Sequence Analysis of Nuclear rDNA of Anastrepha suspensa

Ribosomal DNA sequence data has been important in elucidatingmolecular evolution, discerning phylogenetic relationships, and in developing species diagnostics. Species in the genus Anastrepha Schiner, particularly members of the Fraterculus Species Group, are considered the most important native pests of fruit in the New World. This study presents the Þrst complete rDNA sequence data spanning the 5.8S to the internal transcribed spacer ITS2 of a species in this genus, Anastrepha suspensa (Loew). The GC content of the rDNA genes in A. suspensa was 50.8 to 40% for the 5.8S and 2S genes, respectively, but spacers were 84% AT rich. Spacer and gene lengths were of similar size to those found in other tephritids. Except for A. fraterculus s.l. (Wiedemann), spacers of other tephritid taxawereAT rich andcontainednumerous simple repeats. Sequence alignmentwith A. fraterculus s.l. indicated minor differences in the 5.8S rRNA gene, but the ITS2a was identical and the 2S gene differed by a single transition. The ITS2 ofA. fraterculus s. l. was unusual in having a 41.7% GCcontentwith three regions ofC repeats. The ITS2 ofA. suspensahadhigher percent identity values with Þve species in other genera than it did with A. fraterculus s.l., suggesting an unusually high divergence rate in the latter.