Author: Jonathan Losos Page 131 of 133

Professor of Biology and Director of the Living Earth Collaborative at Washington University in Saint Louis. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.

Nature’s Lunch Box

By Jonathan Losos

On February 2, 2011

In Introduced Anoles, Natural History Observations, New Research

Little blue heron snacks on A. sagrei. Photo copyright bullfrog101, http://www.flickr.com/photos/43104350@N02/4463474718/sizes/l/in/photostream/

In the West Indies and southeastern U.S., the enormous population size of anole species makes them an important component of the ecosystem. In the rainforest of Puerto Rico, for example, the three most common anole species consume an estimated 450,000 insects per hectare. The flip side of this abundance is that anoles—small, not very fast, presumably tasty—may be an important food source for many other species. Indeed, most West Indian snakes eat anoles and, collectively, anoles constitute more than 50% of the diet of West Indian snakes. Similarly, many types of birds will eat anoles at least occasionally (e.g., 40% of the species at one study site in Grenada were observed eating anoles), and some species eat them in large numbers. In addition to birds and snakes, anoles seem to be eaten by just about any flesh-eating animal (or plant) big enough to do so. Other documented predators include many types of lizards (including many instances of cannibalism), dogs, cats, mongooses, frogs, katydids, tarantulas, spiders, whip scorpions, and centipedes (see Lizards in an Evolutionary Tree for citations and further discussion).

Despite the ecosystem importance of anoles, and particularly of predation on them, there is still a lot we don’t know about who eats anoles, when and how. For this reason, field studies are needed, and everyone should be encouraged to document observations they make. For example, a recent post on the “Anolis Lizard” page on Facebook provided a link to a video of a crab eating an unfortunate A. agassizi (itself a remarkable and little known species from Malpelo Island in the Pacific). I am unaware of any previous evidence of crab predation on anoles, and scavenging can be ruled out because the poor lizard is still alive. This situation may be atypical, though, because Malpelo is essentially one big rock, and thus the anoles are always on the ground.

Anoles at the Land-Ocean Interface

By Jonathan Losos

On January 31, 2011

In New Research

Anolis sagrei amidst the seaweed. Photo courtesy David Spiller.

Traditionally, ecologists have studied food web interactions within particular habitats with the idea that what happens in Vegas stays in Vegas. The idea is that habitats are discrete entities and most ecological interactions occur among species within that habitat, rather than across habitats. In recent years, however, that view has been challenged by the recognition that organisms and resources can cross habitat boundaries. For example, when bears catch migrating salmon, the fish carcasses wash ashore, and the nutrients released from their decay—as well as from the bears pooping in the woods—can link the productivity of the oceans to the terrestrial realm. Increasingly, such cross-habitat/ecosystem interactions are being seen as having major effects on food web functioning.

In a pair of recent papers, the UC-Davis anole team reports elegant field studies on the role that the brown anole, A. sagrei, plays in mediating these effects.

A Sad Day for Anolekind

By Jonathan Losos

On January 28, 2011

In New Research

It's tough when you're below plants in the food chain.

Read the article here and see the amazing photos here.

Hope for Haitian Biodiversity

By Jonathan Losos

On January 25, 2011

In Notes from the Field

Nat Geo just posted an article on the rediscovery of six species of Haitian frogs thought to be extinct. This seemed like a good excuse to re-tell the story of the recent rediscovery of Anolis eugenegrahami from Haiti. This remarkable “semi-aquatic” anole, known from only a single, highly degraded locality, had not been seen in quite some time until an intrepid team of herpetologists set out to look for them. Read what they found here. Now, if only someone could find A. darlingtoni….

Sexual Dimorphism and Species Richness

By Jonathan Losos

On January 22, 2011

In Classics from the Literature

The figure above is a re-drawing from Schoener’s classic 1977 Biology of the Reptilia paper. Though “Competition and the Niche” has been widely cited, this figure, buried in the midst of the 102-page opus, has not gotten the attention it deserves. It shows that sexual size dimorphism in anoles is greatest on islands in which no other anole species are present and declines as function of the number of other anole species on an island. Anole community size is strongly correlated with island species richness, so this trend indicates that dimorphism and community richness are negatively related.

Why might this be?

Forum: What Makes the Best Lizard Lasso?

By Jonathan Losos

On January 17, 2011

In Notes from the Field, Research Methods

During recent fieldwork with several graduate students, the topic of lizard noosing materials came up. I was accused of being an old fogey for my continued use of dental floss to make my nooses. By contrast, these young whippersnappers used some yellow stuff, pictured above. I can’t remember what it is, but it seems all the rage these days. I know that other people use various types of fishing line (I think the yellow stuff is one such type), and that everyone has their own preference. Of course, lizard noosing has doubtless been independently invented many times in various places around the world with all kinds of materials. I’ve seen local boys use blades of grass—quite effective!—in several places in the Caribbean, and once in Sri Lanka, I saw the locals using copper wire on a Calotes (not recommended). So, given all these options, what are the advantages and disadvantages of various noose materials?

Mainland and Caribbean Anole Morphology Compared

By Jonathan Losos

On January 11, 2011

In New Research

Anolis aequatorialis from Ecuador

Caribbean anoles are renowned for the repeated evolution of ecomorphs, the same set of habitat specialists evolving independently on each island in the Greater Antilles. But what about in mainland Central or South America, where the majority of anole species occur? Mainland anoles have received relatively little research attention, particularly with regard to questions of ecomorphology (but see Alan Pounds’ fabulous paper from 1988), primarily because mainland species are both less abundant than Caribbean taxa as well as more cryptic, making data collection much more difficult. Mainland anoles are, as a first approximation, as diverse ecologically and morphologically as Caribbean anoles, and a preliminary study found that most mainland anoles do not fit neatly into any of the Caribbean ecomorph classes. Now, in a much broader study, Schaad and Poe compared the morphology of 255 species for seven morphological characters: snout-vent length, sexual size dimorphism, femur length, head length, lamella number, snout scale number, and the ratio of tail to snout-vent length. They found that very few species are, on morphological grounds, similar to Caribbean ecomorphs. Most of the species that do have similarity are, surprisingly enough, categorized as grass-bush anoles, although ecologically most of these species do not seem to use grass-bush habitats, from what we know of their ecology. This paper represents a good step forward in our understanding of the evolutionary diversification of mainland anoles, and how it compares to what has occurred in the Caribbean. The next step will not be so simple, however—getting habitat data for all these species.

Anole Talks at the 2011 SICB Meeting

By Jonathan Losos

On January 8, 2011

In New Research

The just concluded SICB meeting in Salt Lake City featured 19 talks on anoles. You can see the titles and authors here, or go to here to check out the abstracts. Anyone who attended want to tell us about the meetings?

Norops’ last stand?

By Jonathan Losos

On January 7, 2011

In All Posts, Notes from the Field

In the mid-1980’s, Guyer and Savage proposed dividing Anolis into five genera. This proposal has mostly been rejected by the anole community, for reasons detailed in Poe (2004), Lizards in an Evolutionary Tree and the Wikipedia Norops page. The main reason is that although Guyer and Savage’s proposed genus Norops is monophyletic, all of the other proposed genera are not. Moreover, given the uncertainty that still exists about relationships at the base of the anole tree, sundering anoles into well-supported monophyletic subclades is still not possible. Finally, in Guyer and Savage’s initial paper, Anolis sensu lato was found to be monophyletic—so why bother? Even though we now know that Chamaeleolis, Chamaelinorops, and Phenacosaurus arose from within Anolis, it is much simpler to sink these genera into Anolis rather than to try to break anoles into umpteen different genera—many poorly supported.

Despite these points, and the general support for retention of an unsullied Anolis, support for Norops has one last redoubt, in Central America, and with particular strength in Costa Rica. There, the use of Norops is nearly ubiquitous, as evident in the Reptiles of Costa Rica flashcard pictured above (and for sale throughout the country).

Results of the Costa Rica cristatellus Expedition

By Jonathan Losos

On January 5, 2011

In Classics from the Literature, Notes from the Field

Map from http://www.costaricamapproject.com/InfoMaps/topographic.html

I’ve completed the brief survey of the distribution of A. cristatellus in Costa Rica (see previous post for explanation). The work was hampered by rainy and cool weather. Nonetheless, several new localities were identified. In particular, we found cristatellus in Bribri, very close to the Panamanian border. We actually went to the border town of Sixaolo, and even walked across the bridge, setting foot in Panama for a full 90 seconds (border officials apparently routinely allow tourists across the border to take a photo). However, by that time, the weather was very overcast and cool, and no lizards were out. Were I a betting man, I’d wager that cristatellus is already in the land of the canal.