Meeting Abstract

P3-77   -   The role of diet composition on melanin pigmentation and melanin trade-offs Britton, SE*; Davidowitz, G; University of Arizona; University of Arizona sbritton@email.arizona.edu

Pigmentation in animals is often based on availability of dietary precursors. When these are limited, pigmentation may be associated with resource allocation trade-offs. While many animals show intraspecific variation in melanin pigmentation, little work has investigated the dietary basis of this variation or the consequences of resource allocation decisions. Although melanin can be synthesized de novo by animals, the amino acid precursors, tyrosine and phenylalanine, must be derived from the diet. In this study we ask how diet composition influences larval cuticular melanization and melanin trade-offs in the white-lined sphinx moth, Hyles lineata. In this species melanin pigmentation is environmentally induced and highly variable in the late larval stages. H. lineata is a geographically widespread diet generalist and individuals likely encounter high variation in diet composition that is often limited in amino acids. Melanin pigmentation might be expected to trade-off with traits such as flight, since the precursors are also needed to build flight muscles, and reproduction, since the precursors are allocated to eggs. We raised H. lineata larvae under conditions known to induce a high degree of melanization (low temperature and short photoperiod). Larvae were raised on diets that varied in the amount of phenylalanine and tyrosine but similar in overall macronutrient content. We quantified percent melanization using digital image analysis. We found that larvae from diets low in precursors had a reduced degree of melanin pigmentation. Next, we will test whether degree of melanin pigmentation trades-off with investment into flight or reproduction in the adults by measuring caloric investment to the abdomen and thorax. We show that diet can play an important role in melanin pigmentation and highlight the importance of considering specific micronutrients on the dynamics of allocation trade-offs across life stages.