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Title: Routes to cooperation in the rifleman Acanthisitta chloris.
Author: Hodges, Stephanie A.
ISNI:       0000 0004 2742 7418
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2012
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In cooperatively breeding species, 'helpers' assist in raising non-descendant offspring. In many cooperative species, delayed dispersal of offspring provides the permissive conditions for kin-directed helping and helpers gain indirect fitness benefits by enhancing productiviry of non-descendant kin. However, kin-directed cooperation may also arise via other routes, where offspring disperse before becoming helpers, but limited dispersal and demographic processes allow kin association within extended networks of relatives. In such systems, kin discrimination may be important for individuals to maximise fitness by directing care towards relatives and to avoid the risk of inbreeding. In this thesis I investigated the cooperative breeding system of the rifleman Acanthisitta chloris in a study population at Kaikoura, New Zealand. Routes to helping were diverse and flexible, and helpers were not constrained by age, sex or breeding status. In contrast to previous reports, I showed riflemen helpers were closely related to the recipients of their care. Furtherrnore, adult helpers were associated with increased offspring recruitment and thus, could gain substantial indirect fitness benefits. The social and genetic background against which helping operates was also investigated. Both sexes showed localised natal dispersal resulting in positive fine-scale genetic structure. Whilst this may promote sociality in the rifleman, it also generated a significant risk of inbreeding risk. However, the relatedness of pairs was lower than expected under biologically realistic models of random mating, suggesting active inbreeding avoidance through mate choice. The proximate mechanism of kin recognition was investigated but r found no evidence of active kin recognition using experimental playbacks of vocalisations. Overall, this thesis shows that cooperation riflemen occurs among relatives living in kin networks that arise through limited dispersal by both sexes. The increased productivity of helped broods indicates that kin selection has played an important role in the evolution of helping in the rifleman.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available