The genetic landscape of Fennoscandian wolves. Exploring founder lineages and shared inbreeding events.

Abstract

This thesis investigates the genetic structure and admixture of Scandinavian wolves, focusing on the origins of the founders and their connections to Finland and Russia, utilizing high-resolution genomic data. The Scandinavian wolf population was extinct in the wild in 1970, with an immigrating pair recolonizing the area in 1983, followed by inbreeding and an additional 4 founders to date. We aimed to explore the overlap of runs of homozygosity (ROH) segments between Scandinavian and Finnish wolves while employing admixture and PCA analyses on published samples from the named locations. The Admixture and PCA results indicate that early founders predominantly originated from Russian and Finnish populations, confirming previous findings regarding their lineage. In contrast, later founders exhibited a mixed genetic origin from a subgroup in Finland that was difficult to geographically pinpoint, but clustered around central, southern and western Finland. Additionally, shared inbreeding events were identified between contemporary Scandinavian wolves and Finnish wolves, both following the arrival of the early founders in 1983 & 1991 and late founders in 2008 & 2013. Shared inbreeding events across clusters and temporal classes strengthen this. Notably, late founders bear signs of inbreeding events occurring in Scandinavia before their arrival, evident of gene flow to Finland early enough to affect subsequent gene flow back to Scandinavia. This also refutes assumptions of unrelated founders and immigrants to Scandinavia in pedigree studies that lay the groundwork for wildlife management decisions of the species. However, the small sample size from South-western Finland remains a limitation of this study, highlighting potential for improvement in future studies. Overall, our results contribute to the specific knowledge gaps of the founders’ origins and shed light on previous suspicions of gene flow between the neighboring populations which is of importance for the genetics-focused management of the Scandinavian wolf population.