Entomology and Nematology Department, University of Florida, Gainesville, FL, USA.
Southern California Edison, Los Angeles, CA, USA.
J Evol Biol. 2021 Apr;34(4):653-660. doi: 10.1111/jeb.13766. Epub 2021 Feb 8.
Animals have encountered novel foods at points throughout history, due to factors such as range expansions and niche shifts driven by competition. One of the first challenges presented by novel foods is how to eat them. Mouthpart morphology is thus critical during the process of host shifts. Developmental plasticity in mouthparts is one potential mechanism that may allow animals to tolerate new foods and eventually to thrive upon them. Here, we investigated the extent to which insect mouthparts from two geographically distant populations can converge in morphology when feeding on common resources. We conducted a common garden/reciprocal transplant experiment using two populations of the cactus bug, Narnia femorata, that differ in mouthpart length. This insect uses straw-like mouthparts (hereafter 'beak') to get through the cactus fruit wall to reach the pulp inside. Our experimental results revealed clear developmental plasticity in beak length. Insects from both populations grew longer beaks when they fed on the cactus fruit with the thicker walls, and they grew shorter beaks when they fed on the cactus fruit with the thinner walls. Thus, insects from distant populations exhibited immediate developmental responses to a new food, and in the predicted directions. These results suggest that some fauna may be able to respond more rapidly than predicted when they encounter novel plants.
动物在历史上的各个时期都会遇到新的食物，这是由于竞争导致的范围扩大和生态位转移等因素造成的。新食物带来的第一个挑战之一是如何食用它们。因此，在宿主转移过程中，口器形态至关重要。口器的发育可塑性是一种可能使动物能够耐受新食物并最终在其上茁壮成长的潜在机制。在这里，我们研究了当以常见资源为食时，来自两个地理上遥远种群的昆虫口器在形态上可以在多大程度上趋同。我们使用两种形态长度不同的仙人掌虫 Narnia femorata 进行了一个共同花园/相互移植实验。这种昆虫使用类似吸管的口器（以下简称“喙”）穿透仙人掌果实的外壁，到达里面的果肉。我们的实验结果显示出喙长度的明显发育可塑性。当它们以较厚壁的仙人掌果实为食时，来自两个种群的昆虫会长出更长的喙，而当它们以较薄壁的仙人掌果实为食时，它们会长出更短的喙。因此，来自遥远种群的昆虫对新食物表现出了即时的发育反应，而且方向是可预测的。这些结果表明，某些动物群在遇到新植物时可能能够比预期更快地做出反应。
