Once upon a time was a species that colonized a new environment, e.g. a newly formed archipelago or a lake, providing a variety of different, unexploited resources, where it rapidly diversified into a suite of species adapted to use their environment in different ways. This is the classical story of adaptive radiation (Simpson, 1953). Now imagine that not one, but two species from two distant lineages which are both known to sometimes radiate when each occurs alone colonize such a new environment at around the same time, perhaps even more than two. How do they partition niches among each other? Or do they? Do they diversify independently or do they constrain or promote each other’s diversification? We are addressing these questions studying unusually diverse assemblages of whitefish and char coexisting in the same young pre-alpine lakes.
