image: A coalition of three young spotted hyenas elicits a submissive response from a larger groupmate. view more
Credit: Image courtesy of Kate Yoshida (photographer).
A study suggests that by forming alliances to challenge higher-ranked individuals, spotted hyenas can increase their dominance rank, which can be passed to offspring. Rank acquisition in captive populations of nonhuman animals is well-studied, but rank reversal in wild populations is poorly understood. Females are dominant in spotted hyena clans, but little is known about how an individual's social status may fluctuate over time. Eli D. Strauss and Kay E. Holekamp longitudinally analyzed 12,505 aggressive interactions among five generations of female spotted hyenas from four wild clans living in Kenya between 1988 and 2014. The authors logged daily observations of hyena groups around dawn and dusk. When challenging a higher-ranked opponent, female hyenas were more likely to defeat and surpass it in rank when support from other females was available. Individuals who moved up in social rank also improved their lifetime reproductive success. The offspring of individuals who survived to reproductive maturity inherited their mother's acquired rank and increased fitness. Maternal rank inheritance and high fitness caused individual rank within clans to decline over time as the offspring of higher-ranking females joined the hierarchy. The findings provide insight into how social rank changes over time, according to the authors.
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Article #18-10384: "Social alliances improve rank and fitness in convention-based societies," by Eli D. Strauss and Kay E. Holekamp.
MEDIA CONTACT: Eli D. Strauss, Michigan State University, East Lansing, MI; tel: 530-902-7435; email: straussed@gmail.com
Journal
Proceedings of the National Academy of Sciences