AGONISTIC RELATIONSHIPS AND SEXUAL-BEHAVIOR PATTERNS IN MALE GUPPIES, POECILIA-RETICULATA

Two experiments were conducted to assess the influence of agonistic relationships among male guppies on their sexual and aggressive behaviour under different social conditions. In experiment 1, each male of small mixed-sex groups of guppies was systematically removed and reintroduced to the group. Only during the alpha male reintroduction were there any changes in the sexual behaviour of the remaining males; the female-preferred sigmoid display of the beta males was depressed. During reintroductions, the alpha male was responsible for most aggression directed towards the reintroduced male. Females also responded aggressively towards the reintroduced males, particularly the alpha male. In experiment 2, an unfamiliar male was introduced to each established mixed-sex group. Again, rank-related behaviour was evident; most aggression directed towards the unfamiliar male was performed by the alpha male. The unfamiliar male also performed fewer sigmoid displays than did the alpha male. Thus, agonistic relationships among males may be responsible for suppression of sexual behaviour by subordinate and non-resident males and should be considered as a factor in sexual selection processes in guppies. (C) 1995 The Association for the Study of Animal Behaviour