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ESR 50:81-91 (2023)  -  DOI:

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

Lance Adams1,*, Kady Lyons2, Janet Monday1, Elizabeth Larkin1, Jennifer Wyffels3,4

1Aquarium of the Pacific, 100 Aquarium Way, Long Beach, CA 90802, USA
2Georgia Aquarium, 225 Baker Street, Atlanta, GA 30313, USA
3Delaware Biotechnology Institute, University of Delaware, 15 Innovation Way, Newark, DE 19711, USA
4Ripley’s Aquariums, 7576 Kingspointe Parkway, Suite 188, Orlando, FL 32819, USA
*Corresponding author:

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

KEY WORDS: Reproduction · Allometry · Survivorship · Food consumption · Deformities

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Cite this article as: Adams L, Lyons K, Monday J, Larkin E, Wyffels J (2023) Costs of parthenogenesis on growth and longevity in ex situ zebra sharks Stegostoma tigrinum. Endang Species Res 50:81-91.

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