Author: Jonathan Losos

The green thing on the left doesn’t look like a real anole to me.  But apparently it’s convincing enough to both predators and other anoles, because both attack them, as evident by the bite marks they leave on these clay doppellizards.  McMillan and Irschick deployed these faux lizards in trees in two areas in New Orleans, on the Tulane campus and in a wilder area outside of town.  In the wild area, the models had bites marks clearly identifiable as belonging to lizard jaws (photo on right), and others that were from birds or other presumed predators.  By contrast, perhaps not surprisingly, on the lovely grounds of Tulane, models were bitten by anoles, but not by predators.  Also not surprisingly, there were no bites of any kind in either locality in the winter, and many more in the spring and fall.  You might say to yourself: maybe lizards and predators just like to bite clay or anything new that shows up in their environment.  How do we know that they actually thought they were attacking a lizard?  Well, we don’t, of course, but the researchers did put out cubes made of the same material, and none of these were attacked, which lends some credence to the possibility that these models, cartoonish as they seem, may have passed for the real thing.  McMillan and Irschick, following others, suggest that these models may serve as a proxy for levels of predation and intraspecific aggression.

Anoles only lay one egg at a time.  This penurious habit has been speculated to result from their arboreal lifestyle—because they spend so much time running around on vertical surfaces, they can’t afford to be weighed down by a big clutch of eggs.  Reasonable enough, but is there any evidence that carrying eggs has any cost to female anoles?  In a recent study in Ethology, Johnson et al. find that in A. carolinensis, as the mass of the egg increased, display behavior and movement rates decreased, suggesting that females are less active as they become more gravid.  Whether this is inactivity results because females are more vulnerable to predators or for other reasons is not known.