TY - JOUR
T1 - Using physiology to predict the responses of ants to climatic warming
AU - Diamond, Sarah E.
AU - Penick, Clint A.
AU - Pelini, Shannon L.
AU - Ellison, Aaron M.
AU - Gotelli, Nicholas J.
AU - Sanders, Nathan J.
AU - Dunn, Robert R.
N1 - Funding Information:
This work was supported by a US Department of Energy PER award [DEFG02-08ER64510 to R.R.D., A.M.E., N.J.G., and N.J.S.]; a National Aeronautics and Space Administration Biodiversity Grant [ROSES-NNX09AK22G to R.R.D. and N.J.S.]; a National Science Foundation Career grant [NSF-0953390 to R.R.D.]; a National Science Foundation Dimensions of Biodiversity grant [NSF-1136703 to N.J.S., R.R.D., N.J.G., and A.M.E.]; and the S.E. Climate Science Center (US Geological Survey).
PY - 2013/12
Y1 - 2013/12
N2 - Physiological intolerance of high temperatures places limits on organismal responses to the temperature increases associated with global climatic change. Because ants are geographically widespread, ecologically diverse, and thermophilic, they are an ideal system for exploring the extent to which physiological tolerance can predict responses to environmental change. Here, we expand on simple models that use thermal tolerance to predict the responses of ants to climatic warming. We investigated the degree to which changes in the abundance of ants under warming reflect reductions in the thermal niche space for their foraging. In an eastern deciduous forest system in the United States with approximately 40 ant species, we found that for some species, the loss of thermal niche space for foraging was related to decreases in abundance with increasing experimental climatic warming. However, many ant species exhibited no loss of thermal niche space. For one well-studied species, Temnothorax curvispinosus, we examined both survival of workers and growth of colonies (a correlate of reproductive output) as functions of temperature in the laboratory, and found that the range of thermal tolerances for colony growth was much narrower than for survival of workers. We evaluated these functions in the context of experimental climatic warming and found that the difference in the responses of these two attributes to temperature generates differences in the means and especially the variances of expected fitness under warming. The expected mean growth of colonies was optimized at intermediate levels of warming (24°C above ambient); yet, the expected variance monotonically increased with warming. In contrast, the expected mean and variance of the survival of workers decreased when warming exceeded 4°C above ambient. Together, these results for T. curvispinosus emphasize the importance of measuring reproduction (colony growth) in the context of climatic change: indeed, our examination of the loss of thermal niche space with the larger species pool could be missing much of the warming impact due to these analyses being based on survival rather than reproduction. We suggest that while physiological tolerance of temperature can be a useful predictive tool for modeling responses to climatic change, future efforts should be devoted to understanding the causes and consequences of variability in models of tolerance calibrated with different metrics of performance and fitness.
AB - Physiological intolerance of high temperatures places limits on organismal responses to the temperature increases associated with global climatic change. Because ants are geographically widespread, ecologically diverse, and thermophilic, they are an ideal system for exploring the extent to which physiological tolerance can predict responses to environmental change. Here, we expand on simple models that use thermal tolerance to predict the responses of ants to climatic warming. We investigated the degree to which changes in the abundance of ants under warming reflect reductions in the thermal niche space for their foraging. In an eastern deciduous forest system in the United States with approximately 40 ant species, we found that for some species, the loss of thermal niche space for foraging was related to decreases in abundance with increasing experimental climatic warming. However, many ant species exhibited no loss of thermal niche space. For one well-studied species, Temnothorax curvispinosus, we examined both survival of workers and growth of colonies (a correlate of reproductive output) as functions of temperature in the laboratory, and found that the range of thermal tolerances for colony growth was much narrower than for survival of workers. We evaluated these functions in the context of experimental climatic warming and found that the difference in the responses of these two attributes to temperature generates differences in the means and especially the variances of expected fitness under warming. The expected mean growth of colonies was optimized at intermediate levels of warming (24°C above ambient); yet, the expected variance monotonically increased with warming. In contrast, the expected mean and variance of the survival of workers decreased when warming exceeded 4°C above ambient. Together, these results for T. curvispinosus emphasize the importance of measuring reproduction (colony growth) in the context of climatic change: indeed, our examination of the loss of thermal niche space with the larger species pool could be missing much of the warming impact due to these analyses being based on survival rather than reproduction. We suggest that while physiological tolerance of temperature can be a useful predictive tool for modeling responses to climatic change, future efforts should be devoted to understanding the causes and consequences of variability in models of tolerance calibrated with different metrics of performance and fitness.
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U2 - 10.1093/icb/ict085
DO - 10.1093/icb/ict085
M3 - Article
C2 - 23892370
AN - SCOPUS:84893732452
SN - 1540-7063
VL - 53
SP - 965
EP - 974
JO - Integrative and comparative biology
JF - Integrative and comparative biology
IS - 6
ER -