The role of adaptation in determining resistance to climatic change in ecological communities

Man-made climate change poses a grave threat to the survival of plant and animal species. This is because each species has a particular preference or tolerance for the climate - an optimum climatic range suitable for survival and reproduction. Beyond this optimum, the individuals within species can survive if they migrate to other locations where the environment is more suitable or by making plastic adjustments to their physiology or morphology to suit the new conditions. However, phenotypic plasticity has limits, and many species won't be able to move quickly enough to escape climate change or will be trapped on islands of suitable habitat. In this case, the remaining option is in situ adaptation. This involves survival of the individuals in each population that are fittest (best adapted) under the new climate, and the inheritance of the traits conferring fitness through the genes that control them. This propensity for adaptation is important, because it tells us whether species will be able to offer long-term resistance to the effects of climate change in the places where they currently occur. While researchers have considered the effects of adaptation in individual species, they have not considered consequences of adaptation occurring within ecological communities. This broader perspective is crucial, since most species do not exist in isolation, but coexist with other species instead. Species occurring together in communities interact through competition for resources or through dependency on other species as food, prey or hosts. These links and connections between species might, for example, mean that adaptation to climate change in one species influences persistence or extinction in one or more other species in the community. If so, then our expectation of how biodiversity will respond to the climate is not based on sound foundations, and might differ substantially from what will actually occur. This large gap in knowledge leads me to want to answer three very fundamental questions in my project: (a) Are populations of different species within communities able to adapt to climate change? More specifically are the species that succeed under climate change the ones that have adapted? (b) What influence does success or failure of one species in the community (whether or not through adaptation) have on the performance of other interacting species and their persistence in the community? (c) What impact does non-climatic environmental variation have on the spatial distribution of the genetic diversity that controls adaptation to climate? In this project, I will investigate the mechanism driving the resistance of species-rich grassland communities to 16 years of simulated climate change in a unique climate change experiment. I will use a classical experimental design widely employed to identify adaptation - the reciprocal transplant experiment (RTE) - to determine whether species that have increased or decreased in abundance in response to the manipulations have also adapted to them. I will also use a novel modification to the RTE design, where entire microcosm communities are reciprocally transplanted, to dissect the impact of success or failure of species under climate change on other members of the community. Finally, I will use high throughput sequencing technology to identify the regions of plant genomes that likely control adaptation. Using this information I will investigate the impact of non-climatic environmental variability on the distribution of adaptive climate-related genetic diversity. The ultimate goal of the project is to facilitate a mechanistic understanding of the responses of grassland communities to environmental changes at the level of interacting individuals and their genes. This will result in a detailed knowledge of how humans impact on plant communities and how they might respond, such that we can better plan their management before decline occurs.