Effects of Parentage and Competitor Phenology on the Growth of Larval Hyla Chrysoscelis

Abstract

Larvae of four sibships (a 2 x 2 factorial cross) of Hyla chrysoscelis were raised in three competition regimens. These were competitors (larval Rana catesbeiana) absent, competitors introduced simultaneously with Hyla, and competitors introduced 11 d after Hyla. Hyla body mass at day 41 of growth was influenced by level of competition, timing of competitor introduction, and effects of male and female parent. Rana introduced simultaneously with Hyla reduced Hyla mass at day 41 more than did Rana introduced 11 d later. Female parentage affected body mass at day 41 additively. The effects of male parentage depended on the timing of competitor introduction: when Rana were introduced simultaneously with Hyla, offspring of male 2 were larger at day 41 than offspring of male 1. When Rana were introduced 11 d after Hyla, offspring of male 1 were larger at day 41 than offspring of male 2. This interaction between the effects of male parentage and timing of competitor introduction suggests that some genotypes may exhibit tradeoffs between maximum growth rate and competitive ability, and that phenological variation may lead to selection among genotypes in the natural population.