Rapid within- and transgenerational changes in thermal tolerance and fitness in variable thermal landscapes

Phenotypic plasticity may increase the 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

Ectotherms in variable thermal landscapes: a physiological evaluation of the invasive potential of fruit flies species

Climate change and biological invasions pose one of the greatest threats to biodiversity. Most analyses of the potential biological impacts have focused on changes in mean temperature, but changes in thermal variance may also impact native and invasive organisms, although differentially. We assessed the combined effects of the mean and the variance of temperature on the expression of heat shock protein (hsp90) in adults of the invasive fruit fly Drosophila melanogaster and the native D. gaucha in Mediterranean habitats of central Chile. We observed that, under these experimental conditions, hsp90 mRNA expression was higher in the invasive species but absent in the native one. Apparently, the biogeographic origin and niche conservatisms are playing a role in the heat shock response of these species under different putative scenarios of climate change. We suggest that in order to develop more realistic predictions about the biological impact of climate change and biological invasions, one must consider the interactions between the mean and variance of climatic variables, as well as the evolutionary original conditions of the native and invasive species

The interplay between thermal tolerance and life history is associated with the biogeography of Drosophila species

Background: Physiological tolerances are important determinants of the biogeography of species. Questions: What is the relationship between thermal tolerance and the biogeographic origin of species? What are the relationships between thermal tolerance and life-history traits? Organisms: Four Drosophila species, two from a tropical biogeographic area (D. melanogaster and D. simulans) and two from a temperate geographic zone in the Andes mountains (D. pavani and D. gaucha). Methods: We assessed upper and lower lethal temperature. We used thermal limits to construct a thermal tolerance polygon that represents the total thermal range of each species after acclimation at different ambient temperatures. We also measured differences in life history (fertility and egg-to-adult viability) between species. Conclusions: Both temperate species have broader thermal tolerance ranges than either tropical species. But temperate species have lower fitness at higher temperatures than tropical species,

Differential responses to thermal variation between fitness metrics

Temperature is a major factor affecting population abundance and individual performance. Net reproductive rate (R0) and intrinsic rate of increase (r) differ in their response to different temperature regimes, and much of the difference is mediated by generation time (Tg). Here, we evaluate the effects of thermal mean and variability on R0, r and Tg, at four population densities in Drosophila melanogaster. The results show that R 0, r and Tg present differential responses to thermal variation. Although temperature effects on R0 and Tg are non-linear, r response was negligible. R0 and Tg comprise a generational time scale, while r is at a chronological time scale. Thus, we argue that individuals growing under different thermal environments perform similarly on a chronological scale, but differently on a generational scale

Biogeographic origin and thermal acclimation interact to determine survival and hsp90 expression in Drosophila species submitted to thermal stress

The relationship between thermal tolerance and environmental conditions has been extensively studied in . Drosophila. However, comparisons of thermal tolerance of laboratory-bred flies derived from distinct geographic locations have produced puzzling results. We studied the differential expression of heat shock protein (HSP) after heat (34. °C) and cold (-. 4. °C) temperature treatments in two species of . Drosophila flies, with distinct biogeographic origins (tropical = . D. melanogaster and Andean = . D. gaucha), previously exposed to sublethal acclimation temperatures (10, 20 and 30. °C). Also we evaluated the relationship between thermal acclimation and survival value as a proxy of fitness. We found a positive relationship between thermotolerance and the patterns of . hsp90 transcript expression in both species. Nevertheless, in the cases in which . hsp90 mRNA expression does not match thermotolerance induction, the biogeographic origin of the species could explain such mismatches. Survival at upper and lower experimental temperatures were also related with species origin. © 2012 Elsevier Inc.Funded by CONICYTAT 24090012 to F. Boher and FONDAP1501–0001 to F. Bozinovic.Peer Reviewe

Rapid within‐ and transgenerational changes in thermal tolerance and fitness in variable thermal landscapes

Phenotypic plasticity may increase the 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