Temporal variation favors the evolution of generalists in experimental populations of Drosophila melanogaster

In variable environments, selection should favor generalists that maintain fitness across a range of conditions. However, costs of adaptation may generate fitness trade-offs and lead to some compromise between specialization and generalization that maximizes fitness. Here, we evaluate the evolution of specialization and generalization in 20 populations of Drosophila melanogaster experimentally evolved in constant and variable thermal environments for 3 years. We developed genotypes from each population at two temperatures after which we measured fecundity across eight temperatures. We predicted that constant environments would select for thermal specialists and that variable environments would select for thermal generalists. Contrary to our predictions, specialists and generalists did not evolve in constant and spatially variable environments, respectively. However, temporal variation produced a type of generalist that has rarely been considered by theoretical models of developmental pl...

在可变环境中，自然选择应倾向于那些能在多种环境条件下维持适合度（fitness）的泛化型（generalist）种群。然而，适应代价可能引发适合度权衡，并在特化（specialization）与泛化之间形成某种折中方案，以实现适合度最大化。本研究以经过3年恒定与可变热环境实验演化的20个黑腹果蝇（Drosophila melanogaster）种群为研究对象，评估其特化与泛化的演化历程。我们从每个种群在两种温度条件下构建了实验基因型，随后在8种不同温度下测定其繁殖力（fecundity）。我们此前预测，恒定热环境会选择出热特化型（thermal specialist）种群，而可变热环境则会选择出热泛化型（thermal generalist）种群。与我们的预测相悖的是，特化型与泛化型种群并未分别在恒定环境和空间可变环境中演化形成。然而，时间异质性所催生的一类泛化型种群，却极少被发育相关理论模型所纳入考量……