Reproductive suppression and inbreeding avoidance in wild populations of co-operatively breeding meerkats (Suricata suricatta) |
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Authors: | M J O’Riain N C Bennett P N M Brotherton G McIlrath T H Clutton-Brock |
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Institution: | (1) Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ, UK, GB;(2) Department of Zoology and Entomology, University of Pretoria, 0002, Republic of South.Africa, ZA |
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Abstract: | Meerkats live in co-operatively breeding familial groups in which reproduction is monopolised by a dominant pair of breeders.
Offspring of the breeders are behaviourally subordinate, and typically remain in their natal group as sexually mature, non-breeding
helpers. In this study, we investigated the proximate factors limiting subordinate reproduction. Evidence for reproductive
suppression by dominants was investigated by comparing life history, behaviour and hormonal profiles of dominants and subordinates.
Baseline levels of plasma luteinising hormone (LH) were significantly higher in dominant than in subordinate females. However,
following an exogenous injection of gonadotrophin-releasing hormone (GnRH), both categories had comparable concentrations
of circulating LH. There were no significant differences in pre- or post-GnRH challenge LH levels in dominant or subordinate
males. Reproduction in both dominant and subordinate females rarely occurred in the absence of unrelated males. Given that
groups typically comprise parents and offspring, lack of suitable mates emerged as the primary constraint on subordinate reproduction.
When this constraint was removed, subordinates typically bred but at a lower rate than dominants. This difference in reproduction
may be attributed to intrasexual competition manifested through direct interference by dominant females through subordinate
evictions, infanticide and the abandoning of subordinate litters. We argue that differences in reproductive regulation within
mammalian co-operative breeding systems may be explained by differences in the mating strategy (inbreeding versus outbreeding)
and the probability that subordinates in obligate outbreeding species will encounter unrelated opposite-sex partners.
Received: 19 April 2000 / Accepted: 17 July 2000 |
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Keywords: | Suppression Co-operative breeding Inbreeding avoidance Social |
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