Lack of multiple paternity in the oceanodromous tiger shark (Galeocerdo cuvier)

Abstract

Multiple paternity has been documented as a reproductive strategy in both viviparous and ovoviviparous elasmobranchs, leading to the assumption that multiple mating may be ubiquitous in these fishes. However, with the majority of studies conducted on coastal and nearshore elasmobranchs that often form mating aggregations, parallel studies on pelagic, semi-solitary species are lacking. The tiger shark (Galeocerdo cuvier) is a large pelagic shark that has an aplacental viviparous reproductive mode which is unique among the carcharhinids. A total of 112 pups from four pregnant sharks were genotyped at nine microsatellite loci to assess the possibility of multiple paternity or polyandrous behaviour by female tiger sharks. Only a single pup provided evidence of possible multiple paternity, but with only seven of the nine loci amplifying for this individual, results were inconclusive. In summary, it appears that the tiger sharks sampled in this study were genetically monogamous. These findings may have implications for the genetic diversity and future sustainability of this population.

Genetic population structure and demography of an apex predator, the tiger shark Galeocerdo cuvier

“…It is noteworthy that no known tiger shark nurseries have been identified in the Indo‐Pacific, leaving unanswered the hypothesis of female fidelity to coastal pupping areas. The tiger shark is also one of the few species for which multiple paternity (polyandry) has not been identified, although only eight litters in total have been investigated (Holmes et al., ; Pirog, Magalon, & Jaquemet, ). Yet, this behavior is hypothesized to be linked to philopatry and more structured populations (Chapman, Prodohl, Gelsleichter, Manire, & Shivji, ), and the predominance of monoandry in the tiger shark may be another indication pointing to an absence of female philopatry to specific nurseries.…”

Retrospective Genomics Suggests the Disappearance of a Tiger Shark (Galeocerdo Cuvier) Population Off South-Eastern Australia

“…Hawaiian Islands, tiger sharks seem to have a different pattern of migration depending on their sex, where females show partial migrations possibly related to reproductive purposes while males do not display such behaviour 46 . Further, the species also displays life history traits that are remarkably different to other elasmobranchs, such as only producing single-sired litters while other species employ multiple paternity as a mating strategy 52 . Females producing litters consisting of pups sired by different males is widely documented to increase the genetic quality of offspring, maintain genetic variation in a population, or increase effective population size 53,54 .…”

Multiple paternity in two populations of finetooth sharks (Carcharhinus isodon) with varying reproductive periodicity

“…Mobbing or crowding, which occurs when multiple males simultaneously attempt to coerce mating with a single female, has been observed in nurse sharks (Pratt & Carrier, 2001) and whitetip reef sharks (Whitney et al, 2004). By comparison, recent studies on multiple paternity in the tiger shark-a large, pelagic species in which aggregations have not been observed-showed an absence of MP, both in four litters from the east coast of Australia (Holmes et al, 2018) and four from TA B L E 2 Summary mating system statistics the western Indian Ocean (Pirog et al, 2020). Support for increased multiple mating among organisms that aggregate more densely can also be found among other taxa, such as sea turtles (for a review, see Lee et al, 2018).…”