Data from: Micro- and macroevolutionary trade-offs in plant-feeding insects

A long-standing hypothesis asserts that plant-feeding insects specialize on particular host plants because of negative interactions (trade-offs) between adaptations to alternative hosts, yet empirical evidence for such trade-offs is scarce. Most studies have looked for microevolutionary performance trade-offs within insect species, but host-use could also be constrained by macroevolutionary trade-offs caused by epistasis and historical contingency. Here we used a phylogenetic approach to estimate the micro- and macroevolutionary correlations between use of alternative host-plant taxa within two major orders of plant-feeding insects: Lepidoptera (caterpillars) and Hemiptera (true bugs). Across 1604 caterpillar species, we found both positive and negative pairwise correlations between use of eleven host-plant orders, with overall network patterns suggesting that different host-use constraints act over micro- and macroevolutionary timescales. In contrast, host-use patterns of 955 true bug species revealed uniformly positive correlations between use of the same host-plant orders over both timescales. The lack of consistent patterns across timescales and insect orders indicates that host-use trade-offs are historically contingent rather than universal constraints. Moreover, we observed few negative correlations overall despite the wide taxonomic and ecological diversity of the focal host-plant orders, suggesting that positive interactions between host-use adaptations, not trade-offs, dominate the long-term evolution of host use in plant-feeding insects.

长期以来存在一项广为认可的假说：植食性昆虫会特化于特定寄主植物，其原因在于昆虫对不同寄主的适应性之间存在负相互作用（即适应性权衡），但此类权衡的实证证据却较为匮乏。既往多数研究均致力于探寻昆虫物种内部的微进化性能权衡，然而寄主利用策略也可能受到由上位性(epistasis)与历史偶然性(historical contingency)所导致的宏进化权衡的约束。本研究采用系统发育分析方法(phylogenetic approach)，针对两大植食性昆虫类群——鳞翅目(Lepidoptera，幼虫为毛虫)与半翅目(Hemiptera，真蝽类昆虫)——估算了其对不同寄主植物类群的利用情况之间的微进化与宏进化相关性。在1604种毛虫样本中，我们发现11个寄主植物目的利用情况之间存在正负两种两两相关性，整体的网络模式表明，不同的寄主利用约束分别作用于微进化与宏进化时间尺度。与之形成鲜明对比的是，955种半翅目昆虫的寄主利用模式显示，在两类时间尺度下，其对同一寄主植物目的利用情况均呈现出一致的正相关性。不同时间尺度与昆虫类群间缺乏统一模式这一结果表明，寄主利用权衡具有历史偶然性，而非普适性约束。此外，尽管所聚焦的寄主植物目涵盖了广泛的分类学与生态学多样性，但整体上我们仅观察到极少的负相关性，这暗示寄主利用适应性之间的正相互作用而非权衡效应，主导了植食性昆虫寄主利用策略的长期演化。