This genetic signature in vertebrates is mostly attributed to the mechanism of terminal fusion automixis, the restoration of diploidy by fusion of the egg with a polar body 12, although gametic duplication also leads to elevated homozygosity and in most cases cannot be disregarded as the potential mechanism 3. Parthenogenetic offspring in these populations were identified among sexually produced offspring based on their unusually high levels of genetic homozygosity. In particular, parthenogenesis has been demonstrated in wild vertebrate populations: pit viper snakes 15 and sawfish 8. Novel lines of evidence can help elucidate the prevalence and function of parthenogenesis in vertebrates. This raises questions regarding the adaptive strategy of facultative parthenogenesis in these isolated incidences or whether parthenogenesis in most vertebrates is accidental 14. Most documented cases of facultative parthenogenesis in vertebrates have been recorded from females in captive environments that have had no exposure to male conspecifics during their entire reproductive lifetime 3, 6. Mammals are an exception as facultative parthenogenesis does not naturally occur in this group due to intracellular processes such as genomic imprinting during gametogenesis 13. Facultative parthenogenesis, the occurrence of asexual reproduction in otherwise sexually producing species, is found more widely across major vertebrate groups including reptiles, birds, bony fish and six species of sharks and rays 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Obligate parthenogenesis, where all individuals within a species reproduce asexually, is restricted to the Squamate reptiles 2, 3. Occurrences of parthenogenetic reproduction in vertebrate organisms have been increasingly documented (recorded from >0.1% of extant vertebrate species) 1. Zebra sharks can breathe without moving forward – they have the ability to pump water into their spiracles.Parthenogenesis is a natural form of asexual reproduction in which embryos develop in the absence of fertilisation. Their tendency to stay close to the ocean floor keeps Zebra sharks close to their common prey (mollusks) and allows the Zebra shark long periods of rest. Zebra sharks are also known as “carpet sharks” because of their bottom-dwelling behavior. A Zebra shark is not likely to harm humans in the wild. Even when hunting, the Zebra shark spends most of its time near the ocean floor and displays sluggish, easygoing behavior. They usually hunt at night.Īlthough sharks have a reputation as aggressive predators, zebra sharks tend to take it easy most of the day. Although their mouths are small, Zebra sharks have strong jaws that can crush mollusk shells. Their diet includes shelled mollusks, like clams, but Zebra sharks may also eat smaller fish such as herring. These sharks eat mostly from the ocean floor. As the Zebra shark matures, its pattern changes from stripes to spots. The Zebra shark is named for the stripes it displays while young.
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