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Genetic differentiation and phylogeography of Mediterranean-North Eastern Atlantic blue shark (Prionace glauca, L. 1758) using mitochondrial DNA : panmixia or complex stock structure?

Leone, A; Urso, I; Damalas, D; Martinsohn, J; Zanzi, A; Mariani, S; Sperone, E; Micarelli, P; Garibaldi, F; Megalofonou, P; Bargelloni, L; Franch, R; Macias, D; Prodöhl, P; Fitzpatrick, S; Stagioni, M; Tinti, F; Cariani, A

Genetic differentiation and phylogeography of Mediterranean-North Eastern Atlantic blue shark (Prionace glauca, L. 1758) using mitochondrial DNA : panmixia or complex stock structure? Thumbnail


Authors

A Leone

I Urso

D Damalas

J Martinsohn

A Zanzi

S Mariani

E Sperone

P Micarelli

F Garibaldi

P Megalofonou

L Bargelloni

R Franch

D Macias

P Prodöhl

S Fitzpatrick

M Stagioni

F Tinti

A Cariani



Abstract

Background
The blue shark (Prionace glauca, Linnaeus 1758) is one of the most abundant epipelagic shark inhabiting all the oceans except the poles, including the Mediterranean Sea, but its genetic structure has not been confirmed at basin and interoceanic distances. Past tagging programs in the Atlantic Ocean failed to find evidence of migration of blue sharks between the Mediterranean and the adjacent Atlantic, despite the extreme vagility of the species. Although the high rate of by-catch in the Mediterranean basin, to date no genetic study on Mediterranean blue shark was carried out, which constitutes a significant knowledge gap, considering that this population is classified as “Critically Endangered”, unlike its open-ocean counterpart.
Methods
Blue shark phylogeography and demography in the Mediterranean Sea and North-Eastern Atlantic Ocean were inferred using two mitochondrial genes (Cytb and control region) amplified from 207 and 170 individuals respectively, collected from six localities across the Mediterranean and two from the North-Eastern Atlantic.
Results
Although no obvious pattern of geographical differentiation was apparent from the haplotype network, Φst analyses indicated significant genetic structure among four geographical groups. Demographic analyses suggest that these populations have experienced a constant population expansion in the last 0.4–0.1 million of years.
Discussion
The weak, but significant, differences in Mediterranean and adjacent North-eastern Atlantic blue sharks revealed a complex phylogeographic structure, which appears to reject the assumption of panmixia across the study area, but also supports a certain degree of population connectivity across the Strait of Gibraltar, despite the lack of evidence of migratory movements observed by tagging data. Analyses of spatial genetic structure in relation to sex-ratio and size could indicate some level of sex/stage biased migratory behaviour.

Citation

Leone, A., Urso, I., Damalas, D., Martinsohn, J., Zanzi, A., Mariani, S., …Cariani, A. (2017). Genetic differentiation and phylogeography of Mediterranean-North Eastern Atlantic blue shark (Prionace glauca, L. 1758) using mitochondrial DNA : panmixia or complex stock structure?. PeerJ, 5, e4112. https://doi.org/10.7717/peerj.4112

Journal Article Type Article
Acceptance Date Nov 9, 2017
Publication Date Dec 6, 2017
Deposit Date Dec 11, 2017
Publicly Available Date Dec 11, 2017
Journal PeerJ
Publisher PeerJ
Volume 5
Pages e4112
DOI https://doi.org/10.7717/peerj.4112
Keywords General Biochemistry, Genetics and Molecular Biology, General Neuroscience, General Agricultural and Biological Sciences, General Medicine
Publisher URL http://dx.doi.org/10.7717/peerj.4112
Related Public URLs https://peerj.com/
Additional Information Funders : European Commission, Joint Research Center (JRC);University of Bologna, Italy
Projects : MEDBLUESGEN—A population genetic study on Mediterranean blue shark for stock identification and conservation
Grant Number: JRC/IPR/2014/G.3/0023/NC and Contract number 259844

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