Study Of Polychaete Taxonomy Based On COI DNA Sequence

As the exploration of biological world deepens, taxonomy is now beyond the limits of morphology. In 2003, Hebert suggested that the mitochondrial cytochrome c oxidase I(COI) DNA sequence be a universal molecular marker for animal identification, equalivalent as ‘barcode’. To date, there is more and more application of COI gene in DNA barcoding for animal identification.Polychaeta is the most speciose Class in Annelida. The class of species is typical marine invertebrate with wide range of distribution. Many of polychaetes are baits of other marine animals and dominant species found in the investigation of marine ecosystem diversity. Polychaetes need to be protected, utilized, and even controlled. Compared to other invertebrates, they are more challenging for taxonomy and phylogeny with morphological methods. This may be because their sampling method is limited, different species often share same habitats, and most species have a pelagic larval period. So in addition to morphology, it is significant to build a DNA barcode reference library for polychaete taxonomy.To start a DNA barcode reference library for polychaetes from the coast of East China Sea. We sampled along the intertide zones from Zhejiang to Fujian during JanuraryOctuber, 2015. After morphological observation and charaterization, we amplified and sequenced mitochondrial CO I gene sequence for individual samples. In total, we identified 8 species that belonged to 6 genera and 4 families by morphological methods and gained 33 CO I gene sequences of polychaete at the length of 680 bp to 930 bp. The result of sequence comparion that included those from GeneBank and BOLD(http://www.barcodinglife.org) is almost in accordance with the morphological idetification. Seven squences of Perinereis wilsoni and 3 squences of Marphysa sanguinea have not been available in BOLD. The sequence of our samples named Halosydna brevisetos is merely in 88% similarity with the sequence on GeneBank. Based on Kimura 2-Parameter method calculated with CO I gene sequence data, the average intraspecies distance is 2.11%, while the distance among species with genus is 28.5%. The gap between the distance of intraspecies and interspecies illustrated that the CO I DNA sequence can be used for barcodes of polychaete. In addition, we designed a pair of primers for amplifing CO I of polychaete with high A+T on sequences.