Environmental versus geographical determinants of genetic structure in two subalpine conifers.
Alpine ecosystems are facing rapid human-induced environmental changes, and so more knowledge about tree adaptive potential is needed. This study investigated the relative role of isolation by distance (IBD) versus isolation by adaptation (IBA) in explaining population genetic structure in Abies alba and Larix decidua, based on 231 and 233 single nucleotide polymorphisms (SNPs) sampled across 36 and 22 natural populations, respectively, in the Alps and Apennines. Genetic structure was investigated for both geographical and environmental groups, using analysis of molecular variance (AMOVA). For each species, nine environmental groups were defined using climate variables selected from a multiple factor analysis. Complementary methods were applied to identify outliers based on these groups, and to test for IBD versus IBA. AMOVA showed weak but significant genetic structure for both species, with higher values in L. decidua. Among the potential outliers detected, up to two loci were found for geographical groups and up to seven for environmental groups. A stronger effect of IBD than IBA was found in both species; nevertheless, once spatial effects had been removed, temperature and soil in A. alba, and precipitation in both species, were relevant factors explaining genetic structure. Based on our findings, in the Alpine region, genetic structure seems to be affected by both geographical isolation and environmental gradients, creating opportunities for local adaptation.
['Mosca|Elena|E|', 'González-Martínez|Santiago C|SC|', 'Neale|David B|DB|']
D028202:Abies D000222:Adaptation, Physiological D000704:Analysis of Variance D002980:Climate D018744:DNA, Plant D017753:Ecosystem D004777:Environment D056426:Genetic Loci D040342:Genetic Structures D005828:Genetics, Population D005838:Genotype D005843:Geography D028221:Larix D028201:Pinaceae D020641:Polymorphism, Single Nucleotide D017422:Sequence Analysis, DNA D014197:Trees
isolation by distance isolation by adaptation environmental gradient landscape genetics outlier locus detection