Michael D. Sorenson | USGS Science

USGS2022

As the goose flies: Migration routes and timing influence patterns of genetic diversity in a circumpolar migratory herbivore

Migration schedules and the timing of other annual events (e.g., pair formation and molt) can affect the distribution of genetic diversity as much as where these events occur. The greater white-fronted goose ( Anser albifrons ) is a circumpolar goose species, exhibiting temporal and spatial variation of events among populations during the annual cycle. Previous range-wide genetic assessments of the nuclear genome based on eight microsatellite loci suggest a single, largely panmictic population despite up to five subspecies currently recognized based on phenotypic differences. We used double digest restriction-site associated DNA (ddRAD-seq) and mitochondrial DNA (mtDNA) sequence data to re-evaluate estimates of spatial genomic structure and to characterize how past and present processes have shaped the patterns of genetic diversity and connectivity across the Arctic and subarctic. We uncovered previously undetected inter-population differentiation with genetic clusters corresponding to sampling locales associated with current management groups. We further observed subtle genetic clustering within each management unit that can be at least partially explained by the timing and directionality of migration events along with other behaviors during the annual cycle. The Tule Goose ( A. a. elgasi ) and Greenland subspecies ( A. a. flavirostris ) showed the highest level of divergence among all sampling locales investigated. The recovery of previously undetected broad and fine-scale spatial structure suggests that the strong cultural transmission of migratory behavior restricts gene flow across portions of the species’ range. Our data further highlight the importance of re-evaluating previous assessments conducted based on a small number of highly variable genetic markers in phenotypically diverse species.

Circumpolar Arctic↗

USGS2019

Identification of single nucleotide polymorphisms for use in a genetic stock identification system for greater white-fronted goose (Anser albifrons) subspecies wintering in California

California provides wintering habitat for most greater white-fronted geese ( Anser albifrons [GWFG]) in the Pacific Flyway and this population has rapidly increased since the 1980s. Increased harvest of GWFG wintering in California may prevent agricultural depredation while providing increased hunting opportunities. However, changes in harvest levels are unlikely to be uniform across the species because of the presence of multiple subspecies of GWFG in the Pacific Flyway, each with their own population distribution and trends. White-fronted geese in the Cook Inlet Basin of south-central Alaska, a potentially vulnerable subspecies (Tule goose, A. a. elgasi ), are among the geese that winter predominantly in the Sacramento Valley and Suisun and Napa marshes of north-central California. Efforts to limit sport harvest of Tule geese are complicated because although the subspecies is phenotypically larger and darker in color than other subspecies, they can be difficult to identify in the field and in hunter bag checks. To assist in an accurate assessment of Tule goose harvest, we used double-digest restriction site-associated deoxyribonucleic acid sequencing (ddRAD-seq) techniques to develop a genetic stock identification panel of single nucleotide polymorphisms (SNPs) to differentiate Tule geese from individuals belonging to other GWFG subspecies and populations that winter in California. Although the panel we developed was designed and tested for Fluidigm SNP-type technology, the ddRAD-seq sequences can be used to design SNP panels for use in other platforms.

Alaska, California↗