Developmental Genetics and Evolution of Butterfly Colour Patterns

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Species are the fundamental units of biology, but unlike similar units in chemistry and physics, the exact properties that make species different from one another are not fully understood. The goal of evolutionary developmental biology is to understand genetic variation and developmental mechanisms responsible for phenotypic differences between species. The proposed research uses buckeye butterflies (genus Junonia, formerly Precis) as a model for studying the evolutionary genetic and developmental basis for species differences. Colour pattern development in the North American common buckeye butterfly, J. coenia, has been studied extensively. The genus originated in Africa and it was thought that only 4 Junonia species occurred in the New World. Since 2009, phylogenetic work (much of it from my laboratory) has clarified taxonomy and identified cryptic Junonia species. There are now 10 described New World Junonia species, with others that are yet undescribed (especially in South America). New World Junonia species differ in colour pattern, body size, phenology, flight behaviour, and geographic range. Many species specialize on distinct larval host plants, facilitating the long-term co-occurrence of species in the same habitat. Yet, most Junonia species hybridize readily in captivity and all species can be reared on the same laboratory diet. My laboratory has shown that hybridization and gene flow between Junonia species also occurs in nature. These attributes combined with the diverse tools and resources already available in J. coenia (many cloned genes and rapidly increasing genomic resources, methods for hormonal manipulation, developmental perturbation, gene expression, and transgenesis) make this genus an excellent system for understanding speciation and the evolution and development of species differences. The research program focuses on the morphological differences between Junonia species: in particular, our objectives are to identify patterns of evolution and the genetic and developmental basis for variation in body size and colour pattern. Body size strongly influences how butterflies interact with their biotic and abiotic environment, while eyespots have an important role in anti-predator defense. Thus, we will be studying the genetic and developmental basis of ecologically important morphological traits. The scientific approach uses a novel combination of research methodologies to investigate patterns of diversification, hybridization, and the developmental genetic basis for differences in morphology among Junonia species. Significance and broader impacts: This research will train highly qualified personnel in cutting-edge experimental techniques to identify the genes, developmental processes, and evolutionary mechanisms responsible for making species different from one other with respect to phenotypic traits of ecological importance.