Crocodile Virgin Birth In Costa Rica Is First For Science History Books Know Why Expert Says
does not require genetic traits from sperm
Sexual reproduction in species such as humans requires sperm to fertilize an egg and form an embryo. In terms of evolution, sexually reproducing species are considered more advanced, as their offspring are genetically diverse, with unique gene combinations from their parents. This diversity can be important if a species needs to adapt. It also reduces adverse genetic mutations, which are often associated with inbreeding (when close relatives mate). The American alligator swimming in a river in Costa Rica was one such American alligator. Uwe Bergwitz/Shutterstock Virgin births are a form of asexual reproduction because they do not require genetic traits from sperm. But, unlike other forms of asexual reproduction, they require an egg.
Unfertilized eggs are often produced by the female—you may have had unfertilized eggs from a house hen for breakfast this morning—and if unfertilized eggs are not eaten, they eventually perish. But there is one exception. Birth without fertilization, known as parthenogenesis, occurs when an unfertilized egg develops into an embryo. It doesn’t necessarily have to be genetically identical to the mother – it depends on how the egg cell develops. Parthenogenic offspring can be either full or half clones of the mother. Half clones are produced when embryonic cells split in half before multiplying. Full clones are formed when an embryo multiplies complete cells. Hence half clones have less genetic diversity than full clones.
Female zebra shark gives birth to multiple babies with DNA
Not only do they lack the genetic diversity of organisms created in sexual reproduction, but they also inherit only about half of their mother’s genetic diversity. Some species, called facultative parthenogens, alternate between sexual and asexual reproduction. They mainly rely on sexual reproduction, but can use asexual reproduction if necessary. Birth without fertilization, which usually results in female offspring, is thought to trigger many conditions. For example, when there are not many males around. It is often reported in caged animals, including bonnethead sharks, where the animals are kept in single-sex enclosures. Passing on genes Even when males are around, females can still use parthenogenesis. For example, last year a female zebra shark gave birth to multiple babies with DNA that didn’t match any of the males at the Chicago Aquarium where she lived.
This phenomenon astonished the researchers. Perhaps the female did not like those with whom she lived. If the environment is poor, asexual reproduction involves less effort than sexual reproduction, as the female does not need to waste time and energy searching for mates. For example, many cases of parthenogenesis have been discovered in geckos, snakes and lizards that live in dry and harsh climates such as high altitudes. Female animals may also reproduce asexually to take advantage of favorable changes in conditions. The spiny-cheek crayfish is native to the Americas, but was introduced to Europe with a temperate climate.
Birth without fertilization even in dinosaurs!
Reproducing asexually, it reached many European waterways. Although many invasive species are larger and stronger than natives, parthenogenesis is another factor that may contribute to their success. Genetic testing techniques that can more easily identify parthenogenesis are helping researchers discover that more and more species are capable of producing children without fertilization. The revelation of parthenogenesis in the American crocodile suggests a common ancestral link between archosaurs, or proto-reptiles, including dinosaurs, pterosaurs (flying reptiles), birds, and crocodilians.
Since parthenogenesis occurs in birds and crocodilians, it is possible that birth occurred without fertilization in dinosaurs as well. A pregnant crocodile without fertilization is eerily reminiscent of a scene in Jurassic Park when scientists claimed there was nothing to worry about, as they could control the park’s population by making sure all dinosaurs produced females, so naturally Naturally no child will be born. But in the words of the film’s chaos theorist, Dr. Ian Malcolm (played by Jeff Goldblum): “Life just finds a way.
Louise Gentle, Principal Lecturer in Wildlife Conservation, Nottingham Trent University)