Patterns and consequences of within population variation in reproductive strategies

A reproductive strategy consists of a set of coevolved traits shaped by natural selection that characterize an organism's ability to reproduce. Most theoretical and empirical investigations of the variation in reproductive tactics have studied variation above the population level. However, since natural selection and microevolution are both population phenomona it is important to understand the patterns and consequences of variation in reproductive tactics at the population level before we can fully understand the significance of such variation at higher taxonomic levels. In this thesis I present a combination of laboratory and field data that describe the variation in reproductive tactics among individuals and the consequences of this variation for larval performance and survival at an oligophagous population of the butterfly Euphydryas editha.; Significant variation was found among females in egg weight but not in cluster size. The variation in both egg weight and cluster size was independent of female body weight, date of female eclosion, and each other. Female body weight declined with maternal age, whereas cluster size, egg weight, and frequency of oviposition showed no consistent trend with maternal age. Larval diet did not affect either female body weight, egg weight or cluster size. However, the consequences of variation in egg weight and cluster size were dependent on host plant species. Increasing cluster size was advantageous for larval performance on Pedicularis semibarbata, but was negatively correlated with growth rates for larvae on Collinsia torreyi. Variation in egg weight was found to be positively correlated with larval growth rates for larvae on C. torreyi but was not found to be correlated with growth rates for larvae on P. semibarbata. Variation in egg weight was not correlated with variation in larval survival in the field on either host species.