Martin Laporte

Telephone: (418) 656-2131 #408455

Evaluating the importance of phenotypic plasticity in the origin of the dwarf morph in the lake whitefish (Coregonus cupleaformis).

Louis Bernatchez (Supervisor)

I have a particular interest in phenotypic plasticity, more precisely in the capacity of the organisms to modify their phenotype in response to an environmental stimulus. This capacity has a substantial impact on the evolutionary history of the species because i) it is heritable and responds to evolutionary forces, ii) it increase the fitness of the individuals by allowing quick adjustment in response to environmental changes and iii) it facilitates the dispersion and colonization of organisms to new environments. Therefore, evaluating the plastic capacity of different phenotypic traits in different environments is a major asset in the goal of increasing our knowledge of the evolutionary history of different populations or genetically related species.

During my post-doctorate, I will evaluate the importance of the phenotypic plasticity in the origin of the "dwarf" morph of the white fish (Coregonus cupleaformis). This species is separated into two ecotypes, "normal" and "dwarf". It is now recognized that the "dwarf" morph, living in a limnetic habitat, derived from the "normal" morph, living in a benthic habitat. We will compare the phenotypic plasticity of the "normal" and "dwarf" forms on several phenotypic traits (e.g.: morphology, gene expression, physiology, mitochondrial activity...) in different water velocities as a first step, but also in different anoxic conditions. We chose these environmental conditions because it is considered that a higher necessity to swim is present in limnetic habitat and anoxia is present in the benthic one. The results will allow us to verify if the plastic capacity of the "normal" morph of the white fish allowed the colonization of the limnetic habitat. We also predict that the plastic capacity of the "dwarf" morph have been lost during the specialization process to the limnetic habitat.