Introgressive hybridisation between two widespread sharks in the east Pacific region

Diana A Pazmiño; Lynne van Herderden; Colin A Simpfendorfer; Claudia Junge; Stephen C Donnellan; E Mauricio Hoyos-Padilla; Clinton A J Duffy; Charlie Huveneers; Bronwyn M Gillanders; Paul A Butcher; Gregory E Maes

doi:10.1016/j.ympev.2019.04.013

Introgressive hybridisation between two widespread sharks in the east Pacific region

Mol Phylogenet Evol. 2019 Jul:136:119-127. doi: 10.1016/j.ympev.2019.04.013. Epub 2019 Apr 11.

Affiliations

¹ Galápagos Science Center, Universidad San Francisco de Quito, Isla San Cristóbal, Galápagos 200150, Ecuador; Centre for Sustainable Tropical Fisheries and Aquaculture, College of Science and Engineering, James Cook University, Townsville, 4811 QLD, Australia; Comparative Genomics Centre, College of Science and Engineering, James Cook University, Townsville, 4811 QLD, Australia. Electronic address: dapazmino@usfq.edu.ec.
² Centre for Sustainable Tropical Fisheries and Aquaculture, College of Science and Engineering, James Cook University, Townsville, 4811 QLD, Australia; Comparative Genomics Centre, College of Science and Engineering, James Cook University, Townsville, 4811 QLD, Australia.
³ Centre for Sustainable Tropical Fisheries and Aquaculture, College of Science and Engineering, James Cook University, Townsville, 4811 QLD, Australia.
⁴ School of Biological Sciences and Environment Institute, The University of Adelaide, SA 5005, Australia; Havforskningsinstituttet (Institute of Marine Research, IMR), Tromsø, Norway.
⁵ School of Biological Sciences and Environment Institute, The University of Adelaide, SA 5005, Australia; South Australian Museum, North Terrace, Adelaide 5000, Australia.
⁶ Pelagios-Kakunjá A.C., Sinaloa 1540, La Paz, Baja California Sur CP 23020, Mexico.
⁷ Auckland War Memorial Museum, The Domain, Auckland, New Zealand; Department of Conservation, Private Bag 68908, Newton, Auckland 1145, New Zealand.
⁸ College of Science and Engineering, Flinders University, Adelaide, 5042 SA, Australia.
⁹ School of Biological Sciences and Environment Institute, The University of Adelaide, SA 5005, Australia.
¹⁰ New South Wales Department of Primary Industries, National Marine Science Centre, Coffs Harbour, 2450 NSW, Australia.
¹¹ Centre for Sustainable Tropical Fisheries and Aquaculture, College of Science and Engineering, James Cook University, Townsville, 4811 QLD, Australia; Comparative Genomics Centre, College of Science and Engineering, James Cook University, Townsville, 4811 QLD, Australia; Laboratory of Biodiversity and Evolutionary Genomics, University of Leuven, B-3000 Leuven, Belgium; Laboratory for Cytogenetics and Genome Research, Center for Human Genetics, Genomics Core, KU Leuven, 3000 Leuven, Belgium.

PMID: 30981810
DOI: 10.1016/j.ympev.2019.04.013

Abstract

With just a handful of documented cases of hybridisation in cartilaginous fishes, shark hybridisation remains poorly investigated. Small amounts of admixture have been detected between Galapagos (Carcharhinus galapagensis) and dusky (Carcharhinus obscurus) sharks previously, generating a hypothesis of ongoing hybridisation. We sampled a large number of individuals from areas where the species co-occur (contact zones) across the Pacific Ocean and used both mitochondrial and nuclear-encoded SNPs to examine genetic admixture and introgression between the two species. Using empirical analytical approaches and simulations, we first developed a set of 1873 highly informative SNPs for these two species to evaluate the degree of admixture between them. Overall, results indicate a high discriminatory power of nuclear SNPs (F_ST = 0.47, p < 0.05) between the two species, unlike mitochondrial DNA (Φ_ST = 0.00 p > 0.05), which failed to differentiate these species. We identified four hybrid individuals (∼1%) and detected bi-directional introgression between C. galapagensis and C. obscurus in the Gulf of California along the east Pacific coast of the Americas. We emphasize the importance of including a combination of mtDNA and diagnostic nuclear markers to properly assess species identification, detect patterns of hybridisation, and better inform management and conservation of these sharks, especially given the morphological similarities within the genus Carcharhinus.

Keywords: Elasmobranchs; Hybridisation; Introgression; Misidentification; Single nucleotide polymorphisms.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Bayes Theorem
California
Computer Simulation
DNA, Mitochondrial / genetics
Geography
Hybridization, Genetic*
Mitochondria / genetics
Pacific Ocean
Phylogeny
Polymorphism, Single Nucleotide / genetics
Sample Size
Sharks / genetics*

Substances

DNA, Mitochondrial