title: Glacial refugia and modern genetic diversity of 22 western North American tree species.
abstract: North American tree species, subspecies and genetic varieties have primarily evolved in a landscape of extensive continental ice and restricted temperate climate environments. Here, we reconstruct the refugial history of western North American trees since the last glacial maximum using species distribution models, validated against 3571 palaeoecological records. We investigate how modern subspecies structure and genetic diversity corresponds to modelled glacial refugia, based on a meta-analysis of allelic richness and expected heterozygosity for 473 populations of 22 tree species. We find that species with strong genetic differentiation into subspecies had widespread and large glacial refugia, whereas species with restricted refugia show no differentiation among populations and little genetic diversity, despite being common over a wide range of environments today. In addition, a strong relationship between allelic richness and the size of modelled glacial refugia (r(2) = 0.55) suggest that population bottlenecks during glacial periods had a pronounced effect on the presence of rare alleles.
authors.affiliation: Department of Renewable Resources, University of Alberta, 751 General Services Building, Edmonton, Alberta, Canada T6G 2H1 drr3@ualberta.ca.
authors.forename: David R
authors.initials: DR
authors.lastname: Roberts
authors.affiliation: Department of Renewable Resources, University of Alberta, 751 General Services Building, Edmonton, Alberta, Canada T6G 2H1.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hamann
mesh_terms: D057231:Climate Change; D014644:Genetic Variation; D046448:Ice Cover; D058974:Phylogeography; D063148:Plant Dispersal; D014197:Trees / Q000235:genetics* / Q000502:physiology; D014481:United States
keywords: allozyme; last glacial maximum; palaeoecology; phylogeography; quaternary; species distribution models