Tug-of-war over reproduction in a cooperatively breeding cichlid |
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Authors: | Dik Heg Ian M Hamilton |
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Institution: | (1) Department of Behavioural Ecology, Zoological Institute, University of Bern, CH-3032 Hinterkappelen, Switzerland;(2) Department of Evolution, Ecology and Organismal Biology, Department of Mathematics, The Ohio State University, Columbus, OH, 43210, U.S.A. |
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Abstract: | In group-living animals, dominants may suppress subordinate reproduction directly and indirectly, thereby skewing reproduction
in their favour. In this study, we show experimentally that this ability (‘power’) is influenced by resource distribution
and the body size difference between unrelated dominants and subordinates in the cichlid Neolamprologus pulcher. Reproduction was strongly skewed towards the dominant female, due to these females producing more and larger clutches and
those clutches surviving egg eating better than those of subordinate females, but was not so when subordinates defended a
patch. If breeding shelters were provided in two patches, subordinate females were more likely to exclusively defend a patch
against the dominant female and breed, compared to when the same breeding resource was provided in one patch. Relatively large
subordinate females were more likely to defend a patch and reproduce. Females also directly interfered with each other’s reproduction
by eating the competitors’ eggs, at which dominants were more successful. Although dominant females benefited from subordinate
females due to alloparental care and an increase in egg mass, they also showed costs due to reduced growth in the presence
of subordinates. The results support the view that the dominant’s power to control subordinate reproduction determines reproductive
partitioning, in agreement with the predictions from tug-of-war models of reproductive skew. |
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Keywords: | Cooperation Cooperative breeding Reproductive skew Egg cannibalism Growth Status Cichlidae |
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