It was astonishing when a female crocodile laid eggs in January 2018, considering she had been living alone at a zoo in Costa Rica for 16 years.
Crocodiles are sometimes known to lay sterile eggs, but some of the crocodile eggs that were laid appeared to thrive One of these eggs even matured in an incubator, resulting in a baby crocodile that was stillborn but perfectly formed.
Biology Letters researchers have discovered that this baby crocodile was a product of parthenogenesis, which means that it was born of a virgin and contained genetic material from only the mother. While parthenogenesis has been observed in other creatures, such as king cobras and sawfish, this is the first time it has been seen in crocodiles.
As an egg cell matures in a mother’s body, it divides repeatedly to produce a final product with half the necessary genetic material for an individual. Typically, three smaller cellular sacs, known as polar bodies, are formed as byproducts, which usually disintegrate. However, in vertebrates capable of parthenogenesis, one polar body may fuse with the egg, creating a cell with the complete set of chromosomes required to form an individual despite not being fertilized by a father.
Parthenogens usually aren’t as healthy as typical offspring are, but fortunately, most live long enough to reproduce sexually and have healthy offspring.
It is possible that this trait allows a species to survive when no mates are available. However, parthenogenesis isn’t always in response to a lack of mates. As some scientists found in 2020, lizards can mate normally and lay clutches of eggs with some normal offspring and some parthenogens.
So, another explanation for why this reproductive process exists is that this is a trait that just doesn’t have enough downsides for evolution to eliminate it. Parthenogenesis may be an ability determined by a single gene carried down from generation to generation.
This phenomenon is common among crocodiles, birds, lizards, and snakes. “What this tells us is it’s very likely that this also happened in pterosaurs and dinosaurs,” Dr. Booth said. A common ancestor would explain how these animals share such a trait.
Unfortunately, parthenogenesis cannot be confirmed without DNA analysis due to confusing similarities with delayed conception. We currently have no way of retrieving dinosaur DNA and therefore cannot perform a test for parthenogenesis.
“We’ll never be able to prove they could do it,” said Dr. Booth. “But it suggests they had the ability.”
Crocodiles are sometimes known to lay sterile eggs, but some of the crocodile eggs that were laid appeared to thrive One of these eggs even matured in an incubator, resulting in a baby crocodile that was stillborn but perfectly formed.
Biology Letters researchers have discovered that this baby crocodile was a product of parthenogenesis, which means that it was born of a virgin and contained genetic material from only the mother. While parthenogenesis has been observed in other creatures, such as king cobras and sawfish, this is the first time it has been seen in crocodiles.
As an egg cell matures in a mother’s body, it divides repeatedly to produce a final product with half the necessary genetic material for an individual. Typically, three smaller cellular sacs, known as polar bodies, are formed as byproducts, which usually disintegrate. However, in vertebrates capable of parthenogenesis, one polar body may fuse with the egg, creating a cell with the complete set of chromosomes required to form an individual despite not being fertilized by a father.
Parthenogens usually aren’t as healthy as typical offspring are, but fortunately, most live long enough to reproduce sexually and have healthy offspring.
It is possible that this trait allows a species to survive when no mates are available. However, parthenogenesis isn’t always in response to a lack of mates. As some scientists found in 2020, lizards can mate normally and lay clutches of eggs with some normal offspring and some parthenogens.
So, another explanation for why this reproductive process exists is that this is a trait that just doesn’t have enough downsides for evolution to eliminate it. Parthenogenesis may be an ability determined by a single gene carried down from generation to generation.
This phenomenon is common among crocodiles, birds, lizards, and snakes. “What this tells us is it’s very likely that this also happened in pterosaurs and dinosaurs,” Dr. Booth said. A common ancestor would explain how these animals share such a trait.
Unfortunately, parthenogenesis cannot be confirmed without DNA analysis due to confusing similarities with delayed conception. We currently have no way of retrieving dinosaur DNA and therefore cannot perform a test for parthenogenesis.
“We’ll never be able to prove they could do it,” said Dr. Booth. “But it suggests they had the ability.”
