Allozyme electrophoretic evidence for a complex of species within the Bactrocera tau group (diptera: Tephritidae) in Thailand

Abstract

Electrophoretic analysis of the Bactrocera (Zeugodacus) tau-like flies collected from wild populations coupled with morphological observation and cytological evidence has revealed seven species within this taxon, temporarily designated as species A (= B. tau s.s), C, D, E, F, G and I. These enzyme electrophoretic characteristics distinguishing these species (including four sympatric and two allopatric species) are described in this study. The value of Wright's fixation index, FST, among populations was found to be +0.769. Partitioning of each species reduced the mean FSTto +0.053. This suggests strong species-specific mating. UPGMA clustering of Nei's unbiased genetic distance was estimated by analysis of allele frequencies at 12 enzyme loci. The resulting dendrogram shows that two lineages exist in the B. tau complex, one consisting of species C and I and the other comprising four species including B. tau s.s. (=A), species D, E, F and G. Of these, species F and G are truly sibling species because of their morphological similarity.