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Age-related reproductive effort in male chimpanzees: terminal investment or alternative tactics?
Muller, Martin N; Sabbi, Kris H; Thompson, Melissa Emery; Enigk, Drew K; Hagberg, Lindsey; Machanda, Zarin P; Menante, Ashley; Otali, Emily; Wrangham, Richard W.
Afiliación
  • Muller MN; Department of Anthropology, University of New Mexico, Albuquerque, NM, U.S.A.
  • Sabbi KH; Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, U.S.A.
  • Thompson ME; Department of Anthropology, University of New Mexico, Albuquerque, NM, U.S.A.
  • Enigk DK; Department of Anthropology, University of New Mexico, Albuquerque, NM, U.S.A.
  • Hagberg L; Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, U.S.A.
  • Machanda ZP; Department of Anthropology, Tufts University, Medford, MA, U.S.A.
  • Menante A; Department of Anthropology, Tufts University, Medford, MA, U.S.A.
  • Otali E; Kibale Chimpanzee Project, Makerere University Biological Field Station, Fort Portal, Uganda.
  • Wrangham RW; Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, U.S.A.
Anim Behav ; 213: 11-21, 2024 Jul.
Article en En | MEDLINE | ID: mdl-39007109
ABSTRACT
Because senescence impairs the ability of older males to compete successfully for mates, male reproductive strategies are expected to change with age. The terminal investment hypothesis proposes that older males, who could die soon, should take greater risks to obtain mating opportunities. Another possibility is that older males avoid such risks, adopting alternative reproductive tactics, such as increased affiliation with females, increased reliance on coalitions or sexual coercion to continue to compete with younger animals. We tested these hypotheses in wild chimpanzees, Pan troglodytes schweinfurthii, of the Kanyawara community, Kibale National Park, Uganda, where old males sire offspring at relatively high rates. Our data set included >40 000 incidents of male aggression and >5800 copulations observed between 2005 and 2017. We found that, even as their dominance status declined, old males maintained relatively high copulation rates, especially with established mothers. There was no evidence for terminal investment in response to ageing. Males became generally less aggressive as they aged. Neither did old males form affiliative bonds with females, nor use sexual coercion more frequently, as alternative reproductive tactics. Old males did, however, participate in coalitionary aggression at higher rates than young males and increased the proportion of their aggression that was coalitionary over time. Coalitions were positively associated with mating success, particularly for low- and middle-ranking males. These results support the hypothesis that ageing male chimpanzees use coalitions as an alternative reproductive tactic. The lack of evidence for terminal investment in response to ageing appears to reflect a broader mammalian pattern in which males who rely on fighting to secure mating opportunities avoid excessive risk taking as their formidability wanes.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Anim Behav Año: 2024 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido
Texto completo
Añadir a Mi BVS
Imprimir
XML
PubMed Links
Buscar en Google

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Anim Behav Año: 2024 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido