BBSRC MIBTP - A system biology approach to study mechanisms of response to anthropogenic stress in aquatic ecosystems using Daphnia as emerging model system

The decline of water quality due to anthropogenic changes (e.g. climate change, land use, sewage inflow, chemical pollution) is a recognized threat to ecosystem services and to the economy. However, the causes and effects of such changes occur over many decades, and are therefore difficult to measure and hence difficult to regulate. The growing application of genomics to species with well-studied ecologies has helped to identify mechanisms of adaptation, including variation in gene regulatory regions, genic polymorphism and copy number variation [1]. However, we have yet to understand the mechanisms of adaptation of natural species to anthropogenic stress. This limits our ability to assess the resilience of natural systems to human-driven changes, with severe implication for ecosystem services and the economy. Accurate measurements of the effects of human driven changes on natural populations and communities is critical for gauging the effects of ecological drift, anthropogenic or otherwise, on biodiversity. To date, such changes have been poorly documented, owing, in part, to the paucity of datasets spanning long periods of time (e.g. several decades or centuries). To design a study across the time-span of multiple human careers, we propose a revolutionary approach that dramatically advances the state-of-the-art to generate longitudinal data within the scope of a single research project. Propagules from sedimented biological archives offer the unique opportunity to go beyond time-scales determined by human life- and career-spans [2]. Stratified banks can be sampled (cored) preserving their temporal arrangements and accurately dated, thereby aligning their local population and community histories to known changes in the environment, or to environmental changes inferred from analyses of the sediments or soils. Species of the genus Daphnia are by far the best studied metazoans in the practise of "resurrection ecology" (study of evolutionary and ecological features of animals hatched from resting stages)[3]. They are keystone species (playing a central role in food-webs) in still water environments and sentinel species for water quality (this species has been used for decades in ecotoxicology to test water quality), as well as key models in the study of adaptive responses to environmental change[4,5].
The main objective of this project is to identify mechanisms of adaption to anthropogenic stress to identify environmental tipping points for key European water bodies. To meet this goal the current project will identify the types of structural variation (gene polymorphism, CNV, inversions, gain/loss of alleles) and gene networks that are the most frequent targets of natural selection. By comparing the evolutionary trajectory of alleles in different genetic backgrounds (originating from different locations in Europe), the targets of selection and their temporal trajectories will be assesed and repeatability of evolutionary dynamics assessed. In addition, the contribution of individual variants to adaptation will be stablished. Trans-generational data will be obtained by studying animals resurrected from biological archives with known history of past exposure to specific anthropogenic stressors (e.g. eutrophication resulting from land use).