SFB-TRR 212

Individualised niches in a variable environment – Consequences for environmental change responses and for species interactions

Population density affects many aspects of an individual’s life: resource competition, social environment and potential aggressive encounters, as well as mating opportunities and competition for mates. Building on the conceptual understanding on the emergence and maintenance of individualised (density) niches we now explore the consequences of individualised niches and the NC³-mechanisms for higher-level processes, in particular for a population’s response to environmental change and for species interactions.

In two parts of the project, we will explore the consequences of individualised niches for a species’ response to environmental change and for interactions with other species.

1. We aim to extend non-linear averaging theory to account for interactions between an individual’s trait and its micro-environment, including the NC³-mechanisms, and density dependence. With the help of this new modelling framework, we aim to understand the consequences of ITV and the NC³-mechanisms for population dynamics and persistence in a variable and systematically changing environment, in a general mathematical model, and in models for Antarctic fur seals and fire salamanders.
2. We aim to build a two-dimensional non-linear averaging theory including individual-by-individual trait interactions, with particular focus on NC³-mechanisms and density effects. Based on this framework, we aim to understand the consequences of ITV and the NC³-mechanisms in general for competitive interactions, consumer-resource interactions, and mutualistic or parasitic host-symbiont interactions, and in the specific cases of herbivore adaptation to a new host plant and for the interaction between sticklebacks and their parasites.

The overarching goal of this project is to explore the consequences of individualised niches and the NC³-mechanisms for higher-level processes, in particular a population’s response to environmental change and whether or not the population can persist and the population dynamics of interacting species.

All in all, this project will serve to bring a more realistic and dynamic niche concept to studies of intraspecific trait variation and its consequences.