Tag Archives: thermal tolerance

Incorporating evolutionary adaptation in species distribution modelling reduces projected vulnerability to climate change

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Authors: Alex Bush, Karel Mokany, Renee Catullo, Ary Hoffmann, Vanessa Kellermann, Carla Sgrò, Shane McEvey, and Simon Ferrier

Published in: Ecology Letters, volume 19, issue 12 (December 2016)

Abstract

Based on the sensitivity of species to ongoing climate change, and numerous challenges they face tracking suitable conditions, there is growing interest in species’ capacity to adapt to climatic stress.

Here, we develop and apply a new generic modelling approach (AdaptR) that incorporates adaptive capacity through physiological limits, phenotypic plasticity, evolutionary adaptation and dispersal into a species distribution modelling framework.

Using AdaptR to predict change in the distribution of 17 species of Australian fruit flies (Drosophilidae), we show that accounting for adaptive capacity reduces projected range losses by up to 33% by 2105. We identify where local adaptation is likely to occur and apply sensitivity analyses to identify the critical factors of interest when parameters are uncertain.

Our study suggests some species could be less vulnerable than previously thought, and indicates that spatiotemporal adaptive models could help improve management interventions that support increased species’ resilience to climate change.

Citation

Bush A, Mokany K, Catullo R, Hoffmann A, Kellermann V, Sgrò C, McEvey S, Ferrier S (2016) Incorporating evolutionary adaptation in species distribution modelling reduces projected vulnerability to climate change. Ecology Letters PDF DOI

Limited scope for plasticity to increase upper thermal limits

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Authors: Belinda van Heerwaarden, Vanessa Kellermann and Carla M Sgrò

Published in: Functional Ecology, volume 30, issue 12 (December 2016)

Summary

Increases in average temperature and the frequency of extreme temperature events are likely to pose a major risk to species already close to their upper physiological thermal limits. The extent to which thermal phenotypic plasticity can buffer these changes and whether plasticity is constrained by basal tolerance levels remains unknown.

We examined the effect of developmental temperature under both constant and fluctuating thermal regimes (developmental acclimation), as well as short-term heat hardening, on upper thermal limits (CTmax) in a tropical and temperate population of Drosophila melanogaster.

We found evidence for thermal plasticity in response to both developmental acclimation and hardening treatments; CTmax increased at warmer developmental temperatures and with a prior heat hardening treatment. However, hardening and acclimation responses were small, improving CTmax by a maximum of 1·01 °C. These results imply that overheating risk will only be minimally reduced by plasticity.

We observed significant associations between developmental temperature and both basal CTmax and hardening capacity (a measure of the extent of the plastic response). Basal CTmax increased, while hardening capacity decreased, with increasing developmental acclimation temperature. This indicates that increases in basal heat resistance at warmer temperatures may come at the cost of a reduced capacity to harden.

While plasticity in CTmax is evident in both populations of D. melanogaster we studied, plastic increases in upper thermal limits, particularly at warmer temperatures, may not be sufficient to keep pace with temperature increases predicted under climate change.

Citation

van Heerwaarden B, Kellerman V, Sgrò CM (2016) Limited scope for plasticity to increase upper thermal limits. Functional Ecology PDF DOI

Evolutionary capacity of upper thermal limits: beyond single trait assessments

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Authors: Shaun Blackburn, Belinda van Heerwaarden, Vanessa Kellermann and Carla M Sgrò

Published in: Journal of Experimental Biology, volume 217, number 11 (June 2014)

Abstract

Thermal tolerance is an important factor influencing the distribution of ectotherms, but we still have limited understanding of the ability of species to evolve different thermal limits.

Recent studies suggest that species may have limited capacity to evolve higher thermal limits in response to slower, more ecologically relevant rates of warming. However, these conclusions are based on univariate estimates of adaptive capacity.

To test these findings within an explicitly multivariate context, we used a paternal half-sibling breeding design to estimate the multivariate evolutionary potential for upper thermal limits in Drosophila melanogaster. We assessed heat tolerance using static (basal and hardened) and ramping assays.

Additive genetic variances were significantly different from zero only for the static measures of heat tolerance. Our G matrix analysis revealed that any response to selection for increased heat tolerance will largely be driven by static basal and hardened heat tolerance, with minimal contribution from ramping heat tolerance.

These results suggest that the capacity to evolve upper thermal limits in nature may depend on the type of thermal stress experienced.

Citation

Blackburn S, van Heerwaarden B, Kellermann V, Sgrò CM (2014) Evolutionary capacity of upper thermal limits: beyond single trait assessments. Journal of Experimental Biology PDF DOI