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There's More Than One Way for Fruit Flies to Beat the Heat ...
Reference
van Heerwaarden, B. and Sgro, C.M. 2013. Multivariate analysis of adaptive capacity for upper thermal limits in Drosophila simulans. Journal of Evolutionary Biology 26: 800-809.

Background
The authors write that climate change is widely believed to impact ectotherms' distribution, abundance and metabolism, leading to a significant risk of extinction (Deutsch et al., 2008; Huey et al., 2009; Sinervo et al., 2010), especially since it is also widely believed (Stillman, 2002; Jones et al., 2009; Sinervo et al., 2010) that "some ectotherms already exist close to [their] upper thermal thresholds."

What was done
"To test these findings more broadly," in the words of van Heerwaarden and Sgro, they say they "used a paternal half-sibling breeding design to estimate the multivariate evolutionary potential for upper thermal limits in Drosophla simulans," assessing the fruit flies' heat tolerance via three genetically independent traits that were evaluated using "static (basal and hardened) and ramping assays."

What was learned
The two Australian researchers say their analyses revealed "significant evolutionary potential for all three measures of heat tolerance," and that "additive genetic variances were significantly different from zero for all three traits." In addition, they determined that "all three traits would contribute to a response to selection for increased heat tolerance."

What it means
As a result of their findings, van Heerwaarden and Sgro concluded that "reliance on univariate estimates of evolutionary potential may not provide accurate insight into the ability of organisms to evolve upper thermal limits in nature," and that "combinations of all three traits will contribute to the evolution of upper thermal limits in response to selection imposed by a warming climate."

And thus it is that although they may not be cats with nine lives, fruit flies would likely agree that three ways of "beating the heat" in a warming world is a whole lot better than one. And a lot of other creatures could well join with them in this cheerful chorus.

References
Deutsch, C.A., Tewksbury, J.J., Huey, R.B., Sheldon, K.S., Ghalambor, C.K., Haak, D.C. and Martin, P.R. 2008. Impacts of climate warming on terrestrial ectotherms across latitude. Proceedings of the National Academy of Sciences USA 105: 6668-66672.

Huey, R.B., Deutsch, C.A., Tewksbury, J.J., Vitt, L.J., Hertz, P.E., Perez, H.J.A. and Garland, T. 2009. Why tropical forest lizards are vulnerable to climate warming. Proceedings of the Royal Society B: Biological Science 276: 1939-1948.

Jones, S.J., Mieszkowska, N. and Wethey, D.S. 2009. Linking thermal tolerances and biogeography: Mytilus edulis (L.) at its southern limit on the east coast of the United States. Biological Bulletin 217: 73-85.

Sinervo, B., Mendez-de-la-Cruz, F., Miles, D.B., Heulin, B., Bastiaans, E., Cruz, M.V.S., Lara-Resendiz, R., Martinez-Mendez, N., Calderon-Espinosa, M., Meza-Lazaro, R.N., Gadsden, H., Avila, L.J., Morando, M., De la Riva, I.J., Sepulveda, P.V., Rocha, C.F.D., Ibarguengoytia, N., Puntriano, C.A., Masson, M., Lepetz, V., Oksanen, T.A., Chapple, D.G., Bauer, A.M., Branch, W.R., Clobert, J. and Sites Jr., J.W. 2010. Erosion of lizard diversity by climate change and altered thermal niches. Science 328: 894-899.

Stillman, J.H. 2002. Causes and consequences of thermal tolerance limits in rocky intertidal porcelain crabs, genus Petrolisthes. Integrative and Comparative Biology 42: 790-796.

Reviewed 23 October 2013