AbstractInvasive species have led to precipitous declines in biodiversity, especially in island systems. Brown (Rattus norvegicus) and black rats (R. rattus) are among the most invasive animals on the planet, with eradication being the primary tool for established island populations. The need for increased research for defining eradication units and monitoring outcomes has been highlighted as a means to maximize success. Haida Gwaii is an archipelago ~100 km off the northern coast of British Columbia, Canada that hosts globally significant breeding populations of seabirds that are at risk due to invasive rats. Here, we paired sampling of brown (n=287) and black (n=291) rats across the Haida Gwaii archipelago (British Columbia, Canada) with genotyping-by-sequencing (10,770-27,686 SNPs) to investigate patterns of population connectivity and infer levels/direction of gene flow among invasive rat populations in Haida Gwaii. We reconstructed three regional clusters for both species (north, central, south), with proximate populations within regions being largely more related than those that were more distant, consistent with predictions from island biogeography theory. Population assignment of recently detected individuals post-eradication on Faraday, Murchison, and the Bischof Islands revealed all were re-invaders from Lyell Island, rather than being on-island survivors. Based on these results, we identified six eradication units constituting single or clusters of islands that would limit the potential for re-invasion, some of which will need to be combined with biosecurity measures. Overall, our results highlight the importance of targeted research prior to conducting eradications and demonstrates a framework for applying population genomics for guiding invasive species management in island systems. Methodsrano_final.vcf: genotypic data for 297 brown rats (Rattus norvegicus) at 27,686 SNPs generated via ddRAD rara_final.vcf: genotypic data for 242 black rats (Rattus rattus) at 10,770 SNPs generated via ddRAD

rano_final.vcf: genotypic data for 297 brown rats (Rattus norvegicus) at 27,686 SNPs generated via ddRAD

rara_final.vcf: genotypic data for 242 black rats (Rattus rattus) at 10,770 SNPs generated via ddRAD

Individuals were assigned to ddRAD reference populations using the methods outlined in Rannala and Mountain (1997) as implemented in the program Geneclass2 (Piry et al. 2004). Highlighted lines indicate samples that assigned to population other than their sampled population. (XLSX)

AbstractAccurate 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 to 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 in 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.

AbstractBrown rats (Rattus norvegicus) have commensally spread from northern China and Mongolia to become among the most invasive species on the planet. Understanding the proximate source(s) of invasion can inform biosecurity plans and eradication strategies for preventing or mitigating impacts to native biodiversity. The Haida Gwaii archipelago, located off the coast of British Columbia, Canada, is a significant nesting site for 1.5 million seabirds across 12 species, half of which are now threatened by brown rats. Local knowledge points to a European origin in the late 1800’s to early 1900’s, though the true source(s) and firm date(s) of invasion remain unknown. To fill these knowledge gaps, we analyzed genotypic data (16,598 SNPs) for 280 brown rats sampled throughout Haida Gwaii relative to a published global database of potential source populations. Principle component analysis and population assignment tests supported multiple potential invasion sources from Europe and North America. Likewise, demographic modelling best supported two invasions into the islands. The first invasion likely occurred in the early 1900’s into the south-central archipelago from Western Europe followed by a more recent invasion in the early 2000’s from Vancouver, British Columbia, into northern Haida Gwaii. The northern invasion of Haida Gwaii could also be indicative of contemporary gene flow between Haida Gwaii and the mainland, representing a significant biosecurity risk. Our results will inform management strategies for invasive rats in Haida Gwaii, and serve as a guide for studies in other isolated systems worldwide.

Samples were genotyped using a Genotyping-in-Thousands by sequencing (GTseq; Campbell et al. 2015) panel developed in Burgess et al. (2022; https://doi.org/10.1002/ece3.8993) following the modified protocol therein. Raw data were processed using the GTseq workflow (https://github.com/GTseq).

The root of understanding speciation lies in determining the forces which drive it. In many closely-related species, including Sphyrapicus varius, S. nuchalis, and S. ruber, it is assumed that speciation occurred due to isolation in multiple Pleistocene refugia. We used genetic data from 457 samples at the control region, COI, and CHD1Z to examine rangewide population genetic structure and differentiation amongst these three species across each species’ breeding range. In addition, we modelled these species’ ecological niches for the Holocene (~6,000 ya), Last Glacial Maximum (~22,000 ya), and Last Interglacial (~120,000-140,000 ya) to determine if Pleistocene glaciations could have contributed to allopatric distributions, therefore allowing these groups to differentiate. Population genetic data show a potential Pleistocene refugium in Haida Gwaii, an east-west split among S. varius, and low genetic differentiation within each species. Our control region data show some polyphyly, while ...

Threespine stickleback populations are model systems for studying adaptive evolution and the underlying genetics. In lakes on the Haida Gwaii archipelago (off western Canada), stickleback have undergone a remarkable local radiation and show phenotypic diversity matching that seen throughout the species distribution. To provide a historical context for this radiation, we surveyed genetic variation at >1000 single nucleotide polymorphism (SNP) loci in stickleback from over 100 populations. SNPs included markers evenly distributed throughout genome and candidate SNPs tagging adaptive genomic regions. Based on evenly distributed SNPs, the phylogeographic pattern differs substantially from the disjunct pattern previously observed between two highly divergent mtDNA lineages. The SNP tree instead shows extensive within watershed population clustering and different watersheds separated by short branches deep in the tree. These data are consistent with separate colonizations of most watersheds, despite underlying genetic connections between some independent drainages. This supports previous suppositions that morphological diversity observed between watersheds has been shaped independently, with populations exhibiting complete loss of lateral plates and giant size each occurring in several distinct clades. Throughout the archipelago, we see repeated selection of SNPs tagging candidate freshwater adaptive variants at several genomic regions differentiated between marine–freshwater populations on a global scale (e.g. EDA, Na/K ATPase). In estuarine sites, both marine and freshwater allelic variants were commonly detected. We also found typically marine alleles present in a few freshwater lakes, especially those with completely plated morphology. These results provide a general model for postglacial colonization of freshwater habitat by sticklebacks and illustrate the tremendous potential of genome-wide SNP data sets hold for resolving patterns and processes underlying recent adaptive divergences.

Population segregation catalyzes genetic differentiation and can lead to speciation. Population genetic structure is also critically important for population management, especially in species characterized by small, isolated populations. Sandhill Crane (Antigone canadensis) populations of the Pacific Flyway are made up of breeding populations nesting west of the Rocky Mountains, and isolated by intermediate mountain ranges. Current management policy in British Columbia treats all Sandhill Cranes as a single population, whereas in the western United States subpopulations are subject to population specific management. Here, we analyze microsatellite markers, mitochondrial DNA sequences, and mitochondrial haplogroups, derived from 203 individual Sandhill Cranes to elucidate population genetic structure of cranes migrating along the Pacific Flyway to summer breeding habitat on the North and Central Coast of British Columbia and southeast Alaska. STRUCTURE, AMOVA, FST, DAPC, and phylogenetic..., , , # Cryptic population structure in sandhill cranes (Antigone canadensis) of the Pacific Flyway

Dataset DOI: 10.5061/dryad.wwpzgmsw6

Dataset associated with manuscript: Cryptic population structure in Sandhill Cranes (Antigone canadensis) of the Pacific Flyway. Contains microsatellite markers, locations, and population assignments.

Description of the data and file structure

Data file name: SACR_Dryad.Final.csv

Samples (feathers and blood) were collected from Sandhill Cranes from Haida Gwaii BC, Coastal BC, Interior BC, and Alaska populations (west of the Rocky Mountains). Micro-satellite and mtDNA markers were obtained from samples. Please see detailed methods in Joy, R. et al. 2025. Cryptic population structure in Sandhill Cranes (Antigone canadensis) of the Pacific Flyway. Ecology and Evolution. Column descriptors are provided below.

• SampleID: unique sample identifier
• Organism: all samples are of Antigone canadensis (Sandhill Cranes)
• Popula...,