Data from: Is adaptation to climate change really constrained in niche specialists?

Species with restricted distributions make up the vast majority of biodiversity. Recent evidence suggests that Drosophila species with restricted tropical distributions lack genetic variation in the key trait of desiccation resistance. It has therefore been predicted that tropically restricted species will be limited in their evolutionary response to future climatic changes and will face higher risks of extinction. However, these assessments have been made using extreme levels of desiccation stress (less than 10% relative humidity (RH)) that extend well beyond the changes projected for the wet tropics under climate change scenarios over the next 30 years. Here, we show that significant evolutionary responses to less extreme (35% RH) but more ecologically realistic levels of climatic change and desiccation stress are in fact possible in two species of rainforest restricted Drosophila. Evolution may indeed be an important means by which sensitive rainforest-restricted species are able to mitigate the effects of climate change

van Heerwaarden and Sgro (2014). Data from: Is adaptation to climate change really constrained in niche specialists? Proceedings of the Royal Society of London, series B

Excel file containing desiccation data from half-sib full-sib breeding experiments

Data from: The quantitative genetic basis of clinal divergence in phenotypic plasticity

Phenotypic plasticity is thought to be an important mechanism for adapting to environmental heterogeneity. Nonetheless, the genetic basis of plasticity is still not well understood. In Drosophila melanogaster and D. simulans, body size and thermal stress resistance show clinal patterns along the east coast of Australia, and exhibit plastic responses to different developmental temperatures. The genetic basis of thermal plasticity, and whether the genetic effects underlying clinal variation in traits and their plasticity are similar, remains unknown. Here we use line-cross analyses between a tropical and temperate population of D. melanogaster and D. simulans developed at three constant temperatures (18, 25 and 29°C) to investigate the quantitative genetic basis of clinal divergence in mean thermal response (elevation) and plasticity (slope and curvature) for thermal stress and body size traits. Generally, the genetic effects underlying divergence in mean response and plasticity differed, suggesting that different genetic models may be required to understand the evolution of trait means and plasticity. Furthermore, our results suggest that non-additive genetic effects, in particular epistasis, may commonly underlie plastic responses, indicating that current models that ignore epistasis may be insufficient to understand and predict evolutionary responses to environmental change

Data for DRYAD

Data for DRYA

Data from: Limited scope for plasticity to increase upper thermal limits

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

5 day and 23 day acclimation data

5 day and 23 day developmental and adult acclimation data

Data from: Quantifying the relative contributions of the X chromosome, autosomes and mitochondrial genome to local adaptation

During local adaptation with gene flow, some regions of the genome are inherently more responsive to selection than others. Recent theory predicts that X-linked genes should disproportionately contribute to local adaptation relative to other genomic regions, yet this prediction remains to be tested. We carried out a multi-generation crossing scheme, using two cline-end populations of Drosophila melanogaster, to estimate the relative contributions of the X chromosome, autosomes and mitochondrial genome to adaptive divergence in four traits involved in local adaptation (wing size, and resistance to heat, desiccation, and starvation stresses). We found that the mitochondrial genome and autosomes contributed significantly to clinal divergence in three of the four traits. In contrast, the X made no significant contribution to divergence in these traits. Given the small size of the mitochondrial genome, our results indicate that it plays a surprisingly large role in clinal adaptation. In contrast, the X, which represents roughly 20% of the Drosophila genome, contributes negligibly – a pattern that conflicts with theoretical predictions. These patterns reinforce recent work implying a central role of mitochondria in climatic adaptation, and suggest that different genomic regions may play fundamentally different roles in processes of divergence with gene flow

Dryad X-files data

Raw wing size, heat, desiccation and starvation resistance data

Constant temperature data

Raw data for CTmax when flies were developed at six constant temperature