The distribution of fitness between group members was investigated by sampling and genotyping around 400 individuals from two study sites in South Africa for 6-12 microsatellite markers. This data was used first, to construct group pedigrees using parentage analysis to assign maternity and paternity to pups; and second, to calculate relatedness coefficients. Parentage analysis showed that up to 84% and 100% of pups were the offspring of dominant males and females respectively, demonstrating that subordinates rarely invested in their own offspring. Breeding success of subordinate males was predictable by the presence or absence of an unrelated opposite sex breeder, whereas all subordinate females appeared subject to suppression by the dominant female. The majority of subordinates accrued substantial indirect fitness from helping in their natal group. Relatedness measurements revealed that natal subordinates of both sexes, have on average, a relatedness of 0.29 to pups (not significantly different from r=0.25, i.e. that between halfsibs). Non-breeding, immigrant males were unrelated to offspring and so gained no direct or indirect fitness from helping, but had a higher chance of obtaining direct fitness in the future either while subordinate or by gaining dominance. In conclusion, direct fitness benefits are distributed strongly in favour of dominants which invest least in care-provision for young. Only a small proportion of subordinate helpers recruit to the dominant breeding population, due to constraints on breeding from suppression by dominants and/or high ecological constraints on successful dispersal. Helping is prevalent, therefore, as a means by which fitness can be acquired indirectly, by providing care for related young in natal groups. The small proportion of males which disperse successfully from their natal group do not acquire indirect fitness from helping but increase the chance of breeding while subordinate and/or inheriting dominance in the future.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:651828 |
| Date | January 2001 |
| Creators | Griffin, Ashleigh S. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13957 |
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