Strong trans-Pacific break and local conservation units in the Galapagos shark (Carcharhinus galapagensis) revealed by genome-wide cytonuclear markers

Pazmiño, Diana A., Maes, Gregory E., Green, Madeline E., Simpfendorfer, Colin A., Hoyos-Padilla, E. Mauricio, Duffy, Clinton J.A., Meyer, Carl G., Kerwath, Sven E., Salinas-de-Leon, Pelayo, and van Herwerden, Lynne (2018) Strong trans-Pacific break and local conservation units in the Galapagos shark (Carcharhinus galapagensis) revealed by genome-wide cytonuclear markers. Heredity, 120. pp. 407-421.

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Abstract

The application of genome-wide cytonuclear molecular data to identify management and adaptive units at various spatio-temporal levels is particularly important for overharvested large predatory organisms, often characterized by smaller, localized populations. Despite being "near threatened", current understanding of habitat use and population structure of Carcharhinus galapagensis is limited to specific areas within its distribution. We evaluated population structure and connectivity across the Pacific Ocean using genome-wide single-nucleotide polymorphisms (similar to 7200 SNPs) and mitochondrial control region sequences (945 bp) for 229 individuals. Neutral SNPs defined at least two genetically discrete geographic groups: an East Tropical Pacific (Mexico, east and west Galapagos Islands), and another central-west Pacific (Lord Howe Island, Middleton Reef, Norfolk Island, Elizabeth Reef, Kermadec, Hawaii and Southern Africa). More fine-grade population structure was suggested using outlier SNPs: west Pacific, Hawaii, Mexico, and Galapagos. Consistently, mtDNA pairwise Phi(ST) defined three regional stocks: east, central and west Pacific. Compared to neutral SNPs (F-ST = 0.023-0.035), mtDNA exhibited more divergence (Phi(ST) = 0.258-0.539) and high overall genetic diversity (h = 0.794 +/- 0.014; pi = 0.004 +/- 0.000), consistent with the longstanding eastern Pacific barrier between the east and central-west Pacific. Hawaiian and Southern African populations group within the west Pacific cluster. Effective population sizes were moderate/high for east/west populations (738 and 3421, respectively). Insights into the biology, connectivity, genetic diversity, and population demographics informs for improved conservation of this species, by delineating three to four conservation units across their Pacific distribution. Implementing such conservation management may be challenging, but is necessary to achieve long-term population resilience at basin and regional scales.

Item ID: 53568
Item Type: Article (Research - C1)
ISSN: 1365-2540
Funders: Ecuadorian Government (EG), African Coelacanth Ecosystem Programme (ACEP), New Zealand Department of Conservation, Pew Environment Group
Date Deposited: 09 May 2018 08:18
FoR Codes: 06 BIOLOGICAL SCIENCES > 0604 Genetics > 060411 Population, Ecological and Evolutionary Genetics @ 70%
06 BIOLOGICAL SCIENCES > 0604 Genetics > 060408 Genomics @ 30%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8302 Fisheries - Wild Caught > 830204 Wild Caught Fin Fish (excl. Tuna) @ 50%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 50%
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