Author: Jonathan Losos Page 99 of 131

The elegant skink, Plestiodon elegans, in Taiwan. Photo by Gerrut Norval

Most community ecology studies involving anoles focus on interactions between anole species. This is not surprising, because in the Caribbean, anoles are extraordinarily abundant and most of their ecological interactions are, indeed, with other anoles. Less studied are interactions with other taxa, the exception being predator-prey interactions, such as those with curly-tailed lizards (discussed many times in these pages, most recently here).

One widespread group of lizards are skinks, the most species rich family of lizards. There are few reports of anole-skink interactions, probably in large part due to the fact that skink diversity in the Caribbean is relatively low, and many species have been extirpated by human agents. However, anoles have been introduced to places around the world where skinks are more abundant, and some reports of interactions have been made. For example, in the Ogasawara Islands of Japan, A. carolinensis has reached high population densities and has been implicated in the decline of the native skink.

Gerrut Norval has been studying the introduced populations of A. sagrei in Taiwan. He now reports an observation of a somewhat odd interaction between a brown anole and a skink in which the anole fell to the ground from a utility pole and then was quickly chased back up the pole by an elegant skink, Plesiodon elegans. Given the relative size of the two lizards, attempted predation was probably not the cause. Gerrut speculates that this is an example of interspecific territoriality, transcending lizard family lines.

In Taiwan, A. sagrei reaches high population densities (as it does just about everywhere it occurs)–possibly cause for alarm for the native herpetofauna. Norval also mentions some intriguing preliminary observations: A. sagrei seems to attain smaller sizes at sites where it co-occurs with other lizard species. Interesting! Hopefully, we’ll hear more from Gerrut soon on this provocative possibility.

Male Anolis proboscis. Photo by Jonathan Losos

Of all the anoles great and small, near and far, green and brown, one stands out for its combination of elegance, charm, and mystique. I refer, of course, to the Ecuadorian horned anole, Anolis proboscis, denizen of Andean forests, possessor of an enchanted sword, and all-around lizard of mystery. Now, however, the veil has been lifted, as the first reports on the biology of the previously unknown lizard have just been published in Breviora, a journal of the Museum of Comparative Zoology at Harvard.

Rediscovered by birdwatchers. How embarrassing. Photo by Wanda Parrott.

The mystery comes in three acts. The first concerned the continued existence of the horned anole. The species was discovered in 1953 and over the next 13 years, another five were found, all male like the first, all from the vicinity of the Ecuadorian town of Mindo. Then, for four decades…nothing. Many feared the species extinct, perhaps a victim of the deforestation that has ravaged so much of the Western side of the Andes. All this changed in 2005 when a group of birdwatchers spied one crossing a road near Mindo (mind you, this is an arboreal lizard—insert your own joke). Anolis proboscis lives!

The photo above made its way onto the internet and to the attention of Steve Poe, an expert on locating hard-to-find anoles, who led a team of American and Ecuadorian scientists back to Mindo in the summer of 2009. Poe’s approach to finding day-active anoles is seemingly perverse: he stays up all night looking for them. The reason is simple: many anole species sleep on narrow twigs or leaves, presumably because approaching predators will produce vibrations on the flimsy perches, alerting the lizards to impending danger. Although this strategy may be effective in avoiding predators that creep, crawl or slither along branches, it’s not so well-suited to avoid detection by flashlight-toting herpetologists, who are attuned to locating the tiny reptiles—which conveniently blanch to a pale color at night—even when they’re roosting 20-30 feet high in the canopy. Poe’s team quickly located a large number of lizards, establishing that the species not only exists, but seems to have a healthy population.

Unbeknownst to Poe, another team of researchers independently had discovered a new horned anole locality. This team, from the Ecuadorian Museum of Science in Quito, located five specimens of the horned anole at two sites 11-13 km northeast of the original collecting locality, slightly extending the known range of the species. Both groups published detailed descriptions of the anatomy of the species—the Ecuadorian group last year and Poe’s team as the first of the Breviora set published today—describing previously unknown variation in horn size and shape, as well as differences in color and patterning both among males and between the sexes.

And, speaking of differences between the sexes, that leads to the resolution of mystery number two. Ever since the species was first described and the initial half dozen specimens collected, lizard enthusiasts have wondered—what about the females? Do they have horns, too? Of course, in the absence of any information on the natural history of the species, it was hard to have an informed opinion. Is the horn used in self defense, in which case the lady lizards could probably use one as well as the guys? Or is it used by males to fight amongst themselves, or even as an ornament used to woo or titillate? Nobody knew, and so it was anybody’s guess whether the females were nasally adorned or not. But now we know the answer. Before I reveal it, take a moment and take a guess: yes or no? When you’re ready, scroll past the lovely photo of another male and see for yourself.

Male Anolis proboscis. Photo by Luke Mahler

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