Räsänen Katja, Laurila Anssi, Merilä Juha
Department of Population Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18 D, SE-752 36 Uppsala, Sweden.
Evolution. 2003 Feb;57(2):352-62.
Spatially varying directional selection together with restricted gene flow among populations is expected to lead to local adaptation. One environmental factor that potentially causes strong directional selection, but is little explored in evolutionary terms, is naturally and anthropogenically induced acidity. We studied local adaptation to acidity in four Swedish populations (two originating from areas that have suffered from severe anthropogenic acidification during the 1900s and two from areas which have remained neutral due to higher buffering capacity) of the moor frog Rana arvalis in a laboratory experiment by investigating whether differences in acid tolerance correspond to population origin. Embryos were raised from fertilization to hatching at three different pH levels (pH 4.0, 4.25 and 7.5), corresponding to levels experienced by these populations in nature, and acid stress tolerance was measured in terms of embryonic survival, hatchling size, and age. Evidence for local adaptation in all of these traits was found, the acid origin embryos having higher survival and less impaired growth performance under acid conditions than the neutral origin embryos. Our estimated rates of divergence (0.007-0.102 haldanes) suggest a rapid adaptation process in response to anthropogenic environmental change, and that the different traits have evolved at relatively similar rates.
空间变化的定向选择以及种群间有限的基因流动预计会导致局部适应。一种可能导致强烈定向选择，但在进化方面很少被探索的环境因素是自然和人为诱导的酸度。我们通过研究沼蛙（Rana arvalis）的酸耐受性差异是否与种群起源相对应，在实验室实验中对来自瑞典的四个沼蛙种群（两个来自在20世纪遭受严重人为酸化的地区，两个来自由于较高缓冲能力而保持中性的地区）进行了酸度局部适应性研究。胚胎从受精到孵化在三种不同的pH水平（pH 4.0、4.25和7.5）下培养，这与这些种群在自然环境中经历的水平相对应，并根据胚胎存活率、幼体大小和年龄来衡量酸胁迫耐受性。在所有这些性状中都发现了局部适应的证据，与中性起源胚胎相比，酸起源胚胎在酸性条件下具有更高的存活率和生长性能受损更小的特点。我们估计的分化速率（0.007 - 0.102哈代）表明，对人为环境变化存在快速适应过程，并且不同性状以相对相似的速率进化。
