Variation in number and formation of repeat sequences in the rDNA ITS2 region of five sibling species in the Anopheles barbirostris complex in Thailand

Abstract

Repeat sequences of approximately 100 base pairs in length were found in the rDNA ITS2 region of Anopheles barbirostris van der Wulp (Diptera: Culicidae) species A1, A2, A3, A4, and An. campestris-like in the An. barbirostris complex. Variation in the number of repeats was observed among the five sibling species. Specifically, 10 repeats were observed in A1, eight in A2, A4, and campestris-like, and three in A3. Based on similarities in the sequences of the repeats, related repeats were classified into nine groups. Although A2, A4, and the campestris-like species had the same number of repeats, the ITS2 region of the three species contained different groups of repeats. Excluding the repeat sequences facilitated good alignment of the ITS2 region in the five sibling species. Phylogenetic analyses of the 95 isolines were compared with results obtained from mitochondrial genes (COI and COII). The results revealed marked differences among the five sibling species, particularly regarding the ITS2 region of A3, which was more distinct from the other four species than COI and COII. Repeat sequences in the ITS2 region of other Anopheles species retrieved from GenBank also were analyzed. New repeat sequences were found in An. beklemishevi Stegnii and Kabanova, An. crucians Wiedemann and An. funestus Giles, suggesting that the occurrence of repeat sequences in the ITS2 region are not rare in anopheline mosquitoes.

Keywords: concerted evolution, repetitive sequences, sibling species members

Correspondence: yotsuka@oita-u.ac.jp

Editor: Marcelo Jacobs-Lorena was Editor of this paper.

Received: 25 November 2010 | Accepted: 9 June 2011 | Published: 17 October 2011

Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.  

ISSN: 1536-2442 | Volume 11, Number 137

Otsuka Y. 2011. Variation in number and formation of repeat sequences in the rDNA ITS2 region of five sibling species in the Anopheles barbirostris complex in Thailand. Journal of Insect Science 11:137 available online: insectscience.org/11.137