Predators like it hot: Thermal mismatch in a predator-prey system across an elevational tropical gradient.

Abstract

Climate change may have dramatic consequences for communities through both direct effects of peak temperatures upon individual species and through interspecific mismatches in thermal sensitivities of interacting organisms which mediate changes in interspecific interactions (i.e. predation). Despite this, there is a paucity of information on the patterns of spatial physiological sensitivity of interacting species (at both landscape and local scales) which could ultimately influence geographical variation in the effects of climate change on community processes. In order to assess where these impacts may occur, we first need to evaluate the spatial heterogeneity in the degree of mismatch in thermal tolerances between interacting organisms. We quantify the magnitude of interspecific mismatch in maximum (CTmax ) and minimum (CTmin ) thermal tolerances among a predator-prey system of dragonfly and anuran larvae in tropical montane (242-3,631m) and habitat (ponds and streams) gradients. To compare thermal mismatches between predator and prey, we coined the parameters maximum and minimum predatory tolerance margins (PTMmax and PTMmin ), or difference in CTmax and CTmin of interacting organisms sampled across elevational and habitat gradients. Our analyses revealed that: (a) predators exhibit higher heat tolerances than prey (~4°C), a trend which remained stable across habitats and elevations. In contrast, we found no differences in minimum thermal tolerances between these groups. (b) Maximum and minimum thermal tolerances of both predators and prey decreased with elevation, but only maximum thermal tolerance varied across habitats, with pond species exhibiting higher heat tolerance than stream species. (c) Pond-dwelling organisms from low elevations (0-1,500m a.s.l.) may be more susceptible to direct effects of warming than their highland counterparts because their maximum thermal tolerances are only slightly higher than their exposed maximum environmental temperatures. The greater relative thermal tolerance of dragonfly naiad predators may further increase the vulnerability of lowland tadpoles to warming due to potentially enhanced indirect effects of higher predation rates by more heat-tolerant dragonfly predators. However, further experimental work is required to establish the individual and population-level consequences of this thermal tolerance mismatch upon biotic interactions such as predator-prey. ​.