Heat stress and the fitness consequences of climate change for terrestrial ectotherms

Abstract

Summary1. Climate change will increase both average temperatures and extreme summer temperatures. Analyses of the fitness consequences of climate change have generally omitted negative fitness and population declines associated with heat stress. 2. Here, we examine how seasonal and interannual temperature variability will impact fitness shifts of ectotherms from the past to future (2071-2100), by modelling thermal performance curves (TPCs) for insect species across latitudes. 3. In temperate regions, climate change increased the length of the growing season (increasing fitness) and increased the frequency of heat stress (decreasing fitness). Consequently, species at mid-latitudes (20-40°) showed pronounced but heterogeneous responses to climate change. Fitness decreases for these species were accompanied by greater interannual variation in fitness. An alternative TPC model and a larger data set gave qualitatively similar results. 4. How close maximum summer temperatures are to the critical thermal maximum of a species -the thermal buffer -is a good predictor of the change in mean fitness expected under climate change. Thermal buffers will decrease to near or below zero by 2100 for many tropical and mid-latitude species. 5. Our forecasts suggest that mid-latitude species will be particularly susceptible to heat stress associated with climate change due to temperature variation.

Geographic differences in effects of experimental warming on ant species diversity and community composition

“…Our results show weak support for the prediction that warming will have a larger negative effect on ecological communities in warmer locales at lower latitudes , Kingsolver et al 2013. Within the experimental sites, individual species responded variably to warming (Figs.…”

“…2 and 3), potentially complicating our ability to make precise predictions regarding communitylevel responses to climate change. These idiosyncratic responses may be attributed to variation in the abiotic tolerances of different species occupying the same locale and of geographically separated populations within species , Huey et al 2009, Andrew et al 2013, Kingsolver et al 2013.…”

“…Populations and species occupying different locations may vary in their tolerances for abiotic changes , Huey et al 2009, Andrew et al 2013, Kingsolver et al 2013. Additionally, the indirect effects of climate change mediated by species interactions can strengthen or reverse the effects of abiotic change (Suttle et al 2007, Rouifed et al 2010, Pelini et al 2011a.…”

“…In the simplest scenario, the poleward expansion of species geographic ranges may lead to an increase in diversity at higher latitudes, even though some species may disappear locally because they cannot tolerate warmer conditions. Net gains in species richness may arise because warming is unlikely to push many species above their thermal limits (Addo-Bediako et al 2000, Kingsolver et al 2013. Conversely, at lower latitudes, sites should be more likely to lose species with increases in temperature because some species will exceed their critical thermal limits (Addo-Bediako et al 2000, Kingsolver et al 2013 or experience too few days and hours within their range of optimal foraging temperatures.…”

Latitudinal variation in the response of tidepool copepods to mean and daily range in temperature

“…Ectotherms living below their thermal optimum at higher latitudes are expected to benefit from warmer conditions. However, variability on a variety of time scales may expose organisms to periods either below or above their thermal optimum, with potentially major consequences for fitness (Schulte et al 2011, Estay et al 2013, Kingsolver et al 2013, Vasseur et al 2014). …”