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

How to find us ...

Universität Bern

HIGHLIGHTS

PLOS BIOLOGY
The smell of hunger: Norway rats provision social partners based on odour cues of need
K. Schneeberger & M. Taborsky

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FUNCTIONAL ECOLOGY
Sensory ecology and cognition in social decisions
Special feature edited by K. Schneeberger & M. Taborsky

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SCIENCE ADVANCES Alternative male morphs solve sperm performance/longevity trade-off in opposite directions M. Taborsky, D. Schütz, O. Goffinet & G.S.van Doorn

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Media release, University of Bern

 

CURRENT BIOLOGY
Reciprocal trading of different commodities in Norway rats. M.K. Schweinfurth & M. Taborsky

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Nature research highlight
Current Biology dispatch

PNAS - Divergence of developmental trajectories is triggered interactively by early social and ecological experience in a cooperative breeder. Fischer, Bohn, Oberhummer, Nyman & B. Taborsky
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commentary on Fischer et al

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
Approach

Oliveira R., Taborsky M. & Brockmann H.J.
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more information

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) Parental effects in Neolamprologus pulcher: From mother or father?

The experimental work in group of B. Taborsky uses the cooperatively-breeding Lake Tanganyika cichlid Neolamprologus pulcher as model system and investigates how social and ecological components of the early environment influence later life social behaviour, predator responses and cognition. N. pulcher lives in groups consisting of a dominant breeder pair and up to 20 subordinate individuals (‘helpers’). All subordinate group members delay dispersal from their natal groups and act as helpers at least until sexual maturation. Many subordinates stay at the natal territory long after sexual maturity, whereas others disperse rather soon afterwards.
In previous projects, we found that the cooperatively-breeding cichlid fish exhibits two behavioural types, which are determined by the early environment in which the fish grow up. They either (i) help with alloparental care but leave the natal territory early for own breeding or (ii) they show mostly submissive displays towards dominant breeders, but stay for extended periods at the natal territory. Interestingly, their behavioural type is non-genetically inherited the next generation through parental effects. We are currently trying to understand the mechanisms of this parental effect. One question we would like to answer in this Master project is whether the parental effect comes from the mother (maternal effect), from the father (paternal effect), or from both. Paternal effects could arise, for instance, if breeder males influence their female partner’s allocation of nutrients or hormones to eggs shortly before mating, as shown in other fish.
Question: Are parental effects in N. pulcher leading to behavioural specialization due to maternal effects and/or to paternal effects?
We aim to answer this question by breeding offspring
-    from pairs with the same behavioural type (mother and father are of the helping type; mother and father are of the submissive type) and
-    from pairs with opposite behavioural type  (mother is of helping type and father of submissive type, or vice versa)
and compare the behaviour of the different offspring types.

References
•    Fischer, S., Bessert-Nettelbeck, M., Kotrschal, A & Taborsky, B. (2015): Rearing group size determines social competence and brain structure in a cooperatively breeding cichlid. Am. Nat. 186:123–140
•    Fischer, S., Bohn, L., Oberhummer, E., Wikström, C. & Taborsky, B. (2017) Divergence of developmental trajectories is triggered interactively by early social and ecological experience in a cooperative breeder. Proc. Nat. Acad. Sci. USA, 114: E9300-9307
•    Taborsky B. & Oliveira R. F. (2013): Social competence vs responsiveness: similar but not same. A reply to Wolf and McNamara Trends Ecol. Evol. 28:254-255

Betreuer,  Barbara Taborsky: E-Mail


7) How do N. pulcher recognize each other?

Several studies suggest that N. pulcher can recognize each other individually, both by visual cues like facial stripes and by olfaction. However, few people asked HOW individual recognition is actually achieved. In cognition research, successfully ‘passing a cross-modal recognition task’ has been unanimously taken as evidence of ‘human-like’ individual recognition. ‘Passing these tasks’ means that a focal individual is provided with cues perceived in two different sensory modalities (e.g. vision and smell), which come either from the same, familiar conspecific or from two different familiar conspecifics. If the focal shows different behavioural responses if the individual they smell is also the individual they see or if the individual they see and the one they smell are two different individuals, they are considered to have passed the task. This is then taken as proof of individual recognition. In a recent, unpublished study, we detected however that N. pulcher can pass a cross-modal task also if they never met the conspecifics before, so they obviously pass the task without using true individual recognition. This suggests they have other mechanisms available than individual recognition to distinguish between the conspecifics they meet within and outside their social groups.
Thus the broad topic of this project is, which recognition mechanisms and which conspecific cues are used by N. pulcher to recognize (i) well-known group mates and (ii) strangers. 

References
•    Hert, E. 1985 Individual recognition of helpers by the breeders in the cichlid fish Lamprologus brichardi (Poll, 1974). Zeitschrift für Tierpsychologie 68, 313-325.
•    Kohda, M., Jordan, L. A., Hotta, T., Kosaka, N., Karino, K., Tanaka, H., Taniyama, M., and Takeyama, T. 2015 Facial Recognition in a Group-Living Cichlid Fish. Plos One 10, e0142552.
•    Bayani, D.-M., Taborsky, M., Frommen, J.G. (2017): To pee or not to pee: urine signals mediate aggressive interactions in the cooperatively breeding cichlid Neolamprologus pulcher. Behav. Ecol. Sociobiol. 71, 37

Betreuer,  Barbara Taborsky: E-Mail


8) The evolution of offspring dispersal under parent-offspring conflict: a theoretical simulation study

In order to achieve own reproduction and direct fitness, subordinate in cooperative breeders can either queue for a breeding position at the natal territory, or they can disperse and either join a queue elsewhere immediately become a breeder. Parent-offspring conflict over offspring decisions can arise in dependence of local predation risk and group size: offspring may prefer to remain in large groups especially under predation high risk, because large groups provide best protection. In contrast, parents may prefer their offspring to stay in the  natal territory when groups are small, because they need more helpers. In this project we will use individual-based evolutionary simulations to model offspring dispersal decisions. We will model these decisions as state-dependent reaction norms, where group size and predation risk together defines individual state. Building on a similar simulation model in Uller & Pen (2011), we consider a hermaphroditic, haploid population with overlapping generations and the possibility that offspring become subordinate, non-reproducing helpers at the natal territory.

Reference
•    Uller,T. & Pen,I. 2011. A theoretical model of the evolution of maternal effects under parent-offspring conflict. Evolution, 65, 2075-2084

Betreuer,  Barbara Taborsky:  E-Mail