Presenter: Jonas Bush
Authors: Robert Bush, Paul Frandsen
Faculty Advisor: Paul Frandsen
Institution: Brigham Young University
Periodical cicadas of the genus Magicicada are commonly found throughout the Eastern United States, and their loud mating calls can be heard every 13 or 17 years as various broods of nymphs emerge in massive numbers.These cicadas have a tremendous impact on their ecosystems, including serving as a critical food source for many species during years in which they emerge. Magicicada emergences have even been known to have measurable impacts on avian abundance in the years following large broods. Despite the important roles these insects play, scientists have struggled to make sense of the many unique characteristics of these insects, including understanding their abnormally lengthy life cycles, population structure, and evolutionary history. Recent studies have suggested that low effective population sizes (Ne) might help explain observed life cycle patterns and subsequent speciation. To investigate these questions, we analyzed the genomes of two 17-year periodical cicada species (M. septendecim & M. septendecula). We estimated demographic histories and effective population sizes over time using the Pairwise Sequential Markovian Coalescent (PSMC) analysis for both species. We identified gene family expansions using CAFÉ to produce further hypotheses regarding causal genes for life cycle traits. We show here that whole genome analyses can provide unique and valuable insights into the evolutionary history and population growth of periodical cicadas.