Indian Journal of Biotechnology Vol 13, April 2014, pp 165-171

DNA barcoding of Indian based on cox1 gene

Rakshit Ojha1, S K Jalali1*, T M Mushtak Ali2, T Venkatesan1, Sean W Prosser3 and N K Krishna Kumar1 1National Bureau of Agriculturally Important , Hebbal, Bangalore 560 024, 2Department of Entomology, University of Agricultural Sciences, GKVK Campus, Bangalore 560 065, India 3Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph Guelph, Ontario, Canada N1G 2W1

Received 17 January 2013; revised 6 May 2013; accepted 14 June 2013

Sixteen species of collected from Karnataka, India, were sequenced and barcoded for a 658 bp region of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1). This gene is frequently termed as CO1 in barcoding approach and serves as the core of a global bioidentification marker for insects and other . The AT content in DNA of 16 ant species was estimated as 68.55%, which is in accordance with invertebrates. The variance of AT content among species was st nd rd much higher for the 1 base (AT1) compared to the 2 and 3 bases, which were nearly invariant. The distance within species was calculated using Kimura 2-parameter (K2P) and it was 0.166, 0.000 and 0.333% for mean, minimum and maximum, respectively. Moreover, our data also showed some phylogenetic signal. In a neighbor-joining tree for all sequences, two clusters were obtained, the first cluster consisted of subfamilies and , while other clade showed relationship between subfamily Myrmicinae and clustered with subfamily Dolichodrinae, which is not in contradiction with cladistics analysis of morphological data for ants and is consistent with traditional phylogeny of ants. The present results thus favour DNA barcoding as a decisive tool in quick and reliable identifications of ants.

Keywords: Barcodes, cox1, cytochrome c oxidase subunit 1, Indian ants, molecular characterization

Introduction protein analysis has been gaining importance6,7. The science behind classifying living species based About five decades ago, starch gel electrophoresis on shared features, i.e., , has been a part of of proteins was first used to identify species8. human society for centuries. The quantification of Tautz et al9 advocated the case for a DNA-based , which is increasingly decimated, taxonomic system, whereas Hebert et al3 believed presents a daunting challenge to taxonomists because that a single gene sequence would be sufficient to it requires discovery and analysis to proceed at a differentiate vast majority of species, and greatly accelerated pace1. Recognition of subtle proposed the use of the mitochondrial DNA gene anatomical differences between closely related cytochrome c oxidase subunit 1 (cox1) as a global species requires subjective judgment of a specialist identification marker for animals. The cox1 region is and also demands great deal of taxonomic useful for inferring phylogenetic relationships among knowledge2. Hebert et al3 observed that, for critical populations and it is also used as the primary DNA identification of 10-15 million species based on barcode throughout the world3. Although the cox1 morphological diagnosis, a community of 15,000 region is highly conserved, differences do exist in the taxonomists will be required. In order to identify these length and sequence of the regions flanking cox1. species at the rate of expertise available, it may Previous phylogenetic studies hav