McPeek M A
Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA.
Evolution. 2000 Dec;54(6):2072-80. doi: 10.1111/j.0014-3820.2000.tb01250.x.
Previous studies have shown that two or three lineages of Enallagma damselflies, which historically co-existed with fish, recently invaded and adapted to living with large dragonfly predators in fishless waters. In adapting to live with these new predators, lineages shifted behaviorally to using swimming as an evasive tactic against attacking predators, evolved morphological features that made them faster swimmers, and evolved biochemical features to increase refueling strenuous activities like swimming. However, these habitat shifts have occurred in only one of the two primary clades within the genus in North America. Here, I show that clade-level differences exist among species in the ancestral, fish-lake habitat that should make habitat shifts easier to accomplish in the clade in which they have occurred. Specifically, fish-lake species in the clade in which habitat shifts occurred have much higher propensities to swim in the laboratory, swim faster when they do swim, and have higher mass-specific activities for arginine kinase than do species in the other primary clade, in which no extant species are found in fishless waters. These results are discussed in the context of the dynamics of founder events and the potential implications for community structure.
先前的研究表明，历史上与鱼类共存的两到三个伊乐蜻蛉谱系，最近侵入并适应了在无鱼水域与大型蜻蜓捕食者共同生活。在适应与这些新捕食者共存的过程中，这些谱系在行为上转变为利用游泳作为躲避攻击捕食者的策略，进化出使其成为更快游泳者的形态特征，并进化出生物化学特征以增加为诸如游泳等剧烈活动补充能量。然而，这些栖息地转变仅发生在北美该属两个主要分支中的一个分支内。在此，我表明在祖先的鱼类湖泊栖息地中，物种之间存在分支水平的差异，这应该会使栖息地转变在发生转变的分支中更容易实现。具体而言，发生栖息地转变的分支中的鱼类湖泊物种在实验室中有更高的游泳倾向，游泳时游得更快，并且与另一个主要分支中的物种相比，精氨酸激酶的质量比活性更高，而在另一个主要分支中没有现存物种存在于无鱼水域。这些结果在奠基者事件的动态背景下进行了讨论，并探讨了其对群落结构的潜在影响。
