The Deltocephalus-like genera of leafhoppers have posed a difficult problem for workers because of an absence of phylogenetic information and definitive characters necessary for generic separation. Towards obtaining a clearer picture of phylogenies in this group, the investigators hope to perform cladistic and molecular analyses of a subset of 24 nearctic genera in which fusion of the connective and aedeagus appears to represent a synapomorphic character of the subset. A current problem in the field of molecular systematics is that there is no agreement as to which DNA sequences can be used in insect taxonomic studies at the generic level. Almost all molecular systematic studies to date have compared species at higher taxonomic levels. Most of the sequences which have been examined at these levels are monomorphic at lower taxonomic levels. At the other extreme there are sequences which demonstrate extensive intraspecific variation but which may present no recognizable homology at higher taxonomic levels. Funding is requested for one year to examine eight different DNA sequences in leafhoppers selected at four taxonomic levels. Five candidate nuclear regions and three mtDNA regions have been identified. The nuclear DNA regions include: 1,2) two internal spacers (ITS1 and ITS2) in the rDNA cistron, 3) a hypervariable region of the 28s from the rDNA cistron, 4) an intron in the invariant histone H2A gene and 5) the ribosomal S14 protein gene and its intron. The mitochondrial genes are: 1) a region of the 12s rDNA 2) the 16s rDNA and 3) a region of the cytochrome oxidase III gene. All regions will be amplified with PCR and sequenced. These regions will be initially compared among three species in three tribes in the leafhopper subfamily Deltocephalinae, if the sequences show variation at this level, two additional species will be compared within two of the three tribes. If intergeneric variation is detected within tribes then two species within one genus will be examined. If variation is detected at this level then an examination of intraspecific variation will take collection from different geographic populations of one species. With this protocol the taxonomic level at which each of these sequences can be used can be determined. The goal is to identify 2-3 DNA sequences which can be used in an intensive survey of 24 genera of the Deltocephalus-like genera of leafhoppers.
