PS 35-175 - Population genomic analysis of the Atlantic Sea Cucumber (Cucumaria frondosa) from Atlantic Canada to Iceland

Tuesday, August 16, 2022

5:00 PM – 6:30 PM EDT

Located in: ESA Exhibit Hall

Presenting Author(s)

Matthew S. Penney, BSc (Hons), CBU

Graduate Student
Acadia University
Wolfville, Nova Scotia, Canada

Coauthor(s)

DS

Donald T. Stewart

Professor
Acadia University
Wolfville, Nova Scotia, Canada
AS

Aaron A. Shafer

Trent University, Ontario, Canada
TR

Timothy A. Rawlings

Cape Breton University
Sydney, Nova Scotia, Canada

Background/Question/Methods

The Atlantic Sea Cucumber (Cucumaria frondosa) is a commercially harvested lecithotrophic holothurian with a range spanning the North Atlantic and Arctic Oceans. It has a long dispersive larval stage which is distributed by ocean currents. To date, only a single mitochondrial gene sequence has been examined for this species in the North Atlantic, which may lack the resolution to detect higher resolution structuring in this species, and sampling in Nova Scotia specifically was sparse (n = 14). To examine higher resolution structure through Atlantic Canada and Iceland, Restriction Site-Associated DNA Sequencing (RADseq) was used to generate genomic libraries for 74 sea cucumber samples from four locations in Atlantic Canada and one in Iceland. RADseq libraries were demultiplexed and loci were assembled using the STACKS denovo_map.pl pipeline. Loci were filtered for minimum mean coverage, maximum missing data, and minimum Minor Allele Frequency (MAF) using VCFTools. Filtered loci were analyzed for Fst using the populations program in STACKS, clustering analysis was performed in STRUCTURE, and BayeScan was used to identify loci potentially under selection.

Results/Conclusions

A total of 9470 loci were identified post-filtering. Results showed that (1) Fst was higher across loci for Iceland relative to sites in Atlantic Canada, (2) clustering analysis is consistent with the hypothesis that Iceland is genetically distinct from populations in Atlantic Canada, and (3) six loci were identified as potentially under selection. There is also evidence of sub-structuring in Atlantic Canada based on genetic clustering. Differences between Iceland and Atlantic Canada based on Fst differences and genetic clusters can be informative for defining stocks in commercial fisheries. Loci under selection may be useful for Environmental Association Analysis (EAA) to examine selective pressures between populations.