Evolution of Behavior and Associated Structural and Physiological Traits in the Leafhopper Genus Cuerna (Hemiptera, Cicadellidae)

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

Loss of ancestral traits and trait complexes is a pervasive aspect of the evolutionary process, but its causes, mechanisms, consequences, and the possibility of restoration of the lost traits are still poorly understood. The current project aims to explore the patterns of repeated decay and loss of a stereotyped maternal behavior in the North American leafhopper genus Cuerna as a model of the regressive evolution of a complex biological function at the species level. In some of the 31 known species of the genus, females display an ancestral egg-powdering behavior, coating the egg nests with a layer of specialized Malpighian tubule products and displaying a suite of corresponding physiological and structural modifications, while in other species no such behavior is observed. Preliminary phylogenetic analyses suggested that egg-powdering has been lost or lost-and-restored within the genus multiple times. In the three years of the project the investigators will collect detailed comparative data on the egg-laying behavior and associated specializations of the external morphology and the Malpighian tubules for every species of Cuerna. Then, they will analyze these in the context of a detailed DNA-based phylogeny of the genus to address the following questions: Did the changes of particular traits proceed as quantum leaps or gradually? Do morphological, behavioral, and physiological traits display similar evolutionary plasticity? Did they change in a certain order? Did any restorations of lost egg-powdering occur in the evolution of Cuerna? What were the most likely causes of the losses? The study will also result in a taxonomic revision of the genus, which currently contains a number of poorly defined species. The study will contribute to management of economically important species of Cuerna by providing identification aids, as well as behavioral and physiological data for improved integrated pest management. An interactive key to species of Cuerna, complete with bionomical and distribution data, will be served on-line. The project will also provide training for a graduate student in the systematics, molecular phylogenetics, and evolutionary biology of insects.