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Experimental evidence for ovarian hypofunction in sparrow hybrids

  • Fabrice Eroukhmanoff
  • Melissah Rowe
  • Emily R.A. Cramer
  • Fredrik Haas
  • Jo S. Hermansen
  • Anna Runemark
  • Arild Johnsen
  • Sætre Glenn-Peter
Publishing year: 2016-02-24
Language: English
Publication/Series: Avian Research
Volume: 7
Issue: 1
Document type: Journal article
Publisher: BioMed Central

Abstract english

Postzygotic isolation in the form of reduced viability and/or fertility of hybrids may help maintain species boundaries in the face of interspecific gene flow. Past hybridization events between house sparrows (Passer domesticus) and Spanish sparrows (P. hispaniolensis) have given rise to a homoploid hybrid species, the Italian sparrow (P. italiae). Although genetic incompatibilities are known to isolate these three species, the biological consequences of these incompatibilities are still unknown in early generation hybrids.

We investigated whether F1 hybrids between house and Spanish sparrows experience reduced viability or fertility. More specifically, we generated hybrids through controlled crosses in aviaries, and compared ovaries of female hybrids with female of pure-species sparrows.

We found that overall, hybrid ovaries were underdeveloped and that half of all female hybrids exhibited symptoms of ovarian hypofunction (ovarian atrophy and complete absence of developed follicles).

Fertility in hybrids is a common consequence or post-zygotic barriers between species. We discuss these results in light of previous findings on genetic incompatibilities between the parent species and the potential role of incompatibilities in hybrid speciation, a rare evolutionary process in birds.


  • Ecology
  • Zoology
  • Hybrid fitness
  • hybridisation
  • Speciation
  • Passer hispaniolensis
  • Passer domesticus


  • ISSN: 2053-7166
Fredrik Haas
E-mail: fredrik [dot] haas [at] biol [dot] lu [dot] se



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