Sex-biased dispersal pattern in Western lowland gorilla (Gorilla gorilla gorilla) Mélanie Douadi,1 Sylvain Gatti,1 Florence Levréro,1 Magdalena Bermejo,2 Dominique Vallet,1 Annie Gautier-Hion,1 Nelly Ménard,1 and Eric Petit1 1Centre National de la Recherche Scientifique, Ethologie-Evolution-Ecologie, Station Biologique de Paimpont, Université de Rennes, France, 2ECOFAC y Dep. Biología Animal (Vertebrados), Facultad de Biología, Universidad de Barcelona Abstract Using direct observation and population genetic tools, our team aims at understanding the social and genetic structure of western lowland gorilla (G. g. gorilla) at group and population levels. We sampled individuals from six different subpopulations separated by 30 to 100 km in the Odzala National Park in Republic of Congo. One subpopulation was sampled at the social group level. In order to characterize the patterns of dispersion of males and females, we genotyped 70 females and 60 males for one 380 base pair mitochondrial sequence. In addition, males were genotyped for six Y-linked microsatellites. DNA was extracted from faeces. Results show sex-specific genetic structure and confirm discrepancies in the male/female dispersal behaviour. Proportion of variability within social groups remains approximately the same for both sexes. The distinction is found at the subpopulation level: in contrast to males, females are less likely to disperse out of their subpopulation.