My undergraduate research led to a long-term interest in speciation and secondary contact, especially the problem of whether species interactions or physiological factors limit species distributions. My research approaches include a variety of biogeographic, behavioral, historical, and genetic methods and make use of cicadas, which are relatively common hemipteran insects with a worldwide distribution.
My research includes closely related projects concerning the 13- and 17-year periodical cicadas of eastern North America. Periodical cicadas are divided into species, life cycles, broods (or year-classes), and populations, at least one of which emerges somewhere each year. In 1998, I was the co-discoverer of a cryptic periodical cicada species, Magicicada neotredecim, that exhibits a striking pattern of reproductive character displacement where it is sympatric and synchronic with the species M. tredecim (e.g. Cooley et al. 2001). The incompatible sexual signals of these species reduce opportunities for gene flow and provide a rare example of insect premating isolation mediated by song pitch (Cooley et al. 2006). I am actively pursuing three lines of research aimed at understanding speciation and species boundaries in periodical cicadas:
Phylogeny and phylogeography of periodical cicadas. I am part of a research team to develop new molecular markers for periodical cicadas, in order to conduct phylogeographic studies that combine molecular genetic data with ecological niche modeling. A complicating factor has been the discovery of paternal leakage, or transmission of paternal mitochondrial alleles to offspring (Fontaine et al. 2007), which we have found to be surprisingly common in periodical cicadas.
Sound production and reception in cicadas. Cicadas appear to consume very small amounts of energy while making extremely loud sounds. My collaborators and I are studying sound production in cicadas from a neurophysiological perspective. This project makes use of peripheral and central nervous system monitoring and stimulation, high quality acoustical recording, and laser vibrometric measurements of tymbal and eardrum activity. During the 2011 periodical cicada emergence, this project will include a detailed acoustical and neurophysiological study of song-displaced periodical cicadas in the Midwestern zone of reproductive character displacement.
Distribution and abundance of periodical cicadas. Understanding the distributions of periodical cicada species and broods requires a more complete understanding of their ecology and responses to environmental change. Although maps of periodical cicadas have existed for over a century, many current maps of these insects are only modernizations of relatively inaccurate 19th century maps. I am currently leading a project to refine data collection methods, create entirely new, highly detailed georeferenced maps, and develop Ecological Niche Models (ENM) of periodical cicadas. During the 2011 emergence of BRood XIX, we will thoroughly map the emergence of Brood XIX using the third generation of my custom-designed GIS datalogger to refine our understanding of the pattern of reproductive character displacement as well as monitor the contact zone for any changes since the brood last emerged in 1998.
Examples of student research projects
Undergraduate researchers have participated in all aspects of my projects. Examples include Adrianne Smits’ study of female periodical cicada oviposition preferences while at Yale (Smits et al. 2010). A more complex project was Kathryn Fontaine’s project at UCONN investigating the surprisingly common occurrence of paternal mitochondrial leakage in F1 hybrid periodical cicadas (Fontaine et al. 2007). I am also a graduate of an NSF-funded REU program, and I intend to seek NSF-REU funding for additional undergraduate research projects in the future.
My research has general relevance for understanding processes of speciation, the maintenance of species differences, and mating system evolution.