Global Mitochondrial DNA Phylogeography and Population Structure of the Silky Shark, Carcharhinus falciformis

Authors

Christopher R. Clarke, Danah Divers Marine Research Facility
Stephen A. Karl, University of Hawaii - Manoa
Rebekah L. Horn, Nova Southeastern University
Andrea M. Bernard, Nova Southeastern UniversityFollow
James S. Lea, Danah Divers Marine Research Facility
Fabio H.V. Hazin, Universidade Federal Rural de Pernambuco - Brazil
Paulo A. Prodohl, Queen's University Belfast - United Kingdom
Mahmood S. Shivji, Nova Southeastern UniversityFollow

ResearcherID

G-4080-2013

Document Type

Article

Publication Title

Marine Biology

ISSN

0025-3162

Publication Date

5-1-2015

Abstract

Globally, sharks are under enormous pressure from fishing efforts. One such species is the silky shark, Carcharhinus falciformis, which occurs in all the Earth’s tropical oceans and is captured in large numbers in pelagic fisheries. Regionally, the silky shark is listed as Vulnerable to Near Threatened by the International Union for the Conservation of Nature due to high levels of direct and bycatch exploitation. Despite major conservation concerns about this species, little is known about its genetic status and level of demographic or evolutionary connectivity among its regional distributions. We report a genetic assessment of silky sharks sampled across a major portion of the species’ global range. We sequenced the complete mitochondrial DNA control region from 276 individuals taken from the western Atlantic and Indo-Pacific Oceans and the Red Sea. Overall, haplotype and nucleotide diversities were relatively large (0.93 ± 0.01 and 0.61 ± 0.32 %, respectively). Nucleotide diversity in Indo-Pacific sharks, however, was significantly lower and about half that in Atlantic sharks. Strong phylogeographic partitioning occurred between ocean basins. Furthermore, shallow but significant pairwise statistical differentiation occurred among most regional samples within the Indo-Pacific, but not the western Atlantic. Overall, at least five mitochondrial DNA populations of silky sharks were identified globally. Despite historically large population sizes, silky sharks appear to be isolated on relatively small spatial scales, at least in the Indo-Pacific, indicating that conservation and management efforts will need to be exerted at relatively small scales in a pelagic and highly vagile species.

DOI

10.1007/s00227-015-2636-6

Volume

162

Issue

5

First Page

945

Last Page

955

Comments

©Springer-Verlag Berlin Heidelberg 2015

NSUWorks Citation

Christopher R. Clarke, Stephen A. Karl, Rebekah L. Horn, Andrea M. Bernard, James S. Lea, Fabio H.V. Hazin, Paulo A. Prodohl, and Mahmood S. Shivji. 2015. Global Mitochondrial DNA Phylogeography and Population Structure of the Silky Shark, Carcharhinus falciformis .Marine Biology , (5) : 945 -955. https://nsuworks.nova.edu/occ_facarticles/480.