Meeting Abstract
Nutrient availability affects both life-history traits and trade-offs: individuals reared on high quality diets tend to allocate more to a range of fitness-related traits, and trade-offs between such traits are often obscured. While the importance of nutrition for life-history evolution has been extensively studied within species, the relationship is less clear across species. Because species often adapt to low quality diets over time, nutrition may be less important in shaping life histories across species. Here we test the hypothesis that variation in nutrient availability shapes the evolution of life history traits and the expression of trade-offs. Do species on lower nutrient diets allocate less to a range of traits, or must they invest more heavily in individual traits, strengthening underlying trade-offs? Butterflies are a useful system for addressing these ideas because species vary widely in larval diets, which in turn vary in macro- and micronutrient content. We focus on the nitrogen content of a species’ diet as nitrogen is the most important macronutrient for insect herbivores. We found the nitrogen content of a species’ larval diet is correlated with fecundity (both egg number and relative egg size) and eye size. We then test whether the strength of trade-offs between reproductive traits (egg number, egg size, testes size) and other fitness-related traits (eye size, brain size, thorax mass) vary with diet. We discuss how an integrative view of allocation to a range of traits, and throughout an organism’s entire life, is important to understanding life-history evolution.
