Shinohara Tadashi, Takami Yasuoki
Graduate School of Human Development & Environment Kobe University Kobe Japan.
Ecol Evol. 2020 Apr 30;10(11):5089-5096. doi: 10.1002/ece3.6262. eCollection 2020 Jun.
Predator-prey interactions may be responsible for enormous morphological diversity in prey species. We performed predation experiments with morphological manipulations (ablation) to investigate the defensive function of dorsal spines and explanate margins in Cassidinae leaf beetles against three types of predators: assassin bugs (stinger), crab spiders (biter), and tree frogs (swallower). There was mixed support for the importance of primary defense mechanisms (i.e., preventing detection or identification). Intact spined prey possessing dorsal spines were more likely to be attacked by assassin bugs and tree frogs, while intact armored prey possessing explanate margins were likely to avoid attack by assassin bugs. In support of the secondary defense mechanisms (i.e., preventing subjugation), dorsal spines had a significant physical defensive function against tree frogs, and explanate margins protected against assassin bugs and crab spiders. Our results suggest a trade-off between primary and secondary defenses. Dorsal spines improved the secondary defense but weakened the primary defense against tree frogs. We also detected a trade-off in which dorsal spines and explanate margins improved secondary defenses against mutually exclusive predator types. Adaptation to different predatory regimes and functional trade-offs may mediate the diversification of external morphological defenses in Cassidinae leaf beetles.
捕食者与猎物的相互作用可能是导致猎物物种出现巨大形态多样性的原因。我们进行了带有形态学操控（切除）的捕食实验，以研究龟甲亚科叶甲虫的背刺和扩缘在抵御三种捕食者时的防御功能，这三种捕食者分别是猎蝽（刺蛰型）、蟹蛛（撕咬型）和树蛙（吞咽型）。对于主要防御机制（即防止被发现或识别）的重要性，实验结果存在不同支持情况。拥有背刺的完整带刺猎物更容易受到猎蝽和树蛙的攻击，而拥有扩缘的完整带甲猎物则可能避免被猎蝽攻击。为支持次要防御机制（即防止被制服），背刺对树蛙具有显著的物理防御功能，扩缘则能抵御猎蝽和蟹蛛。我们的结果表明主要防御和次要防御之间存在权衡。背刺增强了次要防御，但削弱了对树蛙的主要防御。我们还发现了一种权衡，即背刺和扩缘增强了对相互排斥的捕食者类型的次要防御。对不同捕食方式的适应以及功能权衡可能介导了龟甲亚科叶甲虫外部形态防御的多样化。
