Accurate knowledge of geographic ranges and genetic relationships among populations is important when managing a species or population of conservation concern. Along the western coast of Canada, a subspecies of the northern goshawk ( Accipiter gentilis laingi ) is legally designated as Threatened. The range and distinctness of this form, in comparison with the broadly distributed North American subspecies ( Accipiter gentilis atricapillus ), is unclear. Given this morphological uncertainty, we analyzed genomic relationships in thousands of single nucleotide polymorphisms identified using genotyping‐by‐sequencing of high‐quality genetic samples. Results revealed a genetically distinct population of northern goshawks on the archipelago of Haida Gwaii and subtle structuring among other North American sampling regions. We then developed genotyping assays for ten loci that are highly differentiated between the two main genetic clusters, allowing inclusion of hundreds of low‐quality samples and confirming that the distinct genetic cluster is restricted to Haida Gwaii. As the laingi form was originally described as being based on Haida Gwaii (where the type specimen is from), further morphological analysis may result in this name being restricted to the Haida Gwaii genetic cluster. Regardless of taxonomic treatment, the distinct Haida Gwaii genetic cluster along with the small and declining population size of the Haida Gwaii population suggests a high risk of extinction of an ecologically and genetically distinct form of northern goshawk. Outside of Haida Gwaii, sampling regions along the coast of BC and southeast Alaska (often considered regions inhabited by laingi ) show some subtle differentiation from other North American regions. These results will increase the effectiveness of conservation management of northern goshawks in northwestern North America. More broadly, other conservation‐related studies of genetic variation may benefit from the two‐step approach we employed that first surveys genomic variation using high‐quality samples and then genotypes low‐quality samples at particularly informative loci.

Accurate knowledge of geographic ranges and genetic relationships among populations is important when managing a species or population of conservation concern. In the western Canadian province of British Columbia, a subspecies of the northern goshawk (Accipiter gentilis laingi) is designated as Threatened under the Canadian Species at Risk Act. Historically, the range of this bird of prey has been ambiguous and its genetic distinctness from the other North American subspecies (Accipiter gentilis atricapillus) has not been well established. Given the uncertainty in using morphological traits to assign individual goshawks to these two subspecies, we analyzed genomic relationships in tens of thousands of single nucleotide polymorphisms identified using genotyping-bysequencing of high-quality genetic samples. This genome-wide analysis revealed a genetically distinct population of northern goshawks on the archipelago of Haida Gwaii and subtle genetic structuring among the remainder of our sampling sites within North America. Following from this analysis, we developed targeted genotyping assays for ten loci that are highly differentiated between the two main genetic clusters, allowing the addition of hundreds of low-quality samples to our analysis. This additional information confirmed that the distinct genetic cluster on Haida Gwaii is restricted to that archipelago. As the laingi form was originally described as being based in Haida Gwaii, where the type specimen of that form is from, further study (especially of morphological traits) may indicate a need to restrict this name to the Haida Gwaii genetic cluster.Regardless of taxonomic treatment, our finding of a distinct Haida Gwaii genetic cluster along with the small and historically declining population size of the Haida Gwaii population suggests a high risk of extinction of an ecologically and genetically distinct form of northern goshawk. Outside of Haida Gwaii, sampling regions along the coast of BC and southeast Alaska (often considered regions inhabited by laingi) show some subtle differentiation from other North American regions. We anticipate that these results will increase the effectiveness of conservation management of northern goshawks in northwestern North America. More broadly, other conservation-related studies of genetic variation may benefit from the two-step approach we employed that first surveys genomic variation using high-quality samples and then genotypes low-quality samples at particularly informative loci. otherwise differentiated populations) are unclear, efforts to conserve one of those forms are greatly complicated.Northern goshawks (Accipiter gentilis) living along the coast of British Columbia, Canada, and southeast Alaska, USA, provide an example of a species with unclear boundaries between forms that differ in their conservation status listing. Taverner (1940) determined that northern goshawks from the Haida Gwaii archipelago (called the Queen Charlotte Islands at the time) were more darkly colored than those from the mainland, whe...

Sympatric species pairs provide researchers with the opportunity to study patterns of genomic differentiation during the late stages of speciation and to identify the genomic regions underlying reproductive isolation. The Golden-crowned Sparrow (Zonotrichia atricapilla) and the White-crowned Sparrow (Zonotrichia leucophrys) are broadly sympatric songbirds found in western North America. These sister species are phenotypically differentiated and largely reproductively isolated despite possessing similar mitochondrial genomes, likely due to recent mitochondrial introgression. We used a genotyping-by-sequencing (GBS) approach to determine the structure of nuclear genomic differentiation between these species and also between two hybridizing subspecies of Z. leucophrys, across more than 45,000 single nucleotide polymorphisms (SNPs). The two Z. leucophrys subspecies showed moderate levels of relative differentiation, as well as patterns consistent with a history of recurrent selection in both ancestral and daughter populations. Z. leucophrys and Z. atricapilla show high levels of relative differentiation and strong heterogeneity in the level of differentiation among different chromosomal regions, with a large portion of the Z chromosome showing highly elevated differentiation. Patterns of relative and absolute differentiation and linkage disequilibrium suggest a large inversion on the Z chromosome, with inversion haplotypes that segregate between Z. atricapilla and Z. leucophrys. While mitochondrial DNA differentiation is often emphasized in studies of speciation, differentiation between these Zonotrichia sparrows appears to have occurred first in the Z chromosome and secondarily in autosomes, followed by mitochondrial introgression. This putative inversion has implications for reproductive isolation between these species and adds to a growing body of evidence for the importance of inversions and the Z chromosome in speciation.

No abstract

No abstract