Galloway Laura F
Section of Evolution and Ecology and Center for Population Biology, University of California, Davis, California, 95616.
Evolution. 1995 Dec;49(6):1095-1107. doi: 10.1111/j.1558-5646.1995.tb04436.x.
Recent studies in plant populations have found that environmental heterogeneity and phenotypic selection vary at local spatial scales. In this study, I ask if there is evolutionary change in response to environmental heterogeneity and, if so, whether the response occurs for characters or character plasticities. I used vegetative clones of Mimulus guttatus to create replicate populations of 75 genotypes. These populations were planted into the natural habitat where they differed in mean growth, flowering phenology, and life span. This phenotypic variation was used to define selective environments. There was variation in fitness (flower production) among genotypes across all planting sites and in genotype response to the selective environment. Offspring from each site were grown in the greenhouse in two water treatments. Because each population initially had the same genetic composition, variation in the progeny between selective environments reveals either evolutionary change in response to environmental heterogeneity or environmental maternal effects. Plants from experimental sites that flowered earlier, had shorter life spans and were less productive, produced offspring that had more flowers, on average, and were less plastic in vegetative allocation than offspring of longer-lived plants from high-productivity areas. However, environmental maternal effects masked phenotypic differences in flower production. Therefore, although there was evidence of genetic differentiation in both life-history characters and their plasticities in response to small-scale environmental heterogeneity, environmental maternal effects may slow evolutionary change. Response to local-scale selective regimes suggests that environmental heterogeneity and local variation in phenotypic selection may act to maintain genetic variation.
近期对植物种群的研究发现，环境异质性和表型选择在局部空间尺度上存在差异。在本研究中，我探究是否存在对环境异质性的进化变化，如果存在，这种响应是针对性状还是性状可塑性。我使用黄花沟酸浆的无性克隆体创建了75个基因型的重复种群。这些种群被种植到自然栖息地中，它们在平均生长、开花物候和寿命方面存在差异。这种表型变异被用来定义选择环境。在所有种植地点的基因型之间，适合度（花的产量）存在差异，并且基因型对选择环境有不同反应。每个地点的后代在温室中进行两种水分处理。由于每个种群最初具有相同的遗传组成，选择环境之间后代的差异揭示了对环境异质性的进化变化或环境母体效应。来自开花较早、寿命较短且生产力较低的实验地点的植物，其后代平均有更多的花，并且与来自高生产力地区寿命较长的植物的后代相比，在营养分配上可塑性较小。然而，环境母体效应掩盖了花产量的表型差异。因此，尽管有证据表明在生活史性状及其可塑性方面存在遗传分化以响应小规模环境异质性，但环境母体效应可能会减缓进化变化。对局部尺度选择机制的响应表明，环境异质性和表型选择的局部变异可能有助于维持遗传变异。
