title: Evolution mediates the effects of apex predation on aquatic food webs.
abstract: 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 salamander species prefer different prey species, which explains why adapted spotted salamanders buffer changes in prey composition owing to apex predation. Results suggest that local adaptation can strongly mediate effects from apex predation on local food webs. Community ecologists might often need to consider the evolutionary history of populations to understand local diversity patterns, food web dynamics, resource gradients and their responses to disturbance.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Connecticut, 75 North Eagleville Road, Unit 3043, Storrs, CT 06269, USA. mark.urban@uconn.edu
authors.forename: Mark C
authors.initials: MC
authors.lastname: Urban
mesh_terms: D000818:Animals; D005075:Biological Evolution; D017753:Ecosystem; D020387:Food Chain; D007814:Larva / Q000502:physiology; D061005:Ponds; D011235:Predatory Behavior; D014562:Caudata / Q000145:classification / Q000502:physiology*; D015048:Zooplankton / Q000502:physiology*
keywords: community ecology; eco-evolutionary dynamics; evolutionary ecology; food web; species interactions; top-down effects