In the intimacy of the darkness: Genetic polyandry in deep‐sea luminescent lanternsharks Etmopterus spinax and Etmopterus molleri (Squaliformes, Etmopteridae)

Abstract

Multiple paternity seems common within elasmobranchs. Focusing on two deep-sea shark species, the velvet belly lanternshark (Etmopterus spinax) and the slendertail lanternshark (Etmopterus molleri) we inferred the paternity in 31 E. spinax litters from Norway (three to 18 embryos per litter) and six E. molleri litters from Japan (three to six embryos), using 21 and 10 specific microsatellites, respectively. At least two E. spinax litters were sired from multiple fathers each, with highly variable paternal skew (1:1 to 9:1). Conversely, no clear signal of genetic polyandry was found in E. molleri.

From extraocular photoreception to pigment movement regulation: a new control mechanism of the lanternshark luminescence

“…Twenty-four adult specimens of E. spinax were caught alive during a field session in May 2018 by longlines lowered at 220 m depth in the Raunefjord, Norway (60°169′ N; 05°089′ E) 44,48,71,72,121 . Specimens were directly placed in a 1 m 3 tank filled with running fresh seawater (6 °C) and kept in a dark cold room at Espegrend Marine Station (Bergen University, Norway) 44,48,71,72,121 . Animal procedures were conducted in compliance with the Belgian national guidelines and in agreement with the European directive 2010/63/UE, under the approval of the Animal Ethics Committee of the Université catholique de Louvain in Louvain-la-Neuve.…”

“…Animal procedures were conducted in compliance with the Belgian national guidelines and in agreement with the European directive 2010/63/UE, under the approval of the Animal Ethics Committee of the Université catholique de Louvain in Louvain-la-Neuve. Sharks were treated according to the European regulation for animal research handling and euthanized following the local rules for experimental vertebrate care 73,76,77,121 . Sharks were sexed, measured and weighed before experimentation took place.…”

First evidence of multiple paternity and hybridisation in Australian sawsharks

“…However, analysis of C. galapagensis comes with the caveat that only one litter was available for study (Daly-Engel et al 2006). Furthermore, not all orders have been examined (Lamarca et al 2020), with many groups such as rays (Torres et al 2022) and deep-sea sharks (Duchatelet et al 2020;Nehmens et al 2020) being under-represented in the literature or having yet to be investigated. Addressing this knowledge gap in a wider variety of species will enable a more complete understanding of the ubiquity of multiple paternity among elasmobranchs.…”

“…Some species exhibit low levels of polyandry (<35%), with the majority of litters being sired by a single male (genetic monogamy; e.g. Chapman et al 2004;Daly-Engel et al 2010;Boomer et al 2013;Duchatelet et al 2020), whereas in other species singly sired litters are relatively rare (>85% of litters sired by more than one male; e.g. Feldheim et al 2004;Griffiths et al 2012;Lyons et al 2017).…”

The ups and downs of Atlantic halibut spawning

“…Despite this, we have a detailed understanding of many deep‐water species due to the application of multiple methodologies and the forensic approaches of researchers. Just in the past few years discoveries have been made around the trophic ecology of multiple deep sea shark off the west coast of Portugal thanks to stable isotopes (Graça Aranha et al, 2023), new records of ten deep sea teleosts have been made off north‐eastern Brazil thanks to research trawls (Mincarone et al, 2022), and, multiple paternity was discovered in the deep sea velvet belly lanternshark thanks to molecular genetics (Duchatelet et al, 2020).…”