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Males are sensitive - sex-dependent effect of rearing conditions on nestling growth

  • Balázs Rosivall
  • Eszter Szoellosi
  • Dennis Hasselquist
  • Janos Toeroek
Publishing year: 2010
Language: English
Pages: 1555-1562
Publication/Series: Behavioral Ecology and Sociobiology
Volume: 64
Issue: 10
Document type: Journal article
Publisher: Springer

Abstract english

The sex-dependent effect of environmental conditions on nestlings has been extensively studied in size dimorphic birds. Whether males or females are more sensitive to poor conditions is not yet clear; however, the degree of sexual size-dimorphism, brood size and their interactions seem to influence the pattern. Much less is known about sex-dependent environmental sensitivity in size-monomorphic species, even though it may result in biased sex allocation. We altered the rearing conditions by brood size manipulation in the size-monomorphic collared flycatcher and then examined the sex-specific development of the nestlings. In all analyses, we controlled for the effect of paternity, because one may expect extra-pair young to be of better genetic quality and perform better at least under poor conditions. However, this was not the case, because we did not find any difference in growth rate or fledging size between extra-and within-pair young. We found that male nestlings had the potential for faster growth under favourable conditions, but suffered more under poor conditions. We found no sex x environment interaction for fledging size probably because the growth curves level off before fledging, and the disadvantaged nestlings can catch up with their siblings. The larger sensitivity of males does not explain the previously found seasonal shift in brood sex ratios and contradicts previous findings in another size-monomorphic species where females were more sensitive. This suggests that even in size-monomorphic species, no general rule exists, which determines the more sensitive sex.


  • Biological Sciences
  • Environmental sensitivity
  • Environmental conditions
  • Extra-pair
  • paternity
  • Offspring development
  • Ficedula albicollis
  • Sex differences
  • Sex allocation


  • Molecular Ecology and Evolution Lab
  • ISSN: 1432-0762
Dennis Hasselquist
E-mail: dennis [dot] hasselquist [at] biol [dot] lu [dot] se



+46 46 222 37 08



Research group


Doctoral students and postdocs

Research fellows


Jacob Roved

PhD Students, main supervisor

PhD Students, assistant supervisor


Interview about my research in the Swedish podcast "Forskarn & jag"