Original Paper

Behavioral Ecology and Sociobiology

, Volume 67, Issue 8, pp 1205-1217

First online:

Rapid sperm evolution in the bluethroat (Luscinia svecica) subspecies complex

  • Silje HognerAffiliated withNatural History Museum, University of Oslo Email author 
  • , Terje LaskemoenAffiliated withNatural History Museum, University of Oslo
  • , Jan T. LifjeldAffiliated withNatural History Museum, University of Oslo
  • , Václav PavelAffiliated withLaboratory of Ornithology, Palacký University
  • , Bohumír ChutnýAffiliated with
  • , Javier GarcíaAffiliated withÁrea de Ecología, Facultad de Ciencias Biológicas y Ambientales, Universidad de León
  • , Marie-Christine EybertAffiliated withUniversity of Rennes 1
  • , Ekaterina MatsynaAffiliated withLaboratory of Ornithology, Ecological Centre “Dront”
  • , Arild JohnsenAffiliated withNatural History Museum, University of Oslo

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Spermatozoa are among the most variable animal cell types, and much research is currently directed towards explaining inter- and intraspecific variation in sperm form and function. Recent comparative studies in passerine birds have found associations between the level of sperm competition and both sperm length and sperm velocity. In species with sperm competition, postcopulatory sexual selection may shape the morphology of sperm as adaptations to the female environment. The speed of evolutionary change in sperm morphology at the species level is largely unknown. In this study, we analysed variation in sperm morphology among morphologically distinct and geographically isolated bluethroat subspecies in Europe. Consistent with previous studies, our analyses of mtDNA and nuclear introns suggest recent divergence and lack of lineage sorting among the subspecies. We found significant divergence in total sperm length and in the length of some sperm components (i.e. head and midpiece). There was a significantly positive relationship between pairwise divergences in sperm morphology and mitochondrial DNA, suggesting a role for genetic drift in sperm divergence. The magnitude of sperm length divergence was considerably higher than that in other geographically structured passerines, and even higher than that observed between several pairs of sister species. We hypothesize that the rapid sperm evolution in bluethroats is driven by sperm competition, and that strong postcopulatory sexual selection on sperm traits can lead to rapid speciation through reproductive incompatibilities.


Sperm competition Sperm morphology Sperm size variation Reproductive isolation