In sexual reproduction as we know it, for a female to have offspring, a male needs to fertilize her . However, in the Jurassic World Dominion trailer we have been able to see the ‘raptor’ Blue with a baby, with a color pattern very similar to hers. A puppy that is sure to be yours. We will explore the possibilities of how it could have happened.
life makes its way
In the original park, Mr. Hammond claims to have witnessed the birth of every single creature in the park. Visitors wonder how he could do it in those that have reproduced on their own, in the middle of nature. Dr. Henry Wu then explained to us—and to visitors—that all the animals in Jurassic Park were female . That they had been designed that way.
Dr. Malcolm did not believe that the level of control to which they aspired was even possible, expressing his doubts with one of the most famous quotes in the saga: “life finds its way”.
Some time later, Dr. Grant, accompanied by the children, discovers a dinosaur nest; something that would not be strange if it were not for the fact that the eggs were broken and small footprints came out of the nest, in the same direction. The paleontologist at the time inferred that the frog DNA with which they had “filled the gap” in the genetic sequences could have given the dinosaurs a trait of certain amphibians: changing sex from female to male when they are in an environment of single sex.
This data is real, it is not a filmic fiction. The process is called protogyny , and it was first observed in 1989, in a species of African frog called Hyperolius viridiflavus, although today we know that other species are capable of doing it. Dr. Grant’s intuition could therefore be correct.
But this cannot be the origin of Blue’s offspring. Even with dinosaurs capable of protogyny, there would need to be at least two animals of the same species in order to reproduce. The Jurassic World Dominion trailer opens up a new possibility for us.
Blue as virgin mother
Some animals can reproduce by parthenogenesis , that is, creating a new organism from an unfertilized egg. In some species, the parthenogenetic offspring is always male, and needs fertilization to give rise to new females. In other cases the opposite happens; the unfertilized egg gives rise to a female, and the male is only needed to produce new males.
Could Blue’s offspring be parthenogenetic? — Yes. We assume the film canon in which our protagonist is a Velociraptor , a dinosaur from the dromaeosaurid group —with the corresponding film licenses and with the usual transgenesis of frog DNA and of who knows what other creatures—. In terms of phylogeny, the closest modern animals to dromaeosaurids are, in fact, the only dinosaurs left alive. They are feathered—just like the raptors were—and we call them birds .
We know of parthenogenesis in pigeons, finches, quail, turkeys, chickens, and recently, in condors. In the case of birds, it is a so-called automictic parthenogenesis, where the ovules are normally formed by meiosis, but at the last moment, the nuclei of the two daughter cells fuse to give rise to the unfertilized diploid egg.
Now, the sexual differentiation of birds is different from ours. In humans, there is one pair of chromosomes that designates chromosomal sex; XX for female , XY for male , and it is the sperm, carrying chromosome X or Y, that defines what is to come. Birds, along with many reptiles , also have a sex chromosome with two different shapes, which we call W and Z, but the designation is different: the pair of chromosomes ZZ to designate the male, and ZW for the female. In this case, the sperm, therefore, only contributes a Z chromosome, and it is the ovule that makes the difference, depending on whether it contributes a Z or a W chromosome.
Since the chromosomes separate early in meiosis, only one sex chromosome remains when the final nuclei fuse. If it is a W chromosome, we will have a WW embryo, which is not viable. On the contrary, if it is a Z chromosome, we get a ZZ embryo, which is a male. Therefore, when a female bird has offspring by parthenogenesis, the result will always be a male.
Let us now remember that to speak of parthenogenesis in birds is, inevitably, to speak of parthenogenesis in dinosaurs, since birds are really dinosaurs.
If we assume the close evolutionary proximity that ‘raptors’ have with birds, far greater than they have with other reptiles, Blue could have a chick through parthenogenesis, and it would be male.
Now we will have to wait for the premiere of Jurassic World Dominion, to verify if our hypothesis is correct, or if, taking advantage of film fiction, they have chosen another less likely possibility.
REFERENCES:
Grafe, TU, & Linsenmair, KE 1989. Protogynous Sex Change in the Reed Frog Hyperolius viridiflavus. Copeia, 1989(4), 1024. DOI: 10.2307/1445989
Ramachandran, R., & McDaniel, CD 2018. Parthenogenesis in birds: a review. Reproduction , 155(6), R245-R257. DOI: 10.1530/REP-17-0728
