DNA barcoding discriminates echinoderm species

Abstract

DNA barcode sequences (a 657-bp segment of the mtDNA cytochrome oxidase I gene, COI) were collected from 191 species (503 specimens) of Echinodermata. All five classes were represented: Ophiuroidea, Asteroidea, Echinoidea, Holothuroidea and Crinoidea. About 30% of sequences were collected specifically for this study, the remainder came from GenBank. Fifty-one species were represented by multiple samples, with a mean intraspecific divergence of 0.62%. Several possible instances of cryptic speciation were noted. Thirty-two genera were represented by multiple species, with a mean congeneric divergence of 15.33%. One hundred and eighty-seven of the 191 species (97.9%) could be distinguished by their COI barcodes. Those that could not were from the echinoid genus Amblypneustes. Neighbour-joining trees of COI sequences generally showed low bootstrap support for anything other than shallow splits, although with very rare exceptions, members of the same class clustered together. Two ophiuran species, in both nucleotide and amino acid neighbour-joining trees, grouped loosely as sister taxa to Crinoidea rather than Ophiuroidea; sequences of these two species appear to have evolved very quickly. Results suggest that DNA barcoding is likely to be an effective, accurate and useful method of species diagnosis for all five classes of Echinodermata.

Phylogeography of the sand dollar genus Mellita: Cryptic speciation along the coasts of the Americas

“…One approach to answering this question is the one typically used in COI barcoding. Intraspecific variation of COI in animals (except the Cnidaria) is rarely more than 2% and more typically less than 1% (Avise, 2000); similar values have also been found in echinoderms (Ward et al, 2008). Reproductive barriers between echinoid species have been found to arise in species separated for only 250,000 years (COI divergence of 0.9%), as they did between Echinometra oblonga (Blainville, 1825) in the central Pacific and an unnamed species from the western Pacific (Landry et al, 2003).…”

“…Genetic distance in COI between echinoderm congeners is typically no larger than 15.33% (Ward et al, 2008). Our COI data show that the genetic distance between Leodia and the Pacific M. longifissa-grantii lineage was 45.56%, and between L. sexiesperforata and the Atlantic + Pacific lineage 42.29%.…”

Introduction to the special issue on the Life in Antarctica: Boundaries and Gradients in a Changing Environment (XIth SCAR Biology Symposium)

“…Examples of complex cryptic species are molluscs Allcock et al 2011), amphipods (Havermans et al 2011), echinoderms (Ward et al 2008), annelids (Schüller 2011) and nemerteans (Thornhill et al 2008). The use of molecular tools to standardize comparisons ''barcoding'' and phylogeography has been shown to produce valuable sources of information which often reveal this hidden diversity.…”

Molecular Species Delimitation of Icelandic Brittle Stars (Ophiuroidea)

“…The limits of several species are still unclear though, e.g. Ophiactis abyssicola (M. Sars, 1861) has been suggested to be a cryptic complex of two species on molecular grounds (Ward et al 2008). Ophiacantha fraterna Verrill, 1885 has been separated from Ophiacantha bidentata (Bruzelius, 1805) by Martynov and Litvinova (2008) on the basis of morphological differences, but both species may represent the ex− tremes of a morphologically variable species as intermediate forms are common (Stöhr, unpublished results) but these two species have not been analyzed geneti− cally yet.…”