Charr truth: sympatric differentiation in Salvelinus species

Charrs, Salvelinus species, are characteristic fishes of northern freshwater lakes and rivers. They are highly variable in almost every aspect of their behaviour, morphology and life history. Several possible explanations have been proposed to account for this variability and resolve the taxonomic confusion in this genus. I propose that sympatric trophic polymorphism, in the ecological context of these species, can make sense of this variability. I use examples from charr in Canada and Iceland to construct an evolutionary scenario for this genus.