RELATEDNESS OF MATRILINES, DISPERSING MALES AND SOCIAL-GROUPS IN LONG-TAILED MACAQUES (MACACA-FASCICULARIS)

Genealogical relatedness is thought to be an important causal factor i n the evolution of cooperation. We inferred relatedness on the basis o f 11 blood protein markers using the Queller and Goodnight index of re latedness in a macaque population with long-term demographic records. This estimate reflected independently determined pedigree relationship s in our data set. Mean relatedness among all members of a social grou p was 0.10 but much higher levels of relatedness (0.30-0.47) were foun d among the members of matrilineal families with a high or intermediat e social rank. Groups of dispersing males that had been born into the same social group were sometimes closely related (0.43 and 0.58), but they could also be less related (0.08). We found that the pattern of d istribution of relatedness was associated with gene flow and different ial reproduction in males, rather than with group fission and the pres ence of geographical barriers.