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RESEARCH ARTICLE (Open Access)

First evidence of multiple paternity and hybridisation in Australian sawsharks

Ryan J. Nevatte https://orcid.org/0000-0002-1019-0544 A * , Jane E. Williamson https://orcid.org/0000-0003-3627-4508 A and Michael R. Gillings https://orcid.org/0000-0002-4043-4351 A B
+ Author Affiliations
- Author Affiliations

A School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109, Australia.

B ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW 2109, Australia.

* Correspondence to: rjnevatte@gmail.com

Handling Editor: Bradley Wetherbee

Marine and Freshwater Research 74(7) 586-600 https://doi.org/10.1071/MF22234
Submitted: 14 October 2022  Accepted: 27 March 2023   Published: 19 April 2023

© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Context: Knowledge of sawshark reproductive biology is limited to general parameters such as reproductive mode and litter size. The mating system is currently unknown.

Aim: To test for multiple paternity in the common (Pristiophorus cirratus) and southern (Pristiophorus nudipinnis) sawshark and investigate the occurrence of hybridisation between these two species.

Methods: Pups from a single litter of each species and an adult P. nudipinnis displaying mismatches in its morphology and mitochondrial DNA were genotyped with nuclear single-nucleotide polymorphisms (SNPs). Multiple paternity was assessed using pairwise relatedness and sibship analysis, and hybridisation was examined using three approaches (principal-component analysis, admixture analysis and clustering with NewHybrids).

Key results: Multiple paternity was detected in both species, with two males siring the seven-pup litter in P. cirratus and two males siring the two-pup litter in P. nudipinnis. Hybridisation between the two species was also confirmed, with the mismatched adult identified as a first-generation hybrid.

Conclusions: The mating system of sawsharks involves polyandry, and hybridisation between the two co-occurring Australian species is possible.

Implications: These results provide new information on sawshark reproductive biology and highlight the need for combined use of mitochondrial and nuclear markers in future genetic studies involving these species.

Keywords: elasmobranch, genetics, hybrid, mating system, polyandry, pristiophorid, reproductive biology, single nucleotide polymorphisms.


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