Genetic variation in heat-stress tolerance among South American Drosophila populations
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Spatial or temporal differences in environmental variables, such as temperature, are ubiquitous in nature and impose stress on organisms. This is especially true for organisms that are isothermal with the environment, such as insects. Understanding the means by which insects respond to temperature and how they will react to novel changes in environmental temperature is important for understanding the adaptive capacity of populations and to predict future trajectories of evolutionary change. The organismal response to heat has been identified as an important environmental variable for insects that can dramatically influence life history characters and geographic range. In the current study we surveyed the amount of variation in heat tolerance among Drosophila melanogaster populations collected at diverse sites along a latitudinal gradient in Argentina (24°–38°S). This is the first study to quantify heat tolerance in South American populations and our work demonstrates that most of the populations surveyed have abundant within-population phenotypic variation, while still exhibiting significant variation among populations. The one exception was the most heat tolerant population that comes from a climate exhibiting the warmest annual mean temperature. All together our results suggest there is abundant genetic variation for heat-tolerance phenotypes within and among natural populations of Drosophila and this variation has likely been shaped by environmental temperature.
KeywordsHeat survival Thermotolerance Temperature stress resistance
We thank S. Menon for assistance with flies used in this study. This paper was greatly improved by the helpful comments of R.A. Krebs, R.C. Woodruff, and two anonymous reviews. This work was supported by grants from the US National Science Foundation (IOS-1051770), the KSU Ecological Genomics Institute, the KSU Arthropod Genomics Center to TJM and fellowships (NSF GK-12 and GAANN) to LCF.
- Hoffmann AA, Parsons PA (1991) Evolutionary genetics of environmental stress. Oxford University Press, OxfordGoogle Scholar
- IPCC Report (2007) Climate change 2007: physical science basis. Summary for policy makers approved at the 10th session of Working Group I at the IPCC. IPCC, Paris, Feb 2007Google Scholar
- SAS Institute (2009) SAS/STAT 9.2 user’s guide, 2nd edn. SAS Institute, CaryGoogle Scholar
- Stanley SM, Parsons PA (1981) The response of the cosmopolitan species, Drosophila melanogaster, to ecological gradients. Proc Ecol Soc Aust 11:121–130Google Scholar