Natural selection on cork oak: allele frequency reveals divergent selection in cork oak populations along a temperature cline

Abstract

A recent study of population divergence at neutral markers and adaptive traits in cork oak has observed an association between genetic distances at locus <2/>ZAG46 and genetic distances for leaf size and growth. In that study it was proposed that certain loci could be linked to genes encoding for adaptive traits in cork oak and, thus, could be used in adaptation studies. In order to investígate this hypothesis, here we (1) looked for associations between molecular markers and a set of adaptive traits in cork oak, and (2) explored the effects of the climate on among-population patterns in adaptive traits and molecular markers. For this purpose, we chose 9-year-old plants originating from thirteen populations spanning a broad range of climatic conditions. Plants established in a common garden site were genotyped at six nuclear microsatellites and phenotypically characterized for six functional traits potentially related to plant performance. Our results supported the proposed linkage between locus <2/>ZAG46 and genes encoding for leaf size and growth. Temperature caused adaptive population divergence in leaf size and growth, which was expressed as differences in the frequencies of the alíeles at locus <2/>ZAG46.

Natural regeneration of Fagus sylvatica L. adapts with maturation to warmer and drier microclimatic conditions

“…This would be the case in our study for the potential outlier loci, which without being adaptive markers, could be used for the identification of selection effects. Similar selection effects have been reported in genetic studies of different oak species by using nuclear microsatellites (Neophytou et al, 2010;Ramirez-Valiente et al, 2010;Zhang et al, 2006). Further, large changes in allele frequencies at eight microsatellite loci observed in Drosophila populations indicated selectively-driven changes and provided evidence about genomewide selective sweeps that affect not only fitness but also linked neutral loci (Montgomery et al, 2010).…”

“…These results were confirmed in studies of several tree species by using molecular genetic (Ohsawa and Ide, 2008). In this context, allele frequency differences at microsatellite loci revealed divergent selection in cork oak populations along a temperature cline (Ramirez-Valiente et al, 2010). Given that elevation gradients present many different site conditions, the impact of environmental factors on genetic structures is not evident.…”

Limited Pollen Dispersal Contributes to Population Genetic Structure but Not Local Adaptation in Quercus oleoides Forests of Costa Rica

“…This locus may be in linkage disequilibrium with a region of the genome that is affected by some or all of the factors in the environmental distance matrix. Other studies in the genus Quercus have found significant associations between microsatellite markers and genes coding for traits under selection [ 82 , 93 ]. ZAG15 has been mapped to linkage group 9 near QTL’s for leaf shape [ 94 ] and bud burst [ 95 ], and a study in Q .…”

Influence of environmental heterogeneity on genetic diversity and structure in an endemic southern Californian oak

“…First, populations experiencing different climates could have evolved particular adaptations, and reduced gene flow may be reflecting selection against the establishment of nonlocal genotypes even when neutral microsatellite markers are not involved in these evolutionary processes (Aitken et al. 2008; Ramírez‐Valiente et al. 2009, 2010; Eckert et al.…”