Project description:We used microarrays to investigate the transcriptome of 6 days old male flies exposed to either 15 or 25 C development at either constant or fluctuating temperatures. Further, we investigated gene expression at benign (20C) and high (35C) temperatures With global climate change temperature means and variability are expected to increase. Thus, exposures to elevated temperatures are expected to become an increasing challenge for terrestrial ectotherm populations. While evolutionary adaptation seems to be constrained or proceed at an insufficient pace, many populations are expected to rely on phenotypic plasticity (thermal acclimation) for coping with the predicted changes. However, the effects of fluctuating temperature on the molecular mechanisms and the implications for heat tolerance are not well understood. To understand and predict consequences of climate change it is important to investigate how different components of the thermal environment, including fluctuating thermal conditions, contribute to changes in thermal acclimation. In this study we investigated the impact of mean and diurnal fluctuation of temperature on heat tolerance in Drosophila melanogaster and on the underlying molecular mechanisms in adult male flies. Flies from two constant and two ecologically relevant fluctuating temperature regimes were tested for their critical thermal maxima (CTmax) and associated global gene expression profiles at benign and thermally stressful conditions. Both temperature parameters contributed independently to the thermal acclimation, with regard to heat tolerance as well as the global gene expression profile. Although the independent transcriptional effects caused by fluctuations were relatively small, they are likely to be essential for our understanding of thermal adaptation. Thus, high temperature acclimation ability might not be measured correctly and might even be underestimated at constant temperatures. Our data suggests that the particular mechanisms affected by thermal fluctuations are related to phototransduction and environmental sensing. Thus genes and pathways involved in those processes are likely to be of major importance in a future warmer and more fluctuating climate. Eight experimental groups were analyzed in triplicate, in total 24 Affymetrix GeneChip Drosophila Genome 2.0 Arrays

Project description:We used microarrays to investigate the transcriptome of 6 days old male flies exposed to either 15 or 25 C development at either constant or fluctuating temperatures. Further, we investigated gene expression at benign (20C) and high (35C) temperatures With global climate change temperature means and variability are expected to increase. Thus, exposures to elevated temperatures are expected to become an increasing challenge for terrestrial ectotherm populations. While evolutionary adaptation seems to be constrained or proceed at an insufficient pace, many populations are expected to rely on phenotypic plasticity (thermal acclimation) for coping with the predicted changes. However, the effects of fluctuating temperature on the molecular mechanisms and the implications for heat tolerance are not well understood. To understand and predict consequences of climate change it is important to investigate how different components of the thermal environment, including fluctuating thermal conditions, contribute to changes in thermal acclimation. In this study we investigated the impact of mean and diurnal fluctuation of temperature on heat tolerance in Drosophila melanogaster and on the underlying molecular mechanisms in adult male flies. Flies from two constant and two ecologically relevant fluctuating temperature regimes were tested for their critical thermal maxima (CTmax) and associated global gene expression profiles at benign and thermally stressful conditions. Both temperature parameters contributed independently to the thermal acclimation, with regard to heat tolerance as well as the global gene expression profile. Although the independent transcriptional effects caused by fluctuations were relatively small, they are likely to be essential for our understanding of thermal adaptation. Thus, high temperature acclimation ability might not be measured correctly and might even be underestimated at constant temperatures. Our data suggests that the particular mechanisms affected by thermal fluctuations are related to phototransduction and environmental sensing. Thus genes and pathways involved in those processes are likely to be of major importance in a future warmer and more fluctuating climate.

Project description:As a result of increasing thermal fluctuations and mean temperature values, organisms will experience conditions beyond their physiological limits. In situ adaptation to thermal regimes is mediated via directional selection and phenotypic plasticity. The latter involves physiological and morphological adjustments realized by underlying molecular mechanisms. Understanding species' adaptive capacities requires investigating these adjustive processes. Yet, acclimation through phenotypic plasticity remains largely unexplored, especially at the molecular level; For example, whether cold-adapted species inhabiting freshwater spring ecosystems have evolved adaptive mechanisms to cope with warming of freshwater habitats has, to our knowledge, never been investigated. This work reports a comprehensive proteomics study of the stenotopic species Crunoecia irrorata (Curtis, 1834) (Trichoptera: Lepistomatidae) acclimated to 10, 15 and 20 °C for 168 h. A liquid chromatography tandem mass spectrometry (LC-MS/MS)-based shotgun proteomics approach identified molecular mechanisms underlying acclimation. We constructed a homology-based database by combining genomic and transcriptomic data from related species and quantified 1356 proteins, of which 186 were differentially expressed between temperature treatments. Through functional annotation, we identified candidate proteins facilitating, among others, trehalose accumulation, tracheal system alteration, and heat shock protein regulation, then discuss concomitant ecophysiological implications. These results provide new insights into the mechanisms of adaptive responses to warming of species inhabiting freshwater ecosystems sensitive to climate change. Further, identified candidate proteins will aid in developing targeted experiments to understand their compensatory physiology. To our knowledge, this is the first study utilizing this approach to investigate the nature of phenotypic plasticity of aquatic macroinvertebrates.

Project description:We used custom Nimblegen microarrays representing whole-larval transcriptomes for two species (Erynnis propertius [this submission] and Papilio zelicaon [submitted seperately]) to assess gene expression differences affecting tolerance to climatic regimes. Many individuals were sourced from populations from the northern periphery and center of the species' (shared) range; these were each divided into groups treated under peripheral and central climate regimes, resulting in 4 experimental groups for each species (Peripheral Source, Peripheral treatment; Peripheral Source, Central Treatment; Central Source, Peripheral Treatment; Central Source, Central Treatment). Using technical microarray replicates allowed us to use ANOVA to identify genes whose expression may underlie local adaptation to climate (i.e., those showing an interaction term between source and population). Abstract: Population differences may determine geographic range shifts and adaptive evolution under climate change. Local adaptation in peripheral populations could preclude or slow range expansions, and populations with different genetic make-up could have distinct trajectories that produce complex spatial patterns of population change. To investigate the genetic extent of local responses to climate change, we exposed poleward-periphery and central populations of two Lepidoptera to reciprocal, common-garden climatic conditions and compared whole-transcriptome expression. We found significant expression differences between populations in both species. In addition, several hundred genes including genes involved in energy metabolism and oxidative stress responded in a localized fashion in the species that exhibits greater population structure and local adaptation. Expression levels of these genes are most divergent in the same environment in which we previously detected phenotypic divergence in metabolism. By contrast, we found no localized genes in the species with higher gene flow, reflecting the lack of previously observed local adaptation. These results suggest that population differences do not generalize easily, even for related species living in the same climate, but some taxa deserve population-level consideration when predicting the effects of climate change.

Dataset Information

Fine-scale adaptive divergence and plasticity revealed by genetic and phenotypic variation in a marine invertebrate

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