Egan Scott P, Funk Daniel J
Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA.
Proc Biol Sci. 2006 Apr 7;273(1588):843-8. doi: 10.1098/rspb.2005.3382.
The information-processing hypothesis (IPH) posits that specialist herbivores should make host-associated decisions more effectively than generalists and thus enjoy associated fitness advantages that may help explain the evolutionary prevalence of host-specific insects. This is because generalists must evaluate a greater diversity of host plants/cues than specialists and thus face a cognitive challenge that is predicted to constrain the efficiency and accuracy of their choices. Here, we present the first individual-level evaluation of this hypothesis. This involved experimentally quantifying the specificity, efficiency, and accuracy of host selection, as both larvae and adults, for many individuals representing each of three 'host forms' of Neochlamisus bebbianae leaf beetles. These experiments provided several significant findings: host forms differed in larval specificity, with the more specialized host forms more efficiently and accurately selecting optimal hosts as both larvae and adults. Positive correlations between larval specificity and both efficiency and accuracy across test individuals provided the most direct evidence to date for a biological association between these variables. Our results thus provide strong and consistent support for the IPH at the level of both populations and individuals. Because individual N. bebbianae make many host-associated decisions in nature, our results suggest that cognitive constraints may play a major role in the evolutionary dynamics of ongoing ecological specialization and diversification in this species.
信息处理假说（IPH）认为，专食性食草动物在做出与寄主相关的决策方面应比广食性动物更有效，因此具有相关的适应性优势，这可能有助于解释寄主特异性昆虫在进化上的普遍性。这是因为广食性动物必须比专食性动物评估更多样化的寄主植物/线索，因此面临一种认知挑战，预计这会限制它们选择的效率和准确性。在此，我们首次对这一假说进行个体水平的评估。这涉及通过实验量化寄主选择的特异性、效率和准确性，针对代表新绿萤叶甲三种 “寄主类型” 中每一种的许多个体，分别作为幼虫和成虫进行研究。这些实验得出了几个重要发现：寄主类型在幼虫特异性方面存在差异，更特化的寄主类型在作为幼虫和成虫时都能更高效、准确地选择最优寄主。在测试个体中，幼虫特异性与效率和准确性之间的正相关关系为这些变量之间的生物学关联提供了迄今为止最直接的证据。因此，我们的结果在种群和个体层面都为信息处理假说提供了有力且一致的支持。由于新绿萤叶甲个体在自然环境中会做出许多与寄主相关的决策，我们的结果表明，认知限制可能在该物种正在进行的生态特化和多样化的进化动态中起主要作用。
