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A tri-oceanic perspective: DNA barcoding reveals geographic structure and cryptic diversity in Canadian polychaetes
Christina M Carr1, Sarah M Hardy, Tanya M Brown
1Biodiversity Institute of Ontario, University of Guelph, Guelph, Ontario, Canada. carrc@uoguelph.ca
Plos One
|August 11, 2011
Summary
DNA barcoding reveals underestimated polychaete diversity in Canada. Genetic breaks between Pacific and Atlantic-Arctic lineages indicate long-term separation, partitioning Canadian fauna into two distinct groups.
Area of Science:
- Marine Biology
- Genetics
- Biodiversity Studies
Background:
- Polychaetes are dominant marine invertebrates, yet their diversity and distribution remain poorly understood.
- Many presumed widespread polychaete species comprise cryptic species complexes.
- Gene flow among Canadian polychaete populations across Atlantic, Arctic, and Pacific Oceans is largely untested.
Purpose of the Study:
- To compare morphological and molecular diversity estimates in Canadian polychaetes.
- To assess gene flow and connectivity patterns among populations across Canada's three oceans.
- To investigate the impact of historical events on current polychaete biogeography.
Main Methods:
- Mitochondrial cytochrome c oxidase I (COI) gene sequencing was used for 1876 specimens.
- Analysis included 333 provisional polychaete species.
- Genetic data were analyzed to estimate sequence divergence and population structure.
Main Results:
- Sequence variation revealed 40 times more divergence between species than within species.
- One quarter of recognized species contained divergent lineages, suggesting underestimated species richness.
- Significant genetic breaks were found between Pacific and Atlantic-Arctic lineages, indicating long-term separation and two distinct faunas.
Conclusions:
- DNA barcoding (COI sequencing) is effective for polychaete identification and discovering cryptic species.
- Geographic structuring suggests Pleistocene fragmentation increased Canadian polychaete diversity.
- Polychaete distribution patterns highlight historical separation and distinct faunal partitioning.
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