Dissecting the nature of subtle phenotypic variation in wing colour elements of Müllerian co-mimics

Abstract

Abstract:Polymorphism is common in nature, but few Heliconius species are polymorphic for wing colour patterns. Eastern Brazil H. erato phyllis populations are polymorphic for hindwing elements (red raylets) and studies suggest that trait distribution varies seasonally. We carried a 3-y sampling to evaluate the hypothesis that season, wing length and pollen foraging were associated with morph diversity. Individual phenotypes were scored with regards to number of red elements in the dry and in the wet seasons. Co-mimic H. melpomene nanna was also analysed. We scored 432 H. erato and 513 H. melpomene. Our results confirm polymorphism in H. erato, with individuals showing from one to eight elements, with a mode between five and six. We found that H. melpomene is polymorphic for red dots, varying from two to five (mode = 2). Red basal dots were mostly invariant in H. erato. Even though we found a seasonal change in pollen loads, we found no association between individual phenotypes and season, pollen load scores, or wing length. We reject the hypothesis of ecological correlates of morph frequency, and suggest that trait colour variation in the two species is linked to and constrained by effects on mate recognition.