Abstract
Elasmobranchs display various reproductive modes, which have been key to their evolutionary success. In recent decades there has been a rise in the number of reported cases of foetal abnormalities including fertilised, double-embryos held within one egg capsule, hereafter referred to as twins. Previously, the occurrences of twin egg cases have been reported in two batoid and one shark species. We report the first cases of twins in three species of oviparous elasmobranchs: the undulate ray (Raja undulata), the nursehound (Scyliorhinus stellaris), and the small-spotted catshark (Scyliorhinus canicula). We investigated the genetic relationships between the twins in S. stellaris, and S. canicula using microsatellite markers. Whilst the S. stellaris twins displayed the same genotypes, we found that the S. canicula twin individuals arose through heteropaternal superfecundation. This is the first reported incidence of such a paternity in elasmobranchs. The relationship between environmental change and reproductive strategy in elasmobranchs is unclear and further research is needed to determine its effect on the prevalence and mechanisms of formation of elasmobranch twins.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Elasmobranchii / embryology*
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Elasmobranchii / genetics
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Elasmobranchii / physiology
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Female
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Genotype
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Microsatellite Repeats / genetics*
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Oviparity / genetics*
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Ovum / physiology*
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Twins / genetics*
Grants and funding
The project was funded by the Higher Education Innovation Fund through The University of Manchester’s Knowledge and Innovation Hub for Environmental Stability (HAS), as part of the Natural Environmental Research Council Doctoral Training Program (SAH) and by the Ministry of Higher Education (KPT, Malaysia) (SMM). Merlin Entertainments, Sea Life, Weymouth Adventures Park provided support in the form of salaries for author JDH but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. All authors declare that there are no significant competing professional or personal interests that might have influenced the performance or presentation of the work described in this manuscript. Merlin Entertainments, Sea Life, Weymouth Adventures Park that provided support in the form of salaries for author JDH does not alter our adherence to PLOS ONE policies on sharing data and materials.