Abstract: Many animal species, in particular those that grow over substantial ranges of body size between birth and maturation, occupy different ecological niches in different stages of their life. Frequently such ontogenetic niche shifts are associated with shifts in habitat as well, such that juvenile and adult individuals use different physical environments, exploit different resources and in general interact with entirely different ecological communities. To develop theory about the implications of ontogenetic habitats shifts for the dynamics of such populations and the communities that they are part of in the different habitats, requires a modelling framework that links the life history and the population dynamics and explicitly accounts for the potential feedback of the population on the realised life history. Physiologically structured population models (PSPMs) provide such a framework as they consistently translate the individual life history to the population level, including the nonlinear interactions that individuals are exposed to. In this lecture I use PSPMs to show how the presence of an ontogenetic habitat shift in the life history of a consumer population may lead to the occurrence of alternative, ecological equilibria and create a dependency between predator species in the two different habitats if they forage on different life stages of the same consumer species. On an evolutionary timescale, I will show how a decrease in mortality in the adult habitat may have little immediate ecological effect, but instead triggers an evolutionary process that ends after a delay in a regime shift to a contrasting ecological state.
Those unable to attend can stream the lecture from our YouTube channel