Investigating thermal acclimation effects before and after a cold shock inDrosophila melanogasterusing behavioural assays

Abstract

Acclimation to environmental change can impose both costs and benefits to organisms. In this study we explored to what extent locomotor behaviour of Drosophila melanogaster is influenced by developmental temperature and adult temperature in both the laboratory and the field. Following development at 15, 25, or 31 °C, adult flies were tested for locomotor activity at all developmental temperatures in the laboratory before and after exposure to a cold shock and in the field for their ability to locate resources after a cold shock. Both test (15, 25, and 31 °C) and developmental temperatures strongly affected locomoter activity, with flies developed at 25 °C having the highest activity at all three test temperatures before the cold shock. After the cold shock flies developed at 15 °C had higher activity compared with flies developed at 25 and 31 °C when tested at 15 and 25 °C, and flies developed at 25 °C had the highest activity when tested at 31 °C. Furthermore, flies developed at 31 °C showed longer recovery times following the cold shock at test temperatures of 15 and 25 °C. However, flies acclimated at 15 °C during development did not recover faster at 15 and 25 °C compared with flies developed at 25 °C. There were no significant correlations between recovery time and locomotor activity at any of the test temperatures. Flies developed at 15 °C and exposed to a cold shock before release in the field were much more successful in locating a resource at low field temperatures compared with flies developed at 25 and 31 °C. Our results provide support for both the beneficial acclimation hypothesis and the optimal developmental temperature hypothesis, but the results are highly context dependent and change with the temperature experienced by the individual during its lifetime.

Thermal acclimation and adaptation across populations in a broadly distributed soil arthropod

“…In a recent study, we showed that an increase in heat tolerance in response to heat hardening of O. cincta under laboratory conditions is associated with lowered cold tolerance (Alemu et al, ). However, it has been argued that cost and benefit of thermal plasticity under laboratory conditions might not be ecologically relevant and are context dependent (Bahrndorff, Gertsen, Pertoldi, & Kristensen, ; Kristensen et al, ). In addition, the temperature regimes simulated under laboratory conditions may not reflect the variation and predictability of the temperature changes that could happen under natural conditions, and where other biological and environmental parameters are varying as well (e.g.…”

Acclimation responses to short‐term temperature treatments during early life stages causes long lasting changes in spontaneous activity of adult Drosophila melanogaster

“…Here, we find evidence that there may be critical developmental windows where cold temperatures can change an aspect of the adult phenotype. These data might explain why the conclusions of field recapture studies can deviate from conclusions of laboratory activity studies (Kristensen et al ., ; Bahrndorff et al ., ). Moreover, the present study highlights the importance of measuring traits with different thermal sensitivities.…”

“…We do see a shift in activity with long‐term exposure, although this shift is in the vertical position of the performance curve, such that long‐term exposure to both heat and cold results in reduced activity across all six temperatures. Although this is somewhat unexpected for stimulated movement, it is in accordance with other studies looking at spontaneous movement using DAMs, where flies that develop at intermediate temperatures show higher behavioural activity across test temperatures (Zamudio et al ., ; Gilbert, ; Kjærsgaard et al ., ; Bahrndorff et al ., ). One possible explanation for the lower activity could be that we measure locomotor activity as spontaneous movement and animals that develop at temperatures above or below optimum may be more likely to conserve their energy.…”

Biotic and abiotic factors investigated in two Drosophila species – evidence of both negative and positive effects of interactions on performance

“…An increased negative geotaxis behaviour, i.e. the flies crawled higher, was interpreted as beneficial, because the ability to escape a potential stressful environment is of key importance for fitness66.…”