First records of multiple paternity in the softnose skates, family Arhynchobatidae: Sympterygia acuta as a case study

Abstract

In elasmobranchs, polyandry resulting inmultiple paternity is widespread, though more fre-quently studied in viviparous than oviparous species.Because mating system studies improve understand-ing of species’ resilience and population dynamics,we examined multiple paternity using SNP analysisin the oviparous skate Sympterygia acuta, endemicto the coastal waters of the Southwestern Atlantic.Under controlled aquarium conditions, three clutchesfrom different females maintained both in the absence and presence of males were analysed, consider -ing that elasmobranch females can store sperm andthat sperm storage has been previously suggestedfor this species. Multiple paternity was confirmed inat least two litters of S. acuta using three analyticalapproaches (CERVUS, COLONY, and COANCES-TRY). In two litters, pairs of egg cases laid simulta-neously were fertilized by different males; the nextpair by the same male and the following pair by dif-ferent males. This fertilization pattern may indicatethat females store sperm from a male in only oneoviducal gland or use each gland independently. Sireskew was also observed in at least one clutch. As thefirst report for the Arhynchobatidae family and onlythe third study assessing multiple paternity in an oviparous elasmobranch, these findings enhance ourunderstanding of reproductive strategies and matingsystems in elasmobranchs.