De Meester Luc
Laboratory of Animal Ecology, University of Gent, K.L. Ledeganckstraat 35, 9000, Gent, Belgium.
Evolution. 1996 Jun;50(3):1293-1298. doi: 10.1111/j.1558-5646.1996.tb02369.x.
The frequent use of neutral markers to quantify genetic variation in natural populations emphasizes the role of stochastic events in explaining genetic differentiation between populations. Complementary studies on ecologically relevant traits are needed to assess the role of natural selection acting on adaptive variation in the development of local genetic differentiation. To test the hypothesis of local adaptation in the cyclical parthenogenetic species Daphnia magna, the phototactic behavior in the absence and presence of fish kairomone was assayed for 30 clones derived from resting eggs isolated from three habitats characterized by a different predation pressure by fish. Clones derived from populations in which fish are present were, on average, more negatively phototactic in and more responsive to the presence of fish kairomone than clones derived from a fishless habitat. In addition, the results show a high genetic diversity for the traits studied in all three gene pools investigated, indicating a high potential for microevolutionary changes in behavior of these Daphnia populations in the face of changes in predation pressure. The results of the present study indicate that working with large samples at the expense of having less precise estimates of genotypic values for specific genotypes may result in a loss of information with regard to the evolutionary potential of local populations.
频繁使用中性标记来量化自然种群中的遗传变异，凸显了随机事件在解释种群间遗传分化方面的作用。需要对与生态相关的性状进行补充研究，以评估自然选择在局部遗传分化发展过程中对适应性变异所起的作用。为了检验周期性孤雌生殖物种大型溞的局部适应性假说，对从三个栖息地分离出的静息卵所获得的30个克隆进行了测定，这些栖息地的特点是鱼类的捕食压力不同，测定了在有无鱼类信息素的情况下的趋光行为。与来自无鱼栖息地的克隆相比，来自有鱼种群的克隆平均而言在有鱼类信息素时趋光性更负，且对其反应更强烈。此外，结果显示在所有三个研究的基因库中，所研究的性状都具有高遗传多样性，这表明面对捕食压力的变化，这些大型溞种群在行为上具有发生微进化变化的高潜力。本研究结果表明，以牺牲对特定基因型基因型值的精确估计为代价使用大样本，可能会导致在当地种群进化潜力方面的信息丢失。
