Data from: Genetic basis of local adaptation and flowering time variation in Arabidopsis lyrata

Understanding how genetic variation at individual loci contributes to adaptation of populations to different local environments is an important topic in modern evolutionary biology. To date, most evidence has pointed to conditionally neutral quantitative trait loci (QTL) showing fitness effects only in some environments, while there has been less evidence for single-locus fitness trade-offs. At QTL underlying local adaptation, alleles from the local population are expected to show a fitness advantage. Cytoplasmic genomes also can have a role in local adaptation, but the role of cytonuclear interactions in adaptive differentiation has remained largely unknown. We mapped genomic regions underlying adaptive differentiation in multiple fitness components and flowering time in diverged populations of a perennial plant Arabidopsis lyrata. Experimental hybrids for this purpose were grown in natural field conditions of the parental populations in Norway and North Carolina (NC), USA and in the greenhouse. We found QTL where high fitness and early flowering were associated with local alleles, indicating a role of different selection pressures in phenotypic differentiation. At two QTL regions, a fitness component showing local adaptation between the parental populations also showed signs of putative fitness trade-offs. Beneficial dominance effects of conditionally neutral QTL for different fitness components resulted in hybrid vigor at the Norwegian site in the F2 hybrids. We also found that cytoplasmic genomes contributed to local adaptation and hybrid vigor by interacting with nuclear QTL, but these interactions did not show evidence for cytonuclear coadaptation (high fitness of local alleles combined with the local cytoplasm).

解析单个位点的遗传变异如何助力种群适应不同本地环境，是现代进化生物学的重要研究议题。迄今为止，多数研究证据指向仅在部分环境中表现出适合度效应的条件中性数量性状位点（quantitative trait loci, QTL），而支持单基因座适合度权衡的证据相对匮乏。在介导本地适应的QTL中，本地种群的等位基因通常被认为会展现出适合度优势。细胞质基因组同样可参与本地适应，但核质互作在适应性分化中的作用仍在很大程度上未知。我们在分化种群中定位了与多个适合度组分及开花时间相关的、调控适应性分化的基因组区域，该研究对象为多年生植物 lyrata拟南芥（Arabidopsis lyrata）。为此，我们将实验杂交种分别种植于亲本种群的原生野外生境——挪威与美国北卡罗来纳州（NC），以及温室环境中。我们发现，高适合度与早开花性状与本地等位基因存在关联，这表明不同选择压力在表型分化中发挥了作用。在两个QTL区域中，体现亲本种群间本地适应的某个适合度组分也呈现出潜在适合度权衡的特征。针对不同适合度组分的条件中性QTL所具备的有益显性效应，使得挪威样地中的F2杂交种展现出杂种优势。我们还发现，细胞质基因组可通过与核QTL互作参与本地适应与杂种优势形成，但此类互作并未体现出核质共适应的特征——即本地等位基因与本地细胞质结合后可获得高适合度的模式。