Behavioural ecology

Research interest and experience

I am mainly interested in the evolution of social systems. I approach questions about social evolution using mostly mathematical and computational tools. In my research I try to study a variety of social systems. Which systems I study mostly depends on the possibility to inspire the models on the biology and natural history of social animals. This entails either doing some empirical research, or collaborating closely with more empirically involved researchers. Bellow, you can find a summary of some of the research I have been or are part of.

The evolution of learning in the context of cooperative interactions

Together with Redouan Bshary, Olof Leimar and Arnon Lotem, I am developing models about the evolution of learning in the context of cooperative interactions in the cleaner wrasse system (Labroides dimidiatus). Cleaners are coral reef fish that feed of the parasite load of other fish in the reef (clients). However, during the cleaning encounters cleaners can, and prefer, to feed on the mucus from the clients, effectively harming them. Thus, the interaction cleaner-client involves a conflict of interests between the two partners. Several mechanisms allow cleaners and clients to maintain their fruitful cooperative interaction despite the conflict. Recent evidence indicates that cleaners learn the strategy they use in their interaction with clients. Furthermore, cleaners from different populations seem to have different cognitive abilities when learning their cooperative strategy. These differences suggest that cleaner’s learning process is dependent on the social environment they experience. In our models, we explore the evolution of the cognitive abilities of cleaners. We aim at understanding how ecological conditions determine the evolution learning mechanisms, and how that may explain the differences found in natural populations.

The evolution of eusociality

The evolution of eusociality is considered one of the major transitions in evolution. This transition entails changes in many facets of a species biology, thus, many traits are expected to evolve together. Eusociality’s hallmark trait is worker behaviour, whereby individuals forgo their own reproduction to work in the parental nest. Worker behaviour is known to be promoted by split-sex ratios, that is, when colonies differ in their sex-ratio strategy. However, it is not clear how and whether split-sex ratios and worker behaviour co-evolve. Together with Ido Pen, I develop inclusive fitness models that capture the co-evolution of worker behaviour and sex ratios in the context of life-histories that promote split sex ratios. These types of life-histories are found in families of insects known for their diverse social behaviour. We use these models to show how some traits, found in these insects, are particularly favourable for the evolution of eusociality; thus, they can be considered pre-adaptations.

The evolution of cooperative brood care

Cooperation in social groups is easily undermined by selfish behaviour, unless mechanisms are in place to mitigate conflicts of interest between group members. One such mechanism is to preferentially cooperate with relatives, who have aligned fitness interests by virtue of their shared genes. Alternatively, conflicts can be resolved by means of conditional strategies that enforce the reciprocal trading of services or commodities, enabling (unrelated) partners to negotiate a mutually beneficial outcome. How these two processes – kin selection and negotiation – interact in the evolution of cooperation and sociality remains unclear. Together with Sander van Doorn, Franjo Weissing, Ido Pen and Michael Taborsky, I study this interplay, both with concrete models for cooperative breeding in fish and general theoretical analysis. We have shown that negotiation and kin selection do not necessarily act synergistically, and that kin structure can hamper rather than facilitate the evolution of effective cooperation.

The cultural evolution of cooperation

The role of cultural group selection in the evolution of human cooperation is hotly debated. It has been argued that group selection is more effective in cultural evolution than in genetic evolution, because some forms of cultural transmission (conformism and/or the tendency to follow a leader) reduce intra-group variation while creating stable cultural variation between groups. This view is supported by some models, while other models lead to contrasting and sometimes opposite conclusions. A consensus view has not yet been achieved, partly because the modelling studies differ in their assumptions on the dynamics of cultural transmission and the mode of group selection. To clarify matters, together with Franjo Weissing and Lucas Molleman, we developed individual-based models allowing for a systematic comparison of how different social learning rules governing cultural transmission affect the evolution of cooperation in a group-structured population. From our simulations we conclude that the outcome of cultural evolution strongly reflects the interplay of social learning rules and the mode of group selection.

For more detailed info on these and a few other projects, please visit my website