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

Two experiments were conducted to assess the influence of agonistic re lationships among male guppies on their sexual and aggressive behaviou r under different social conditions. In experiment 1, each male of sma ll mixed-sex groups of guppies was systematically removed and reintrod uced to the group. Only during the alpha male reintroduction were ther e any changes in the sexual behaviour of the remaining males; the fema le-preferred sigmoid display of the beta males was depressed. During r eintroductions, the alpha male was responsible for most aggression dir ected towards the reintroduced male. Females also responded aggressive ly towards the reintroduced males, particularly the alpha male. In exp eriment 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 th e alpha male. Thus, agonistic relationships among males may be respons ible for suppression of sexual behaviour by subordinate and non-reside nt males and should be considered as a factor in sexual selection proc esses in guppies. (C) 1995 The Association for the Study of Animal Beh aviour