Category: New Research Page 56 of 67

Top row, left: A. magnaphallus; Top row, right: A. tropidolepis; 2nd row and 3rd row, left: A. pachypus; 3rd row, right and 4th row: new species, A. benedikti; bottom row: A. pseudopachypus.

Peter Uetz recently pointed us to the Reptile Data Base with a list of all anole species, which appears to be at 378, not including the recently described A. tenorioensis. Make that 380.

The Anolis pachypus complex, a group of high elevation, mid-Central American anoles, has been growing in recent years, with the separate descriptions of A. magnaphallus and A. pseudopachypus both in 2007. Now another species has been recognized, named A. benedikti. Unlike other recent cases in which widespread Central American anoles have been broken into multiple species (e.g., A. tenorioensis), the A. pachypus group is not distinguished by differences in hemipenial shape. By contrast, these species are told apart the good ol’-fashioned way, by differences in dewlap color, as illustrated above.

Anolis benedikti is a cloud fores species found in the Talamancan highlands of eastern Costa Rica and extreme western Panama, predominatly on the Caribbean versant.

How are feet adapted to cling to different surfaces?

Last summer I accompanied Martha Muñoz on her trip to the DR. Earlier this month I came to Harvard to present an overview of her study of thermoregulation in the cybotes clade of anoles at various locations and altitudes, and I got to meet some members of the Losos Lab. The work we did on the trip interested me a lot and since then I’ve decided to pursue a research project of my own. I studied Prof. Losos’ book Lizards in an Evolutionary Tree looking for areas where he suggests opportunities for future work, and compiled a list. Since then, Martha has helped me to zero in on 2 or 3 areas in which I could do some work (these include clinging ability and parasite load). In the meantime, I’d like to share the list of possibilities with everyone. (Click here.)

Happy New Year!

Anole morphology holds an important place in the recent history of evolutionary biology. For example, comparisons of morphology, behavior, and ecology among Anolis species led E. E. Williams to conceptualize ecomorphology (discussed here). The repeated Caribbean anole radiations are also of great importance for studies of convergence, parallelism, and constraint (e.g., here and here). Surprisingly, however, the vast majority of anole research has focused on postcranial characters; comparatively few studies have surveyed variation in head shape and its functional and ecological significance. While strong correlations between relative limb length and microhabitat have been the subject of much research, one cannot overlook the fact that variation in head shape may also have important ecological and evolutionary significance for this genus.

Even a brief visual survey of the MCZ skeletal collection reveals an array of variation in anole head shape: from the robust skull of A. cybotes to the slender skull of A. dolichocephalus to the ornate skulls of Chamaeleolis (Here is a real challenge: Can anyone name the species in the picture?). Harmon et al. (2005) used three-dimensional geometric morphometrics for 21 anole species and concluded that anole heads primarily vary in relative length and depth. To further investigate which skeletal elements contribute to this variation and how many times anoles have independently converged on similar head shapes Sanger et al. recently analyzed skull shape variation among males of 106 Caribbean species (yes, Sanger, that’s me).

Read More

From Falk et al., 2011.

The Gates Foundation today announced a multi-billion dollar initiative to eradicate malaria from all lizardkind. Through a combination of heightened prophylactic use, development of genetically modified lacertilians, and enhanced mosquitivory, the Foundation hopes to eliminate this scourge, which afflicts millions of saurians throughout the world.

Well, maybe some day. But a recent paper on Anolis malaria set my mind a-wandering. Most people, likely the Gates Foundation included, are unaware that malaria is a disease not just of humans, but of many other species as well, including lizards. When I first learned that lizards got malaria, I thought it was just a curiosity, not of particular importance. However, I’ve come to realize that I was very wrong in a number of respects.

First, malaria in some cases can have substantial physiological effects on lizards (though this has yet to be demonstrated in anoles).

Read More

Everyone knows the devastating effect that the chytrid fungus (Batrachochytrium dendrobatidis) has had on amphibian populations almost everywhere in the world–in 2009, it was estimated to infect at least 350 amphibian species on 6 continents.

A sad photograph of frogs killed by the chytrid fungus (image from the UC Riverside Center for Invasive Species Research website)

Read More

Anolis equestris with a radio transmitter attached. Photo courtesy Paul Richards.

Knight anoles, Anolis equestris, are truly the king of anoles. The largest anole species*–with a total length approaching two feet–and a grotesquely handsome and imposing head, these lizards are surely the reigning emperor of anoles.

Little, however, is known about the natural history of these species, other than they will eat anything they can get their jaws on. Introduced into Florida many years ago, Miami populations of knight anoles would seem to be ripe for study, but little work has been published.

Nicholson and Richards have taken a step in filling this void, reporting the results of a year-long radio-tracking study conducted on the grounds of the University of Miami. The authors developed a backpack mounted radio transmitter that they strapped onto the back of knight anoles, and then located them over the course of many months. The units were small (6 g or less) and didn’t seem to hinder the lizards, which were seen mating and engaging in other activities while backpack-clad.

The primary focus of the paper is home range of these lizards, and they report several results. First, knight anoles have a large home range, on average, of about 650 square meters. This result is not surprising, as home range size seems to be strongly correlated with body size among the 15 anole species for which data are available, and the two other large anoles have comparably large ranges.

More surprising is that there is little difference in the size of home ranges of males and females, unlike what is seen in many other anole species, in which male home range is larger, often substantially. Nicholson and Richards attribute this to the arboreality of this species, although other arboreal species, albeit smaller, have also been studied with variable results. I wonder, too, whether gender differences in home range size might correlate with degree of sexual size dimorphism. Certainly, several of the species with low dimorphism had female ranges larger than those of males.

The authors also found substantial overlap in territories of individuals, both within and between sexes, an intriguing finding that suggests that detailed studies of behavior of this species–of which almost nothing is known–would be very interesting. More generally, the biology of the knight anole is mostly a blank slate. These lizards are reasonably common in Miami, and there is great work to be done. Particularly interesting would be the community effects of this species–how does its presence affect the other anole species with which it occurs?

*The largest anole species is actually a matter of dispute, as it may be one of the knight anole’s sibling species, such as A. luteogularis. In all, the equestris species complex is comprised of six species, five of which are very large.

Knight anoles can bite hard and Kirsten Nicholson values her hands. This is how the transmitter’s are placed on the lizard. Photo courtesy Paul Richards.

Kirsten E. Nicholson and Paul M. Richards (2011). Home-range size and overlap within an introduced
population of the Cuban Knight Anole, Anolis
equestris (Squamata: Iguanidae) Phyllomedusa, 10 (1), 65-73