Genome‐wide association to fine‐scale ecological heterogeneity within a continuous population ofBiscutella laevigata(Brassicaceae)

Abstract

Summary• Gene flow, drift and selection can be detected through different signatures across the genome and the landscape. Genetic discontinuities along with their correlation to environmental features can be used to tease out isolation-by-distance and isolationby-time from processes related to selection.• Using spatial statistics (spatial autocorrelation methods, canonical correspondence analysis and partial Mantel tests) dealing with genome-wide amplified fragment length polymorphism (AFLP) under unlikely Hardy-Weinberg assumptions, this study investigates 124 individuals within a continuous population of the autopolyploid Biscutella laevigata (Brassicaceae).• Fine-scale spatial genetic structure was strong and the mosaic-like distribution of AFLP genotypes was consistently associated with habitat factors, even when controlled for geographical distances. The use of multivariate analyses enabled separation of the factors responsible for the repartition of the genetic variance and revealed a composite effect of isolation by distance, phenological divergence and local adaptation to habitats characterised by different solar radiation regimes.• These results suggest that the immigrant inviability barrier facilitated the maintenance of adapted subpopulations to distinct environmental conditions at the local scale.

Fine-scale genetic structure and marginal processes in an expanding population of Biscutella laevigata L. (Brassicaceae)

“…At the plot level, the Shannon diversity index based on AFLP profiles in each 25-m plot was computed according to Parisod and Christin (2008), to analyse patterns of genetic diversity in the population. The relationship between the Shannon diversity index and randomly ordered environmental values was explored by stepwise multiple regression.…”

“…On the basis of the species habitat model (S Joost and C Parisod, unpublished data), the following ecological factors were used. They were chosen because they varied within the habitat of B. laevigata in this study (the range is shown in brackets) and were shown to influence the genetic architecture of populations (Parisod and Christin, 2008). The variables were: degree-days during the growing season (735-921 days degree), elevation (2204-2433 m), number of frost days during growing season (8.9-18.1 days with frost), slope (7-56 1C) and total solar radiation (17 763-63 928 kJ/day).…”

Patterns of Population Structure and Environmental Associations to Aridity Across the Range of Loblolly Pine (Pinus taedaL., Pinaceae)

“…Within-county sampling may be more effective for association analyses than the countylevel approach taken here because fine-scale environmental variation may be of considerable biological relevance (Mitton et al 1998;Parisod and Christin 2008). Alternatively, allele-frequency approaches utilizing local populations have also been shown to be powerful in identifying loci affected by diversifying selection (Hancock et al 2008).…”

“…Correlations between genetic variation and environmental gradients have been identified in a variety of plant species (Antonovics and Bradshaw 1970;Antonovics 1971;Hamrick and Allard 1972;Westfall and Conkle 1992;Linhart and Grant 1996;Mitton 1997;Savolainen et al 2007), and such associations are often interpreted as evidence of natural selection Dudley 1996a,b;Gram and Sork 2001;Vasemägi and Primmer 2005;Parisod and Christin 2008). Renewed interest in identifying correlations between environmental and genetic variation has emerged as high-throughput sequencing and genotyping platforms are applied to functional genetic variation within natural populations of non-model species (cf.…”

Repeated Whole-Genome Duplication, Karyotype Reshuffling, and Biased Retention of Stress-Responding Genes in Buckler Mustard

“…Four individuals of Biscutella laevigata subsp laevigata (2n = 4x = 36) were collected in a previously described population (Parisod and Christin, 2008), grown outdoors for 1 year in a common garden (Botanical Garden of Neuchâtel, Switzerland), and analyzed there.…”