Since my PhD on mixed species associations in arboreal primates,
my research focus has been on interspecific interactions between
vertebrates. I am most interestet in the evolution and maintainance
of mutualism in the light of the risk of exploitation, using the cleaning
mutualsim between the wrasse Labroides dimidiatus and other reef
fish as the main model system. I extended this project by including
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.

In addition, I have worked on predator-prey relationships in my study
on the primates, and I currently investigate a viariety of interspecific
cooperative hunting systems (among others between groupers and
moray eels) in the Red Sea and signalling aspects between prey fish
and groupers.

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 victims
may 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 again,
this project deals with social dilemmas and how they can be solved
under natural conditions.

Finally, I started a project on a flowering plant-pollinator mutualism to
understand why plants (usually) offer nectar rather than trying to save
the energy for other tasks. A key point is to produce 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 nextar provisioning.

In parallel, I became more and more interested in the cognitive and
physiological mechanisms that underlie the behaviour of my study
animals.
Cooperation and cheating has been linked to the Machiavellian
Intelligence Hypothesis, which states that the evolution of a large neo-
cortex in primates is linked to social complexity. We test this idea in a
comparative approach, exposing a variety of cleaner fish species to the
same cognitive experiments.

Finally, I joined a major field project on vervet monkeys in South Africa,
led by Dr. Louise Barrett  (University of Lethbridge), Prof Leslie Brown
(University of Pretoria), Prof Peter Henzi (University of Lethbridge) and
Prof Ronald Noë (University of Strasbourg).
My focus will be on aspects of culture.

Other collaboration partners regarding the fish and plant-insect projects:

Prof Hans Fricke, MPIV Seewiesen:
interspecific cooperative hunting in fishes
Dr. Alexandra Grutter , University of Queensland:
cleaning mutualism
Dr. Rufus Johnstone , University of Cambridge:
game theoretic modelling of cooperation
Prof Rui Oliveira , ISPA, Lisbon:
behavioural endocrinology of fishes
Dr. Lucie Salwiczek , University of Cambridge:
non primate animal cognition
Prof Wolfgang Wickler , MPIV Seewiesen:
non primate animal cognition