hierarchy of chimpanzee
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Answer:
Primate behavioral ecologists have long debated the costs and benefits of group living, but some of the factors that affect chimpanzee social structure include decreased likelihood of predation, resource defense and feeding efficiency, and higher copulatory success because of access to mates (Sakura 1994; Boesch 1996). Chimpanzees live in a fission-fusion social group consisting of a large community that includes all individuals that regularly associate with one another (up to a few hundred individuals) and smaller, temporary subgroups, or parties. These subgroups are unpredictable and can be highly fluid, changing members quickly or lasting a few days before rejoining the community (Goodall 1986; Chapman et al. 1993; Boesch 1996). At Taï, the average party size is between five and eight individuals (Boesch 1996). Party size greatly increases when food availability increases, though, and at Kibale, average party size is 10 but ranges from one to 47 individuals during periods of highest food availability (Mitani et al. 2002). Party size also increases when the estrous females are present (Matsumoto-Oda et al. 1998; Mitani et al. 2002). Party composition is variable, including unisexual and bisexual parties of adolescents or adults, parties of adult females and infants, lone adult females and their offspring, and mixed age and sex parties (Boesch 1996). The most frequently observed party across all chimpanzee communities is the mixed-sex party, though Taï males are the most inclined to associate with females, and Gombe males are the least inclined to do so. At Bossou, though, where the adult sex ratio is skewed, the high number of females relative to males means the most common party composition there is mother-infant (Boesch 1996).
Pan troglodytes
Photo: Frans de Waal
There is a distinct linear dominance hierarchy in male chimpanzees, and males are dominant over females (Goldberg & Wrangham 1997). Males remain in their natal communities while females, in general, emigrate at adolescence, between nine and 14 years old (Nishida et al. 2003). The complete transition between groups may take up to two years, though, and is characterized by vacillating between their natal group and new community (Goodall 1986; Hasegawa 1989; Pusey 1990). Rates of female transfer are much higher at Mahale and Taï than at Gombe and Bossou. This may be attributed to the smaller population size and isolated conditions at Gombe and Bossou; with fewer options, it is more beneficial to remain in their own group and take behavioral precautions to avoid inbreeding (Goodall 1986; Gagneux et al. 1999; Nishida et al. 2003). For female chimpanzees that do emigrate, though, they are not likely to be related to other adult females in their new community and the dominance hierarchy is linked to age (with younger immigrant females ranking the lowest) and the status of their offspring (Nishida 1989). Lactating females generally spend most of their time with their own offspring, though they may be seen with other lactating females in "nursery groups" (Pepper et al. 1999). Females become very sociable during estrus, though, and are seen mostly in bisexual parties (Pepper et al. 1999).
Given the female-biased dispersal pattern, male chimpanzees in a community are more likely to be related to one another than females are to each other, but matrilineal kinship does not always strongly influence patterns of male chimpanzee social behavior. In studies at Kibale, genetic analyses of males support the theory that cooperation is of greater evolutionary significance than kinship affiliation (Goldberg & Wrangham 1997; Mitani et al. 2000). Research at Gombe, on the other hand, has consistently emphasized kinship as the most important underlying factor of the strong social bonds (Goodall 1986). Close relationships between males serve two purposes within chimpanzee communities: inter-community interactions and intra-community politics (Goldberg & Wrangham 1997). Some examples of inter-community interactions include hostile attacks by groups of males and cooperative boundary patrol parties. Intra-community interactions that are dominated by male cooperation include securing and maintaining dominance, mate guarding, and group hunting and meat sharing (Goldberg & Wrangham 1997; Mitani et al. 2000).
First seen at Gombe in 1963, chimpanzee hunting behavior probably evolved because of the direct benefits of a protein source in their largely frugivorous diets, but it is more than nutritionally important; meat is socially important as well (Mitani & Watts 2001). Meat is social currency used to develop and maintain alliances between adult males; it is usually shared reciprocally and non-randomly (Mitani & Watts 2001). Hunting is
Answer:
Explanation:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Pan
Species: P. troglodytes
Binomial name
Pan troglodytes