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Although sex-biased dispersal has profound effects on the viability of small and isolated populations resulting from habitat change and anthropogenic disturbance, the direction and strength of sex-biased dispersal in the endangered Sichuan snub-nosed monkey ( Rhinopithexus roxellana) remains poorly understood. Here, we investigated dispersal patterns of R. roxellana using 15 polymorphic microsatellite loci. Using noninvasive methods we obtained 337 fecal samples from individuals residing in four multilevel troops that inhabit the Shennongjia Nature Reserve (SNR). Our study site contains an isolated population of approximately 1,000 Sichuan snub-nosed monkeys located in the easternmost distribution of the species' range. Our results indicated that the mean coefficient of relatedness among troop members was low (mean relatedness ± SE = 0.038 ± 0.025). However, the mean relatedness of monkeys residing in the same troop was significantly higher than the mean relatedness of monkeys belonging to different troops, suggesting that some members of the same troop were closely relatived. Sex-biased dispersal tests revealed that dispersal in R. roxellana was male-biased. Moreover, analysis of isolation-by-distance indicated that the correlation between pairwise genetic distance and geographical distance was positive for females, while it was negative for males. These data suggest that males tended to disperse further than females, although these values were not statistically significant. Considering previous field data collected on Sichuan snub-nosed monkeys from other sites, we suggest that mating competition among males and female mate choice represent the major causes of male-biased dispersal in R. roxellana. Am. J. Primatol. 76:72-83, 2014. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The golden monkey (Rhinopithecus roxellana) is one of the most endangered primate species due to its dramatically shrinking distribution during the past 400 years. Its populations are restricted to three isolated regions, Qinglin (QL), Sichuan/Gansu (SG), and Shennongjia (SNJ) in China. As with other snub-nosed monkeys in China and Vietnam, the biology and evolution of this species is still poorly known. To assess genetic differentiation and explore the relationships among populations of golden monkeys from different geographic locations, 379 bp of mitochondrial DNA control region (CR) hypervariable segment I (HVI) was studied from 60 individuals. Twelve haplotypes were identified from seven populations within the three regions. Haplotype diversity was high (0.845), whereas nucleotide diversity among all haplotypes was low (0.0331). The most recent common ancestor (TMRCA) among mtDNA haplotypes was estimated to have lived approximately 0.48–0.32 million years ago. None of the haplotypes is shared among any of the three regions. Phylogenetic analysis and AMOVA revealed clear and significant phylogeographic structure between the three regions. However, only SG contained haplotypes of the two main clades, indicating either incomplete random sorting of haplotypes or a complex history with phases of population subdivisions and merging of populations. The phylogeographic structure implies that R. roxellana should be regarded as separate management units (MUs) for each of the three regions. It is likely that recent phylogeographic history has shaped the pattern of genetic differentiation observed in the golden monkey and that its populations have suffered significant demographic fluctuation. Am. J. Primatol. 69:1195–1209, 2007. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]