| The orthopteroid insects are an interesting and diverse assemblage comprising six orders: Orthoptera (grasshoppers, locusts), Grylloptera (crickets, katydids), Dictuoptera (cockroaches, termites, mantids), Notoptera (rock-crawlers/ice bugs), Dermaptera (earwigs) and Cheleutoptera (walking sticks). Many phylogenetic issues within this group remain unresolved. This thesis examines the phylogeny of the orthopteroid insects from both a molecular and morphological perspective based on a combination of original and published data. A two-tiered approach to this research has been taken such that orthopterans representing both high and low taxonomic levels have been examined.; Molecular and morphological characters from selected species representing all major taxa were compared to reveal evolutionary relationships between orthopterans at the ordinal/subordinal/superfamiliaI levels. Portions of one nuclear (18S rRNA) and two mitochondrial (16S and 12S rRNA) genes were sequenced and phylogenetically analyzed using (weighted and unweighted) parsimony and neighbour joining methods. The classic morphological data matrices of Kamp (1973) and Blackith and Blackith (1968) representing higher orthopteran taxonomic ranks were re-investigated using modern analysis tools that were not available at the time of the data's original publication. These molecular and morphological data sets were then analyzed in combination, making this study the first examination of the group based on such a diverse suite of characters. Results are discussed in relation to published phylogenies. Cheleutoptera, Dictuoptera, Gryllodea, Grylloptera and Orthoptera were each shown to be monophyletic. Data support the subordinal positions of termites, mantids and cockroaches, and the ordinal positions of Orthoptera and Grylloptera.; The second study focuses on molecular characters of one grasshopper subfamily, Melanoplinae. Portions of three mitochondrial genes (cytb, COII and 16S rRNA) were sequenced and compared using the same reconstruction methods as for the higher orthopteran study. The trees presented here are the first DNA sequence based phylogenies built for members of the subfamily. The inferred relationships are discussed with reference to morphological similarities and species groups recognized by some orthopterists. Very small genetic distances were revealed between some melanoplines. Data presented here call into question the taxonomic positions of Phoetaliotes, Hesperotettix and Schistocerca . |
