Natural selection on cork oak: allele frequency reveals divergent selection in cork oak populations along a temperature cline (original) (raw)
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Evolutionary Applications, 2020
Most forests worldwide are renewed by natural processes, the exception being artificially planted woodlands, which account for 7% of the world's forests (FAO, 2015). The remaining primary and secondary forests are regenerated by means of seedlings resulting from open pollination between mature trees. Natural processes dominated by competition for light, water and nutrients, and environmental disturbances, exert a strong influence during the early stages of development of the renewed forest stand. Human activities, in the form of silvicultural regimes of various intensities, depending on tree species and country, subsequently superimpose over natural selection regimes, except in primary forests. Thus, most existing forests are subjected to both natural and human-mediated
Acta Oecologica, 2014
A central issue in evolutionary biology is the exploration of functional trait variation among populations and the extent to which this variation has adaptive value. It was recently proposed that specific leaf area (SLA), leaf nitrogen concentration per mass (N mass ) and water use efficiency in cork oak play an important role in adaptation to water availability in the environment. In order to investigate this hypothesis, we explored, first, whether there was population-level variation in cork oak (Quercus suber) for these functional traits throughout its distribution range; if this were the case, it would be consistent with the hypothesis that different rainfall patterns have led to ecotypic differentiation in this species. Second, we studied whether the population-level variation matched short-term selection on these traits under different water availability conditions using two fitness components: survival and growth. We found high population-level differentiation in SLA and N mass , with populations from dry places exhibiting the lowest values for SLA and N mass . Likewise, reduced SLA had fitness benefits in terms of growth for plants under dry conditions. However, contrary to our expectations, we did not find any pattern of association between functional traits and survival in nine-year-old saplings despite considerable drought during one year of the study period. These results together with findings from the literature suggest that early stages of development are the most critical period for this species. Most importantly, these findings suggest that cork oak saplings have a considerable potential to cope with dry conditions. This capacity to withstand aridity has important implications for conservation of cork oak woodlands under the ongoing climate change.