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（seasonal environmental heterogeneity）具有周期性、持续性且地理分布广泛的特征。对于一年多次繁殖的物种而言，跨季节的环境变化可能形成不同的选择机制，进而塑造该类物种的种群生态学特征与生活史适应性。本研究以温带果园中的两个近缘果蝇（Drosophila）物种为研究对象，探究其如何响应跨季节的环境变化。研究人员于6月至11月的四个时间点采集黑腹果蝇（Drosophila melanogaster）与拟果蝇（Drosophila simulans）的自然种群，以评估种群动态及生活史性状核心特征的季节变化。黑腹果蝇的种群特征在季节间呈现显著变化：种群早期被推断为统一的年轻种群，大概率代表越冬存活后诞生的初代种群。从该早期种群中建立的单雌系（isofemale lines）若在同质园环境中培育，其对多种胁迫因子的耐受性与实验室环境下的发育速率均较高，且这两项指标随季节推移逐渐下降。与之相反，野外采集的拟果蝇种群在各季节采样中的年龄分布始终呈异质性；仅耐饥饿性随季节呈现出与黑腹果蝇相似的可预测变化趋势。上述结果表明，这两个果蝇类群在与环境参数季节性异质性及相关选择压力相关的种群与进化动态方面存在根本性差异。