In this thesis I explore assumptions of current models of cooperative breeding and reproductive skew. In the highly social Damaraland mole-rat I examine the questions (1) What benefits do breeders gain from subordinates? (2) Why do helpers help? and (3) Why don't subordinates breed? In answer to (1), benefits to breeders appear to accrue primarily through communal foraging rather than through the provision of alloparental care to young or the reduction of workload. Breeding females contributed most to care of pups, but worked at high rates, even during energetically costly reproductive activities. Subordinate number did not increase litter sizes or pup survivorship. In answer to (2), all cooperative behaviour of subordinates could be explained by simple maximisation of current individual fitness. Mole-rat work levels simply reflected their weight, rather than breeding status, potential kin-selected benefits, or energetic needs of the breeding female. Experimental investigation of communal food storing showed that food storing reflects mole-rats' own weight and hunger state and is insensitive to the hunger state of other colony members. Participation in colony defence was consistent with defence of reproductive status. Attacks on intruders were carried out almost exclusively by breeding mole-rats who attacked primarily same-sex intruders, and subordinates typically did not participate. In answer to (3), there was some evidence that subordinate males pose a reproductive threat to dominant males, but only slight evidence that dominants may control their reproduction. Among females, I found no evidence that dominant control limited the reproduction of subordinate females, and strong evidence that reproductive skew was due to inbreeding avoidance.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:597951 |
| Date | January 2000 |
| Creators | Cooney, R. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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