Widespread genetic similarity between Northwest Atlantic populations of the horse mussel, Modiolus modiolus

Effective conservation planning relies on understanding population connectivity which can be informed by genomic data. This is particularly important for sessile species like the horse mussel (Modiolus modiolus), a key habitat-forming species and conservation priority in Atlantic Canada), yet little genomic information is available to describe horse mussel connectivity patterns. We used more than 8000 restriction-site associated DNA sequencing-derived single nucleotide polymorphisms and a panel of 8 microsatellites to examine genomic connectivity among horse mussel populations in the Bay of Fundy, along the Scotian Shelf, and in the broader northwestern Atlantic extending to Newfoundland. Despite phenotypic differences between sampling locations, we found an overall lack of genetic diversity and population structure in horse mussels in the Northwest Atlantic Ocean. All sampled locations had low heterozygosity, very low FST, elevated inbreeding coefficients, and deviated from Hardy-Weinberg Equilibrium, highlighting generally low genetic diversity across all metrics. Principal components analysis, Admixture analysis, pairwise FST calculations, and analysis of outlier loci (potentially under selection) all showed no independent genomic clusters within the data, and an analysis of molecular variance showed that less than 1% of the variation within the SNP dataset was found between sampling locations. Our results suggest that connectivity is high among horse mussel populations in the Northwest Atlantic, and coupled with large effective population sizes, this has resulted in minimal genomic divergence across the region. These results can inform conservation design considerations in the Bay of Fundy and support further integration into the broader regional conservation network.

Cite this data as: Van Wyngaarden, Mallory et al. (2024). Widespread genetic similarity between Northwest Atlantic populations of the horse mussel, Modiolus modiolus. Published: May 2025. Coastal Ecosystem Science Division, Maritimes Region, Fisheries and Oceans Canada, Dartmouth, NS.

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• Population genetics of unfiltered SNPs (Single...ZIP
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• Population genetics of microsatellitesZIP
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• Environment
• Genetics
• Genomics
• Marine Conservation Target
• Marine conservation areas
• Microsatellites
• Modiolus modiolus
• Nature and Environment
• Northwest Atlantic...
• Oceans
• Science and Technology
• Single nucleotide...

Additional Info

• Maturity Level 1 (54%)
• Maturity Level 2 (38%)
• Maturity Level 3 (0%)
• Maturity Level 4 (0%)
• Maturity Level 5 (0%)
• Maturity Level 6 (0%)

Field	Value
Last Updated	October 20, 2025, 02:32 (UTC)
Created	October 20, 2025, 02:32 (UTC)
Domain / Topic Domain or topic of the dataset being cataloged.	Biota, Environment, Oceans
Title Title for the Dataset.	Widespread genetic similarity between Northwest Atlantic populations of the horse mussel, Modiolus modiolus
Description A description of the dataset.	Effective conservation planning relies on understanding population connectivity which can be informed by genomic data. This is particularly important for sessile species like the horse mussel (Modiolus modiolus), a key habitat-forming species and conservation priority in Atlantic Canada), yet little genomic information is available to describe horse mussel connectivity patterns. We used more than 8000 restriction-site associated DNA sequencing-derived single nucleotide polymorphisms and a panel of 8 microsatellites to examine genomic connectivity among horse mussel populations in the Bay of Fundy, along the Scotian Shelf, and in the broader northwestern Atlantic extending to Newfoundland. Despite phenotypic differences between sampling locations, we found an overall lack of genetic diversity and population structure in horse mussels in the Northwest Atlantic Ocean. All sampled locations had low heterozygosity, very low FST, elevated inbreeding coefficients, and deviated from Hardy-Weinberg Equilibrium, highlighting generally low genetic diversity across all metrics. Principal components analysis, Admixture analysis, pairwise FST calculations, and analysis of outlier loci (potentially under selection) all showed no independent genomic clusters within the data, and an analysis of molecular variance showed that less than 1% of the variation within the SNP dataset was found between sampling locations. Our results suggest that connectivity is high among horse mussel populations in the Northwest Atlantic, and coupled with large effective population sizes, this has resulted in minimal genomic divergence across the region. These results can inform conservation design considerations in the Bay of Fundy and support further integration into the broader regional conservation network. Cite this data as: Van Wyngaarden, Mallory et al. (2024). Widespread genetic similarity between Northwest Atlantic populations of the horse mussel, Modiolus modiolus. Published: May 2025. Coastal Ecosystem Science Division, Maritimes Region, Fisheries and Oceans Canada, Dartmouth, NS.
Tags / Keywords Keywords/tags categorizing the dataset.	Environment Genetics Genomics Marine Conservation Target Marine conservation areas Microsatellites Modiolus modiolus Nature and Environment Northwest Atlantic... Oceans Science and Technology Single nucleotide...
Format (CSV, XLS, TXT, PDF, etc) File format of the dataset.
Dataset Size Dataset size in megabytes.
Metadata Identifier Metadata identifier – can be used as the unique identifier for catalogue entry
Published Date Published date of the dataset.	2025-05-16
Time Period Data Span (start date) Start date of the data in the dataset.
Time Period Data Span (end date) End date of time data in the dataset.
GeoSpatial Area Data Span A spatial region or named place the dataset covers.

Field	Value
Access category Type of access granted for the dataset (open, closed, service, etc).
License License used to access the dataset.	Open Government Licence - Canada
Limits on use Limits on use of data.
Location Location of the dataset.	https://open.canada.ca/data/en/dataset/cc3e54d1-354a-4b03-8188-db64a79b7491
Data Service Data service for accessing a dataset.
Owner Owner of the dataset.	Fisheries and Oceans Canada | Pêches et Océans Canada
Contact Point Who to contact regarding access?	Government of Canada; Fisheries and Oceans Canada; Coastal Ecosystem Science Division (CESD), [email protected]
Contact Point Email The email to contact regarding access?
Publisher Publisher of the dataset.
Publisher Email Email of the publisher.	[email protected]
Author Author of the dataset.
Author Email Email of the author.
Accessed At Date the data and metadata was accessed.

Field	Value
Identifier Unique identifier for the dataset.
Language Language(s) of the dataset
Link to dataset description A URL to an external document describing the dataset.
Persistent Identifier Data is identified by a persistent identifier.
Globally Unique Identifier Data is identified by a persistent and globally unique identifier.
Contains data about individuals Does the data hold data about individuals?
Contains data about identifiable individuals Does the data hold identifiable data about individual?
Contains Indigenous Data Does the data hold data about Indigenous communities?
Portal Type Platform type of the source portal.

Field	Value
Version Version of the datatset	None
Source Source of the dataset.	None
Version notes Version notes about the dataset.
Is version of another dataset Link to dataset that it is a version of.
Other versions Link to datasets that are versions of it.
Provenance Text Provenance Text of the data.
Provenance URL Provenance URL of the data.
Temporal resolution Describes how granular the date/time data in the dataset is.
GeoSpatial resolution in meters Describes how granular (in meters) geospatial data is in the dataset.
GeoSpatial resolution (in regions) Describes how granular (in regions) geospatial data is in the dataset.

Field	Value
Indigenous Community Permission Who holds the Indigenous Community Permission. Who to contact regarding access to a dataset that has data about Indigenous communities.
Community Permission Community permission (who gave permission).
The Indigenous communities the dataset is about Indigenous communities from which data is derived.

Field	Value
Number of data rows If tabular dataset, total number of rows.
Number of data columns If tabular dataset, total number of unique columns.
Number of data cells If tabular dataset, total number of cells with data.
Number of data relations If RDF dataset, total number of triples.
Number of entities If RDF dataset, total number of entities.
Number of data properties If RDF dataset, total number of unique properties used by the triples.
Data quality Describes the quality of the data in the dataset.
Metric for data quality A metric used to measure the quality of the data, such as missing values or invalid formats.

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