Fitness consequences of hybridization between house sparrows (Passer domesticus) and tree sparrows (P. montanus)
Gene transfer may occur following hybridization between closely related species if hybrids are viable and able to breed with individuals of one or both of the parental species. House (Passer domesticus) and tree sparrows (P. montanus) occasionally hybridize and produce viable offspring. Previously, we concluded that male tree × house sparrow hybrids are most probably fertile based on the observation of a male F1 hybrid feeding the nestlings with a female house sparrow in two consecutive clutches. However, recent DNA analyses based on blood samples revealed that all nestlings (4) in the first clutch were sired by a neighbouring house sparrow male, whereas nestlings in the second clutch (2) were not blood sampled and most probably died before fledging. This indicates that extensive extra-pair fertilization confounded our previous conclusion, and indicates that social partnership and attending behaviour can be imprecise measures of paternity.
KeywordsDNA-typing Extra-pair fertilizations Hybrids Passerdomesticus Passermontanus
- Birkhead TR, Møller AP (1998) Sperm competition in birds: evolutionary causes and consequences. Academic Press, LondonGoogle Scholar
- Solberg EJ, Ringsby TH, Altwegg A, Sæther B-E (2000) Fertile house sparrow × tree sparrow (Passer domesticus × Passer montanus) hybrids? J Ornithol 141:102–104Google Scholar