Romain Richard

Consumer life-history in dynamic predator-prey environments

My research is focused on understanding how organisms respond to environmental fluctuations, with an emphasis on consumer-resource systems. Natural systems inherently fluctuate through the combined effects of both predictable, deterministic processes, and unpredictable, stochastic processes. In addition, ecological interactions, such as consumer-resource interactions, can intrinsically generate these kinds of fluctuations: the foraging activity of consumers depletes the resources on which they feed, causing a tendency for these systems to fluctuate. My research uses an integrative framework that includes a close interaction between theory and experiment to test how ecological and evolutionary responses of natural populations emerge from both mechanistic responses at the individual and population level, and the process of natural selection, which mediates the dynamics in gene frequency, and leads organisms to adaptation. Using a Daphnia-algae system as a model study, I developed a range of experiments and models spanning different levels of biological organization involved in these responses. Genetically distinct clones are used to investigate how variation in resource allocation strategies (i.e. how acquired resources are partitioned among growth, survival and reproduction) affects population growth and clonal competitive ability in different dynamical regimes. This approach is complemented by the use of theoretical models to yield a better understanding of the selective pressures generated by such fluctuations, of the behavioural strategies displayed by individuals in response to such pressures, and of the impact of such strategies on the dynamics of the system. Another part of my research focuses on how phenotypic variation and clonal competitive ability emerge from the combined influence of genetic and environmental factors. This research uses microarrays to quantify the patterns of gene expression, at a genomic scale, in different settings.