title: Genetic analysis of male reproductive success in relation to density in the zebrafish, Danio rerio.
abstract: BACKGROUND
  We used behavioural and genetic data to investigate the effects of density on male reproductive success in the zebrafish, Danio rerio. Based on previous measurements of aggression and courtship behaviour by territorial males, we predicted that they would sire more offspring than non-territorial males.
  
  
  RESULTS
  Microsatellite analysis of paternity showed that at low densities territorial males had higher reproductive success than non-territorial males. However, at high density territorial males were no more successful than non-territorials and the sex difference in the opportunity for sexual selection, based on the parameter Imates, was low.
  
  
  CONCLUSIONS
  Male zebrafish exhibit two distinct mating tactics; territoriality and active pursuit of females. Male reproductive success is density dependent and the opportunity for sexual selection appears to be weak in this species.
authors.affiliation: Department of Biology, University of Leicester, University Road, Leicester, UK. rs153@le.ac.uk
authors.forename: Rowena
authors.initials: R
authors.lastname: Spence
authors.forename: William C
authors.initials: WC
authors.lastname: Jordan
authors.forename: Carl
authors.initials: C
authors.lastname: Smith