Sex ratio project

A number of studies have suggested that the sex of the offspring depends on environmental or parental traits. This phenomenon is called sex ratio adjustment. It is of enormous interest to workers of a diverse range of fields including poultry industry, conservation biology and evolutionary ecology. According to the relevant hypotheses, sex ratio adjustment is adaptive that is parents are expected to overproduce the sex that provide larger fitness benefit. However, only very few studies investigated whether this is true. We try to investigate this issue in two bird species and humans. We also investigate how infidelity (a phenomenon frequently observed even in monogamous animals) affects the evolutionary benefit of sex ratio adjustment. By reanalysing published data, we also try to investigate why results on sex ratio adjustment differ between populations.

The project is supported by the K120249 grant from the National Research, Development and Innovation Office.

Research news:

Our meta-analysis on the variation in mate quality dependent sex allocation is now published

Our questionnaire on the fitness benefits of human sex allocation is now open. As we aimed to study the Hungarian population, the questionnaire is available only in Hungarian.

Researchers currently working on the project:


  • Tamás Bereczkei
  • András Láng

Students currently working on the project:

  • Fanni Sarkadi
  • Helga Gyarmathy