Negovetic S, Jokela J
Experimental Ecology, ETH Zürich
Anim Behav. 2000 Oct;60(4):435-441. doi: 10.1006/anbe.2000.1486.
Genetic polymorphism along an environmental gradient may be maintained if disruptive selection on habitat-specific traits leads to a correlated response in traits that reduce gene flow between habitats. We studied a short-distance cline in a population of freshwater snails Potamopyrgus antipodarum in which sexual and clonal snails coexist. Sexuals and clones show a life history cline by depth: snails reproduce at a smaller size in shallower habitats. Clones are also structured genetically across habitats and seem not to mix, even though habitats are within the dispersal distance of the snails and the opportunity for gene flow via migration must be considerable. Because habitat preference may promote divergence in both clones and sexuals along the depth gradient, we investigated whether snails show habitat-specific food choice behaviour that could reduce migration. We tested the food choice behaviour of the snails by exposing them simultaneously to food from their home and adjacent habitats. Both juvenile and adult snails from the shallow shore bank and a mid-water macrophyte habitat preferentially grazed on the vegetation of their original habitats. We suggest that the observed genetic and life history cline may be maintained by food choice behaviour that may promote a partial barrier to gene flow between the habitats. Copyright 2000 The Association for the Study of Animal Behaviour.
如果对特定栖息地性状的歧化选择导致在减少栖息地间基因流动的性状上产生相关反应，那么沿环境梯度的遗传多态性可能会得以维持。我们研究了淡水螺新西兰泥蜗种群中的一个短距离渐变群，其中有性和无性生殖的螺共存。有性和无性生殖的螺在深度上呈现出生活史渐变群：螺在较浅栖息地以较小的体型进行繁殖。无性生殖的螺在不同栖息地之间在遗传上也有结构差异，并且似乎不会混合，尽管栖息地在螺的扩散距离之内，通过迁移实现基因流动的机会必定很大。由于栖息地偏好可能会促进无性和有性生殖的螺沿着深度梯度产生分化，我们研究了螺是否表现出特定栖息地的食物选择行为，这种行为可能会减少迁移。我们通过同时将螺暴露于来自其原生栖息地和相邻栖息地的食物来测试螺的食物选择行为。来自浅岸滩和中水大型植物栖息地的幼螺和成螺都优先啃食其原生栖息地的植被。我们认为，观察到的遗传和生活史渐变群可能是由食物选择行为维持的，这种行为可能会促进在栖息地之间形成部分基因流动障碍。版权所有2000动物行为研究协会。
