![]() ![]() This form of parthenogenesis is more common in plants.įor most organisms that reproduce the first way, through automixis, the offspring typically gain two X chromosomes from their mother. Because these cells never undergo the gene-jumbling process of meiosis, offspring produced this way are clones of their parent, genetically identical. In another form of parthenogenesis, apomixis, reproductive cells replicate via mitosis, a process in which the cell duplicates to create two diploid cells-a kind of genetic copy-and-paste. This process, which has been documented in sharks, slightly shuffles the mother’s genes to create offspring that are similar to the mother but not exact clones. ![]() In one version of parthenogenesis called automixis, an animal can merge a polar body with an egg to produce offspring. The process of meiosis also creates a byproduct: smaller cells called polar bodies, distinct from the fertile egg. (These are called haploid cells cells that contain two chromosomal copies are called diploid cells.) These eggs contain only half the mother’s chromosomes, with one copy of each chromosome. Ovaries produce eggs through a complex process called meiosis, where the cells replicate, reorganize, and separate. But in parthenogenesis, the body finds a unique way of filling in for the genes usually provided by sperm. Each provides half the genetic information necessary to create a living organism. Sexual reproduction involves two ingredients: an egg cell and a sperm cell. Parthenogenesis comes from two Greek roots that literally translate to “virgin creation.” How it works ![]() And in 2006, at England’s Chester Zoo, a Komodo dragon named Flora achieved a similar feat, puzzling keepers. Examples include a zebra shark named Leonie, housed with other female sharks at Australia’s Reef HQ Aquarium, who stunned her keepers in 2016 when three of her eggs hatched into living pups.Ī few years earlier, at Louisville Zoo, a reticulated python named Thelma-who had never even seen a male python-laid six eggs that developed into healthy young snakes. Such events can shock those who care for the animals. The process, called parthenogenesis, allows creatures from honey bees to rattlesnakes to have so-called “virgin births.” But a small subset of animals can have offspring without mating. Only time will tell how well these homozygous zebra shark offspring fare.The vast majority of animals need to breed to reproduce. Laying inviable eggs is one thing (think chickens), but laying viable eggs means these females were undergoing asexual reproduction as confirmed by genetic tests which showed the hatchlings were homozygous. While asexual reproduction in itself is not unusual, switching from sexual to asexual reproduction in Leonie's case (and most mammals) is quite unusual. Amazingly, both Leonie and Lolly have produced five hatchlings. After her mate was removed from the tank to prevent further breeding, she has shared the tank with one of her offspring, a female named Lolly who, since reaching sexual maturity herself, has never lived with a male zebra shark. By 2008, she had started laying eggs and the pair had multiple litters of offspring through sexual reproduction. In 2006 she was transferred to Reef HQ Aquarium in Queensland, Australia where she met her mate. ![]() The story begins in 1999 when Leonie, a zebra shark (aka a leopard shark in Australia), was captured from the wild. Photo of one of Leonie's hatchlings from Tourism and Events Queensland. ![]()
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