Open AccessAncient DNA identifies post‐glacial recolonisation, not recent bottlenecks, as the primary driver of contemporary mt DNA phylogeography and diversity in Scandinavian brown bears
Author(s) -
Bray Sarah C.E.,
Austin Jeremy J.,
Metcalf Jessica L.,
Østbye Kjartan,
Østbye Eivind,
Lauritzen SteinErik,
AarisSørensen Kim,
Valdiosera Cristina,
Adler Christina J,
Cooper Alan
Publication year - 2013
Publication title -
diversity and distributions
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.918
H-Index - 118
eISSN - 1472-4642
pISSN - 1366-9516
DOI - 10.1111/j.1472-4642.2012.00923.x
Subject(s) - ancient dna , phylogeography , glacial period , genetic diversity , holocene , ecology , population , biology , evolutionary biology , norwegian , last glacial maximum , geography , paleontology , phylogenetics , demography , genetics , sociology , gene , linguistics , philosophy
Aim Brown bear populations in Scandinavia show a strong mitochondrial DNA (mt DNA ) phylogeographic structure and low diversity relative to other parts of Europe. Identifying the timing and origins of this mt DNA structure is important for conservation programs aimed at restoring populations to a natural state. Therefore, it is essential to identify whether contemporary genetic structure is linked to post‐glacial recolonisation from divergent source populations or an artefact of demographic impacts during recent population bottlenecks. We employed ancient DNA techniques to investigate the timing and potential causes of these patterns. Location Scandinavia and Europe. Methods Ancient mt DNA sequences from 20 post‐glacial Scandinavian bears were used to investigate phylogeographic structure and genetic diversity over the last 6000 years. Mt DNA from 19 Holocene Norwegian bears was compared with 499 sequences from proximate extant populations in Sweden, Finland, Estonia and western Russia. A single mt DNA sequence from a Holocene Denmark sample was compared with 149 ancient and modern bears from Western Europe. Results All nineteen Holocene Norwegian samples are identical to or closely related to the most common mt DNA haplotype found in northern Europe today. Mt DNA diversity was low and not significantly different from extant populations in northern Europe. In Denmark, we identified a single mt DNA haplotype that is previously unrecorded from Scandinavia. Main conclusions The current discrete phylogeographic structure and lack of mt DNA diversity in Scandinavia is attributed to serial founder effects during post‐glacial recolonisation from divergent source populations rather than an artefact of recent anthropogenic impacts. In contrast to previous interpretations, the recolonisation of southern Scandinavia may not have been limited to bears from a single glacial refugium. Results highlight the importance of conserving the long‐term evolutionary separation between northern and southern populations and identify southern Scandinavia as an important reservoir of mt DNA diversity that is under threat in other parts of Europe.