Predicting organismal vulnerability to climate warming: roles of behaviour, physiology and adaptation

Abstract

A recently developed integrative framework proposes that the vulnerability of a species to environmental change depends on the species' exposure and sensitivity to environmental change, its resilience to perturbations and its potential to adapt to change. These vulnerability criteria require behavioural, physiological and genetic data. With this information in hand, biologists can predict organisms most at risk from environmental change. Biologists and managers can then target organisms and habitats most at risk. Unfortunately, the required data (e.g. optimal physiological temperatures) are rarely available. Here, we evaluate the reliability of potential proxies (e.g. critical temperatures) that are often available for some groups. Several proxies for ectotherms are promising, but analogous ones for endotherms are lacking. We also develop a simple graphical model of how behavioural thermoregulation, acclimation and adaptation may interact to influence vulnerability over time. After considering this model together with the proxies available for physiological sensitivity to climate change, we conclude that ectotherms sharing vulnerability traits seem concentrated in lowland tropical forests. Their vulnerability may be exacerbated by negative biotic interactions. Whether tropical forest (or other) species can adapt to warming environments is unclear, as genetic and selective data are scant. Nevertheless, the prospects for tropical forest ectotherms appear grim.

Plasticity in thermal tolerance has limited potential to buffer ectotherms from global warming

“…The ability to acclimatize to changing thermal conditions is expected to be a primary factor that dictates the vulnerability of taxa to rising temperatures [4][5][6]10,20]. Our broad-scale analysis of thermal tolerance plasticity across ectotherms has many implications for our understanding of the interactions between plasticity and warming.…”

“…As a result, organisms across the globe will be more likely to experience temperatures beyond their physiological limits unless they can in some way buffer themselves from environmental change [2,3]. One mechanism that could greatly reduce the risk of overheating is physiological plasticity in thermal tolerance, such as the reversible changes in thermal tolerance known as acclimation (if measured in the laboratory) or acclimatization (if measured in the field) [4][5][6][7]. For example, the upper thermal tolerance limits of many organisms increase (within individuals) as mean body temperatures rise, meaning that physiological adjustments can potentially compensate for the negative consequences of rising habitat temperatures [8].…”

Hormonally mediated maternal effects, individual strategy and global change

“…A second compensatory response is adaptation by microevolution to new ecological conditions, e.g. thermal adaptation [6][7][8]. Third, individuals within a population may persist in rapidly changing environments by behavioural or physiological compensation, i.e.…”

Lowland biotic attrition revisited: body size and variation among climate change ‘winners’ and ‘losers’

“…Ongoing warming could push ambient temperatures above the thermal neutral zones of many tropical endotherms [3][4][5], suggesting that these species & 2017 The Author(s) Published by the Royal Society. All rights reserved.…”

“…Understanding how species' temporal niches are influenced by sensitivity to climatic factors would greatly improve predictions of climate change impacts across organisms. For example, organisms might be able to cope with being at or near their upper critical thermal limits via behavioural plasticity [4], shifting their activity progressively away from midday and towards twilight and night-time in order to avoid high temperatures [15,16].…”