title: Hybridization and adaptive mate choice in flycatchers.
abstract: Hybridization in natural populations is strongly selected against when hybrid offspring have reduced fitness. Here we show that, paradoxically, pairing with another species may offer the best fitness return for an individual, despite reduced fitness of hybrid offspring. Two mechanisms reduce the costs to female collared flycatchers of pairing with male pied flycatchers. A large proportion of young are sired by conspecific male collared flycatchers through extra-pair copulations, and there is a bias in favour of male offspring (which, unlike females, are fertile) within hybrid pairs. In combination with temporal variation in breeding success, these cost-reducing mechanisms yield quantitative predictions about when female collared flycatchers should accept a male pied flycatcher as a mate; empirical data agree with these predictions. Apparent hybridization may thus represent adaptive mate choice under some circumstances.
authors.affiliation: Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, SE-752 36 Uppsala, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Veen
authors.forename: T
authors.initials: T
authors.lastname: Borge
authors.forename: S C
authors.initials: SC
authors.lastname: Griffith
authors.forename: G P
authors.initials: GP
authors.lastname: Saetre
authors.forename: S
authors.initials: S
authors.lastname: Bures
authors.forename: L
authors.initials: L
authors.lastname: Gustafsson
authors.forename: B C
authors.initials: BC
authors.lastname: Sheldon
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D005260:Female; D006824:Hybridization, Genetic; D008297:Male; D012098:Reproduction; D012726:Sexual Behavior, Animal; D020308:Songbirds / Q000235:genetics / Q000502:physiology*; D013045:Species Specificity