Author: Jonathan Losos Page 48 of 129

Posted by Lorie on Birds and Blooms.

Gunther Kōhler and colleagues have just published in Zootaxa a new revision of some Mexican anoles, including the description of six new species and the sinking of one species. Rather than describing the work, I think it would be more effective to present the title and abstract:

A revision of the Mexican Anolis (Reptilia, Squamata, Dactyloidae) from the Pacific versant west of the Isthmus de Tehuantepec in the states of Oaxaca, Guerrero, and Puebla, with the description of six new species

GUNTHER KÖHLER1, RAÚL GÓMEZ TREJO PÉREZ, CLAUS BO P. PETERSEN & FAUSTO R. MÉNDEZ DE LA CRUZ

We revise the species of anoles occurring along the Pacific versant of Mexico west of the Isthmus de Tehuantepec in the states of Oaxaca, Guerrero, and Puebla. Based on our analyses of morphological and molecular genetic data, we recognize 21 species, six of which we describe as new (i.e., Anolis carlliebi sp. nov., A. immaculogularis sp. nov., A. nietoi sp. nov., A. sacamecatensis sp. nov., A. stevepoei sp. nov., and A. zapotecorum sp. nov.). Furthermore, we synonymize Anolis forbesi Smith & Van Gelder 1955 with Anolis microlepidotus Davis 1954. Of the recognized species, six have smooth ventral scales (i.e., Anolis dunni, A. gadovii, A. liogaster, A. omiltemanus, A. peucephilus, and A. taylori) and 14 have keeled ventral scales (i.e., A. boulengerianus, A. carlliebi, A. immaculogularis, A. megapholidotus, A. microlepidotus, A. nebuloides, A. nebulosus, A. nietoi, A. quercorum, A. sacamecatensis, A. stevepoei, A. subocularis, A. unilobatus, and A. zapotecorum). In one species, A. macrinii, the ventral scales vary from smooth to weakly keeled. For each species we provide color descriptions in life, color photographs in life, descriptions and illustration of hemipenis morphology (if available), descrip-tion of external morphology, distribution maps based on the specimens examined, comments on the conservation status, and natural history notes. Finally, we provide a dichotomous key for the identification of the 21 species of anoles occurring along the Pacific versant of Mexico west of the Isthmus de Tehuantepec in the states of Oaxaca, Guerrero, and Puebla.

Karen Cusick, author of  Lizards on the Fence and tender of Daffodil’s Photo Blog, writes:

You may remember that the Wild Amelia Nature Festival (Amelia Island, FL–just north of where I live) chose the green anole as their Critter of the Year for 2015. I was looking at the Wild Amelia website and they are already starting to gear up for the festival, which will be held May 15-17. They’ve designed a new website logo featuring a green anole, and there are going to be tee shirts with the logo. The website button to buy a tee shirt doesn’t work yet, but that should be fixed as the festival gets closer. I’m going to check on that.

There’s only a small size image of the logo so far, but I’m attaching it anyway. It looks like it’ll be a nice shirt.

They’ve scheduled a series of nature-based seminars in the months leading up to the festival, and the last one is May 12, when the director of the Jacksonville Zoo, Tony Vecchio, will give a presentation about the green anole and the Zoo.

I’ll let you know if I hear any more anole-related news about the festival!

In a recent paper in Herpetology Notes, de Freitas et al. report the third specimen of the species, the first from Brazil and the first in which a living specimen is illustrated.

Look at that schnoz! Reminiscent of some members of the carolinensis species group, such as AA regular A. maynardi from the Cayman Islands.

Here’s the illustration from Ernest Williams’ 1965 description in Breviora.

Photo tweeted by Sarah Knutie. Have we talked about cannibalism previously on AA? A quick search on our search bar finds two hits, one noting such tendencies in knight anoles, the other not very specific. Who’s seen it?

Jessica Alfoldi of the Broad Institute writes:

“Matthew Breen from NCSU has a copy of the Anolis BAC library used in the sequencing and anchoring of the reference Anolis genome:CHORI-318: Green Anole Lizard . He unfortunately no longer has room for it, and will have to throw it out very soon unless someone else can give it a new home. If you would like to have a copy of this BAC library, please email me back as soon as possible.

Thank you,

Jessica”

Lourdes Rodriguez Schettino speaking at the 2009 Anolis symposium

Symposia on anole biology have been held three times in the last 25 years. First, in 1989 as part of the ASIH meetings in San Francisco, then in 1999 in conjunction with the herpetology meetings at Penn State, and most recently as a stand-alone meeting at the Museum of Comparative Zoology at Harvard in 2009. These meetings have been a great success–the MCZ meeting was attended by more than 125 people (take a photographic trip down Memory Lane).

The time has come to think about the next Anolis Symposium. The meeting organizers have settled on 2016 in Miami. We’re considering a number of great venues there, so it should be a fun, anole-filled event, easily accessible for anole researchers from all over.

The question is: when should the symposium be held? In January, right after the holidays? February, in the heart of winter? August, right after the Ecological Society of America meeting in Fort Lauderdale? October, like the last meeting?

We’re going to try to pick the date that works best for most potential attendees, so please comment below and let us know which dates are good or bad, and why.

Anolis sagrei in the Bahamas. Photo by Christian Cox from the Washington Post

In these times of rapidly changing climates, a major question is whether species will be able to survive. Essentially, they have two options: either shift their geographic ranges to stay within their ancestral niches, or adapt to new circumstances. Or, of course, go extinct. In recent years, evolutionary biologists have come to realize that evolutionary change can occur very rapidly when selective pressures are strong. The question is whether it can occur rapidly enough to accommodate quickly changing environments.

A recent study suggested that many tropical lizards are imperiled by a warming world. This study suggested that lizard populations would not be able to adapt rapidly to warmer conditions, but the analysis wasn’t very detailed.

First author Mike Logan hard at work at the field site. Photo reprinted from the Washington Post

In a study that is the first of its kind, Mike Logan and colleagues at Dartmouth have investigated the selective forces that may impinge on lizards as the world warms. The study was conducted on the old workhouse, the brown anole, Anolis sagrei. In essence, what the researchers did was calculate the extent to which sprinting capability was affected by temperature in two populations, one in an area in the Bahamas currently occupied by the anoles, and another in a population transplanted to a warmer era that served as a surrogate for conditions that will be experienced under global warming.

The study was gargantuan in its scope. Each lizard was put through its paces a number of times at each of a number of temperatures. From these data, the researchers could establish the temperature at which each lizard ran fastest and the breadth of temperatures at which they ran reasonably fast (compared to their maximum), which is termed performance breadth. They then marked the animals and returned them to their habitats. They then returned three months later to recapture the lizards to see which had survived and which hadn’t, allowing them to see whether their sprint capability measures were acted upon by natural selection.

It turns out that a fair amount of variation exists in the lizards in terms of both optimal temperature and performance breadth. In the natural habitat in Georgetown, Great Exuma, Bahamas, there was no evidence of selection operating on any of their measures.

The transplant experiment was conducted a year later on the Bahamian island of Eleuthera, which is not all that far from Great Exuma. In this case, the thermal characteristics of the habitat from which lizards were taken were very similar to the study site on Abaco. However, the more open, exposed area into which the lizards were transplanted was several degrees warmer, and also more variable in temperature.

Lizards in the transplanted population experienced body temperatures 1.5 C higher than those in the reference population. When the researchers recaptured the lizards on Eleuthera, they found strong evidence for natural selection, and in the direction expected: lizards that performed better at higher temperatures survived better than those with lower performance optima, and those with a broader thermal range survived better than those more narrowly adapted. In other words, there was strong selection for adaptation to warmer conditions.

The big question is whether populations can adapt to such strong selection pressures. The authors didn’t measure the heritability of the traits—that is, the extent to which adults with higher temperature optima produce offspring with similarly high optima, and such heritability is crucial to predicting evolutionary response. Nonetheless, if these traits have levels of heritability equivalent to that of other thermal performance traits in other species, the authors argue, then the brown anole may well be able to adapt evolutionarily to the warming predicted to occur in the next century.

This paper received a lot of attention in the press and blogosphere. For example, nice articles appeared in the Washington Post and on Scientific American‘s website.

Understanding dispersal—the extent to which organisms move from their place of birth—is of obvious importance in understanding many aspects of the natural history of a species, such as how related individuals are in a population or how genetically distinct one population is from another. Despite the intensive study on Anolis, however, very little is known about their dispersal. This is particularly surprising for species like the green and brown anoles, which are so common in so many places. Now, in a very nice experimental study in Behavioral Ecology, Calsbeek and colleagues have shed light on dispersal in the brown anole in the Bahamas.

Basically, the study went like this: the authors collected a bunch of gravid females from a variety of sites on a single, small island in the Bahamas. They got the lizards to lay eggs in the lab and hatched them out, then released them within three weeks of hatching back on their mom’s island. Each lizard was individually marked. The researchers then returned the following spring to find which animals had survived and how far they had moved. Then, they returned again in the fall to see how these survivors fared over the following summer and whether subsequent survival in this second period varied as a function of the distance they had dispersed in the first period.

There are a lot of interesting specific details and I encourage you to read the paper, but the broader story is this:

1. Males dispersed substantially further than females

2. Surviving males grew faster than surviving females

3. Survival of the lizards was low

4. Among females that survived the first period, those that had dispersed shorter distances survived better in the second period

Surprisingly little is known about the extent of anole dispersal, and so this paper is an important advance. As far as I’m aware, dispersal of only two other anoles have been studied. Here’s a summary from Lizards in an Evolutionary Tree:

“Little is known about the dispersal of anoles. One study of A. limifrons found that most lizards dispersed very little and that the home ranges of many individuals moved little from the juvenile to adult age. The maximum dispersal distance, measured as distance from the center of the juvenile home range to the center of the adult home range, based on 148 individuals, was 45 meters. Both the mean and extremes were greater for males than for females (Andrews and Rand, 1983). Anolis limifrons is a small and short-lived mainland species; it is always possible that larger, longer-lived species may disperse further.

The only other data come from Anolis aeneus, which moves as much as 150 meters or more after hatching to occupy open clearings (Stamps, 1983b, 1990). Ultimately, the lizards move back into shadier areas when they reach subadult size, although it is not known whether they return to the vicinity of their hatching site.

A number of arboreal species are known to disperse across open ground between trees (Trivers, 1976; Hicks and Trivers, 1983; Losos and Spiller, 2005).

James Christensen, a fabulous nature photographer and keen naturalist, made the following comment on the recent post about how anoles react to bird calls. However, the points are so important that they deserve a post of their own, so I’m reprinting them here:

I have spent many hours photographing wild anoles, especially here in Ecuador, and have learned a great deal about their behaviour while watching them through the viewfinder. When the wind picks up and begins to stir the surrounding foliage I can expect my subject to risk rapid movement – therefore, I probably won’t get a viable shot. Conversely, when toucans or furnarids become active in the vicinity I know that my anole will not venture an abrupt movement, so I squint through the viewfinder and start clicking the shutter. What I have noticed is that the anoles – e.g. Anolis gemmosus and A. proboscis – react not only to the calls of these birds, but also to the sound of their wingbeats. The usual response is a cessation of movement and an increased watchfulness; the anole sits very still and peers upward while discreetly swivelling its head. In the case of a very fit male A. gemmosus with whom I spent many hours – over a period of several weeks – upon the disappearance of avian predators he would begin to dewlap, frequently ‘emphatically’, seeming to reassert his local dominance in the wake of forced inactivity. It became clear to me that the sounds of nearby birds triggered a profound shift in behaviour, and that vision played a secondary role in the perception of avian threats – as every neotropical birder knows, foraging birds are heard more readily than seen.

Concerning the above study, it perhaps bears noting that the American Kestrel is not a highly vocal bird, and that it is likely to remain silent while hunting. I have frequently observed toucans apparently hunting in shrubby forest margins, where no fruit-bearing trees were evident and anoles were plentiful, and at such times the birds were always silent – only their deep wingbeats would betray them to a wary anole.