ABR: Evolution of 13- and 17- year Periodical Cicadas

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9807113 Simon Earlier research explored the evolution of periodical cicadas (Genus Magicicada) using mitochondrial gene sequences, nuclear encoded proteins, and abdominal color. Results from the project included a genetic characterization of spatial patterning of mitochondrial and nuclear genomes, identification of three strong genetic boundaries that do not correspond precisely to the boundaries between periodical cicada species, and a realization of the importance of life history variation in the evolution of this unusual genus. In the process of this work, the evolution of conserved and variable regions of the mitochondrial genome was studied and a number of papers were produced which investigated the value of the secondary structure of the molecule for alignment of nucleo- tides and for understanding patterns of site-to-site variation in the rate of nucleotide evolution. The effects of rate variation on evolutionary tree construction, evaluation of support for groupings of species, and calculation of genetic distances were also explored. In 1998 there will be a joint emergence of the only two broods of 13- and 17-year cicadas whose ranges currently overlap. This will provide a unique opportunity to study the genetic boundaries that we previously discovered. Five genetic techniques for identifying 13- versus 17-year cicadas have been perfected. Life-cycle switching will be examined in greater detail for all six of the periodical cicada species. Previously described genetic boundaries will be explored in an attempt to understand their causes. Finally, a new component will be added to the research, an exploration of the effects of ecological interactions on life-cycle timing and species co-evolution. By studying these unusual cicadas we can learn more about how life-history evolution can dramatically effect species evolution and in so doing answer a broad array of questions about periodi- cal cicadas generated by previous NSF-funded research. The ecological component o f this project will lend an added dimension to the study of co-diversification of this unusual group of insects.