title: Pursuing glacier retreat: genetic structure of a rapidly expanding Larix decidua population.
abstract: One of the greatest threats to the long-term viability of migrating plant species is the loss of genetic diversity due to founder effects. Populations can expand as a response to climate change, but it is uncertain if long-lived plant species can maintain sufficient genetic diversity at the leading edge of migrating populations. This study uses an expanding Larix decidua population investigated along a chronosequence at landscape (350 ha) and local (0.8 ha) scales to test whether accelerated migration as a result of climate warming has the potential to intensify genetic erosion. Nine SSR markers revealed similar genetic diversity among eight sub-populations along the chronosequence (overall H(e) = 0.73; SE=0.04). Sub-populations were not genetically differentiated and all sampled individuals (N=730) formed one major genetic cluster indicating homogenizing gene flow despite spatial genetic structure (SGS) up to 80 m. At the local scale, individuals at the leading edge [early successional sub-population (ESSP), N =140] and a sub-population at equilibrium [late successional sub-population (LSSP), N = 290] revealed high genetic diversity in largest-sized cohorts. SGS among juveniles occurred up to 30 m in LSSP but there was no structure in ESSP. Accordingly, a maximum likelihood paternity assignment revealed local gene dispersal in LSSP (2-48 m) and intermediate-to-long distance dispersal into ESSP (115-3132 m). The findings indicate intensive mixing of the genes in this expanding population instead of founder effects and support the view that genetic diversity can be maintained in a long-lived species during rapid population expansion driven by climate warming.
authors.affiliation: Department of Environmental Sciences, ETH Zurich, Universitaetstrasse 16, Zurich, Switzerland.
authors.forename: Andrea R
authors.initials: AR
authors.lastname: Pluess
mesh_terms: D000483:Alleles; D001499:Bayes Theorem; D002980:Climate; D016000:Cluster Analysis; D018744:DNA, Plant / Q000235:genetics; D003710:Demography; D018703:Founder Effect; D051456:Gene Flow / Q000235:genetics; D014644:Genetic Variation / Q000235:genetics*; D005838:Genotype; D046448:Ice Cover; D028221:Larix / Q000235:genetics* / Q000254:growth & development; D018895:Microsatellite Repeats / Q000235:genetics; D013997:Time Factors
chemical_list: D018744:DNA, Plant