title: Frequency-dependent social dominance in a color polymorphic cichlid fish.
abstract: A mechanism commonly suggested to explain the persistence of color polymorphisms in animals is negative frequency-dependent selection. It could result from a social dominance advantage to rare morphs. We tested for this in males of red and blue color morphs of the Lake Victoria cichlid, Pundamilia. Earlier work has shown that males preferentially attack the males of their own morph, while red males are more likely to win dyadic contests with blue males. In order to study the potential contribution of both factors to the morph co-existence, we manipulated the proportion of red and blue males in experimental assemblages and studied its effect on social dominance. We then tried to disentangle the effects of the own-morph attack bias and social dominance of red using simulations. In the experiment, we found that red males were indeed socially dominant to the blue ones, but only when rare. However, blue males were not socially dominant when rare. The simulation results suggest that an own-morph attack bias reduces the social dominance of red males when they are more abundant. Thus, there is no evidence of symmetric negative frequency-dependent selection acting on social dominance, suggesting that additional fitness costs to the red morph must explain their co-existence.
authors.affiliation: Division of Ecology and Evolutionary Biology, Graham Kerr Building, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Dijkstra
authors.forename: Jan
authors.initials: J
authors.lastname: Lindström
authors.forename: Neil B
authors.initials: NB
authors.lastname: Metcalfe
authors.forename: Charlotte K
authors.initials: CK
authors.lastname: Hemelrijk
authors.forename: Mischa
authors.initials: M
authors.lastname: Brendel
authors.forename: Ole
authors.initials: O
authors.lastname: Seehausen
authors.forename: Ton G G
authors.initials: TG
authors.lastname: Groothuis
mesh_terms: D000374:Aggression / Q000502:physiology; D000818:Animals; D023681:Cichlids / Q000235:genetics / Q000502:physiology*; D003163:Competitive Behavior; D005618:Fresh Water; D049810:Genetic Speciation; D008297:Male; D010858:Pigmentation / Q000235:genetics*; D011110:Polymorphism, Genetic; D012641:Selection, Genetic; D012930:Social Dominance; D014739:Victoria