Individual variation and the endocrine regulation of behaviour and physiology in birds: A cellular/molecular perspective

Gregory F. Ball, Jacques Balthazart

Research output: Contribution to journalReview articlepeer-review

120 Scopus citations


Investigations of the cellular and molecular mechanisms of physiology and behaviour have generally avoided attempts to explain individual differences. The goal has rather been to discover general processes. However, understanding the causes of individual variation in many phenomena of interest to avian eco-physiologists will require a consideration of such mechanisms. For example, in birds, changes in plasma concentrations of steroid hormones are important in the activation of social behaviours related to reproduction and aggression. Attempts to explain individual variation in these behaviours as a function of variation in plasma hormone concentrations have generally failed. Cellular variables related to the effectiveness of steroid hormone have been useful in some cases. Steroid hormone target sensitivity can be affected by variables such as metabolizing enzyme activity, hormone receptor expression as well as receptor cofactor expression. At present, no general theory has emerged that might provide a clear guidance when trying to explain individual variability in birds or in any other group of vertebrates. One strategy is to learn from studies of large units of intraspecific variation such as population or sex differences to provide ideas about variables that might be important in explaining individual variation. This approach along with the use of newly developed molecular genetic tools represents a promising avenue for avian eco-physiologists to pursue.

Original languageEnglish (US)
Pages (from-to)1699-1710
Number of pages12
JournalPhilosophical Transactions of the Royal Society B: Biological Sciences
Issue number1497
StatePublished - May 12 2008
Externally publishedYes


  • Oestrogen receptor
  • Sex differences
  • Steroid hormones

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology
  • General Agricultural and Biological Sciences


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