My research focus is on cooperation within and between species
(mutualism). I aim to test game theoretic models and to refine them
in collaboration with theoreticians. Furthermore, I am interested in
links between a game theoretic approach, animal cognition and
behavioural endocrinology. A major future topic will be decision
making in the context of social strategies.

The cleaning mutualism between the wrasse Labroides dimidiatus
and other reef fish has been and will continue to be the main model
system. These cleaners remove ectoparasites from client reef fish
but prefer to eat mucus, which constitutes cheating. We currently
use a comparative approach that includes another cleaner wrasse
L. bicolor, a species that, in contrast to L. dimidiatus, lacks
cleaning stations and thus makes it hard for the clients to achieve
a repeated game.
Cleaning gobies of the Caribbean are interesting because they
actually prefer to cooperate by eating ectoparasites rather than
client mucus. We compare these highly specialized cleaner
species to a variety of facultative cleaners and non cleaning
wrasses to uncover the causes/consequences of cleaning on
cooperation, cognition and physiology.

In addition, I have worked on predator-prey relationships in my
PhD study on arboreal primates in the Ivory Coast, and I currently
investigate a variety of cooperative hunting systems in the Red
Sea and on Lizard Island, Australia. Interspecific collaborative
hunting between groupers and moray eels is interesting because
of the communicative aspects, which include gestures. Yellow
goatfish hunt in groups and are highly coordinated. Both systems
can be subjected to experiments in the laboratory.

A further project focuses on the interactions between sabre tooth
blennies and their reef fish victims out of which the blennies bite
bits of flesh. These interactions interest me in particular as the
victimsmay punish the blennies but face the tragedy of the
commons problem with their conspecifics who also benefit from
any punishment action against the blenny without bearing the
costs of punishment. Thus, this project deals with social dilemmas
and how they can be solved under natural conditions. We recently
conducted lab experiments in Egypt.

We are also about to complete two more exotic projects. The first
is a collaboration with Cris Kuhlmeier on a flowering plant-
pollinator mutualism to understand why plants (usually) offer nectar
rather than trying to save the energy for other tasks. We produced
crossing lines of Petunia plants that offer less nectar than usual
and let their natural pollinators interact with a mixed population to
look for any negative consequences of reduced nectar provisioning.
The second project is on social behaviour and cognition in wild
corvids (rooks and crows) in the Canton of Neuchâtel.
Some publications will come out of this project but I recommend
any colleague interested in staging a similar project to contact us
in order to get some ideas about potential challenges.

Finally, I returned partly to my primatological PhD roots.
In collaboration with Prof Sarah Brosnan we compare cleaner
wrasse to various primates in order to test the specificity of
selection on social intelligence. In addition, I officially lead a
Sinergia project financed by the Swiss Science Foundation to
study social strategies and cognition in vervet monkeys in South
Africa. Collaboration partners are Carel van Schaik  (University
of Zürich), Andy Whiten (University of St.-Andrews) and  Klaus
Zuberbühler  (University of Neuchâtel). The ‘true’ leader and soul
of the project is Erica van de Waal (St.-Andrews).

Key current collaboration partners not mentioned in the text: