Complex social organization reflects genetic structure and relatedness in the cooperatively breeding bell miner, Manorina melanophrys

The cooperatively breeding bell miner, Manorina melanophrys, differs from m ost other cooperative breeding species in the complexity of its social syst em, where discrete social organization occurs on at least three levels. Mic rosatellite markers were used to investigate the degree of genetic structur e underlying the social organization of M. melanophrys by comparing colonie s, coteries and nest contingents. The genetic data confirmed behavioural ob servations of hi. melanophrys living in male kin-based groups between which females disperse short distances to breed. Estimates of F-ST revealed rest ricted gene flow between eight colonies located within 30 km that was signi ficantly associated with geographical distance when the two most distant co lonies were included. Within a high density colony significant differences were found between coteries; analysis of the degree of relatedness between coterie members showed that this is due to related individuals associating preferentially with each other. Similarly, the contingent of individuals at tending a nest were generally close relatives of the young they were aiding , supporting models invoking kin selection as the selective agency mediatin g helping.