抄録
The evolutionary genetic studies of more than ten species or subspecies belonging to the D. nasuta subgroup lead the following conclusions:
Morphological differentiation has been observed qualitatively as well as quantitatively, but closely related species could not be identified by means of the techniques of external morphology.
By the hybridization tests, D. nasuta, Indian D. nasuta, D. albomicans, and D. kepulauana are closely related species, and four subspecies of D, sulfurigaster are close to D, pulaua. D. kohkoa, D, pallidifrons and Taxon-F are related species to D, sulfurigaster, but are differentiated from each other.
Judging from the allozyme analyses, the local populations of D. nasuta were genetically similar in two Esterase loci. The Chiangmai population was differentiated from other allopatric populations of D. sulfurigaster albostrigata.
The pattern of the speciation process in the D. nasuta subgroup was discussed.
