Am Nat. 2020 Feb;195(2):331-348. doi: 10.1086/706813. Epub 2019 Dec 26.
Consumers regularly experience trade-offs in their ability to find, handle, and digest different resources. Evolutionary ecologists recognized the significance of this observation for the evolution and maintenance of biological diversity long ago and continue to elaborate on the conditions under which to expect one or several specialists, generalists, or combinations thereof. Existing theory based on a single evolving trait predicts that specialization requires strong trade-offs such that generalists perform relatively poorly, while weak trade-offs favor a single generalist. Here, we show that this simple dichotomy does not hold true under joint evolution of two or more foraging traits. In this case, the boundary between trade-offs resulting in resource specialists and resource generalists is shifted toward weaker trade-off curvatures. In particular, weak trade-offs can result in evolutionary branching, leading to the evolution of two coexisting resource specialists, while the evolution of a single resource generalist requires particularly weak trade-offs. These findings are explained by performance benefits due to epistatic trait interactions enjoyed by phenotypes that are specialized in more than one trait for the same resource.
消费者在寻找、处理和消化不同资源的能力方面经常面临权衡。进化生态学家很久以前就认识到这一观察结果对生物多样性的进化和维持具有重要意义，并继续详细阐述在何种条件下可以预期出现一个或多个专门从事某项活动的专家、通才或其组合。现有的基于单一进化特征的理论预测，专业化需要很强的权衡，使得通才表现相对较差，而较弱的权衡则有利于单一的通才。在这里，我们表明，在两个或更多觅食特征的共同进化下，这种简单的二分法并不成立。在这种情况下，导致资源专门家和资源通才的权衡之间的界限向较弱的权衡曲率移动。特别是，弱权衡可能导致进化分支，导致两个共存的资源专门家的进化，而单一资源通才的进化则需要特别弱的权衡。这些发现可以通过表型的上位性特征相互作用来解释，这些表型在同一资源的多个特征上专门化，从而享受到表现优势。
