Influence of Size and Date of Emergence on Male Survival and Mating Success in a Dragonfly, Sympetrum rubicundulum

Abstract

In dragonflies larval density and food supply influence the length of the larval period and size at emergence, but their effects on adult fitness are not well understood. I studied the influence of body size at emergence and date of emergence on two components of adult fitness (survival and mating success) in a natural population of the dragonfly Sympetrum rubicundulum. Survival during the 2-week maturation period from emergence to breeding was low for both sexes (2-3 %). There was no significant change in the mean wing length of the population of males between emergence and breeding, indicating that neither large nor small males experienced a survival advantage during maturation. Once males attained reproductive age (13-16 days) they had high continued survival (mean daily survival: 0.96; expected life span: 37.7 days), which was unrelated to wing length or date of emergence. Similarly, the daily mating success of males was not influenced by wing length or date of emergence. These results suggest that natural variation in traits affected by larval growth rate may have little direct influence on adult fitness in male dragonflies.