Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile.
Oecologia. 2010 May;163(1):153-62. doi: 10.1007/s00442-010-1587-3. Epub 2010 Mar 6.
Pollinator-mediated selection is one of the most important factors driving adaptation in flowering plants. However, as ecological conditions change through habitat loss and fragmentation, the interactions among species may evolve in new and unexpected directions. Human-induced environmental variation is likely to affect selection regimes, but as yet no empirical examples have been reported. In the study reported here, we examined the influence of human-induced habitat transformation on the composition of pollinator assemblages and, hence, pollinator-mediated selection on the flower phenotype of Viola portalesia (Violaceae). Our results indicate that pollinator assemblages differed substantially in terms of species composition and visitation rate between nearby native and transformed habitats. Similarly, the insect species that contributed most to visitation rates differed between plant populations. While the magnitude and sign of pollinator-mediated selection on flower length and width did not differ between sites, selection for flower number lost significance in the transformed habitat, and a significant pattern of disruptive selection for flower shape, undetected in the native habitat, was present in the transformed one. Overall, the results of this study suggest that human-induced habitat change may not only modify the species composition of pollinator assemblages, relaxing the selection process on some flower characters, but they may also create new opportunities for fitness-trait covariation not present in pristine conditions.
传粉媒介介导的选择是驱动开花植物适应的最重要因素之一。然而，随着生态条件通过栖息地丧失和碎片化而改变，物种之间的相互作用可能会以新的和意想不到的方向进化。人为引起的环境变化可能会影响选择机制，但到目前为止还没有报道过实证例子。在本研究中，我们研究了人类引起的栖息地转化对传粉媒介组合的影响，从而研究了传粉媒介对 Viola portalesia（Violaceae）花表型的介导选择。我们的结果表明，在附近的原生和转化生境之间，传粉媒介组合在物种组成和访问率方面存在显著差异。同样，对访问率贡献最大的昆虫物种在植物种群之间也存在差异。虽然花长度和宽度的传粉媒介介导选择的幅度和方向在不同地点没有差异，但在转化生境中花数量的选择失去了意义，而在原生境中未检测到的花形状的破坏性选择模式在转化生境中存在。总的来说，这项研究的结果表明，人为引起的栖息地变化不仅可能改变传粉媒介组合的物种组成，从而放松对某些花特征的选择过程，而且还可能为在原始条件下不存在的适应性特征共变创造新的机会。
