Birds of different feather flock together - genetic structure of Taiga Bean Goose in Central Scandinavia

Abstract

SummaryDuring their flightless summer moult, Taiga Bean GeeseAnser fabalis fabalisgather at communal moulting sites. Individuals from the Nord-Trøndelag breeding area in Norway have been observed to join with local individuals on moulting sites in Vilhelmina Municipality, Sweden. These two groups show distinct features in breeding habitat and migratory behaviour, but are they also genetically distinct? We used 12 microsatellite loci for genotyping 109 blood, feather and faecal samples from three sampling areas (Røyrvik in Norway and Stalon and Nästansjö in Sweden) to examine genetic diversity and structure. Clustering and Principal Coordinate analyses of all samples unveiled at least two distinct clusters, which were unevenly distributed over the sampling sites. Grouped by sampling sites, AMOVA and FSTanalyses showed that samples from the three sites differed genetically. These differences were larger between Røyrvik and Nästansjö than between Stalon and the other two. Relatedness was high among the Røyrvik samples. From our results we conclude that one of the clusters describes the Røyrvik breeding subpopulation, while the other(s) breed mainly in Sweden. Although these subpopulations simultaneously use the same moulting area in Vilhelmina, they appear to be ecologically, behaviourally and genetically distinct, in particular the Røyrvik sub-population. For goose conservation and management, we suggest that the Nord-Trøndelag (Røyrvik) subpopulation is considered a separate flyway management unit. Unravelling the Swedish sub-populations will need further study. For bird conservation is general, we suggest active genetic sampling for detailed population structure analyses and subsequent differentiated conservation and/or management schemes.

Genetic assessment reveals inbreeding, possible hybridization, and low levels of genetic structure in a declining goose population

“…Also, the different flyway populations of the barnacle goose ( Branta leucopsis ) studied with single nucleotide polymorphism (SNP) markers showed not only genetic structuring but also genetic exchange between all flyways (Jonker et al, 2013). Contrary to our findings in the Finnish breeding bean geese, genetic structuring was observed with microsatellite markers within the taiga bean geese breeding in Central Scandinavia (belonging to the Western flyway management unit, see Figure 2; de Jong et al, 2019). However, de Jong et al (2019) studied fine‐scale genetic patterns in a geographically restricted area, thus the different scale (family‐level structure in de Jong et al, 2019) of our study could explain the contrasting results.…”

“…Contrary to our findings in the Finnish breeding bean geese, genetic structuring was observed with microsatellite markers within the taiga bean geese breeding in Central Scandinavia (belonging to the Western flyway management unit, see Figure 2; de Jong et al, 2019). However, de Jong et al (2019) studied fine‐scale genetic patterns in a geographically restricted area, thus the different scale (family‐level structure in de Jong et al, 2019) of our study could explain the contrasting results.…”

“…Nuclear genetic diversity appeared not to be reduced within the Finnish taiga bean goose population despite the recent decline in population numbers, as the Scandinavian taiga bean goose and other goose species show similar heterozygosity values ( de Jong et al, 2019;Ely et al, 2017). However, mtDNA diversity was reduced (h = 0.40-0.58) compared to other bean goose subspecies (h = 0.68-0.86; Honka et al, 2017) and numerically abundant greater whitefronted goose (h = 0.68-0.96; Ely et al, 2017), but similar in range to the endangered population of lesser white-fronted goose (h = 0.37-0.53; Anser erythropus; Ruokonen et al, 2004).…”

“…For effective management of the taiga bean goose, population genetic structure should be assessed in order to preserve genetic diversity. Previously, the population genetic structure of the taiga bean goose has only been studied within a limited area in Central Scandinavia belonging to the Western flyway management unit (de Jong et al, 2019).…”