Genetic analysis of group composition and relatedness in white-headed langurs.

We collected fecal samples of white-headed langurs from 3 of the 4 remaining habitat fragments (Fa, Fb and CZ) located in southwestern Guangxi, China in Nov 2005, and used 5 microsatellite loci and the SRY gene to assess the relatedness between 46 langurs within and between groups. We observed 2 forms of group structure: one-male/multi-female groups (OMGs) and all-male groups (AMGs). One AMG in Fa was composed of 2 generations, included a father, 2 sons and 1 unrelated male, and all OMGs in all 3 habitats included 1 resident male, several adult females and offspring. Of the 21 identified father-offspring cases, the resident male fathered 20 (95%) and the non-resident male sired 1 (5%), suggesting that adult males had overwhelming priority of access to females as the resident male in an OMG, while the non-resident male may also have the opportunity to adopt surreptitious mating strategies.