Phylogenomic Study of 36 Polychaete Species in a North Norwegian Fjord

Annelida, the segmented worms, is a highly diverse animal phylum that includes over 15,000 described species. Polychaeta is one of the major groups of Annelida, also called bristle worms. The vast majority of them are marine, including more than 11,000 described species. In this thesis, we created a new bioinformatics pipeline which produced I) 26 novel COI sequences with length between 913bp and 3391bp, II) 12 novel nearly completed mitochondrial genomes with length between 12331bp and 17681bp and III) 9 novel partial mitochondrial genomes. Among the 12 nearly completed mitochondrial genomes, we find out IV) 2 novel Annelida mitochondrial gene orders. Furthermore, we used 1) single gene: COI, 2) multiple genes from partial mitochondrial genomes and 3) nearly completed mitochondrial genomes to perform the phylogenomic study for Polychaete phylogeny. The results show that COI sequences are probably not the best genetic marker whereas partial or nearly completed mitochondrial genomes have high potentials to resolve the phylogenetic relationships among Polychaetes. Moreover, we propose the phylogenetic relationships among Polychaetes are 1) most of the species that come from same Order/Suborder/Family form monophyletic clades, 2) the species that come from different Order/Suborder/Family, evolutionary direction from I) Ampharetidae  Spionidae  Orbiniidae  Aphroditiformia; II) Ampharetidae  Nephtyidae; III) Ampharetidae  Maldanidae  Aphroditiformia. Owenia fusiformis is the basal group with high bootstrap support 1000. Finally, Order Sabellida, Family Ampharetidae and Orbiniidae, are probably the important taxa during Polychaete phylogeny that future study could focus more on.