Incomplete control and concessions explain mating skew in male chimpanzees

Joel Bray, Anne E. Pusey, Ian Gilby

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Sexual selection theory predicts that because male reproductive success in mammals is limited by access to females, males will attempt to defend access to mates and exclude rivals from mating. In mammals, dominance rank is correlated with male reproductive success; however, the highestranking (alpha) male rarely monopolizes reproduction completely. To explain why, incomplete control models propose that alpha males simply cannot control other males’ access to mates. If true, then dominance rank should be a key factor influencing subordinate (non-alpha) male mating success. Alternatively, the concession model states that alpha males can prevent other males from gaining access to mates but posits that they concede matings to subordinates in exchange for social favours. This predicts that a male’s grooming interactions with the alpha should mediate his access to females. We test these predictions using 36 years of data, encompassing the tenures of eight alpha male chimpanzees at Gombe National Park, Tanzania. Incomplete control models were most strongly supported. At a given copulation event, the probability that the alpha was the male that mated was negatively associated with the number of males and sexually receptive females in the party. Additionally, as the number of males increased, high dominance rank was associated with an increased likelihood that a particular non-alpha male mated. The concession model, however, was also supported. The amount of time a male spent grooming with the alpha was positively associated with his likelihood of mating when the alphawas present in the party. As grooming is a major affiliative component of male social relationships, our results suggest that social bonds with dominant individuals are leveraged for mating access, particularly in species in which males form coalitions.

Original languageEnglish (US)
Article number20162071
JournalProceedings of the Royal Society B: Biological Sciences
Volume283
Issue number1842
DOIs
StatePublished - Nov 16 2016

Fingerprint

Pan troglodytes
Mammals
Grooming
grooming
dominance (genetics)
concession
reproductive success
mammal
mammals
Copulation
Tanzania
mating success
copulation

Keywords

  • Alpha male
  • Grooming for tolerance
  • Mating success
  • Pan troglodytes schweinfurthii
  • Reproductive skew
  • Social bonds

ASJC Scopus subject areas

  • Medicine(all)
  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)

Cite this

Incomplete control and concessions explain mating skew in male chimpanzees. / Bray, Joel; Pusey, Anne E.; Gilby, Ian.

In: Proceedings of the Royal Society B: Biological Sciences, Vol. 283, No. 1842, 20162071, 16.11.2016.

Research output: Contribution to journalArticle

@article{06ae1f24b7ee47309c2f052a2e358339,
title = "Incomplete control and concessions explain mating skew in male chimpanzees",
abstract = "Sexual selection theory predicts that because male reproductive success in mammals is limited by access to females, males will attempt to defend access to mates and exclude rivals from mating. In mammals, dominance rank is correlated with male reproductive success; however, the highestranking (alpha) male rarely monopolizes reproduction completely. To explain why, incomplete control models propose that alpha males simply cannot control other males’ access to mates. If true, then dominance rank should be a key factor influencing subordinate (non-alpha) male mating success. Alternatively, the concession model states that alpha males can prevent other males from gaining access to mates but posits that they concede matings to subordinates in exchange for social favours. This predicts that a male’s grooming interactions with the alpha should mediate his access to females. We test these predictions using 36 years of data, encompassing the tenures of eight alpha male chimpanzees at Gombe National Park, Tanzania. Incomplete control models were most strongly supported. At a given copulation event, the probability that the alpha was the male that mated was negatively associated with the number of males and sexually receptive females in the party. Additionally, as the number of males increased, high dominance rank was associated with an increased likelihood that a particular non-alpha male mated. The concession model, however, was also supported. The amount of time a male spent grooming with the alpha was positively associated with his likelihood of mating when the alphawas present in the party. As grooming is a major affiliative component of male social relationships, our results suggest that social bonds with dominant individuals are leveraged for mating access, particularly in species in which males form coalitions.",
keywords = "Alpha male, Grooming for tolerance, Mating success, Pan troglodytes schweinfurthii, Reproductive skew, Social bonds",
author = "Joel Bray and Pusey, {Anne E.} and Ian Gilby",
year = "2016",
month = "11",
day = "16",
doi = "10.1098/rspb.2016.2071",
language = "English (US)",
volume = "283",
journal = "Philosophical Transactions of the Royal Society B: Biological Sciences",
issn = "0800-4622",
publisher = "Royal Society of London",
number = "1842",

}

TY - JOUR

T1 - Incomplete control and concessions explain mating skew in male chimpanzees

AU - Bray, Joel

AU - Pusey, Anne E.

AU - Gilby, Ian

PY - 2016/11/16

Y1 - 2016/11/16

N2 - Sexual selection theory predicts that because male reproductive success in mammals is limited by access to females, males will attempt to defend access to mates and exclude rivals from mating. In mammals, dominance rank is correlated with male reproductive success; however, the highestranking (alpha) male rarely monopolizes reproduction completely. To explain why, incomplete control models propose that alpha males simply cannot control other males’ access to mates. If true, then dominance rank should be a key factor influencing subordinate (non-alpha) male mating success. Alternatively, the concession model states that alpha males can prevent other males from gaining access to mates but posits that they concede matings to subordinates in exchange for social favours. This predicts that a male’s grooming interactions with the alpha should mediate his access to females. We test these predictions using 36 years of data, encompassing the tenures of eight alpha male chimpanzees at Gombe National Park, Tanzania. Incomplete control models were most strongly supported. At a given copulation event, the probability that the alpha was the male that mated was negatively associated with the number of males and sexually receptive females in the party. Additionally, as the number of males increased, high dominance rank was associated with an increased likelihood that a particular non-alpha male mated. The concession model, however, was also supported. The amount of time a male spent grooming with the alpha was positively associated with his likelihood of mating when the alphawas present in the party. As grooming is a major affiliative component of male social relationships, our results suggest that social bonds with dominant individuals are leveraged for mating access, particularly in species in which males form coalitions.

AB - Sexual selection theory predicts that because male reproductive success in mammals is limited by access to females, males will attempt to defend access to mates and exclude rivals from mating. In mammals, dominance rank is correlated with male reproductive success; however, the highestranking (alpha) male rarely monopolizes reproduction completely. To explain why, incomplete control models propose that alpha males simply cannot control other males’ access to mates. If true, then dominance rank should be a key factor influencing subordinate (non-alpha) male mating success. Alternatively, the concession model states that alpha males can prevent other males from gaining access to mates but posits that they concede matings to subordinates in exchange for social favours. This predicts that a male’s grooming interactions with the alpha should mediate his access to females. We test these predictions using 36 years of data, encompassing the tenures of eight alpha male chimpanzees at Gombe National Park, Tanzania. Incomplete control models were most strongly supported. At a given copulation event, the probability that the alpha was the male that mated was negatively associated with the number of males and sexually receptive females in the party. Additionally, as the number of males increased, high dominance rank was associated with an increased likelihood that a particular non-alpha male mated. The concession model, however, was also supported. The amount of time a male spent grooming with the alpha was positively associated with his likelihood of mating when the alphawas present in the party. As grooming is a major affiliative component of male social relationships, our results suggest that social bonds with dominant individuals are leveraged for mating access, particularly in species in which males form coalitions.

KW - Alpha male

KW - Grooming for tolerance

KW - Mating success

KW - Pan troglodytes schweinfurthii

KW - Reproductive skew

KW - Social bonds

UR - http://www.scopus.com/inward/record.url?scp=84995476652&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84995476652&partnerID=8YFLogxK

U2 - 10.1098/rspb.2016.2071

DO - 10.1098/rspb.2016.2071

M3 - Article

C2 - 28120796

AN - SCOPUS:84995476652

VL - 283

JO - Philosophical Transactions of the Royal Society B: Biological Sciences

JF - Philosophical Transactions of the Royal Society B: Biological Sciences

SN - 0800-4622

IS - 1842

M1 - 20162071

ER -