Discipline: Ecology Environmental and Earth Sciences
Ajibola Opakunle - Saint Olaf College
Co-Author(s): Rebecca E. Forkner, George Mason University, Fairfax, VA
Lepidoptera co-evolve with their plants hosts; yet, the role of plants in generating variation in butterfly wing patterns is understudied, especially given the primary role that wing eyespots and colors play in mating, mimicry, and crypsis. To determine if host plants generate variation in wing patterns in the model butterfly, Vanessa cardui, and to investigate the interaction of host plant effects with temperature, we reared V. cardui larvae on plant genera of differing quality and chemistry, as well as on artificial diet, and exposed pupae to heat shock. We hypothesized that less suitable host plants would have greater impacts on wing morphology. After pupation, pupae from each larval host plant were weighed, measured, and assigned to control (ambient temperature) or heat shock (24 hours at 40°C) treatments. At eclosion, butterflies were euthanized and wings removed and photographed. Pattern analysis to determine changes in eyespot size; area of yellow, orange, or blue eyespot pigments; size of parafocal elements; and distance of parafocal elements from the submarginal vein was conducted using ImageJ software and Principle Component Analysis. Although survivorship was too low on most host plants to assess differences, larvae reared on Plantago were smaller in hindwing size and differed in wing pattern elements compared to Carduus and artificial diet reared larvae prior to heat shock. After pupae were exposed to heat shock, both Carduus and Plantago-reared specimens differed in hindwing size and total area of yellow, blue, and orange pigments primarily in the M2 and CuA2 eyespots compared to specimens’ feed artificial diet. Our results are the first to demonstrate that host plant identity creates variation in eyespot size and color rather than just in overall wing hue or melanism. Consequences of such phenotypic variation for the evolution of new Lepidoptera species will depend on links between observed phenotypes and genotypes or epigenetic gene expression. A wider range of research that examines morphology and its interaction with environment is necessary to understand how climate changes will influence evolution and extinction. Further studies should determine if conclusions from this study apply to other species in the Nymphalidae, including both temperate and tropical species with intricate wing patterns and seasonal polyphenism.Not Submitted
Funder Acknowledgement(s): We thank the National Science Foundation (Grant Number: DBI 1659816), The Neall Family Charitable Foundation, & students, faculty, and staff at UVA's Blandy Experimental Farm.
Faculty Advisor: Dr. Rebecca Forkner, firstname.lastname@example.org
Role: I took part or mainly conducted every aspect of this research. I raised all the butterflies and cultivated a large majority of the plants needed for the research. I did all the Image J software collection for the wings and data collection during development. I did a large majority of placing the butterflies in incubation and euthanizing the butterflies.