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Phenotypic plasticity may increase performance and fitness and allow
organisms to cope with variable environmental conditions. We studied
within-generation plasticity and transgenerational effects of thermal
conditions on temperature tolerance and demographic parameters in
Drosophila melanogaster. We employed a fully factorial design, in which
both parental (P) and offspring generations (F1) were reared in a constant
or a variable thermal environment. Thermal variability during ontogeny
increased heat tolerance in P, but with demographic cost as this treatment
resulted in substantially lower survival, fecundity and net reproductive
rate. The adverse effects of thermal variability (V) on demographic
parameters were less drastic in flies from the F1, which exhibited higher
net reproductive rates than their parents. These compensatory responses
could not totally overcome the challenges of the thermally variable
regime, contrasting with the offspring of flies raised in a constant
temperature (C) that showed no reduction in fitness with thermal
variation. Thus, the parental thermal environment had effects on thermal
tolerance and demographic parameters in fruit-fly. These results
demonstrate how transgenerational effects of environmental conditions on
heat tolerance, as well as their potential costs on other fitness
components, can have a major impact on populations’ resilience to warming
temperatures and more frequent thermal extremes.
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