David, Andrew A.; Cahill, Jordan. (2020). Tri-oceanic connectivity of the supposedly cosmopolitan polychaete, Harmothoe imbricata (Annelida: Polynoidae): insights from the COI marker. Marine Biology Research. 16(4): 256-264.
In this study, we investigated the global population genetic structure of the polychaete,
Harmothoe imbricata, to determine connectivity patterns within the species. We sequenced
the mtDNA marker, cytochrome c oxidase I (COI) from 29 specimens sampled across three
sites from the New England coast of the United States. These were supplemented with 145
archived sequences from GenBank and the Barcode of Life Database, representing 16 global
populations, which encompassed three broadly defined marine biogeographic regions: the
Atlantic, Pacific and Arctic. The resulting haplotype network and pairwise AMOVA results
showed marked structure across all the major biogeographic regions and also provides
evidence for cryptic diversity in the species. Haplotypes from Arctic populations were more
closely related to each other than those from the northwestern and northeastern Atlantic.
Two evolutionary divergent lineages were recovered from Los Angeles, California and
Manitoba, Canada. The highest genetic diversity was observed in the Arctic populations,
providing evidence for an Arctic origin for H. imbricata. While human-mediated introductions
may have likely contributed to some of the genetic patterns observed in this study, future
work should incorporate a nuclear DNA component which could shed more light on
contemporary movement of this species across large spatial scales.