Maternal condition does not influence birth sex ratios in anubis baboons (Papio anubis)

Joan B. Silk, Shirley C. Strum

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Trivers and Willard predicted that when parental condition has differential effects on the fitness of male and female offspring, parents who are in good condition will bias investment toward the sex that benefits most from additional investment. Efforts to test predictions derived from Trivers and Willard's model have had mixed results, perhaps because most studies have relied on proxy measures of parental condition, such as dominance rank. Here, we examine the effects of female baboons condition on birth sex ratios and post-natal investment, based on visual assessments of maternal body condition. We find that local environmental conditions have significant effects on female condition, but maternal condition at conception has no consistent relationship with birth sex ratios. Mothers who are in poorer condition at the time of conception resume cycling significantly later than females who are in better condition, but the sex of their infants has no effect on the time to resumption of cycling. Thus, our findings provide strong evidence that maternal condition influences females' ability to reproduce, but females do not facultatively adjust the sex ratio of their offspring in relation to their dominance rank or current condition.

Original languageEnglish (US)
Article numbere12750
Pages (from-to)1-7
Number of pages7
JournalPloS one
Issue number9
StatePublished - 2010
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General


Dive into the research topics of 'Maternal condition does not influence birth sex ratios in anubis baboons (Papio anubis)'. Together they form a unique fingerprint.

Cite this