The secondary structure of ITS2 in Anterastes ( Orthoptera, Tettigoniidae ) species: It's utility in species characterisation, barcoding and phylogeny

The tools to define biodiversity have changed through time. DNA sequences are widely used to define biodiversity because of providing objective data and becoming suitable for computerisation. The ITS2 transcripts are using as species barcode markers in many lineages. Altough, its potential as a barcode marker for animals waits to be tested. The aim of present study is characterization of ITS2 and to examine the utility of barcoding species and resolving phylogenetic relationships in the genus Anterates (Orthoptera, Tettigoniidae, Tettigoniinae) A data matrix was established from 142 ITS2 samples representing all species in Anterastes. In total 57 unique haplotypes were detected from these 142 sequences. After checking for the pseudo genes the final length of the ITS2 sequences in the matrix was 267-268 base. The average GC content was %60, 58. The secondary structure of the transcripts were constructed using the appropriate softwares. Then both the matrices of linear sequences and secondary structures were subjected to phylogenetic analyses. Both data sets resulted in poorly resolved phylogenetic trees. The secondary structures produced by softwares contains the Helix I, Helix IA, Helix II, Helix IIA ve Helix III each with highly conserved sequences. Additionally, a forth helix was determined in the haplotypes from A. disparalatus ve A. serbicus. No compensatory base changes were determined in any of the haplotypes. The following conclusions were arrived in the light of results: (i) The length of ITS2 sequences in Anterastes is below the average in other animals but higher than that of Poecilimon, the only known other Orthoptera, (ii) the GC content in Anterastes ITS2 sequences is over the content in other animals, (iii) The secondary structure of ITS2 sequences has some departures from other eukaryotes. The presence of Helix IA between Helix I and Helix II is unique among eukaryotes and that of Helix IIA between Helix II and Helix III is unique among Orthoptera, (iv) each helix is highly conserved and variations are in the regions outside helices, (v) the linear sequences of ITS2 are phylogenetically uninformative and the secondary structures have not provided additional phylogenetic information in Anterastes, and (vi) No compensatory base changes were determined and so the ITS2 marker has low potential for barcoding.