How resource phenology affects consumer population dynamics
Climate change drives uneven phenology shifts across taxa, and this can result in changes to the phenological match between interacting species. While changes in the relative phenology of partner species are well documented, few studies have addressed the question of how these changes impact long-term population dynamics. To answer this question, we develop a phenologically explicit Zonneveld-type model describing general consumer-resource interactions.
Using our model, which focuses on univoltine insects, we show how climate-driven changes in resource phenology can be re-interpreted as transformations in the year-to-year recursion relationships defining consumer population dynamics. This perspective provides a straightforward path for interpreting the long-term population consequences of phenology change. Specifically, we find that phenology change in consumer-resource systems can result in extinction of the consumer population, changes in the abundance of the consumer population, and changes in the dynamics of the consumer population (stable equilibrium, year-to-year oscillations, chaos). By considering these changes in the context of consumer recursion relationships, we are able to relate specific outcomes of phenology change to particular species traits that govern the shape of the recursion relationship, for example consumer fecundity or the nature of consumer competition.