Relationships and Classification of Primitive Hexapods and Insects

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This project will examine the phylogenetic relationships of four basal hexapod groups--Entognatha, Thysanura, Paleoptera and Plecoptera--using a combination of molecular sequence and morphological data. In the origin of these four lineages, we find the fundamental events that define insect diversity since the Devonian. Illuminating the relationships among these groups will allow a more precise interpretation of their attributes. Moreover, robust cladograms of extant taxa will aid in our understanding of problematic fossil taxa. DNA sequences will be determined for the nuclear 18S rDNA regions. These data will be combined directly with a matrix of morphological features. Representative taxa will be chosen for each of the higher groups based on the systematic relationships at lower hierarchical levels. Using the conclusions of earlier studies, cladistically distant taxa will be chosen to infer the ground plans of Hexapoda, Insecta, Dicondylia, and Neoptera. Alcohol-preserved and dried museum specimens will be used to assure the inclusion of the most basal lineages possible, thereby yielding a more robust data set. This approach, combining multiple loci, phylogenetically based sampling and extensive morphological analysis, ensures that this work will increase our understanding of the evolution and systematics of these, the oldest hexapod lineages.