Head of Division
Prof. Dr. Michael Taborsky

Institut für Ökologie und Evolution
Telefon: +41 31 631 91 11
Telefax: +41 31 631 91 41
E-Mail:   claudia.leiser@iee.unibe.ch

Ethologische Station Hasli
Wohlenstrasse 50a
CH-3032 Hinterkappelen

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Universität Bern


PNAS - Predation risk drives social complexity in cooperative breeders. Groenewoud, Frommen, Josi, Tanaka, Jungwirth & Taborsky
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The evolution of cooperation based on direct fitness benefits. Phil Trans theme issue compiled and edited by Taborsky M., Frommen JG & Riehl C. (2016)
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NATURE COMMUNICATIONS Kinship reduces alloparental care in cooperative cichlids where helpers pay-to-stay
Zoettl M., Heg D., Chervet N. & Taborsky M. (2013)
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Social competence: an evolutionary approach
Taborsky, B. & Oliveira, R.F.
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Larval helpers and age polyethism in ambrosia beetles
Biedermann P.H.W. & Taborsky M.
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Animal personality due to social niche specialisation
Bergmueller R. & Taborsky M.
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Environmental Change Enhances Cognitive Abilities in Fish
Kotrschal, A. & Taborsky, B.
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Extended phenotypes as signals
Franziska C. Schaedelin and Michael Taborsky
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On the Origin of Species by Natural and Sexual Selection
G. Sander van Doorn, Pim Edelaar, Franz J. Weissing
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Cambridge University Press
Alternative Reproductive Tactics: An Integrative

Oliveira R., Taborsky M. & Brockmann H.J.
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Master or Bachelor projects at the Behavioural Ecology Division

The following list covers the major themes that are currently investigated in the department Behavioural Ecology. In each case we list a number of questions that may be studied in the context of a Master or Bachelor Thesis. In general, our approach involves lab and field observations and experiments, and theoretical modelling.

1) Evolution and Ecology of Cooperative Breeding

We study the behavioural ecology of cooperative breeding in the cichlid fish Neolamprologus pulcher/brichardi from Lake Tanganyika. This cichlid lives in extended families: both male and female offspring remain in their natal territory and help to defend and maintain the territory and to raise broods produced by the territory owners. Currently, we are mainly interested in the importance of ecology (e.g. predation, habitat, density) and mutual relationships between group members.

- Do helpers pay to stay in the territory in dependence of the predation risk?
- Does the propensity to help depend on the social status in the group?
- How do relative competitive ability or vulnerability to predators influence the decision
  to help or disperse?  (Experimental or theoretical work, using transition matrix modelling)
- How do helpers’ decisions to delay dispersal and help relate to their territorial defence, emigration
  from home and attempted immigration onto territories? (Theoretical modelling)
- Do helpers retard growth as a strategic decision to remain tolerated in the group?
- Do individuals reciprocate help in a direct, indirect or generalized way?

For more information: Research [Cooperative breeding]
Betreuer, Michael Taborsky: Website / E-Mail

2) Evolution and Ecology of Alternative Reproductive Tactics

We study evolutionary mechanisms involved in the origin and maintenance of alternative reproductive tactics, with a shell brooding Lake Tanganyika cichlid as a model system. Three different male morphs occur in this species: (1) large nest building males which collect empty snail shells in which females lay and tend eggs, and two types of parasitic males; (2) medium sized opportunistic males and (3) specialized dwarf males that are only 2% of nest male size. Presently we study the importance of the breeding substrate for male and female reproductive decisions, and the mechanisms of sperm competition between different types of males.

- Do females choose males by selecting specific shell sizes for spawning?
- How do different types of males specialize in spawning behaviour, ejaculates and sperm?
- What is the influence of different male traits on spawning success?
- Do nest males distinguish between own and strange offspring, and how?

For more information: Research [Reproductive behaviours]
Betreuer, Michael Taborsky: Website / E-Mail

3) Sociality of Ambrosia Beetles

Ambrosia beetles are bark beetles that are haplodiploid like eusocial hymenoptera, and they show very high levels of inbreeding and local mate competition. They cultivate fungi to “digest” wood for them, which requires intensive maintenance that is shared among the female offspring of a foundress. All these features predispose this group to advanced sociality. However, surprisingly little is known about the degree of cooperation and sociality existing in this taxon, despite its magnificent role as a model system to study the evolution of eusociality. Currently we are mainly interested in the cooperative behaviour of non-reproductive group members in colonies of the native species Xyleborinus saxeseni.

- What determines dispersal of female brood care helpers (ecological conditions, need for help)?
- How does the behaviour of non-reproductive group members influence colony productivity?
- Do males produce offspring successfully by outbreeding, and how

For more information: Research [Sociality in beetles]
Betreuer, Michael Taborsky: Website / E-Mail

4) Reciprocity in Norway Rats

Behaviour directed towards conspecifics depends on previous social experience. This has been known for long in the context of resource competition (winner and loser effects). Recently, we found a similar mechanism to work also in the sociopositive context: A rat that received help from anonymous social partners is more likely to help another (unknown) rat to obtain food than a rat that did not receive such help. We study whether such “generalized reciprocity” is context specific and which behavioural and physiological mechanisms are responsible for this altruism.

- Do rats that received help in one context help others more likely also in a different
  behavioural context (e.g. food acquisition and comfort behaviour)?
- Is the propensity to help influenced by circulating levels of specific hormones?
- Does generalized reciprocity also work in closed groups of different sizes?
For more information: Research [Cooperation in rats]
Betreuer, Michael Taborsky: Website / E-Mail

5) Relationship between Mating Pattern and Parental Care

Theory proposes a close functional relationship between the patterns of mating and parental care. However, little experimental evidence exists to test theoretical predictions. Eretmodus cyanostictus is a rare example of a monogamous mouthbrooding fish in which both parents incubate the clutch successively. There is an apparent conflict over the timing of the shift of young from female to male. We would like to understand the ultimate reasons for monogamy in this model system (e.g. joint defence or brood care, lack of alternative mating opportunities).

- What determines the parental share in brood care (e.g. body condition, sex ratio)?
- Which sex is in control of timing of the female-to-male shift of young?
- How can such successive parental care be evolutionary stable? (Game theory modelling)
Betreuer, Barbara Taborsky: Website / E-Mail

6) Maternal effects in a mouthbrooding cichlid

Simochromis pleurospilus is a mouthbrooding cichlid endemic to Lake Tanganyika, Zambia. In a first experiment, in which the growth of S. pleurospilus young hatched from big and small eggs under high and low food conditions was closely tracked, we found that juveniles from big eggs have a size advantage up to 42 days compared to juveniles from small eggs kept under the same food conditions. The question remains how certain survival related behaviours change with juvenile size under high and low food conditions (as food conditions may have additive effects).
S. pleurospilus females care for their young in two phases: In the first incubation phase, which lasts approximately 14 days, she has the young continuously in the mouth. In the second phase, (also about 14 days) she lets them out for feeding and takes them back in her mouth when there is a threat. We know that egg weight determines the size of the young at 14 days after hatching, but in how far does the mother influences the size of the young in the two week period after this (the second incubation phase)?

- Do juveniles have a biological significant difference in reactive distance?
- How close do fish from different sizes approach predators?
- Does sensitivity to predator odour cues vary with size and food ration?
- Do the periods a mother lets her young out to feed differ with her body condition and social rank?
- Can the mother “teach” the young which fish it has to fear?
- It’s known that some cichlids actively make sounds in behavioural interactions; do S. pleurospilus mothers “call” their young back?
- Does the time a mother lets her young out differ with the egg size she produces?
- Do the sizes of the eggs influence the moment of complete independence and the number of young that are released after the second incubation phase?
Betreuer,  Michael Taborsky: Website / E-Mail