Six-Lined Racerunner

These pretty little lizards were the fastest-moving thing on the ground in the Florida sandhills. I saw them every day, but I never managed to get a photo of one in situ. I caught this one in a snake trap and snapped this shot just before letting it go. Look at those crazy long toes!

The six-lined racerunner is a type of whiptail lizard, the only one found in the east. There are more in the southwest. You might have heard of those; they’re known for a very interesting trait. Some populations of whiptail lizards are all female. They reproduce by parthenogenesis. No males required!

This is not the same thing as the asexual reproduction you see in plants, where a part of an organism is broken off and an entirely new one grows from it. That’s cloning, in which the offspring and the parent have the same set of chromosomes. In parthenogenesis, no new DNA is introduced, but the existing chromosomes still go through meiosis, so the offspring are not genetically identical to the parent. And, honestly, my several attempts at a paragraph explaining how that works only reminded me that it’s been a long time since I took a genetics class, so I’ll do us all a favor and just point you to Wikipedia’s entry on parthenogenesis.

We tend to think of only plants and some invertebrates as reproducing asexually, but it’s more common in vertebrates than you might have thought. Some of the other species it’s been documented in include hammerhead sharks, boa constrictorsKomodo dragons, and domestic turkeys. While looking for examples, I discovered that I’m already familiar with some local snakes capable of parthenogenesis: the cottonmouth and copperhead — a 2012 study found genetic evidence in both species! No matter how you feel about venomous snakes, that is pretty damned cool.