High migration rates shape the postglacial history of amphi‐Atlantic bryophytes

Abstract

Paleontological evidence and current patterns of angiosperm species richness suggest that European biota experienced more severe bottlenecks than North American ones during the last glacial maximum. How well this pattern fits other plant species is less clear. Bryophytes offer a unique opportunity to contrast the impact of the last glacial maximum in North America and Europe because about 60% of the European bryoflora is shared with North America. Here, we use population genetic analyses based on approximate Bayesian computation on eight amphi-Atlantic species to test the hypothesis that North American populations were less impacted by the last glacial maximum, exhibiting higher levels of genetic diversity than European ones and ultimately serving as a refugium for the postglacial recolonization of Europe. In contrast with this hypothesis, the best-fit demographic model involved similar patterns of population size contractions, comparable levels of genetic diversity and balanced migration rates between European and North American populations. Our results thus suggest that bryophytes have experienced comparable demographic glacial histories on both sides of the Atlantic. Although a weak, but significant genetic structure was systematically recovered between European and North American populations, evidence for migration from and towards both continents suggests that amphi-Atlantic bryophyte population may function as a metapopulation network. Reconstructing the biogeographic history of either North American or European bryophyte populations therefore requires a large, trans-Atlantic geographic framework.

Divergent evolution and niche differentiation within the common peatmossSphagnum magellanicum

“…This scenario is likely to be associated with the end of the Last Glacial Maximum when populations surviving in different refugia came into contact during the Holocene. Low effective population sizes of current populations of expanse and margin morphs compared to their ancestral population (see Table 3) is congruent with a population bottleneck during the Last Glacial Maximum, an event extensively documented in other studies (Fedorov and Stenseth, 2002; Knowles and Richards, 2005; Steele and Storfer, 2006; Désamoré et al, 2016).…”

No borders during the post‐glacial assembly of European bryophytes

“…; Désamoré et al . ). These prior distributions, which ranged between 10 −7 and 10 −4 substitutions/site/myr, were sampled independently, allowing for different posterior probability distributions to characterise the substitution rates of each locus.…”

“…We used published sequence data (Désamoré et al . ) and another 1941 newly produced sequences following the protocols of Désamoré et al . () to expand the geographical and taxonomic sampling (Table ).…”

“…) and another 1941 newly produced sequences following the protocols of Désamoré et al . () to expand the geographical and taxonomic sampling (Table ). Specimens of liverworts were sequenced at 2–3 cpDNA loci including both coding and non‐coding regions.…”

Corrigendum

“…In the published paper (Désamoré et al . ), Aurélie Désamoré, Jairo Patiño, Benjamin Laenen and Alain Vanderpoorten were identified as having contributed equally to the study.…”