School of Natural Sciences, Linnaeus University, SE-391 82 Kalmar, Sweden.
Evolution. 2011 Sep;65(9):2530-40. doi: 10.1111/j.1558-5646.2011.01324.x. Epub 2011 May 10.
Evolutionary theory predicts an interactive process whereby spatiotemporal environmental heterogeneity will maintain genetic variation, while genetic and phenotypic diversity will buffer populations against stress and allow for fast adaptive evolution in rapidly changing environments. Here, we study color polymorphism patterns in pygmy grasshoppers (Tetrix subulata) and show that the frequency of the melanistic (black) color variant was higher in areas that had been ravaged by fires the previous year than in nonburned habitats, that, in burned areas, the frequency of melanistic grasshoppers dropped from ca. 50% one year after a fire to 30% after four years, and that the variation in frequencies of melanistic individuals among and within populations was genetically based on and represented evolutionary modifications. Dark coloration may confer a selective benefit mediated by enhanced camouflage in recently fire-ravaged areas characterized by blackened visual backgrounds before vegetation has recovered. These findings provide rare evidence for unusually large, extremely rapid adaptive contemporary evolution in replicated natural populations in response to divergent and fluctuating selection associated with spatiotemporal environmental changes.
进化理论预测了一个相互作用的过程，即时空环境异质性将维持遗传变异，而遗传和表型多样性将缓冲种群免受压力，并允许在快速变化的环境中快速适应进化。在这里，我们研究了矮小草螽（Tetrix subulata）的颜色多态性模式，结果表明，在前一年遭受火灾破坏的地区，黑化（黑色）变体的频率高于未燃烧的栖息地，在燃烧地区，黑化草螽的频率从火灾后一年的约 50%下降到四年后的 30%，并且黑化个体在种群间和种群内的频率变化是基于遗传的，代表了进化的修饰。暗色素可能通过在植被尚未恢复的最近遭受火灾破坏的地区提供增强的伪装提供选择性优势，这些地区的视觉背景为黑色。这些发现为在复制的自然种群中对时空环境变化相关的发散和波动选择做出响应的异常大、极快的当代适应性进化提供了罕见的证据。
