Paternity and relatedness in wild chimpanzee communities

Abstract

The genetic structure of three contiguous wild chimpanzee communities in West Africa was examined to determine the extent to which the community, the mixed-sex social unit of chimpanzees, represents a closed reproductive unit. An analysis of paternity for 41 offspring resulted in 34 cases of paternity assignment to an adult male belonging to the same community. Among the 14 offspring for which all potential within-community fathers have been tested, one likely case of extra-group paternity (EGP) has been identified, suggesting an incidence of EGP of 7%. This more extensive analysis contradicts a previous genetic study of the Taï chimpanzees that inferred 50% extra-group fathers. We suggest, based on direct comparison of results for 33 individuals at 1 microsatellite locus and direct comparison of paternity assignments for 11 offspring, that the error rate in the previous study was too high to produce accurate genotypes and assignments of paternity and hence caused the false inference of a high rate of EGP. Thus, the community is the primary but not exclusive unit for reproduction in wild chimpanzees, and females do not typically reproduce with outside males. Despite the inferred low level of gene flow from extra-community males, relatedness levels among the community males are not significantly higher than among community females, and the distribution of genetic relationships within the group suggests that, rather than a primarily malebonded social structure, the group is bonded through relationships between males and females. Kinship may explain cooperative behaviors directed against other communities, but is unlikely to explain the high levels of affiliation and cooperation seen for male within-community interactions.

The limited impact of kinship on cooperation in wild chimpanzees

“…In the three primate populations where paternal sibling nepotism has been studied (rhesus macaques at Cayo Santiago, baboons at Amboseli, and chimpanzees at Ngogo), the majority of similarly aged dyads do not consist of paternal siblings (Table 1, second row). Age proximity may not be a reliable cue for paternal sibship in these populations because male reproductive skew at any given time is not extreme, and males produce offspring throughout their entire adult life rather than only during a narrow time window (32)(33)(34)(35)(36). At Ngogo, patterns of male reproduction result in a situation where members of different age cohorts are as closely related to each other as individuals of the same age cohort (Fig.…”

Coalitions in theory and reality: a review of pertinent variables and processes

“…As we will see below, coalitions can serve different functions (van Schaik et al, 2006); they can be observed among different sex and age classes (reviewed in Chapais, 1995); they can involve kin (e.g., Riss & Goodall, 1977;Chagnon & Bugos, 1979;Wahaj et al, 2004), non-kin (e.g., Vigilant et al, 2001;Langergraber et al, 2007;Schülke et al, 2010), and friends or acquaintances (Hruschka & Henrich, 2006;Hruschka, 2010). As this brief review makes clear, coalitionary patterns are varied, and understanding this diversity would be greatly enhanced by formal modelling that would allow us to identify the general conditions under which coalition formation is expected to evolve, characterize the degree of variability expected, and predict when coalitions should, and should not, occur.…”

“…Observations of female white-faced capuchins, gorillas and white-nosed coatis also reveal that, like female Old World monkeys, individuals are more likely to aid their kin instead of non-kin in disputes (Watts, 1997;. In studies of white-faced capuchins, Barbary macaques, bonnet macaques, chimpanzees and bottlenose dolphins, males sometimes form coalitions with their kin more often than with non-kin (Silk, 1992;Widdig et al, 2000;Langergraber et al, 2007; but see Vigilant et al, 2001). In some species mothers are known to provide aid to sons in conflicts with other males (Surbeck et al, 2011; see also Chapais, 1983;Kutsukake & Hasegawa, 2005).…”

Remote collection of animal DNA and its applications in conservation management and understanding the population biology of rare and cryptic species

“…Instead, DNA obtained from wadges, faeces, plucked hairs and shed hairs collected from night nests has provided a wealth of data on phylogeography, gene flow, social structure and kinship in wild chimpanzees (Constable et al 2001;Vigilant et al 2001), gorillas (Jensen-Seaman and Kidd 2001), bonobos (Gerloff et al 1999), Hanuman langurs (Launhardt et al 2001), orangutans (Utami et al 2002) and lemurs (Nievergelt et al 2002). Microsatellite genotyping was performed on faecal samples from an Indonesian orangutan (Pongo pygameus abelii) population that has been the subject of a long-term behavioural study with an emphasis on male reproductive strategies (Utami et al 2002).…”

“…Fernando et al 2000;Garnier et al 2001;Vigilant et al 2001;Utami et al 2002). This number is likely to increase, as more researchers become aware of the vast potential for molecular analysis in gleaning useful biological data from non-invasive samples.…”