No evidence for adaptive differential sex allocation in red junglefowl (Gallus gallus)

Timothy H. Parker*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


In many situations, selection should favor females that bias the sex ratio of their offspring. Two commonly examined factors potentially influencing offspring sex ratio are paternal ornamentation and maternal condition. Male junglefowl with larger combs are attractive to females. I housed female Red Junglefowl (Gallus gallus) with sterile male consorts and artificially inseminated them with sperm from other males that the females never saw. I found no relationship between either the comb size of the consort or the comb size of the sperm donor and the sex ratio of the offspring. I previously reported a significant sex ratio bias related to maternal mass in Red Junglefowl. However, that analysis was based on sex ratio data not weighted for brood size and assuming a normal distribution. Here, I show that this effect disappears when I conduct a more appropriate analysis weighting sex ratio according to brood size and accounting for the binomial error distribution. I also failed to find evidence that male chicks hatch from larger eggs than female chicks. These results suggest that Red Junglefowl females may not bias the sex ratio of their brood in response to either their own condition or the attractiveness of the males with whom they copulate. Furthermore, these results demonstrate the importance of choosing the correct methods of sex ratio analysis.

Original languageEnglish
Pages (from-to)1161-1168
Number of pages8
Issue number4
Publication statusPublished - 2005
Externally publishedYes


  • Binomial distribution
  • Gallus gallus
  • Generalized linear mixed model
  • Red Junglefowl
  • Sex ratio
  • Sexual selection


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