Forsman
authors.affiliation: US Geological Survey, Forest and Rangeland Ecosystem Science Center Corvallis, OR, USA.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Mullins
authors.affiliation: US Geological Survey, Forest and Rangeland Ecosystem Science Center Corvallis, OR, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Haig
keywords: Strix occidentalis; US Endangered Species Act; conservation; introgression; long-distance dispersal; microsatellites; spotted owl; subspecies