Genetic and epigenetic bases of life history strategies in the capelin
Investigating the molecular bases of life history variation is a central goal for demographers and evolutionary biologists. We tackle this issue in the capelin (Mallotus villosus), a small fish with a circumpolar distribution, that has two contrasted life history strategies: “beach-spawning” (BS) fish reproduces within the intertidal zone where environmental conditions experienced by embryos and larvae are highly unpredictable. “Dermersal-spawning” (DS) fish breeds in sites located at water depth ranging from five to 250 meters where environmental conditions are relatively predictable. BS fish are facultatively iteroparous while DS fish are strictly semelparous. These alternative phenotypes can be found in two glacial lineages from North America and Europe. Using whole genome sequencing (WGS) and bisulfite-converted WGS, we investigate the genetic (i.e., punctual mutations, copy number variants) and epigenetic (i.e., methylation) bases of those contrasted life history strategies. We are especially interested in quantifying the relative contribution of those molecular mechanisms to the parallel evolution of life history strategies in North America and Europe capelin lineages.
Life history and host population response to infectious disease in amphibians
The negative impact of parasites on survival and reproduction of wild animals is widely recognized. Theory and empirical evidences both indicate that parasites can regulate (i.e. produce cyclic population oscillations), crash (i.e. produce population collapse) or destabilize (i.e. produce irregular fluctuations) its host populations. Host demographic processes and plasticity in life-history traits are compensatory responses that can counteract (or even cancel out) at the population scale the negative effects of a parasite-driven reduction in survival or reproduction. These compensatory responses are strongly modulated by host life history characteristics. In this project, we investigate how compensatory mechanisms may mitigate the detrimental effects of the chytridiomycosis, a fungal disease caused by Batrachochytrium dendrobatidis and B. salamandrivorans, on survival in two amphibian species from South America (Rhinoderma darwinii) and Australia (Litoria aurea).
Transgenerational dispersal plasticity and gene expression in a ciliate
Transgenerational plasticity (TGP) is a central mechanism in the evolution of the living world. TGP occurs when abiotic and biotic environmental conditions alter the phenotype of parents and when those changes then affect offspring phenotypic expression. Dispersal, the movement of individuals potentially leading to gene flow, is a highly relevant candidate for investigating TGP mechanisms. Dispersal is a complex and multidimensional phenotype, which is highly plastic at all its stages (i.e., emigration, immigration, and transience) and under partial genetic control. Studies have suggested that TGP may facilitate the transmission of traits across generations that improve dispersal in a given environmental context, while offering the possibility to reverse or explore other phenotypic states if the environment changes again. In this project, we investigate TGP for dispersal-related traits and the related fitness consequences in the protist Tetrahymena thermophila. We investigate the genetic and transcriptional bases of transgenerational dispersal plasticity by combining experimental evolution and NGS approaches.
Intra- and transgenerational effects of pesticides in amphibians
Pesticides have critical effects on individual phenotype by affecting behavior (i.e., personality traits) and life history components (i.e., fecundity, growth, and survival), which ultimately has detrimental effects on population dynamics. In species with complex life cycles such as pond-breeding amphibians, exposure to pesticides at early stages may have detrimental delayed effects on individual phenotype and performance later in life. Furthermore, those deleterious effects on phenotype may be transferred to the next generation via transgenerational plasticity – although empirical evidences are very scarce in non-model species. In this project, we investigate intra- and transgenerational effects of pesticide in a pond-breeding amphibian, Xenopus laevis. We examine how pesticide exposure at larval stage negatively affects personality traits, growth, survival, and breeding performances. Furthermore, we investigate pesticide-related TGP at the next generation, measuring offspring phenotype and performances before and after metamorphosis. We also examine the molecular bases of pesticide-related TGP by quantifying gene expression profile.