The adaptive significance of UV reflectance in the jumping spider, cosmophasis umbratica (araneae: salticidae)

Abstract

This study aimed to examine the adaptive significance of ultraviolet reflectance and the ultimate causes of female mate-choice, by using the sexually dimorphic jumping spider Cosmophasis umbratica as study subject. Mate choice experiments revealed that UV chroma and brightness are determinants of a male¿s mating success in this salticid species. When preferred and non-preferred males were mated with females, preferred males were found to confer higher fitness on their offspring, allowing females to enjoy indirect genetic benefits. When reared on diets of different nutritional contents, diet quality was found to be positively correlated to UV reflectance and size, indicating that UV reflectance is a reliable indicator of male quality in this species. In conclusion, the findings in this thesis support the hypotheses that UV-reflecting ornamentations in C. umbratica play important roles in female mate choice by functioning as reliable indicators of male quality, and choosy females gain indirect genetic benefits.