Evolution mediates the effects of apex predation on aquatic food webs

Ecological and evolutionary mechanisms are increasingly thought to shape local community dynamics. Here, I evaluate if the local adaptation of a meso-predator to an apex predator alters local food webs. The marbled salamander (Ambystoma opacum) is an apex predator that consumes both the spotted salamander (Ambystoma maculatum) and shared zooplankton prey. Common garden experiments reveal that spotted salamander populations which co-occur with marbled salamanders forage more intensely than those that face other predator species. These foraging differences, in turn, alter the diversity, abundance and composition of zooplankton communities in common garden experiments and natural ponds. Locally adapted spotted salamanders exacerbate prey biomass declines associated with apex predation, but dampen the top-down effects of apex predation on prey diversity. Countergradient selection on foraging explains why locally adapted spotted salamanders exacerbate prey biomass declines. The two salamande...生态与进化机制日益被认为对局域群落动态具有塑造作用。本研究旨在评估：中捕食者（meso-predator）对顶级捕食者（apex predator）的局域适应是否会改变局域食物网结构。斑背钝口螈（Ambystoma opacum）是一种顶级捕食者，其捕食对象涵盖斑点钝口螈（Ambystoma maculatum）以及二者共享的浮游动物猎物。同质园实验（common garden experiment）结果显示：与斑背钝口螈共存的斑点钝口螈种群，其觅食强度高于遭遇其他捕食者物种的种群。这类觅食行为差异进而改变了同质园实验与自然池塘中浮游动物群落的多样性、丰度与组成结构。经局域适应的斑点钝口螈会加剧顶级捕食所引发的猎物生物量下降，但却会缓解顶级捕食对猎物多样性的下行调控效应（top-down effects）。针对觅食行为的反梯度选择（countergradient selection），可解释为何经局域适应的斑点钝口螈会加剧猎物生物量的下降。这两种钝口螈……