THE EVOLUTION OF MULTIPLE MALE TRAITS IN THE YELLOW-BROWED LEAF WARBLER

I examined how male competition and female choice influence the evolut ion of multiple male traits in the yellow-browed leaf warbler, Phyllos copus inornatus, by investigating the roles of colour patches, territo ry size, body weight and song rate in sexual selection. Comparison of 3 years of observational studies and 3 years of experimental studies, in which the colour patches on the wings of males were experimentally altered, suggest several mechanisms that may explain the evolution of multiple characters in males. First, females based their choice of mat es on several male characters, not a single character. Second, the mal e characters preferred by females were different in observational and experimental studies. Females apparently preferred high-quality males as mates, and were able to vary the characters used in mate choice to distinguish these individuals under both experimental and observationa l conditions. Third, the characters important in male competition diff ered from those that formed the basis of female choice: the manipulati on of colour patch size directly affected male territory size but was not associated with female choice. These results may provide an explan ation for the diversity of sexual ornaments shown by males of many spe cies. (C) 1998 The Association for the Study of Animal Behaviour.