Do you remember watching Jurassic Park in 1994? Industrialist John Hammond, head of bio-engineering company InGen, creates a theme park called Jurassic Park featuring cloned dinosaurs and prehistoric plants, on the Costa Rican island of Isla Nublar. Following an accident at the site, lawyer Donald Gennaro, representing his investors, orders he gets experts to certify his park is safe.
Hammond takes a group consisting of Gennaro, Mathematician and Chaos Theorist Ian Malcolm, Paleontologist Dr. Alan Grant and Paleobotanist Dr. Ellie Sattler, to see the park he has created, all of whom are shocked to see living dinosaurs upon arriving. Hammond reveals that InGen created the dinosaurs through cloning - the process used preserved DNA in amber, with DNA from frogs used to fill in missing genomes. When Dr. Henry Wu points out breeding is prevented by having all dinosaurs genetically engineered as females, Malcolm theorizes that nature will overcome this obstacle in time.
And Hammond indeed was proved wrong. What Hammond did not know was that there are some frogs which change their sex/gender overnight. It was the DNA of such frogs that had been used to fill in the missing links of the preserved DNA of the dinosaurs.
After the storm passes the following morning, Dr. Grant comes across broken egg shells with the children and realizes the dinosaurs were given the DNA of Common Reed Frogs who can overcome a single-sex environment, thus proving Malcolm right that breeding control methods would fail.
Conclusion: Keeping films aside, researchers have observed frogs spontaneously changing genders in the lab. Now they’re observing it in the wild too, and it’s not a natural process. More and more male frogs are becoming females, complete with fully functioning reproductive organs. The frog-feminizing culprit? A common weed killer called atrazine.
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| Frogs mating. |
For some creatures, like reptiles and fish, sex can be heavily influenced by the environment. Sea turtles that grow up in warmer sand are more likely to become female, for example. Mammals, however, are much more bound to genetics: If you’re genotypically male in the womb, you’re likely to develop outwardly as such.
Amphibians such as frogs lay somewhere in the middle. They’re mainly influenced by genetics, but the environment also plays a role. In the laboratory, certain pollutants like synthetic estrogens and herbicides have been shown to induce genetically male frogs to develop outwardly as females.
A commonly used pesticide known as atrazine can turn male frogs into females that are successfully able to reproduce, a new study finds.
While previous work has shown atrazine can cause sexual abnormalities in frogs, such as hermaphroditism (having both male and female sex organs), this study is the first to find that atrazine’s effects are long-lasting and can influence reproduction in amphibians.
Banned in Europe, atrazine ends up running into rivers and lakes where it wreaks havoc on frog sexual development, suppressing production of testosterone (the male sex hormone) and boosting the female sex hormone estrogen. Not good news for amphibian populations that are already declining from climate change, loss of habitat and invasive species.