Data and coding files for: Within population plastic responses to combined thermal-nutritional stress differ from those in response to single stressors, and are genetically independent across traits in both males and females

Phenotypic plasticity helps animals to buffer the effects of increasing
thermal and nutritional stress created by climate change. Plastic
responses to single and combined stressors can vary among genetically
diverged populations. However, less is known about how plasticity in
response to combined stress varies among individuals within a population
or whether such variation changes across life-history traits. This is
important because individual variation within populations shapes
population-level responses to environmental change. Here, we used isogenic
lines of Drosophila melanogaster to assess plasticity of egg-to-adult
viability and sex-specific body size for combinations of two temperatures
(25°C or 28°C) and three diets (standard diet, low caloric diet, or low
protein:carbohydrate ratio diet). Our results reveal substantial
within-population genetic variation in plasticity for egg-to-adult
viability and wing size in response to combined thermal-nutritional
stress. This genetic variation in plasticity was a result of
cross-environment genetic correlations that were often < 1 for both
traits, as well as changes in the expression of genetic variation across
environments for egg-to-adult viability. Cross-sex genetic correlations
for body size were weaker when the sexes were reared in different
conditions, suggesting that the genetic basis of traits may change with
the environment. Further, our results suggest that plasticity in
egg-to-adult viability is genetically independent from plasticity in body
size. Importantly, plasticity in response to diet and temperature
individually differed from plastic shifts in response to diet and
temperature in combination. By quantifying plasticity and the expression
of genetic variance in response to combined stress across traits, our
study reveals the complexity of animal responses to environmental change,
and the need for a more nuanced understanding of the potential for
populations to adapt to ongoing climate change.