Hedendaagse evolutie modificeert de gecombineerde effecten van temperatuur en een metaal in een natuurlijke populatie

Heat waves are a major component of global change, and have become more frequent, more intense and of longer duration. Heat waves are increasingly causing mortality and therefore likely strong selection agents driving strong and rapid evolution of natural populations. In addition, toxicants are another important global change stressor threatening biodiversity in aquatic ecosystems. There is increasing evidence that warming can magnify the negative effects of toxicants. This synergetic interactions may seriously threaten biodiversity. A central aim of this thesis is to investigate the response of aquatic organisms to the combined effects of heat waves and toxicants. To cope with stressors, natural populations may rely on rescue effects. Besides plastic rescue, there is increasing insight that also evolutionary rescue may be needed to guarantee long-term population persistence. In addition, also interactions of a host species with its microbiome have recently been suggested as a potentially pivotal novel type of rescue effects. I will study all three types rescue effects to cope with heat waves and pollutants and will pay special attention to this understudied rescue type. Besides coping with the stressor themselves, another challenge for natural populations to persist under global change is to cope with the changed biotic interactions under these stressors. Building on the clear evidence of warming and toxicants shaping trophic cascades, I will test their combined impact on how the gut microbiome shapes predator-prey interactions and thereby modulate trophic cascades. To address these research objectives, I will study the single and combined effects of heat waves and a toxicant on an aquatic invertebrate (the water flea Daphnia magna) and its microbiome, and the resulting ecological effects on an aquatic tritrophic food chain.