Patterns of dispersal in Sumatran siamangs (Symphalangus syndactylus): preliminary mtDNA evidence suggests more frequent male than female dispersal to adjacent groups.

Gibbons of both sexes have been observed emigrating from their natal groups, but the consequences of dispersal in gibbons are poorly understood, and it is unclear whether these are the same for both sexes. I sequenced a 350-bp fragment of mitochondrial DNA from 18 adults in seven siamang (Symphalangus syndactylus) groups at the Way Canguk Research Station in southern Sumatra to assess patterns of matrilineal relatedness among and within siamang groups, and to assess their fit with different patterns of sex-specific dispersal. A total of 11 haplotypes were identified in the seven study groups; 50% of adult males in five contiguous groups shared a haplotype with a member of an immediately adjacent group, whereas only 16.7% of females shared a haplotype with a neighbor. The apparent difference persisted if only same-sex individuals were considered (37.5% of males vs. 0% of females). Four of the seven study groups contained two adult males and a single adult female. In three multimale groups, the three adults all had different haplotypes, suggesting that neither male was the retained adult offspring of the female, whereas in the fourth group, the haplotype of one male was identical with that of the adult female. The high diversity of haplotypes and the absence of clustering among female haplotypes in the study neighborhood suggest that female dispersal to territories adjacent to the natal group may be relatively rare. The presence of some clustering of male haplotypes suggests that shorter dispersal distances may be more common in males. (c) 2006 Wiley-Liss, Inc.