Female chimpanzees avoid inbreeding even in the presence of substantial bisexual philopatry

• Published in: Royal Society open science Vol. 11; no. 1; pp. 230967 - 14
• Main Authors: White, Lauren C, Städele, Veronika, Ramirez Amaya, Sebastian, Langergraber, Kevin, Vigilant, Linda
• Format: Journal Article
• Language: English
• Published: England The Royal Society Publishing 01-01-2024; The Royal Society
• Subjects: Anthropogenic factors; bisexual philopatry; Bisexuality; Breeding; Chimpanzees; dispersal; Documents; Encroachment; exome capture; Females; Inbreeding; inbreeding avoidance; Males; Monkeys & apes; National parks; Offspring; Organismal and Evolutionary Biology; Pan troglodytes; Pan troglodytes schweinfurthii; Philopatry; relatedness; Uganda; exome capture; relatedness; bisexual philopatry; dispersal; chimpanzees; inbreeding avoidance
• ISSN: 2054-5703; 2054-5703
• DOI: 10.1098/rsos.230967

Inbreeding (reproduction between relatives) often decreases the fitness of offspring and is thus expected to lead to the evolution of inbreeding avoidance strategies. Chimpanzees (
) are expected to avoid inbreeding as they are long-lived, invest heavily in offspring and may encounter adult, opposite sex kin frequently, especially in populations where both males and females commonly remain in the group in which they were born (bisexual philopatry). However, it is unclear whether substantial bisexual philopatry has been a feature of chimpanzees' evolutionary history or whether it is a result of recent anthropogenic interference, as the only groups for which it has been documented are significantly impacted by human encroachment and experience notable rates of potentially unsustainable inbreeding. Here we use 14 years of observational data and a large genomic dataset of 256 481 loci sequenced from 459 individuals to document dispersal and inbreeding dynamics in an eastern chimpanzee (
) community with low levels of anthropogenic disturbance. We document the first case of substantial bisexual philopatry in a relatively undisturbed chimpanzee community and show that, despite an increased inbreeding risk incurred by females who do not disperse before reaching reproductive age, natal females were still able to avoid producing inbred offspring.