Biology subjects

Cockerell, F.

Publications and source records attributed to Cockerell, F..

5 recordsLinked to original sources

bioRxiv2026

Why development time matters: temperature influences plasticity while nutritional stress reshapes selection and evolutionary potential

The time it takes organisms to reach adulthood is often considered a central life-history trait that influences fitness and is highly plastic across environments. Despite its importance, direct estimates of how selection on development time varies across combinations of environmental stressors remain rare, limiting our understanding of its role in population responses to environmental change. We reared 68 full-sibling families of the vinegar fly, Drosophila melanogaster, at two temperatures (14{degrees}C and 28{degrees}C) on two diets (standard and low-calorie), and measured development time, body size (mass and wing size), egg-to-adult viability and productivity (number of offspring). Temperature caused the largest plastic response, with development taking 4-5 times longer at 14{degrees}C, whereas the low-calorie diet extended development by 20-30%. Yet diet, not temperature, changed directional selection on development time. On the standard diet, faster development was associated with higher fitness at both temperatures. On the low-calorie diet, this advantage disappeared, and at 14{degrees}C slower-developing females tended to produce more offspring. Viability selection showed consistent patterns. The low-calorie diet also increased evolvability in development time c.10-16-fold at both temperatures, and genetic correlations between diets were close to zero, indicating strong genotype-by-environment interactions. Plasticity in development time was not associated with fitness in any treatment. Overall, we provide evidence that development time is a functional trait whose relationship with fitness depends on the environment. Nutritional stress induced a smaller plastic response in development time than temperature, but had a larger effect on directional selection and evolvability. The stressor causing the greatest plastic change in a functional trait is therefore not necessarily the one that shapes its selection and evolution.

evolutionary biology↗

bioRxiv2026

Interactions between thermal and nutritional stress reveal cryptic adaptive potential

Predicting whether populations can adapt fast enough to persist under global change requires understanding how adaptive potential changes with the environment. Theory predicts that cryptic genetic variation hidden under benign conditions may be released under stress, but empirical tests are rare and typically manipulate single stressors in isolation, which is not realistic under global change. Using a quantitative genetic breeding design with Drosophila melanogaster, we quantified additive genetic variance in fitness (female productivity) across combinations of temperature and nutritional stress. We found that nutritional stress increased genetic variance at cold and hot margins. Temperature and diet also interacted to shape which genotypes performed best: nutritional stress weakened genetic correlations across temperatures at the hot margin, whereas genetic correlations across diets strengthened at the cold margin. Adaptive potential is therefore environment-dependent and multidimensional, meaning single stressor experiments are likely to systematically misrepresent adaptive capacity under realistic global change scenarios.

evolutionary biology↗

bioRxiv2025

Local adaptation in climate tolerance at a small geographic scale contrasts with broad latitudinal patterns

While climate adaptation is typically quantified across broad gradients, the potential for adaptation to the same environmental variables at small scales is rarely tested. If local-scale environmental heterogeneity can generate patterns of adaptation similar to broad gradients, then we currently underestimate adaptive capacity to global change. We quantified population variation in climate tolerance traits and their plasticity for five populations of Drosophila melanogaster from a 3000-km latitudinal gradient, which we contrasted with eight local populations from an environmentally heterogeneous 600x300km area. Population variation in stress tolerance at the local scale was comparable to that across latitude. Consistent with local adaptation, populations from warmer and drier environments showed greater heat and desiccation tolerance, and populations from more predictable environments showed greater plasticity. Climate adaptation at smaller geographic scales can therefore be comparable to adaptation across broad geographic scales. However, patterns of adaptation often changed across geography, which makes predicting responses to global change challenging.

evolutionary biology↗

bioRxiv2025

Variation in temperature but not diet determines the stability of latitudinal clines in tolerance traits and their plasticity

Latitudinal clines are routinely used as evidence of adaptation across broad climatic gradients. However, if environmental variation influences the strength of latitudinal clines, then clinal patterns will be unstable, and using patterns of adaptation to predict population responses to global change will be difficult. To test whether environmental variation influences latitudinal clines, we sampled five populations of Drosophila melanogaster spanning 3000-km of east coast Australia, and measured stress tolerance (heat, cold and desiccation) and body size on flies that developed in six combinations of temperature (13{degrees}C, 25{degrees}C and 29{degrees}C) and diet (standard and low-calorie) treatments. We found latitudinal clines where populations further from the equator had larger wings, higher cold tolerance and lower heat tolerance. For all traits, temperature determined the strength of latitudinal clines, whereas diet had little influence. Steeper clines often emerged in warmer treatments, created by latitudinal clines in plasticity. In the warmest temperature, higher latitude populations showed larger increases in heat tolerance, larger reductions in desiccation tolerance but smaller decreases in cold tolerance. Heat tolerance was the only trait that supported the climate variability hypothesis and a trade-off between plasticity and tolerance. Environment-dependent latitudinal clines are therefore likely to determine variation in population responses to global change.

evolutionary biology↗

bioRxiv2023

Fluctuating temperatures exacerbate nutritional stress during development in Drosophila melanogaster

Recent studies suggest that elevated temperatures interact with nutrition to exacerbate the negative effects of poor nutrition. Furthermore, populations adapted to distinct environments differ in their sensitivity to combined thermal and nutritional stress. However, most studies have tested these effects using constant temperatures, even though animals in the wild experience daily and seasonal thermal fluctuations. Here, we used two locally-adapted populations of D. melanogaster from the east coast of Australia (a tropical and a temperate population) to ask whether temperature fluctuations interact with nutrition in the same manner as constant temperature conditions to shape life history traits, and how this differs across populations. We found that fluctuating temperatures exacerbate the negative effects of a poor diet when compared to constant temperatures. Moreover, the negative effects of nutritional stress were significantly greater in the tropical population. In contrast, we found that the temperate population was able to utilize nutrition in unique ways to maintain optimal viability under warmer temperatures. Our findings reveal the ways in which temperature and nutrition interact to impact key life history traits in geographically distinct populations, while also highlighting the importance of using temperature assays representative of natural diel cycles when examining insect responses to climate change.

evolutionary biology↗