Universität Bern

HIGHLIGHTS

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.
Book
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Animal personality due to social niche specialisation
Bergmueller R. & Taborsky M.
Book
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Environmental Change Enhances Cognitive Abilities in Fish
Kotrschal, A. & Taborsky, B.
Book
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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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Sperm competition in mouthbrooding cichlids?


Project leader:

Many species show multiple mating by females, however the benefits incurred by this behaviour are often unclear. Multiple mating is obviously adaptive for males as they can thereby sire more offspring. For females the benefits are less obvious as one male can usually deliver enough sperm to sire the whole clutch. Several hypotheses have been suggested to explain this widespread phenomenon. We investigate this in a mouthbrooding, lekking cichlid from Lake Tanganyika.

The study species is Ophthalmotilapia ventralis (Ectodini, Cichlidae). Males form leks and make small sand bowers (circular sand patch) on top of rocks (usually of the size of 20 x 30 cm). Leks can be quite large with hundreds of males. Females visit many males before, during and after the egg-laying phase. They keep the eggs in their mouth for about 3 weeks and then release fully developed fry into the water column. They lay 10-20 eggs with, on average, 3.5 males, making up to 30 visits to different males while spawning.

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The visits to so many males may serve to induce sperm competition. Sperm competition may serve as a selection mechanism to sort out genetically less fit sperm. O. ventralis produce a mucus in their testes that appears to prolong sperm longevity. Females may further gain direct benefits from spawning with particular males. Males may vary in their ability of providing a safe habitat where the female can spawn her eggs without loosing them to predators. However, it may be adaptive not to stay too long with one male as the courtship activity may draw the attention of predators and the male may not be able to keep is territory safe any longer. This mechanism can promote polyandry. We investigate these possibilities both theoretically and empirically. Experiments and observations are done both in the laboratory and in Lake Tanganyika.

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