Ralph Bergmüller

research interest

I am interested in understanding the mechanisms and the evolution
of cooperative behaviour in humans and other animals. Moreover,
I study the evolutionary causes and consequences of consistent
individual differences in behaviour between individuals of the same
species, i.e. animal personality.

Animal personality

Behaviours are considered to be among the most flexible traits in
animals and often reflect conditional responses upon the
behaviours of others, or to changing environmental conditions.
However, despite of the often presumed advantages of behavioural
flexibility, individuals within the same species or populations often
consistently differ in their behaviour, that is, some individuals are
consistently more aggressive, more explorative, or shyer than others.
I am interested in how this variation in behaviour can result from,
or affect social interactions and cooperation.

Human cooperation

Since Hardin's (1968) seminal publication, the 'tragedy of the
commons' describes the situation of a cooperation breakdown
that occurs when individual and group interests are in conflict
(e.g. when individuals use a common resource or a public good).
If individuals act selfishly, thereby depleting a resource on
which all depend, this leads to the tragedy of the commons.
Typical real life examples include land use, over fishing, climate
change and peace. I am interested in understanding in how far
evolutionary approaches might help to contribute towards
improving cooperation to solve public goods problems with help
of field experiments in real life settings in humans.

Photo by M. Taborsky:
Group of Neolamprologus pulcher, breeder male defending the
territory against the predator Lepidiolamprologus elongatus

Cooperative breeding

In the cooperatively breeding Lake Tanganyika cichlid Neolamprologus
pulcher, I investigated two main decisions of helpers: why they stay in
the territory instead of leaving to reproduce on their own, and why they
help raising offspring of others. I could show experimentally that ecological
constraints, particularly the lack of vacant sites suitable for independent
breeding prevent helpers to disperse and breed on their own. Further more
I found evidence supporting the 'pay-to-stay hypothesis' which
proposes that, in order to be allowed to stay in the dominants territory,
subordinates pay a 'rent' by helping the dominants to raise their offspring.
Field observations and experiments suggest that helpers may strategically
disperse between groups which may lead to a biological market situation
were helpers trade for instance their ability to help for access to a high
quality territory.

Animal cognition

The differences in cognitive abilities between species might
be strongly linked to the challenges animals encounter in their
natural and social environment. Cleaner fish (Labroides dimidiatus)
rely completely on the food they obtain from the client fish that visit
cleaner stations to get cleaned from their parasites. However, besides
removing the parasites from their clients tissue cleaners appear to
prefer to feed on their clients' mucus which they obtain when biting
the client fish. This results in a conflict of interests between cleaners
and their clients with regards to goods and services exchanged in
interactions. I use a comparative approach to test the cognitive
capabilities of different species of wrasses in the context of co-
operation from an ecological perspective.

Primate behavioural ecology

In the Tai National Park in Ivory Coast I studied the link between feeding
ecology and the social organisation in the terrestrial sooty mangabeys
(Cercocebus torquatus atys). The results of this study suggest that
mangabeys react to changes in the distribution of food in time and space
by adjusting their group size.


since 2005
with Prof. Bshary, University of Neuchâtel
Research associate and teaching assistant
University of Bern and the University of Neuchâtel
PhD thesis
with Prof. Taborsky, University of Bern



room: D 126

Tel: +41 032 718 3123


Université de Neuchâtel
Institut de Biologie
Rue Emile-Argand 11
CH-2000 Neuchâtel

Tel. +41 32 718 30 14
Fax +41 32 718 30 01