Utility of DNA barcoding for Tellinoidea: a comparison of distance, coalescent and character-based methods on multiple genes.

DNA barcoding has become a promising tool for rapid species identification using a short fragment of mitochondrial gene. Currently, an increasing number of analytical methods are available to assign DNA barcodes to taxa. The methods can be broadly divided into three main categories: (i) distance-based methods (the classical approach and the automatic barcode gap discovery (ABGD) approach), (ii) coalescent-based methods (the monophyly-based method and the general mixed Yule coalescent (GMYC) model) and (iii) the character-based method (CAOS). This study is set out to evaluate the availability of each method in barcoding Tellinoidea on the cytomchrome c oxidase subunit I (COI) and the 16 small-subunit ribosomal DNA (16S rDNA) genes. As a result, the character-based method was found to be the best in all cases, especially on a genus level. For distance-based methods, the elaborate one gained a success equal or greater than the basic one. The traditional coalescent-based method nicely delimited all of the tellinoideans on a species level. The GMYC model, which is the most radical, clearly inflated the number of species units by 34.6 % for COI gene and by 58.8 % for 16S gene. Thus, we conclude that CAOS better approximates a real barcode, and suggest the use of the ABGD method and the monophyly-based method for primary partitions. Additionally, COI gene may be more suitable as a standard barcode marker than 16S gene, particularly for tree-based methods.