Assessing multiple paternity in three commercially exploited shark species: Mustelus mustelus, Carcharhinus obscurus and Sphyrna lewini

Abstract

In this study, multiple paternity (MP) was investigated in three commercially important shark species, common smoothhound Mustelus mustelus, dusky shark Carcharhinus obscurus and scalloped hammerhead Sphyrna lewini occurring in southern Africa. Reduced marker panels of between five and six microsatellite loci were constructed for each species and used to genotype and assess the presence of MP in a total of 60 M. mustelus individuals from six litters, 90 C. obscurus individuals from 14 litters and 54 S. lewini individuals from 13 litters. Analysis in GERUD and COLONY revealed the presence of MP in all three species. Multiple paternities were observed in 67, 35 and 46% of the litters of M. mustelus, C. obscurus and S. lewini, with corresponding average sire size of 1·6, 1·4 and 2·0, respectively. The variation in the rate of MP among the three species is in accordance with previous studies whilst the comparatively high frequency of MP observed for M. mustelus, matches what has previously been reported for shark species demonstrating aggregation behaviour.

Reproductive biology, multiple paternity and polyandry of the bull shark Carcharhinus leucas

“…mean ± SE embryo L T = 27.80 ± 0.50 cm). Paternal skew was also observed in polyandrous litters of C. obscurus (Rossouw et al, 2016), as well as in the gummy shark Mustelus antarcticus Günther 1870 and the rig shark Mustelus lenticulatus Phillipps 1932 (Boomer et al, 2013).…”

“…Mechanisms of paternal skews are mainly related to post-copulatory processes (Jennions & Petrie, 2000), such as cryptic female choice, timing or order of males mating and sperm competition (Boomer et al, 2013;Fitzpatrick & Evans, 2014;Jennions & Petrie, 2000;Rossouw et al, 2016). Without excluding the mechanisms cited above, it may also point to post-zygotic processes, such as nutrients relocation between defective and viable embryos, as highlighted in the mouse Mus musculus (Zeh & Zeh, 1997).…”

How many daddies: microsatellite genotyping reveals polyandry in a live‐bearing clinid fish Muraenoclinus dorsalis

“…Polyandry and multiple mating not only provide individual-level benefits but are also associated with several population-level benefits (Zane et al, 1999;Avise et al, 2002;Bo et al, 2016;Rossouw et al, 2016). By reducing the variation in male reproductive success, multiple mating and polyandry act to increase effective population sizes, in turn aiding to reduce the loss of allelic diversity and maintain levels of heterozygosity and genetic diversity within a population (Zane et al, 1999;Bo et al, 2016;Rossouw et al, 2016). In addition, evidence further suggests that multiple mating may act to reduce the potential costs of inbreeding (Avise et al, 2002;Bo et al, 2016).…”

Evidence for sperm storage in common smoothhound shark Mustelus mustelus and paternity assessment in a single litter from South Africa

“…(), an even larger percentage of MP is reported for the species in Kwa‐Zulu Natal on the east coast of South Africa, where MP was determined in four out of six litters (67%). Several studies in species of Mustelus reveal that the frequency of MP, measured as the percentage of multiple‐sired litters, not only differs between species but also amongst populations (Byrne & Avise, ; Boomer et al, ; Chabot & Haggin, ; Farrell et al, ; Marino et al, ; Rossouw et al, ). Furthermore, a few of these studies also reveal a high variability in the relative paternal contribution of males within species (Boomer et al, ; Farrell et al, ; Rossouw et al, ).…”

“…() and Rossouw et al . () used bi‐parentally inherited microsatellite markers to test the presence or absence of multiple paternity (MP, where a single litter is sired by multiple males) in M . mustelus litters and ascribed the presence of MP to a polyandrous mating system (where females mate with multiple males in a single breeding season).…”