Jens Krause

Schwarmverhalten der Tiere

Prof. Dr. Jens Krause
Ich werde am Anfang ein paar Sequenzen von kollektivem Verhalten (Vogelschwärme, Fischschwärme, Büffelherden etc.) zeigen, um den Zusammenhang mit dem Symposium und die Motivation für die Forschung zu verdeutlichen. Im zweiten Teil werde ich einige Computersimulationen (zum Teil auf Video) zeigen, an denen die Grundprinzipien von Tierschwärmen veranschaulicht werden. Wir haben in der Vergangenheit für diverse Fernsehsendungen Material zur Verfügung gestellt und haben einige schöne Aufnahmen, die sehr gut in diesen Rahmen passen.

Research Topics
My research interest is focused on the mechanisms and functions of group-living in animals. Group-living has a wide range of potential benefits and costs which can be investigated experimentally both in the field and/or the laboratory. Potential projects for postgraduates include:

Cost-Benefit Analysis of Spatial Positions in Animal Groups
Groups have a physical dimension and shape, and there is growing evidence that the costs and benefits of grouping are not homogeneously distributed across space so that individual group members experience differential fitness returns according to their specific group position. The objectives of this project are 1) to assess the potential for an uneven distribution of predation risks across different group positions 2) to predict strategies by which individual group members can minimise risk by changing the speed and direction of locomotion resulting in changes of their relative position to other group members 3) to investigate the consequences of position changes of individuals (in response to risk gradients) for the spatial structure of the overall group.

The use of individual-based models for the understanding of group-level and population-level behaviours
A large part of behavioural studies found in the literature are concerned with the behaviour of individual animals whereas ecological studies are usually concerned with an investigation of entire populations or the interactions between different species (or the study of entire food-webs). Our aim is to combine the two approaches with one another by using individual-based modelling which allows us to address the larger picture of what happens at the group- or population level based on an understanding of the behaviour of the individual. Individual-based models (IBM) are computer simulations that allow for the interactions of individual animals (either with each other or with the environment) and on this basis make predictions for phenomena at the group- or population level. One of the main advantages of IBMs is that they allow us to test which processes underlie observed patterns (e.g. grouping behaviour) and thus facilitate an understanding of the dynamic mechanisms that are at work in the shaping of ecological systems. We have selected a lake in Eastern Canada where we use IBMs to investigate the social organisation of fish. In particular we use IBMs to predict the number and composition of fish shoals on the basis of information on the size and structure of fish populations.

Influence of Parasites on Fish Behaviour
We investigate parasites with a complex life cycle that use fish as intermediate hosts. The aim is to understand how parasites potentially manipulate their fish hosts to increase the probability of transmission to their final host. Few field studies have been conducted on this so far. We work on a trematode worm (Crassiphiala bulboglossa) that is capable of changing the shoaling behaviour of fish in a way that makes an increased transmission to the final host, the belted kingfisher, likely. One of the challenges is to design tests that determine whether the transmission probability of infected fish to the final host is indeed increased by the parasite.

Research Interests
Mechanisms and functions of group living in animals
My research interest is focused on the mechanisms and functions of group-living in animals. Group-living has a wide range of potential benefits and costs which can be investigated experimentally both in the field and/or the laboratory. Potential projects for postgraduates include:

Cost-Benefit Analysis of Spatial Positions in Animal Groups
Groups have a physical dimension and shape, and there is growing evidence that the costs and benefits of grouping are not homogeneously distributed across space so that individual group members experience differential fitness returns according to their specific group position. The objectives of this project are 1) to assess the potential for an uneven distribution of predation risks across different group positions 2) to predict strategies by which individual group members can minimise risk by changing the speed and direction of locomotion resulting in changes of their relative position to other group members 3) to investigate the consequences of position changes of individuals (in response to risk gradients) for the spatial structure of the overall group.

The use of individual-based models for the understanding of group-level and population-level behaviours
A large part of behavioural studies found in the literature are concerned with the behaviour of individual animals whereas ecological studies are usually concerned with an investigation of entire populations or the interactions between different species (or the study of entire food-webs). Our aim is to combine the two approaches with one another by using individual-based modelling which allows us to address the larger picture of what happens at the group- or population level based on an understanding of the behaviour of the individual. Individual-based models (IBM) are computer simulations that allow for the interactions of individual animals (either with each other or with the environment) and on this basis make predictions for phenomena at the group- or population level. One of the main advantages of IBMs is that they allow us to test which processes underlie observed patterns (e.g. grouping behaviour) and thus facilitate an understanding of the dynamic mechanisms that are at work in the shaping of ecological systems. We have selected a lake in Eastern Canada where we use IBMs to investigate the social organisation of fish. In particular we use IBMs to predict the number and composition of fish shoals on the basis of information on the size and structure of fish populations.

Influence of Parasites on Fish Behaviour
We investigate parasites with a complex life cycle that use fish as intermediate hosts. The aim is to understand how parasites potentially manipulate their fish hosts to increase the probability of transmission to their final host. Few field studies have been conducted on this so far. We work on a trematode worm (Crassiphiala bulboglossa) that is capable of changing the shoaling behaviour of fish in a way that makes an increased transmission to the final host, the belted kingfisher, likely. One of the challenges is to design tests that determine whether the transmission probability of infected fish to the final host is indeed increased by the parasite.

Jens Krause 1/5 Fotos © Cordia Schlegelmilch 2004