Data from: Humidity affects genetic architecture of heat resistance in Drosophila melanogaster

Laboratory experiments on Drosophila have often demonstrated increased heritability for morphological and life-history traits under environmental stress. We used parent-offspring comparisons to examine the impact of humidity levels on the heritability of a physiological trait, resistance to heat, measured as knockdown time at constant temperature. Drosophila melanogaster were reared under standard non-stressful conditions and heat-shocked as adults at extreme high or low humidity. Mean knockdown time was decreased in the stressful dry environment but there was a significant sex-by-treatment interaction: at low humidity females were more heat resistant than males, whereas at high humidity the situation was reversed. Phenotypic variability of knockdown time was also lower in the dry environment. The magnitude of genetic correlation between the sexes at high humidity indicated genetic variation for sexual dimorphism in heat resistance. Heritability estimates based on one-parent – offspring regressions tended to be higher under desiccation stress and this could be explained by decreased environmental variance of heat resistance at low humidity. There was no indication that the additive genetic variance and evolvability of heat resistance differed between the environments. The pattern of heritability estimates suggests that populations of D. melanogaster may have a greater potential for evolving higher thermal tolerance under arid conditions.针对果蝇（Drosophila）的实验室实验已多次证实，在环境胁迫下，其形态学与生活史性状的遗传力（heritability）会显著提升。本研究采用亲子代比较法（parent-offspring comparisons），探究湿度水平对生理性状——耐热性（resistance to heat）——遗传力的影响，该性状以恒温条件下的击倒时间（knockdown time）作为衡量指标。实验所用黑腹果蝇（Drosophila melanogaster）先在标准非胁迫环境中饲养，待其发育为成虫后，分别在极端高湿或低湿条件下接受热激处理。结果显示，干旱胁迫环境下成虫的平均击倒时间有所缩短，但实验观测到显著的性别-处理互作（sex-by-treatment interaction）效应：低湿条件下雌性果蝇的耐热性强于雄性，而高湿条件下该趋势恰好相反。此外，干旱环境下击倒时间的表型变异度（phenotypic variability）也有所降低。高湿条件下雌雄果蝇间的遗传相关（genetic correlation）强度，反映了耐热性存在与性二态性（sexual dimorphism）相关的遗传变异。基于单亲-子代回归（one-parent-offspring regressions）得到的遗传力估计值，在干旱胁迫条件下往往更高，这一现象可归因于低湿环境下耐热性的环境方差（environmental variance）降低。本研究未观测到不同环境下耐热性的加性遗传方差（additive genetic variance）与可进化性（evolvability）存在显著差异。遗传力估计值的分布模式表明，黑腹果蝇种群在干旱环境下具备更强的演化出更高耐热性的潜力。