Data from: Seasonal variation in life history traits in two Drosophila species

Seasonal environmental heterogeneity is cyclic, persistent and
geographically widespread. In species that reproduce multiple times
annually, environmental changes across seasonal time may create different
selection regimes that may shape the population ecology and life history
adaptation in these species. Here, we investigate how two closely related
species of Drosophila in a temperate orchard respond to environmental
changes across seasonal time. Natural populations of Drosophila
melanogaster and D. simulans were sampled at four timepoints from June
through November to assess seasonal change in fundamental aspects of
population dynamics as well as life history traits. D. melanogaster
exhibit pronounced change across seasonal time: early in the season, the
population is inferred to be uniformly young and potentially represents
the early generation following overwintering survivorship. D. melanogaster
isofemale lines derived from the early population and reared in a common
garden are characterized by high tolerance to a variety of stressors as
well as a fast rate of development in the laboratory environment that
declines across seasonal time. In contrast, wild D. simulans populations
were inferred to be consistently heterogeneous in age distribution across
seasonal collections; only starvation tolerance changed predictably over
seasonal time in a parallel manner as in D. melanogaster. These results
suggest fundamental differences in population and evolutionary dynamics
between these two taxa associated with seasonal heterogeneity in
environmental parameters and associated selection pressures.

季节性环境异质性具有周期性、持续性且在地理上广泛分布。对于年繁殖多次的物种而言，季节性时间尺度上的环境变化可能催生差异化的选择模式，进而塑造该类物种的种群生态学特征与生活史适应性。本研究聚焦温带果园中的两种近缘果蝇属（Drosophila）物种，探究其在季节性时间尺度下对环境变化的响应。研究人员于6月至11月间的四个时间节点采集黑腹果蝇（Drosophila melanogaster）与拟果蝇（Drosophila simulans）的自然种群样本，以评估种群动态核心维度及生活史性状的季节性变化。黑腹果蝇的种群特征在季节性时间尺度上呈现显著变化：种群早期的个体年龄结构均一且以年轻个体为主，推测其为越冬存活后产生的初代种群。从该早期种群中分离得到并在同质园环境下饲养的黑腹果蝇单雌系，对多种胁迫因子具有较高耐受性，且在实验室环境下发育速率较快，但该发育速率会随采样季节的推移逐渐下降。与之形成鲜明对比的是，拟果蝇的野生种群在各季节采样中的年龄结构始终呈现异质性；仅其饥饿耐受性会随季节变化呈现可预测的同向变化，与黑腹果蝇的变化模式一致。上述研究结果表明，这两个类群在种群与进化动态上存在根本性差异，该差异与环境参数的季节性异质性及相关选择压力紧密关联。