title: Sex-biased dispersal in western lowland gorillas (Gorilla gorilla gorilla).
abstract: We explored two hypotheses related to potential differences between sexes in dispersal behaviour in western lowland gorillas (Gorilla gorilla gorilla). Direct observations suggest that immature females have more opportunities to move between breeding groups than immature males. The distribution of kin dyadic relationships within and between groups does not, however, support this hypothesis. At larger geographical scales, dispersal is likely to be easier for males than females because of the solitary phase most blackbacks experience before founding their own breeding group. However, previous work indicates that males settle preferentially close to male kin. By specifically tracing female and male lineages with mitochondrial and Y-chromosomal genetic markers, we found that male gorillas in the 6000 km2 area we surveyed form a single population whereas females are restricted to the individual sites we sampled and do not freely move around this area. These differences are more correctly described as differences in dispersal distances, rather than differences in dispersal rates between sexes (both sexes emigrate from their natal group in this species). Differences in resource competition and dispersal costs between female and male gorillas are compatible with the observed pattern, but more work is needed to understand if these ultimate causes are responsible for sex-biased dispersal distances in western lowland gorillas.
authors.affiliation: Ethologie Evolution Ecologie, UMR 6552, Université de Rennes I-CNRS, Station Biologique, 35380 Paimpont, France.
authors.forename: Melanie I
authors.initials: MI
authors.lastname: Douadi
authors.forename: Sylvain
authors.initials: S
authors.lastname: Gatti
authors.forename: Florence
authors.initials: F
authors.lastname: Levrero
authors.forename: Gaëtan
authors.initials: G
authors.lastname: Duhamel
authors.forename: Magdalena
authors.initials: M
authors.lastname: Bermejo
authors.forename: Dominique
authors.initials: D
authors.lastname: Vallet
authors.forename: Nelly
authors.initials: N
authors.lastname: Menard
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Petit
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D004272:DNA, Mitochondrial / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D006071:Gorilla gorilla / Q000235:genetics* / Q000502:physiology; D006239:Haplotypes; D006801:Humans; D017422:Sequence Analysis, DNA; D012737:Sex Factors; D014998:Y Chromosome / Q000235:genetics
chemical_list: D004272:DNA, Mitochondrial