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的本地环境，是现代进化生物学的重要研究课题。迄今为止，多数研究证据均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），而支持单位点适合度权衡的证据相对较少。在介导本地适应的QTL中，本地种群的等位基因通常会表现出适合度优势。细胞质基因组同样可参与本地适应过程，但核质互作在适应性分化中的作用在很大程度上仍未明确。我们在多年生植物 lyrata鼠耳芥（Arabidopsis lyrata）的分化种群中，定位了与多个适合度组分及开花时间的适应性分化相关的基因组区域。为此，我们将实验杂交种分别种植于亲本种群的原生野外环境：美国北卡罗来纳州（NC）与挪威的自然生境，以及温室环境中。我们发现，高适合度与早开花性状均与本地等位基因相关联的QTL，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，反映亲本种群间本地适应的某个适合度组分同样表现出潜在的适合度权衡迹象。针对不同适合度组分的条件中性QTL所具有的有益显性效应，使得挪威试验点的F2代杂交种表现出杂种优势。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的形成，但这类互作并未表现出核质共适应的迹象——即本地等位基因与本地细胞质结合所带来的高适合度。