Few genetic and environmental correlations between life history and stress resistance traits affect adaptation to fluctuating thermal regimes

Abstract

Few genetic and environmental correlations between life history and stress resistance traits affect adaptation to fluctuating thermal regimes T Manenti, JG Sørensen, NN Moghadam and V Loeschcke Laboratory selection in thermal regimes that differed in the amplitude and the predictability of daily fluctuations had a marked effect on stress resistance and life history traits in Drosophila simulans. The observed evolutionary changes are expected to be the result of both direct and correlated responses to selection. Thus, a given trait might not evolve independently from other traits because of genetic correlations among these traits. Moreover, different test environments can induce novel genetic correlations because of the activation of environmentally dependent genes. To test whether and how genetic correlations among stress resistance and life history traits constrain evolutionary adaptation, we used three populations of D. simulans selected for 20 generations in constant, predictable and unpredictable daily fluctuating thermal regimes and tested each of these selected populations in the same three thermal regimes. We explored the relationship between genetic correlations between traits and the evolutionary potential of D. simulans by comparing genetic correlation matrices in flies selected and tested in different thermal test regimes. We observed genetic correlations mainly between productivity, body size, starvation and desiccation tolerance, suggesting that adaptation to the three thermal regimes was affected by correlations between these traits. We also found that the correlations between some traits such as body size and productivity or starvation tolerance and productivity were determined by test regime rather than selection regime that is expected to limit genetic adaptation to thermal regimes in these traits. The results of this study suggest that several traits and several environments are needed to explore adaptive responses, as genetic and environmentally induced correlations between traits as results obtained in one environment cannot be used to predict the response of the same population in another environment.

Experimental Approaches for Testing if Tolerance Curves Are Useful for Predicting Fitness in Fluctuating Environments

“…These data clearly demonstrate that evolutionary processes are distinct in fluctuating and constant temperature environments. Recent work on the insect, Drosophila simulans, draws similar conclusions (Manenti et al, 2016).…”

“…heat shock survival or in tolerance curve parameters (Scheiner, 1993;Kellermann et al, 2009;Ketola et al, 2014;Kristensen et al, 2015). However, as stated here the adaptive benefit of heritable variation in some proxy of fitness in a constant environment might be minor in fluctuating environments if it is not genetically correlated with fitness in fluctuating environments (Ketola et al, 2014;Manenti et al, 2016). What is crucially missing in most quantitative genetic experiments performed so far is correlating the abovementioned proxies to fitness in fluctuating environments.…”

Thermal‐specific patterns of longevity and fecundity in a set of heat‐sensitive and heat‐resistant genotypes of Drosophila melanogaster

“…Fluctuating thermal regimes are suggested to have a greater ecological relevance than constant regimes as they are more representative of natural environments (Klepsatel et al., ; Manenti et al., ). Fluctuating temperatures can yield different results for a variety of traits when compared to constant temperatures (Bozinovic et al., ; Vanin et al., ; Manenti et al., ). Our results showed that longevity differences between heat‐resistant and heat‐sensitive stocks at constant temperatures disappear at fluctuating temperatures.…”

“…Changes in environmental conditions can change trait interactions differently (Sgrò & Hoffmann, ), and temperature has been shown to affect trait correlations (Norry & Loeschcke, ; Klepsatel et al., ; Manenti et al., ). Furthermore, fluctuating temperatures are expected to demand higher energetic costs (Hoffmann et al., ; Bowler & Terblanche, ), which may result in negative correlations between stress resistance and life‐history traits in flies exposed to fluctuating thermal regimes (Manenti et al., ). In this regard, our results show that the expected genetic correlation between heat resistance and longevity depends on the thermal conditions in which longevity is assayed.…”

Effects of photoperiod on life‐history and thermal stress resistance traits across populations of Drosophila subobscura

“…Despite the importance of day length for multiple life‐history traits and for the ability to cope with stressful thermal conditions, most experimental studies investigating the ability to perform in environments with variable temperatures have neglected the role of photoperiod and its importance for stress resistance and for shaping the distribution of species (Ketola & Saarinen, ; Kristensen, Kjeldal, Schou, & Lund, ; Manenti, Sørensen, Moghadam, & Loeschcke, ). In the present study, we investigate the importance of seasonal variation in day length on stress resistance and life‐history traits of five populations of Drosophila subobscura distributed across North Africa and Europe spanning the latitudes 31°N to 59°N (Table ).…”