Costs of parthenogenesis on growth and longevity in ex situ zebra sharks Stegostoma tigrinum

The zebra shark Stegostoma tigrinum , a popular aquarium fish, is an endangered species that known to readily reproduce both sexually and through facultative parthenogenesis while in human care. Artificial insemination trials took place between 2011 2013 resulted the hatching of 2 produced (herein heterozygotes) 10 parthenogenetic sharks allowed for retrospective comparison growth, feeding longevity offspring from distinct reproductive modes. Parthenogenetic were generally smaller at hatch than their heterozygous counterparts and, after first several months post-hatch, failed increase mass length same rate as heterozygotes. exhibited non-normal swimming behaviors such spiraling, spy hopping head standing, which may have been correlated with gradual decline ability some properly suction feed. Median lifespan parthenotes was 1.05 yr (range: 0.27-6.64 yr); one heterozygotes lived 2.37 age, other alive time this writing August 2022 had reached maturity. By contrast, longest surviving perished just prior reaching sexual maturity (~5.5 ~6.5 yr). Parthenogenesis has documented among ex situ S. maintained aquariums across globe, study demonstrates substantial negative costs fitness compared siblings. reduced implications managing populations care well conservation efforts.