DNA Barcoding and Molecular Phylogeny of Drosophila lini and Its Sibling Species.

Yi-Feng Li,Jian-Jun Gao,Masanori J Toda,Ryoko Segawa,Yao-Guang Hu,Kuniko Kawai,Shuo-Yang Wen

doi:10.1155/2012/329434

Abstract

Drosophila lini and its two sibling species, D. ohnishii and D. ogumai, are hardly distinguishable from one another in morphology. These species are more or less reproductively isolated. The mitochondrial ND2 and COI-COII and the nuclear ITS1-ITS2 regions were sequenced to seek for the possibility of DNA barcoding and to reconstruct the phylogeny of them. The character-based approach for DNA barcoding detected some diagnostic nucleotides only for monophyletic D. ogumai, but no informative sites for the other two very closely species, D. lini and D. ohnishii, of which strains intermingled in the molecular phylogenetic trees. Thus, this study provides another case of limited applicability of DNA barcoding in species delineation, as in other cases of related Drosophila species. The molecular phylogenetic tree inferred from the concatenated sequences strongly supported the monophyly of the cluster of the three species, that is, the lini clade. We propose some hypotheses of evolutionary events in this clade.

Highlights

Studies of just diverging populations or species shed light on speciation mechanisms
Seven isofemale strains of D. lini, four strains of D. ohnishii, and two strains of D. ogumai were used as focal OTUs, and one strain each of D. kikkawai, D. bocki, D. leontia, and D. barbarae of the kikkawai complex, and one strain each of D. jambulina and D. seguyi belonging to the montium subgroup were added as ingroup OTUs (Table 1)
The NJ tree for 13 strains of D. lini and its siblings showed that D. ogumai was monophyletic but that D. lini and D. ohnishii were nonmonophyletic with overlap of strains of these two species (Figure 1)

Summary

Introduction

Studies of just diverging populations or species shed light on speciation mechanisms. An important evolutionary process in speciation is the diversification of genes between populations. Most comprehensive information on gene (DNA) evolution associated with speciation has been accumulated for the Drosophila melanogaster species subgroup, especially the D. simulans clade (e.g., [1,2,3,4,5,6]), and the D. obscura species group [7, 8]. Speciation mechanisms have been less explored in the D. montium species subgroup, in spite of its highest species diversity (= 89) [9] in the melanogaster group, with a variety of species at different stages of speciation process. Molecular markers have been used to detect cryptic species under incipient speciation process. “DNA barcoding” is proposed as a promising tool for rapid identification of known species, that is, “species identification,” and for discovery and delimitation of species, that is, “species discovery” or “DNA taxonomy” [11,12,13]

Methods

Results

Conclusion