Sexual selection by female choice in guppies (Poecilia reticulata)

[摘要] I investigated some evolutionary implications of female mate choice in a feralpopulation of guppies (Poecllia reticultuai. I performed correlative and manipulativeexperiments to establish the relationship between female mate choice and othersexually selective forces including iutermale aggression and sneak copulation, andthe exaggerated secondary sex characters (ornaments) of male guppies. Orange(carotenoid) ornamentation is the best predictor of male attractiveness and matingsuccess, a relationship which held under manipulation. Black (melanin) is sometimescorrelated with male mating success. Mnnipulatiug the black area of males revealsthat it is important to male attractiveness, and this appears to be in the form of asignal amplifier of male orangeness. This is the fi.st experimental evidence for avisual signal amplifier. For both orange and black areas, the relationship betweenabsolute area and fluctuating asymmetry is positive and significant, suggesting thatneither is n signal of male condition. These results arc Interpreted in the context oftheories of the evolution of multiple male ornaments. Females are able to expresstheir preference for orange with the first mature male they ever encounter, uuggestlngan important role for genetic determination in female preferences. This iscorroborated by high repeatability of female mate choice behaviour. Experiencemodifies a female's preferences as she is able to adjust her response to a male inrelation to the ornamentation of (at least) the previous male she saw. Mate copyinghas no mensurable effect on the outcome of female mate choice decisions.

[发布机构] University of the Witwatersrand