A female zebra shark named Leonie was separated from her long-term mate. Then somehow, four years later, she had three female babies. (As Jeff Goldblum said, "Life finds a way!") At first researchers thought she may have been storing sperm, which would have allowed her to fertilize her eggs later from a sperm cache. Sperm storage is relatively widespread in birds, reptiles, and mammals, so this was a plausible theory*.
However, Christine Dudgeon and colleagues found that the babies only had their mother's DNA. They had been produced asexually! Not only that, but one of her babies went on to have several babies asexually as well. All of the babies were female, and were produced without any input from males.
Oddly enough, lots of vertebrates are able to reproduce asexually, including some fish, birds, and reptiles. "Facultative parthenogenesis," or asexual reproduction in a species that tends to reproduce sexually, is generally seen in captive animals that have never met an individual of the opposite sex. Scientists often observe these individuals switching from asexual to sexual reproduction when they are introduced to a mate. However, the case of Leonie the zebra shark, where she switched from sexual to asexual reproduction, is very rare.
The authors write that facultative female parthenogenesis may be a "‘holding on’ mechanism, through maintaining female lineages until potential male mates become available again following immigration." It makes sense that this level of reproductive flexibility would be selected for!
Now for the important question: could dinosaurs have reproduced asexually in Jurassic Park? It is, indeed, plausible that female dinosaurs (with or without frog DNA) could make babies asexually. Some living relatives of dinosaurs (birds) have this ability. However, asexual reproduction has some problems: without genetic diversity, populations can be weak and unstable. Further, as mutations accumulate and genetic "defects" arise, there is no sexual recombination to purify the genome. Asexual reproduction is like the ultimate form of inbreeding.
So to finally resolve the Jurassic Park question, we will have to wait to see the results of Dr. Victoria McCoy's research: she is looking at real-life dinosaur feathers preserved in amber. Stay tuned!
Leonie the zebra shark (Stegostoma fasciatum) met her male partner at an aquarium in Townsville, Australia, in 1999. They had more than two dozen offspring together before he was moved to another tank in 2012. From then on, Leonie did not have any male contact. But in early 2016, she had three baby sharks. Intrigued, Christine Dudgeon at the University of Queensland in Brisbane, Australia, and her colleagues began fishing for answers.