Adaptation to climate change: what can Drosophila studies tell us?
The University of Melbourne, Australia
Many insects appear to have at least some ability to evolve and adapt to stresses associated with climate change. Studies on cosmopolitan Drosophila species suggest high levels of heritable variation for coping with thermal stresses and aridity, for developing near-thermal thresholds and for avoiding stressful conditions by entering reproductive diapause. This heritable variation has led to the development of clinal variation in traits and genes along climatic gradients, and in one case there is even evidence for evolving clines in response to recent climate change. However, the evolutionary potential of Drosophila species with restricted distributions may be much more limited. In several rainforest species, levels of heritable variation for tolerating cold and dry conditions appear low enough to limit adaptive responses. This means that species making up a large proportion of biodiversity and the most sensitive to drier conditions may have difficulty adapting via evolutionary shifts. Two hypotheses about why this might be the case are proposed and evaluated, and applications to other species groups susceptible to the effects of climate change are discussed.