Author: Jonathan Losos Page 108 of 131

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.

Anolis lineatus from Curaçao

Several previous posts have discussed the odd case of Anolis lineatus on Curaçao, whose dewlap differs from one side to the other. Rand and Rand reported this in 1967, but the observation was pretty much forgotten until earlier this year, when Matt Brandley and compatriots confirmed the Rands’ claim. Shortly thereafter, Melissa Losos and I travelled to Curaçao as well and observed the same phenomenon, allaying concerns that the Brandley team was covering for the Rands.

But since these posts, many AA readers have no doubt been sleepless at night, pondering the obvious question: what about A. lineatus on Aruba? Do they, too, have mismatched throat fans? Indeed, one could imagine a scenario in which they might not. Asymmetry is a common result of low levels of genetic variation (although there is a lot of quibbling about this in the literature). Curaçao is downstream in an ocean current sense from Aruba. Thus, it could be that the Curaçao population of A. lineatus was founded by one or few Arubians, and thus the resulting founder effect gave rise to the dewlap discordance.

An exciting hypothesis that I am pleased to immediately quash:

Can You Name Three Things Wrong With This?

By Jonathan Losos

On January 21, 2012

In All Posts

For reasons I can’t recall, I stumbled across this stamp on the internet. There are three things wrong with this. What are they? Ok, one of them is more an oddity than a problem, and that’s a pretty easy one. But I bet no one can come up with either of the other two.

Battle of the Sexes: When Dewlaps Differ

By Jonathan Losos

On January 20, 2012

In Natural History Observations

Anolis insignis above, Anolis transversalis below. Males on left, females on right. Photos appeared in Lizards in an Evolutionary Tree, photographed by Steve Poe (insignis), Arthur Georges (male transversalis) and Alexis Harrison (female transversalis).

Sexual dimorphism–differences between the sexes–have been greatly studied in anoles, and so has dewlap color and patterning. But little research has been directed to the phenomenon of sexual differences in dewlap color or pattern. Such differences are relatively rare in Caribbean islands, but much more common in mainland species. Why does this occur? Nobody knows. In fact, what female anoles use their dewlaps for has been little studied (another phenomenon, fodder for a future post, is differences in the size of the dewlap between the sexes, which can be quite substantial).

In any case, here’s a sampling of dimorphic dewlaps.

Anolis fitchi (female and male), and Anolis orcesi (female and male)

Photos courtesy Melissa Woolley.

Name That Little Known Anole

By Jonathan Losos

On January 15, 2012

In All Posts

Mystery lizard

Here’s a lousy photo of its dewlap, in case that helps.

lousy photo of dewlap

More on the Intriguing Anole of Curacao, Anolis lineatus

By Jonathan Losos

On January 14, 2012

In Notes from the Field

Anolis lineatus. Photo by Jonathan Losos

Matt Brandley recently posted on the remarkable anole of Curaçao, Anolis lineatus, which is notable for having a dewlap that is different on its two sides. Taking advantage of an invitation to participate in a conference in Aruba in January (the travails of life as a scientist), I’ve come to Curaçao to check up on this lizard, which I’ve never previously seen. The dewlap situation sounds remarkable, but there’s a second reason this species is of interest.

Many islands in the Lesser Antilles are home to only one anole species, and the anoles on these islands are renowned for the extent of their convergent evolution to each other and to trunk-crown anoles of the Greater Antilles. Schoener was the first to show that one-species island anoles tend to be remarkably similar in body size, a pattern reaffirmed most recently by Poe et al. The convergence extends beyond size, however, as these species also are very similar in their habitat use (similar to trunk-crown anoles in being arboreal but using a wide range of microhabitats) and their body proportions, such as the length of their limbs and the size of their toepads.

That leads to the question: is this a phenomenon solely of the Lesser Antilles and the two anole lineages that occur there (the bimaculatus Group anoles in the northern half of the island chain and the roquet Group in the south)? Or do solitary anoles anywhere converge on this pattern? Anolis lineatus is a particularly good test, because it comes from a lineage (the chrysolepis species group, about which we will hear more soon) that is not only distantly related to the other two, but is composed of anoles whose habitat and morphology are nothing like those of the solitary anoles.

So, I’m aiming to not only take a peek at lineatus’s throat fan, but also collect data on where it occurs and what it’s morphology looks like. First indications are that lineatus is a chunky anole, not unlike some solitary anoles such as marmoratus or oculatus, but perhaps more similar to trunk-ground anoles than to trunk-crowns.

Habitat-wise, though, lineatus is clearly a surprise—it’s not very arboreal, at least in my day and a fraction of data collection. It’s usually pretty low to the ground, rarely over 1.5 meters high, and often on large rocks or rock walls. More like a trunk-ground anole than a trunk-crown. Moreover, though I’ve been looking for it in the vicinity of human habitations, I’ve yet to see it on a building wall. Bottom line: it’s just not that arboreal.

To be honest, the anole that immediately comes to mind is Anolis gingivinus. This species is a bit hard to categorize: it occurs on some Lesser Antillean islands by itself, but on others it is sympatric with a second species (A. pogus). Moreover, on all islands, it tends to be found relatively low to the ground and not surprisingly, morphologically it’s more trunk-ground-like than typical solitary anoles. Of course, I haven’t actually seen gingivinus in nearly 20 years, so my memory may be faulty.

And we shouldn’t forget the Malice of Nature, which leads me expect to open my door tomorrow and see an anole on the ground, which immediately runs up the wall and out of sight.

By the way, there are other cool lizards here. Lots of green iguanas, for example, but also the very cool and herbivorous Cnemidophorus murinus, endemic to Curaçao and nearby Bonaire.

Cnemidophorus murinus. Photo by Jonathan Losos

Chromosome Evolution in Anoles: A Study Waiting to Happen

By Jonathan Losos

On January 11, 2012

In Research Methods

Anole karyotypes from Gorman and Atkins, Herpetologica, 1968.

George Gorman, who pioneered the use of molecular tools to study anole phylogenetics from the late 1960’s to the early 1980’s, asks:

“Why not examine karyotypes of Dactyloa?”

He says:

“In the 1960’s and ‘70’s, before the DNA revolution, the systematic examination of karyotypes of reptilian taxa mushroomed, and, to some extent helped orient our thinking about relationships among various clades. This was certainly the case within Anolis at various hierarchical levels, from species determination to definition of distinct species groups. To my knowledge, there has been very little added to our knowledge about karyotypes of mainland Anolis that Etheridge placed in the latifrons series of Alpha Anolis, now frequently referred to as the Dactyloa clade. (if these are long-lost terms, Etheridge’s Beta anoles are the Norops section; all other lineages are within his “Alpha” section).

Background

There is a very pervasive, either primitive or convergently arrived at, karyotype among the Sauria…consisting of 12 metacentric macrochromosomes, and 24 microchromosomes. This karyotype may be found in many families and in all species of many genera within families. This was also the known published karyotype of A. carolinensis….the only anole that had been examined until about 1965.

Here’s a brief summary of what followed:

Happy Anole New Year

By Jonathan Losos

On January 11, 2012

In All Posts

Better late than never.

Winter Anoles: Thermoregulating in the Cold

By Jonathan Losos

On January 10, 2012

In Natural History Observations

Braving the elements in Charleson.

We all think of anoles as warm weather, tropical beasties, but of course, that’s not entirely the case. Many live at quite high elevations and are active at cool temperatures. For example, this past summer we saw A. orcesi active (as active as it gets) when temperatures were 20 C and below.

In addition, anoles get relatively far north into temperate areas of the United States. One might think that they’d just go to sleep in the winter and not come back out til the spring warmth, but that’s not the case. Faithful contributor Marc Tollis discusses one recent observation over on his own blog, Anolis Tollis.

Anolis cristatellus, and Life’s Unexpected Twists and Turns

By Jonathan Losos

On January 8, 2012

In All Posts

Read all about it here.

Posthumous Co-Authorship: What Are the Rules?

By Jonathan Losos

On January 3, 2012

In New Research

In a recent AA exchange, it was noted that Ernest Williams’ last publication appeared 11 years after his death. Anthony Geneva wondered “how far one could take posthumous co-authorship. What’s stopping me from including Darwin as a co-author on my next manuscript?”

Indeed, just what are the rules? Are you comfortable with the idea that a paper may be published in the future and the deceased you listed as a co-author, without the opportunity to agree to be a coauthor, much less comment on or contribute to its content? What’s to keep someone just from tacking on the names of prominent figures in a bid to make a paper more publishable or to gain more attention?

In this case, the paper, Poe et al. (2009), made clear their rationale: