Data from: Adaptive evolution to novel predators facilitates the evolution of damselfly species range shifts

Most species have evolved adaptations to reduce the chances of predation. In many cases adaptations to coexist with one predator generate tradeoffs in the ability to live with other predators. Consequently, the ability to live with one predator may limit the geographic distributions of species, such that adaptive evolution to coexist with novel predators may facilitate range shifts. In a case study with Enallagma damselflies, we used a comparative phylogenetic approach to test the hypothesis that adaptive evolution to live with a novel predator facilitates range size shifts. Our results suggest that the evolution of Enallagma shifting from living in ancestral lakes with fish as top predators, to living in lakes with dragonflies as predators, may have facilitated an increase in their range sizes. This increased range size likely arose because lakes with dragonflies were widespread, but unavailable as a habitat throughout much of the evolutionary history of Enallagma because they were historically maladapted to coexist with dragonfly predators. Additionally, the traits that have evolved as defenses against dragonflies also likely enhanced damselfly dispersal abilities. While many factors underlie the evolutionary history of species ranges, these results suggest a role for the evolution of predator-prey interactions.

绝大多数物种均已演化出反捕食适应性策略，以降低被捕食的风险。在多数情境下，为与某一类捕食者共存而形成的适应性演化，会与物种应对其他捕食者的生存能力产生权衡效应。由此，物种适应某一类捕食者的能力可能会限制其地理分布范围，因此针对新型捕食者的适应性演化或可推动物种分布范围的扩张。本研究以蟌属（Enallagma）豆娘为研究对象，采用比较系统发育学方法，验证了“针对新型捕食者的适应性演化可促进物种分布范围扩张”这一假说。研究结果显示，蟌属物种从祖先栖息的以鱼类为顶级捕食者的湖泊，转向栖息于以蜻蜓为捕食者的湖泊的演化过程，或推动了其分布范围的扩大。这类分布范围的扩张可能源于：以蜻蜓为捕食者的湖泊本就广泛分布，但在蟌属演化的绝大多数历史时期，这类栖息地并不适宜其生存——这是因为历史上蟌属物种无法与蜻蜓捕食者共存。此外，为抵御蜻蜓捕食而演化出的防御性状，或同时提升了豆娘的扩散能力。尽管物种分布范围的演化历史受诸多因素共同调控，但本研究结果表明，捕食者-猎物相互作用的演化在其中发挥了关键作用。