Where does biodiversity come from? What role does ecology play in the origins of different life forms? I ask these questions about 'the life aquatic' (no doubt fed by early Cousteau specials…), in order to understand how new types and species of fish have evolved in lakes that formed after the last glaciation about 12,000 years ago (in other words, most lakes in Canada…). While this seems a long time period, it is actually a mere 'tick' of the evolutionary or geological clock. The diversity of fishes in postglacial lakes is influenced by processes that occurred long ago in glacial refugia, more recently during dispersal across the postglacial 'lakescape', and most recently within the young lakes that I can swim in.
We have explored the role of species interactions (competitors, predators, and parasites), the affect of prey resources, niches and habitats (on the bottom, in the water column, or in vegetation…), and even abiotic conditions (basin topography?) on biodiversity in sunfishes, sticklebacks and walleye. I am very interested in the origins and consequences of diversity within single populations. Trophic polymorphism occurs when different types of individuals appear adapted to use different prey, habitats, or environments within a single population. Such systems are like time travel, giving us insights into the earliest stages of divergence that can lead to divergent populations and perhaps new species. Recently, we have been studying the role of phenotypic plasticity in the divergence of different forms in novel environments. Plasticity is the capacity of a single genotype to produce different phenotypes depending on environmental cues. We have found that the plastic responses to local conditions are one of the very first things to change during divergence. This raises interesting questions about the role of plasticity in evolution that will no doubt occupy us for years to come.