SFB-TRR 212

Modelling the evolution of individual differences in niche choice, niche conformance, and niche construction

There is overwhelming evidence for widespread between-individual differences in behavioural phenotypes. In our collaborative research centre initiative, we aim at explaining these differences by using an individualised version of the ecological niche concept. The current project will use theoretical models that are inspired by theoretical studies from evolutionary and behavioural ecology with the goal to improve our understanding of the evolution and maintenance of between-individual differences as they are often described alongside studies examining behavioural syndromes or animal personality.

In our project, three conceptually different sets of models will be generated to examine the theoretical conditions that will lead to the evolution and maintenance of individualized behavioural niche variation through genetic differences, adaptive phenotypic plasticity and through experiencing the random components of imperfect cues. In these three sets of models, we will mainly use two aspects of behaviour that are very important for fitness, exploration and mate choice.

1. The first set of models will examine conditions that make it likely to maintain genetic variation with respect to individual niches. These models will, for example, assume trade-offs between adaptations across different mechanisms facilitating individualised niches. One focus of these models will be to examine under which conditions trade-offs between the three mechanisms of niche choice, conformance and construction can lead to the maintenance of genetic variation.
2. The second set of models has the task to clarify how and under which environmental conditions adaptive phenotypic plasticity can cause variation in the individualised niche. The frequently used prediction that those individuals that have higher reproductive value should be less bold because they have more to lose, is one possibility how state-dependent plasticity can lead to different behavioural niches. In our project, we will concentrate on routes to between-individual differences that assume no initial differences in reproductive value. Such dynamic plasticity is in line with the key prediction of the CRC initiative that individualised niches are not constant over the life of organisms. In addition, we will explore how continuous between-individual variation in states can potentially generate continuous adaptive variation in niche conformance.
3. The third type of models will assume that individuals' behavioural decisions rely on important but not perfectly reliable information regarding the individual-specific relative costs for exploration or mate choice. With these models, we will clarify the effect that random between-individuals differences in information state can have in causing variation in realised individual niches.

The above described theoretical models will mainly focus on exploration strategies and mate choice decisions, and each of the three sets will be designed with two main aims. The first will be to predict conditions that lead to multiple fitness peaks and thus likely will lead to the evolution and maintenance of between-individual differences in behaviour. The second main aim will be to explore how continuous between-individual variation in behaviour can be explained for any of the NC³ axes. In contrast to most previous models that assume binary trait variation, these models may shed light on how continuous variation in behaviour between individuals can be maintained. Taken together, the current project will explore theoretical possibilities to explain the evolution and maintenance of between-individual variation and especially the continuous behavioural variation that is very often observed in empirical studies concerning niche choice, niche conformance and niche construction.