Reptile Sex Determination Is Hot Topic
The sex of many reptiles is determined by the temperature in the nest where the eggs incubate. Now researchers have shown that the offspring's temperature-dependent sex assignment is connected to their later reproductive success. Karen Hopkin reports.
SUBSCRIBE TO Science Quickly
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Every expectant mother gets asked the same question: boy or girl? For mammals like us, it’s an easy call. Two X chromosomes you get pink booties. X and a Y you get blue. But for some reptiles, the answer depends on the weather. Well, on the temperature to be precise. For many lizards and turtles and gators, the sex of the hatchlings depends on the temperature in the nest where the eggs incubate.
But why would animals bother with such a seemingly slapdash system for assigning sex? The only logical answer is: there must be some benefit. Each sex must fare better at the temperature that tends to produce that sex. A fine theory, but no one has been able to test it. Until now.
In the January 20 online issue of Nature, scientists at Iowa State University describe how they used hormones to produce lizards with the “wrong sex”—animals that came out male even though they were incubated at the female temperature. And vice versa. They found that females born and raised at the female temperature made more babies than females hatched at the wrong, male temperature. Ditto for the males. Call it the Goldilocks principle. You’re born at a temperature that’s just right—at least if you’re a lizard.
—Karen Hopkin
Subscribe to Support Independent Journalism
Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.
When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.
Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber
