Heating up eco-evolutionary dynamics: thermal adaptation exacerbates the ecological consequences of warming

Authors: David C. Fryxell, Eric P. Palkovacs

Year: 2016 (xlviii)

Abstract

Predictions about the impacts of climate change on ecosystems have been based largely on studies that place organisms adapted to current climate conditions into future climate scenarios. Such an approach assumes that today’s organisms will be interacting in tomorrow’s climate. However, climate change causes adaptive evolution, which may change ecological interactions and alter predictions for ecosystem responses. We tested whether thermal adaptation in the common desert aquatic invader, wester n mosquitofish (Gambusia affinis), has ecological effects and asked whether those effects dampen or exacerbate the consequences of warming. We used recently diverged mosquitofish populations from a warm-source and a cool-source to examine divergence in traits. We then tested ecosystem effects in ambient and warmed (+2 C) experimental ponds. Populations showed trait divergence consistent with thermal adaptation; warm-source fish grew slower and were relatively smaller at maturity. In experimental ponds, warming reduced zooplankton body size and biomass. The introduction of mosquitofish exacerbated this effect, with the warm- source population causing a greater shift towards small-bodied zooplankton taxa than the cool-source population. Our results suggest that thermal adaptation may be an important pathway by which climate warming can impact ecosystems. Experiments that test the ecosystems effects of climate warming using organisms adapted to current climate conditions may underestimate these effects.