Plastic responses to four environmental stresses and cross-resistance in a laboratory population of Drosophila melanogaster

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1. Acclimation or hardening to one stress in arthropods can lead to a plastic response, which confers increased resistance to other stresses. Such cross-resistance may indicate shared physiological
resistance mechanisms and a possibility of joint evolution for resistance traits.
2. In this study, we tested for cross-resistance using Drosophila melanogaster as a model system.Adult females were assayed for resistance to cold, heat, desiccation and starvation following cold
acclimation, heat hardening, desiccation hardening and starvation acclimation, resulting in 12 pretreatment-by-test combinations for estimating potential cross-resistance effects. The
acclimation ⁄ hardening regimes were chosen so that flies enhanced their resistance to the same type of stress as that used for the particular pretreatment.
3. Two cases of cross-resistance were found, with desiccation-hardened and starvation-acclimated flies being more resistant than control ones in heat and desiccation resistance tests, respectively. In four cases, no acclimation ⁄ hardening effect was observed, and for six pretreatment-by-test combinations, the effect of acclimation ⁄ hardening was negative.
4. We also revealed that heat and desiccation hardening as well as acclimation to starvation had a cost under non-stressful conditions leading to reduced longevity. Cold acclimation did not affect longevity, although its effect was difficult to estimate precisely: during pretreatment at a low temperature, biological ageing of the flies might be delayed.
5. The pattern of acclimation ⁄ hardening responses considered in the context of literature data on stress resistance indicates that expression of heat-shock proteins is not likely to contribute to
the observed cross-resistance, but other probable general stress resistance mechanisms such as reduction of metabolic rate and accumulation of energy reserves might be involved.
6. The lack of cross-resistance induced by acclimation ⁄ hardening treatments suggests that in an environment with multiple stresses, evolution of shared protective systems associated with plastic
responses may be constrained.
TidsskriftFunctional Ecology
Sider (fra-til)245-253
Antal sider9
StatusUdgivet - feb. 2012

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