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Background: Evolutionary theory predicts that antagonistically selected alleles, such as those with divergent pleiotropic effects in early and late life, may often reach intermediate population frequencies due to balancing selection, an elusive process when sought out empirically. Alternatively, genetic diversity may increase as a result of positive frequency-dependent selection and genetic purgin
The ability of ectotherms to respond to changes in their thermal environment through plastic mechanisms is central to their adaptive capability. However, we still lack knowledge on the physiological and functional responses by which ectotherms acclimate to temperatures during development, and in particular, how physiological stress at extreme temperatures may counteract beneficial acclimation resp
Division of reproductive behaviour and alloparental care are key aspects of many animal societies. In cooperatively breeding species, variation in helping effort and unequal task participation are frequently observed. However, the extent to which the reproductive state of an individual affects the tasks performed during offspring care remains poorly understood. In the social spider Stegodyphus dum
Studies on thermal acclimation in insects are often performed on animals acclimated in the laboratory under conditions that are not ecologically relevant. Costs and benefits of acclima-tion responses under such conditions may not reflect costs and benefits in natural popula-tions subjected to daily and seasonal temperature fluctuations. Here we estimated costs and benefits in thermal tolerance lim
The ability to respond evolutionarily to increasing temperatures is important for survival of ectotherms in a changing climate. Recent studies suggest that upper thermal limits may be evolutionary constrained. We address this hypothesis in a laboratory evolution experiment, encompassing ecologically relevant thermal regimes. To examine the potential for species to respond to climate change, we exp
Multiple environmental factors acting in concert can interact and strongly influence population fitness and ecosystem composition. Studies investigating interactions usually involve only two environmental factors; most frequently a chemical and another abiotic factor such as a stressful temperature. Here we investigate the effects of three environmental factors: temperature, an insecticide (dimeth
When obtaining samples for population genetic studies, it is essential that the sampling is random. For Drosophila, one of the crucial steps in sampling experimental flies is the collection of eggs. Here an egg collection method is presented, which randomizes the eggs in a water column and diminishes environmental variance. This method was compared with a traditional egg collection method where eg
Many natural populations experience inbreeding and genetic drift as a consequence of nonrandom mating or low population size. Furthermore, they face environmental challenges that may interact synergistically with deleterious consequences of increased homozygosity and further decrease fitness. Most studies on inbreeding–environment (I-E) interactions use one or two stress levels, whereby the resolu
Inbreeding increases homozygosity, which is known to affect the mean and variance of fitness components such as growth, fecundity and mortality rate. Across inbred lines inbreeding depression is typically observed and the variance between lines is increased in inbred compared to outbred lines. It has been suggested that damage incurred from increased homozygosity entails energetic cost associated
* Thermal limits of ectotherms have been studied extensively and are believed to be evolutionarily constrained, leaving ectotherms at risk under future climate change. Phenotypic plasticity may extend the thermal limits, but we lack detailed characterizations of thermal limit reaction norms as well as an understanding of the interspecific variation in these reaction norms. * Here, we investigated
There is interest in pinpointing genes and physiological mechanisms explaining intra- and interspecific variations in cold tolerance, because thermal tolerance phenotypes strongly impact the distribution and abundance of wild animals. Laboratory studies have highlighted that the capacity to preserve water and ion homeostasis is linked to low temperature survival in insects. It remains unknown, how
The ability to move is essential for many behavioural traits closely related to fitness. Here we studied the effect of inbreeding on locomotor activity (LA) of Drosophila melanogaster at different ages under both dark and light regimes. We expected to find a decreased LA in inbred lines compared to control lines. We also predicted an increased differentiation between lines due to inbreeding. LA wa
Drosophila melanogaster is often used as a model organism in evolutionary biology and ecophysiology to study evolutionary processes and their physiological mechanisms. Diets used to feed Drosophila cultures differ between laboratories and are often nutritious and distinct from food sources in the natural habitat. Here we rear D. melanogaster on a standard diet used in our laboratory and a field di
Physiological adaptation through acclimation is one way to cope with temperature changes. Biochemical studies on acclimation responses in ectotherms have so far mainly investigated consequences of short-term acclimation at the adult stage and focussed on adaptive responses. Here, we assessed the consequences of rearing Drosophila melanogaster at low (12°C), benign (25°C) and high (31°C) temperatur
Environmental changes may stress organisms and stimulate an adaptive phenotypic response. Effects of inbreeding often interact with the environment and can decrease fitness of inbred individuals exposed to stress more so than that of outbred individuals. Such an interaction may stem from a reduced ability of inbred individuals to respond plastically to environmental stress; however, this hypothesi
Coping with cold winter conditions is a major challenge for many insects.In early spring we observed newly emerged Drosophila subobscura, which had overwintered as larvae and pupae. As temperatures increase during spring these flies are faced with higher minimum and maximum temperatures in their natural microhabitat. Thus, there is a potential costly mismatch between winter and early spring acclim
Terrestrial ectotherms are challenged by variation in both mean and variance of temperature. Phenotypic plasticity (thermal acclimation) might mitigate adverse effects, however, we lack a fundamental understanding of the molecular mechanisms of thermal acclimation and how they are affected by fluctuating temperature. Here we investigated the effect of thermal acclimation in Drosophila melanogaster
Mechanistic trade-offs between traits under selection can shape and constrain evolutionary adaptation to environmental stressors. However, our knowledge of the quantitative and qualitative overlap in the molecular machinery among stress tolerance traits is highly restricted by the challenges of comparing and interpreting data between separate studies and laboratories, as well as to extrapolating b
The ability of insects to cope with stressful temperatures through adaptive plasticity has allowed them to thrive under a wide range of thermal conditions. Developmental plasticity is generally considered to be a non-reversible phenotypic change, e.g. in morphological traits, while adult acclimation responses are often considered to be reversible physiological responses. However, physiologically m
