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Among vertebrate classes, fishes exhibit by far the greatest variability in competitive and cooperative behaviors in male reproduction. Scramble competition between reproductive males is one possibility. Another possibility occurs when resources, mates, or locations can be monopolized, in which case males may invest in primary access to fertilizations by(More)
Several hypotheses aim to explain the evolution of helping behavior, but conclusive experimental support for evaluating the relative importance of individual hypotheses is still larking We report on two field experiments* conducted to test the "territory inheritance" and "pay-to-stay" hypotheses in the cooperatively breeding cichlid fish Neolamprologus(More)
Fish exhibit an enormous variety of reproductive patterns. There is external and internal fertilization, simultaneous and sequential hermaphroditism as well as gonochorism, and an extremely widespread occurrence of parasitic reproductive behaviour among males. In most fish species there is a great size range of reproductive males, setting the stage for(More)
Field data show that in the cichlid fish Lamprologus brichardi conspecifics other than the reproducing pair help in brood care and territory maintenance. The expected degree of relatedness between helpers and the eggs or larvae they tend lies between 0.25 and 0.5, decreasing with the helper's age. This decrease might influence the point of time at which(More)
Neolamprologus pulcher, a cooperatively breeding cichlid fish from Lake Tanganyika, lives in permanent social groups comprising one breeding pair and helpers of both sexes. Variation in group size (1–14 helpers) provides an opportunity to investigate factors that affect how many helpers remain in a group and in turn how group size affects reproductive(More)
Genetic techniques and long-term behavioural observations were combined to investigate dispersal patterns and changes in social position in Neolamprologus pulcher, a co-operatively breeding cichlid from Lake Tanganyika. Comparisons of genetic variance (FST) across subpopulations demonstrated that fish were genetically more similar to individuals from(More)
The ‘pay-to-stay hypothesis’ proposes that subordinate group members help dominants in order to be tolerated in the territory. Accordingly, helpers should be punished if they are not helping sufficiently and should increase helping behaviour thereafter. We tested whether helping and social behaviours of group members of the cooperatively breeding cichlid(More)
Environmental conditions are thought to be responsible for the extent and benefits of cooperative breeding in many animal societies, but experimental tests are scarce. We manipulated predator pressure in the cooperatively breeding cichlid Neolamprologus pulcher in Lake Tanganyika, where predators have been suggested to influence helper and breeder survival,(More)
We measured the metabolic rates as a direct estimate of energy expenditure of individual Neolamprologus pulcher, a cooperatively breeding cichlid fish, when resting and when performing agonistic, submissive or digging behaviours in a respirometer. Standard and routine metabolic rates increased linearly with body mass (range 0.9–8.4 g) when plotted on a(More)
Petra Dierkes, Dik Heg,* Michael Taborsky, Eva Skubic and Roland Achmann Konrad Lorenz Institute for Comparative Ethology, Austrian Academy of Sciences, Vienna, Austria Department of Behavioural Ecology, Zoological Institute, University of Bern, Hinterkappelen, Switzerland Ludwig Boltzmann Institute of Immuno-, Cytoand Molecular Genetic Research, University(More)