School of Life Sciences, Arizona State University, Tempe, Arizona 85287.
Evolution. 2014 Mar;68(3):720-8. doi: 10.1111/evo.12296. Epub 2013 Nov 20.
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 plasticity. Specifically, genotypes from the temporally variable selective environment were more fecund across all temperatures than were genotypes from other environments. These patterns suggest certain allelic effects and should inspire new directions for modeling adaptation to fluctuating environments.
在多变的环境中，选择应该有利于能够在多种条件下保持适应力的通才。然而，适应的代价可能会产生适应力的权衡，导致专业化和通用性之间的某种妥协，从而使适应力最大化。在这里，我们评估了 20 个黑腹果蝇种群在恒定和可变热环境中经过 3 年的实验进化后的专业化和通用性的演变。我们从每个种群中开发了两种温度下的基因型，然后在八种温度下测量了它们的繁殖力。我们预测，恒定环境会选择热专家，而可变环境会选择热通才。与我们的预测相反，专家和通才并没有分别在恒定和空间可变的环境中进化。然而，时间变化产生了一种通才，这是发育可塑性理论模型很少考虑的。具体来说，来自时间可变选择环境的基因型在所有温度下的繁殖力都比其他环境中的基因型更高。这些模式表明某些等位基因的影响，并应激发对波动环境适应的建模的新方向。
