Genome-wide SNPs reveal low effective population size within confined management units of the highly vagile Galapagos shark (Carcharhinus galapagensis)

Pazmiño, Diana A., Maes, Gregory E., Simpfendorfer, Colin A., Salinas-de-León, Pelayo, and van Herwerden, Lynne (2017) Genome-wide SNPs reveal low effective population size within confined management units of the highly vagile Galapagos shark (Carcharhinus galapagensis). Conservation Genetics, 18 (5). pp. 1151-1163.

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Abstract

The Galapagos shark (Carcharhinus galapagensis) is one of over thirty shark species inhabiting the Galápagos Marine Reserve (GMR), where it is a priority species for conservation. Identifying stock structure and effective population size for species-specific management and effective conservation of this top predator is important. We examined stock structure, connectivity and effective population size of Galapagos sharks among GMR locations using genome-wide neutral Single Nucleotide Polymorphism (8103 SNP) and mtDNA markers. Potential historical gene flow and/or sex-biased dispersal were also examined using the mitochondrial control region (997 bp). Cluster analyses of neutral SNPs revealed two differentiated stocks in the GMR—a western (Isabela Island) and eastern (San Cristóbal and Santa Cruz Islands) stock. Effective population size (Ne) estimates of approximately 200 suggest these populations are susceptible to ongoing natural and anthropogenic stressors and are of concern for long term resilience of populations. Mitochondrial DNA failed to identify distinct stocks, with AMOVA analyses indicating most genetic variation occurs within, rather than among locations. This pattern of genome-wide nuclear (but not mtDNA) discrimination among neighbouring islands either points to possible sex-biased dispersal by females or identifies limitations of the single organelle mtDNA marker at such small spatial scales. Regional differences across the archipelago or in behaviour may be implicated in the observed population structure. Further research focusing on a larger, Pacific wide analysis of population connectivity and effective population size at a broader spatial scale is required, to estimate the extent of discreteness and potential local adaptation. Potential adaptive units (AUs) in Galapagos sharks should ultimately be identified to leverage adaptive management and fisheries forensics applications.

Item ID: 51053
Item Type: Article (Research - C1)
ISSN: 1566-0621
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A version of this publication was included as Chapter 2 of the following PhD thesis: Pazmiño Jaramillo, Diana Alexandra (2017) Population genomics informs conservation and management of the Galapagos shark (Carcharhinus galapagensis) at local, regional and oceanic scales. PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: Ecuadorian Government (EG), EcoCiencia Foundation (EC)
Projects and Grants: EG National Secretary of Higher Education, Science and Technology (SENESCYT) scholarship, EC EcoFondo grant
Date Deposited: 11 Oct 2017 00:25
FoR Codes: 06 BIOLOGICAL SCIENCES > 0604 Genetics > 060411 Population, Ecological and Evolutionary Genetics @ 80%
07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070402 Aquatic Ecosystem Studies and Stock Assessment @ 20%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 100%
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