Understanding what we cannot see: a genetic approach to the mating system of the Southern Lanternshark, Etmopterus granu
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ORIGINAL PAPER
Understanding what we cannot see: a genetic approach to the mating system of the Southern Lanternshark, Etmopterus granulosus Melissa C. Nehmens1 · Kevin A. Feldheim2 · David A. Ebert1,3,4 Received: 9 November 2019 / Accepted: 3 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The Southern Lanternshark, Etmopterus granulosus, is a deep-sea shark commonly found throughout the oceans of the southern hemisphere and frequently caught as bycatch in deep-sea fisheries. Despite its common occurrence, little is known about this species’ life history and reproductive biology. Here, we develop species-specific microsatellite markers to better understand the mating system of E. granulosus. Eighteen litters were opportunistically collected as bycatch along the Madagascar Ridge, Walter’s Shoal, and Southern Indian Ocean Ridge. Novel microsatellite loci were used to test for the presence and frequency of multiple paternity and morphological data were obtained from mothers to examine whether litter size or polyandry correlated with female size. Multiple paternity was found in 33% of litters, but no significant relationship between either litter size or the occurrence of polyandry and female size was found, although some adult individuals were found to have high internal relatedness. The frequency of multiple paternity in conjunction with these other factors could be indicators of mating between relatives or a reduction in population size due to fishing pressure.
Introduction The use of genetic techniques in conjunction with observable behavior has revolutionized our understanding of mating systems; a classic example of which is the ornithological paradigm of monogamy (Lack 1968) that was dismantled with the use of DNA analysis (Westneat et al. 1990; Dixon et al. 1994; Birkhead and Møller 1995). One of the first studies to employ DNA to examine the mating system of a shark examined only a single litter (Feldheim et al. 2001), and Responsible Editor: O. Puebla. Reviewed by undisclosed experts. * Melissa C. Nehmens [email protected] 1
Moss Landing Marine Laboratories, Pacific Shark Research Center, 8272 Moss Landing Rd., Moss Landing, CA 95039, USA
2
Pritzker Laboratory for Molecular Systematics and Evolution, Field Museum, 1400 S. Lake Shore Drive, Chicago, IL, USA
3
Department of Ichthyology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA 94118, USA
4
South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa
despite advances in the use of genetic techniques to examine population structure, reproduction, and conservation genetics (Dudgeon et al. 2012), the understanding of mating systems within elasmobranchs remains limited. The majority of mating system studies on elasmobranchs have employed microsatellite markers, highly polymorphic short tandem repeats that allow researchers to obtain a genetic fingerprint of each individual. Few elasmobranch studies have large enough sample sizes for an in
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