Genome-wide effects of postglacial colonization in Arabidopsis lyrata

Abstract

The perennial outcrossing Arabidopsis lyrata is becoming a plant model species for molecular ecology and evolution. However, its evolutionary history, and especially the impact of the climatic oscillations of the Pleistocene on its genetic diversity and population structure, is not well known. We analyzed the broad-scale population structure of the species based on microsatellite variation at 22 loci. A wide sample in Europe revealed that glaciations and postglacial colonization have caused high divergence and high variation in variability between populations. Colonization from Central Europe to Iceland and Scandinavia was associated with a strong decrease of genetic diversity from South to North. On the other hand, the Russian population included in our data set may originate from a different refugium probably located more to the East. These genome-wide patterns must be taken into account in studies aiming at elucidating the genetic basis of local adaptation. As shown by sequence data, most of the loci used in this study do not evolve like typical microsatellite loci and show variable levels of homoplasy: this mode of evolution makes these markers less suitable to investigate the between-continent divergence and more generally the worldwide evolution of the species. Finally, a strong negative correlation was detected between levels of within-population diversity and indices of differentiation such as F ST . We discuss the causes of this correlation as well as the potential bias it induces on the quantification and interpretation of population structure.

Population structure and historical biogeography of European Arabidopsis lyrata

“…Furthermore, our results from chloroplast diversity revealed a pattern consistent with recent sudden population expansion (Figure 3). Thus we consolidate previous observations (Muller et al, 2008;Ross-Ibarra et al, 2008) and conclude that nearly the entire range of A. l. petraea has been strongly influenced by recent historical events.…”

“…Our results contrast with two earlier European-wide diversity studies, which did not recover a distinct northern European population (Muller et al, 2008;Ross-Ibarra et al, 2008). These studies elected to investigate wider genetic diversity patterns and included samples of North American A. l. lyrata (Muller et al, 2008;Ross-Ibarra et al, 2008).…”

“…A phylogeographic model of central European survival, with subsequent post-glacial population expansion into northern Europe was proposed after analysing microsatellite variation (Clauss and Mitchell-Olds, 2006;Muller et al, 2008). Similar conclusions were reached by a recent SNP analysis (Ross-Ibarra et al, 2008).…”

“…These studies elected to investigate wider genetic diversity patterns and included samples of North American A. l. lyrata (Muller et al, 2008;Ross-Ibarra et al, 2008). Multi-locus sequencing studies have established that the European (A. l. petraea) and North American (A. l. lyrata) taxa are substantially differentiated (Wright et al, 2003(Wright et al, , 2006.…”

“…Over the last decade regional and larger scale studies have provided insights into the genetic structure of A. l. petraea populations (Jonsell et al, 1995;van Treuren et al, 1997;Clauss and Mitchell-Olds, 2006;Gaudeul et al, 2007;Muller et al, 2008). A phylogeographic model of central European survival, with subsequent post-glacial population expansion into northern Europe was proposed after analysing microsatellite variation (Clauss and Mitchell-Olds, 2006;Muller et al, 2008).…”