Organisms have always been confronted with changes in environmental conditions, either in space or time. However, the number and rate of anthropogenic alterations impose so intense selective pressures that biodiversity is irreversibly impacted. As well, biodiversity monitoring shows that extinction rate due to global change continues to increase. Plasticity and adaptability are key eco-evolutionary processes that could mitigate biodiversity loss in the face of environmental changes. However, few studies have determined how the combined effects of anthropogenic stressors affect the immediate and evolutionary response of organisms. POLLUCLIM aims at experimentally studying a freshwater organism’s response to the combined effects of climate warming and pollution. Using laboratory microcosms of a ciliate, I will first determine the plastic response to warmer and/or polluted environments (4 different pollutants) of a panel of genotypes. I will then study the probability of evolutionary rescue to these stressors, and determine if exposure to a stressful environment influences the evolutionary response to another stressful environment. Finally, I will relate adaptive patterns to genetic backgrounds and mutagenesis effects of stressors. At the end, the project should improve our understanding of tolerance and adaptability patterns to multiple anthropogenic stressors, with access to the underlying molecular mechanisms.

At the current warming rate, many organisms should go extinct if they are not able to disperse or adapt locally, which often involves plastic responses. In ectotherms, warming influences plastic life history traits with an acceleration of early life production at the expense of longevity and senescence. This may be due to trade-offs involving warming-induced oxidative stress and telomere shortening. Although pace-of-life acceleration may provide short-term benefits, it also increases sensitivity to limited resources, extreme climate events and unusual nighttime thermal conditions. Thus, in an increasingly warmer climate, ectotherms could reach critical physiological thresholds that would precipitate their decline. To date, physiological mechanisms and ecological consequences of this pace-of-life acceleration are poorly characterized. Here, we will combine experimental, observational and analytical approaches to unlock critical gaps in our understanding of thermal plasticity of life history. We will focus on a bimodal reproductive lizard (Zootoca vivipara), which offers a unique context to analyze how evolutionary transition between oviparity and viviparity influenced pace-of-life acceleration. Using long-term data sets and surveys across climatic gradients, we will document patterns of pace-of-life acceleration in response to climate warming in the two reproductive modes, focusing on vulnerable populations of the warm margin. In addition, we will perform outdoor and laboratory experiments to identify physiological tipping points in the context of day-night asymmetry of warming and extreme climate events. Given their major potential role in this thermal plasticity, non-energetic trade-offs will be quantified using longitudinal and cross-sectional assays of oxidative stress and telomere length dynamics. Altogether, this project will highlight patterns, mechanisms, and consequences on population viability of pace-of-life acceleration in response to climate warming.

Individuals should benefit from settling in habitats that maximise their fitness, a form of dispersal plasticity named habitat choice. Theory predicts that habitat choice can deeply modify the consequences of dispersal for ecological and evolutionary dynamics compared to the often-assumed random dispersal. However, our empirical knowledge of the drivers of habitat choice evolution and its ecological consequences remains rudimentary. This research project aims at identifying the environmental conditions favouring habitat choice evolution and at quantifying its consequences for the dynamics of populations. To do so, we will adopt an experimental approach using spatially explicit microcosms of an actively dispersing ciliate. This experimental system offers an excellent opportunity to validate or reject theoretically-derived predictions over multiple generations and thus to provide breakthrough advances about the environmental drivers and consequences of dispersal evolution.

GENESIS has been designed to answer both applied and fundamental research questions about biological adaptation to global and local environmental changes. Maintaining stable and functioning ecosystems under the current global changes is probably the biggest future challenge for conservation management and failing to address these issues is predicted to entail substantial economic repercussions. One of the key aspects of designing efficient conservation strategies is to understand how population structure affects the potential of natural populations to adapt to changing environmental conditions. GENESIS proposes to address a central question in Conservation Biology regarding «the role of genetic diversity and phenotypic plasticity in adapting to changing environmental conditions?» Genesis uses the framework of biological invasion to answer these questions. This is a particularly pertinent framework as the challenge for an invasive species is to respond quickly and efficiently to changes in the selective regime imposed by the colonised ecosystem. Also, a series of stochastic sampling events associated with the colonisation process is predicted to result in strong genetic drift in invasive populations, providing the opportunity for rapid evolutionary change through both selection and drift, and the majority of studies report marked phenotypic change in invasive populations. Providing empirical support for these debates has hitherto been difficult since it requires investigating the relationship between neutral and selected loci at a genomic level and the role of phenotypic plasticity in maintaining the fitness under novel and often contrasting environmental conditions. Genomic approaches in combination with studies of ecologically significant traits provide the opportunity to address such issues. Next-generation sequencing techniques now make feasible the comprehensive scanning of the genome of non-model organisms, thus overcoming the limitations of previous studies which had to rely on a small number of putatively neutral loci. Recent advances in genetic data analysis have provided the tools so that evolutionary processes in wild populations can be inferred from molecular data. Molecular based pedigrees can be used for quantitative genetic analysis and the implementation of high resolution genomic data will increase the power of such approaches significantly. The resulting information on heritability of ecologically significant life history traits or behaviours is crucial in accurately predicting responses to selection and is a key element of GENESIS. This will be achieved by an integrated approach using state-of-the-art genomic approach in combination with an experimental investigation of ecologically significant traits, trophic niche and reproductive behaviour. The invasion framework used in GENESIS is Pseudorasbora parva, a small fish native to Asia. It is an ideal model to address the research gaps outlined above as 1) previous studies have provided information on colonisation history, phenotypic and genetic diversity of invasive population; a prerequisite for a powerful study design; 2) P. parva is the most notorious invasive fish in Europe with devastating impact on native fish fauna through competition and disease introduction and hence research on this species has a high relevance to society; 3) an extensive tissue collection from 22 native/25 invasive populations for genetic and morphological analysis is readily available. All fish have been marked individually to be able to link morphological, life history traits, trophic level using stable isotope analysis and genetic data; 4) it is an ideal model species to use under laboratory conditions with short generation times, small body sizes and high reproductive effort. GENESIS will therefore significantly increase our understanding of factors that promote establishment success of invasive species and the response of small fragmented populations to climate change.

Human activities induce rapid climate change that poses major threats to global biodiversity, ecosystem functions, and ultimately to the fate of mankind. Forecasting and mitigating these detrimental effects is thus an urgent challenge. Warming not only increases the speed of biochemical reactions but also influences the phenotype of species trough plastic or selective processes. One ubiquitous phenotypic response to climate change is the reduction of ectotherm body size with temperature—the warmer it is, the smaller they get—. This temperature-induced body size shift has been proposed as the third universal species response to global warming altogether with shifts in phenology and species geographical distribution. However, the ecological consequences of temperature-induced body size shift on communities remain largely unexplored. This is an important gap, both for fundamental and applied research, as body size determines many ecological properties such as fecundity, growth rate, trophic position and community stability. Thus, knowledge of how temperature-induced body size shift modulates species interactions is important for understanding and predicting climate change impacts on ecological systems. The project EcoTeBo combines modelling and experimental approaches to investigate the ecological consequences of warming and body size shift on trophic interactions, community dynamics and ecosystem functions. EcoTeBo focuses on top predator body size reduction because (i) body size reductions appear to be stronger at high trophic levels and (ii) top predator body size is an important determinant of food web stability, especially in aquatic food webs that are strongly size-structured and top-down regulated. To achieve this ambitious objective, EcoTeBo brings together researchers with highly complementary expertise on trophic interactions, community ecology, ecosystem functioning, aquatic ecosystems, ecological models and management of large experimental infrastructures. By simultaneously manipulating temperature and top predator body size in simple and complex freshwater systems, we will provide: (1) A unique experimental test of the ecological impacts of temperature-induced body size shifts on the strength of trophic interaction, community dynamics, and ecosystem functions. (2) An unprecedented assessment of the relative effects of temperature and top predator body size on trophic interactions and community dynamics by combining modelling and experiments at different levels of complexity (i.e. food chain and whole community). (3) Novel food web models accounting for phenotypic responses to temperature with predictions connected to the stability of freshwater ecosystems, in terms of both their temporal variability and persistence. To our knowledge, EcoTeBo would be one of the first project to investigate the consequences of temperature-induced body size shifts on different components of trophic interactions, community dynamics and ecosystem functions. By exploiting the synergies between new theories and experimental tests in simple and more complex freshwater systems, we will disentangle the relative effects of temperature and body size shift on various ecological features and identify the mechanisms driving these effects. In addition to novel and important scientific results, EcoTeBo will facilitate the integration of trait based approach into climate change research and ease the detection and mitigation of climate change impacts by developing predictive models and using body size as a bio-indicator of ecosystem functioning.