Population genomic analyses reveal a highly differentiated and endangered genetic cluster of northern goshawks (Accipiter gentilis laingi) in Haida Gwaii

Abstract

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.

Demographic history shaped geographical patterns of deleterious mutation load in a broadly distributed Pacific Salmon

“…Still, our inference of SC supports the hypothesis that smaller micro-refugia have persisted along the Pacific Coast [43,64]. In particular, the Haida Gwaii archipelago is known for high endemism, and its role as a refugium for mammals, invertebrates, and angiosperms is well established [64][65][66]. The divergence time inferred between populations from California and Haida Gwaii was relatively recent (39 KyA), in the range of inferred divergence times for bird species from the region [67] and in the time frame of the last interglacial period 55 to 25 KyA.…”

Long-term population decline of a genetically homogenous continental-wide top Arctic predator

“…2018), Bald Eagle Haliaeetus leucocephalu; F ST = 0.037-0.203 (Judkins et al . 2019), and Northern Goshawk Accipiter gentilis; F ST = 0-0.093 (Geraldes et al . 2019).…”

The taxonomic status of Palearctic and Nearctic populations of northern goshawk Accipiter gentilis (Aves, Accipitridae): New evidence from vocalisations

“…In statistical analysis, the recordings of the Palearctic gentilis-group, which comprise multiple subspecies, were treated as a single operational taxonomic unit (OTU) because there were no major subdivisions in a mitochondrial Control Region phylogeny (Kunz et al 2019). The Nearctic recordings represented three subspecies, A. g. atricapillus, A. g. laingi and A. g. apache, which were treated as a single OTU based on the results of Geraldes et al (2019) and Kunz et al (2019).…”

“…In an analysis of short mitochondrial COI sequences, Breman et al (2013) found that A. g. gentilis was more closely related to black sparrowhawk A. melanoleucus than to A. g. atricapillus but with very poor support. Using genomic DNA sequences, Geraldes et al (2019) found a deep divergence between Palearctic and Nearctic populations of A. gentilis. In a detailed mitochondrial DNA study, Kunz et al (2019) showed that Nearctic A. g. atricapillus, A. g. laingi and A. g. apache (hereafter atricapillus-group) and the Palearctic subspecies of A. gentilis (hereafter gentilis-group) formed reciprocally monophyletic groups which were not sister groups because the gentilis-group was closer to Meyer's goshawk A. meyerianus, Henst's goshawk A. henstii and A. melanoleucus than to the atricapillus-group.…”