Author: Jonathan Losos Page 33 of 130

A typical PCA table that I trawled from the internet.

This post isn’t really very anole-specific, but because lots of studies of anoles use principal component analyses, I think it’s at least tangentially relevant.

PCA is a way of to reduce the variation in a data set to a few dimensions by constructing new variables that combine variables that are highly correlated with each other into a smaller number of variables called PC axes. I won’t go into the details of the method here, because Ambika Kamath explains all in a post she wrote on her blog a while back.

What I want to mention here is how we interpret these new statistical axes. Back in my day, computer programs spit out a matrix of numbers like the one above, which we called “loadings.” These values represented how strongly an individual’s value for each variable was correlated with the individual’s score on the new axes. So, for example, in the table above, values on PCA axis one correlate most strongly with an individual’s values for the top four variables (sodium, calcium, magnesium and chloride concentrations) and most weakly with melt percentage and some other variables.

Now, everyone uses the computer program R to conduct PCAs, and R, too, spits out “loadings.” But those are not your father’s loadings (or my loadings). Rather, those values are the coefficients of the new equation that defines the PCA axis (a PCA axis is a linear regression of all the variables). Thus, in the example above, individuals that scored high on PCA 1 would have the largest largest concentrations of the top four variables; an individuals melt percentage would have little impact on an individual’s score on PC I. Back in the day, we could also access those values, but we called them “coefficients.”

Does this really matter? Only to the extent that what much of the literature used to call “coefficients” is now called “loadings” and what used to be called “loadings” apparently isn’t routinely spit out by R. And, more importantly, most R users are completely unaware of the switcheroo.

Ambika did a very preliminary analysis to see whether the values of coefficients (new “loadings”) and correlations (old “loadings”) are very different. Her tentative conclusion is that they aren’t, so maybe this doesn’t matter much, but it might be worth looking into more.

Elsewhere on Anole Annals, Silas Ginn responsed to a question about what shape anole eggs have. I believe his response deserves a wider audience and so am putting it up here as its own post:

Indeed, anole eggs are long and skinny when they’re laid. But due to their leathery flexible skin, they can expand like a balloon and will grow with age and moisture. I’ve only got experience with Knight anoles, green anoles and probably four or five types of different brown anoles, but they’re all about the same – except that the Knight anoles HATCH at the same size as a green or brown anole.

As for hatchlings of green or browns, they’re so tiny it’s just remarkable! My old workplace was “infested” with a few species of geckoes (in Calgary Alberta, Canada – of all places!) and the baby geckoes popped up all over the place, especially in the filing cabinets where they obviously preferred to lay their eggs between pieces of paper, due to their being hidden & protected so well.

But yeah, at one point I brought in some house-plants – this was a huge ware-house complex where we ran an aquarium fish and reptile importer supplying Western Canada’s pet-shops, plus an outlet to the public, and a custom tank building shop in the back, quite a lot of space and amounting to more than 700 aquariums all told – and the whole place with 35-40ft ceilings and kept at upwards of 30-degrees Celcius all of the time, naturally humidity was such that it actually RAINED inside of the place on a regular basis – a problem in that it brought down the decades-old asbestos spray-on fire retardant insulation material from the ceilings – but we had some very nice sky-lights as well, if it had been kept up better it would’ve made a fantastic space well I mean really fantastic ’cause I loved it even WITH the dust and cockroaches ha-ha.

ANYWAY yeah I brought in some house-plants to liven the place up – should’ve left ’em when I moved on, ’cause they’ve all died since. There was a huge Munstera deliciosa “swiss-cheese plant” which I potted up on top of overhead wooden beams that had been there for decades, as some type of over-head system for a belt-driven power supply back when it was a SWEAT SHOP and then a SLAUGHTER HOUSE for chickens, yuck – we kept the beams for our water supply and oxygen for bagging fish, plus running heated/de-gassed tank-change water, and a master air-line gang-way for running hundreds of little valves off of for all of the little bubblers etc.

But yeah what I did with it MYSELF, was to support some house plants. And this one Munstera got HUGE – it sent out aerial roots, if you know Munstera you know the type I mean – but THESE ones got long enough that not only did they hang down the nine-ten feet to drink from a puddle on the ground beneath it (how did it know there was a puddle there?) which pooled on the polished concrete floor, from leaking tanks, over-spills from the automated tank over-flow water-change system (tanks were individual, and what looked like the typical system where everything’s on a loop, was simply a fill line from huge tanks in the back, run with big pumps only during water changes, and the over-flow went directly to the drains. Which were typically blocked up and one such drain which had been permanently blocked by our swimming-pool canister type “Sand-Filter” from our Koi pond system (several ponds ganged together on one filter) had a huge cray-fish living at the bottom of it, as though the building itself were a concrete island with a lake or ocean below it, and drain pipes more like tunnels carved by urchins or other such burrowing creatures … such was the ecosystem of the place!)

Anyway yeah, that Munstera plant threw out aerial roots that first reached the puddle on the floor, but then I began to wrap ’em around the wooden beams to keep ’em out of the way, and they kept growing down and down – once they’d got a taste of the mineral-rich water down at the bottom there was no stopping ’em! And I kept looping ’em over and over, they kept growing until this became a semi-daily task, where the roots would grow more than ten inches in one night! INSANE house-plants.

But the best of ’em all, was a 30ft Ficus tree. I had been keeping my Knight anoles in ficus trees from the very beginning, and they’d laid their eggs in the pot at the bottom, whereupon they hatched out better than any other time when I tried to incubate ’em artificially.

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AA regular James Stroud aims to find out. The following is taken from the FIU (Florida International University) News:

FIU biology student James Stroud has observed a non-native species of lizard in Bermuda, a potential problem for the island’s critically endangered Bermuda skink.

A two-year conservation project studying the island’s lizard populations led to the discovery of the Cuban brown anole, a species once rumored to inhabit the North Atlantic island, but was never verified until now.

“The Cuban brown anole most likely reached Bermuda by human transport,” said Stroud, a Ph.D. student in theKenneth Feeley Lab. “These lizards hitch rides between ports as unintended stowaways amongst cargo, usually in nursery plants and building materials. Although further research is needed to confirm it, this route of introduction seems likely.”

The introduction of the Cuban anole could pose difficulties for the endangered Bermuda skink, the island’s only native lizard species. Also known as a rock lizard, the skink is listed as critically endangered in the International Union for Conservation of Nature’s (IUCN’s) Red List, the world’s authority on the conservation status of plant and animal species. According to the researchers, Cuban brown anoles excel at thriving outside of their native geographical area. The lizards can live in a variety of natural and human-made habitats, and feed on a variety of prey, potentially putting them at an advantage to other lizard species who might not be as tolerant.

“We have discovered that the Cuban brown anole does not yet overlap its distribution with the Bermuda skink,” Stroud said. “Therefore, the potential effects of the non-native brown anole on the native Bermuda skink are currently unknown. This topic forms part of our ongoing research interests in Bermuda.”

After surveying all of Bermuda, Stroud found populations of the Cuban lizard at all life stages indicating they are thriving in the central part of the island. He also found the established Jamaican anole continues to be found all over the island, but the Antiguan anole has significantly expanded into areas where the Barbadian lizards live. The discovery was made alongside former FIU doctoral student Sean Giery and Bermuda’s Department of Conservation Services.

Originating in Cuba and the Bahamas, the Cuban brown anole is one of the most widespread lizards outside of its native area with large populations found from Florida to Texas, California, Hawaii, Costa Rica, Singapore and Taiwan. Cuban brown anoles can be found in urban environments including downtown Miami and natural environments such as the Everglades. Anoles are very diverse group of lizards and about 372 species are currently known to exist.

Stroud recently traveled to Costa Rica where he conducted the first-ever study of the Cuban brown anole’s ecology and distribution in the Central American country. He is devoting his doctoral research to studying the evolution, interactions and community patterns of Anolis lizards in the tropics.

Two years ago, we reported on a lovely wedding cake with green anole atop, from the nuptial festivities of Alex Gunderson and his wife Katie. Now word comes to us of another anole wedding. AA correspondent Kristin Winchell, who doubles as a grad student in Liam Revell’s lab, was married to Jonathan Zschau this past September on Nantucket Island. As the photo above attests, the wedding cake was tastefully adorned with a bride, a groom, and an anole.

Actually, it was a double wedding. A photo of the second bride, Ms. Ann Ole, is pictured below (made by the groom’s aunt).

Anolis toldo. Photo by Luis Diaz.

Luis Diaz reported on Facebook the discovery of the lizard shown above. He reports: “Anolis toldo, adult female; third individual of the species known and first specimen in the National Museum of Natural History of Cuba. The discovery of this specimen was a result of the joint expedition by the National Museum of Natural History of Cuba and the American Museum of Natural History. It was found on October 19, 2015, at night, on a tree fern in a new location (outside the only known: the plateau of El Toldo ). This is one of the few photos of the species.” The photo was tagged aat Alejandro de Humboldt National Park.

It’s just come to AA‘s attention that the University of Texas School of Journalism posted an article on invasive anoles in Texas, featuring Yoel Stuart. Check out the article online, and the nifty, albeit chameleon-tainted, poster below.

I’m sure there’s a story behind this photo circulating on Facebook, but I don’t know what it is. Anyone care to speculate?

The last week has seen a spirited discussion of the pros and cons of splitting recognized genera into multiple, smaller genera. We’ve had 34 comments already. Check it out! And if you’re an advocate of splitting genera, that viewpoint has been getting the short end of the stick and could use more support.

As a tangent, the topic of subspecies has come up, and David Hillis has strongly argued for reviving its use. Here’s what he has to say:

First, I don’t think either species or subspecies are “clades.” Species are lineages (the branches on the tree of life). Sexual recombination among individuals results in tokogenetic relationships within species. Clades, on the other hand, are monophyletic groups of lineages on the tree of life. Rather than being defined by tokogenetic relationships, they are defined by phylogenetic relationships.

Traditionally, subspecies are geographical races of species. In other words, they are geographically distinct populations that nonetheless meet and interbreed at contact zones. Sometimes, these contact zones are very broad, as with broad-banded versus southern copperheads. If the contact zones are very narrow, and there is strong evidence that the contact zone is a genetic sink (there is no gene flow across the zone, because of strong selection against hybrids), then I agree that the two entities can be considered separate lineages, and hence species. But in many recent cases, as with the copperhead example, there is abundant evidence that the contact zone is NOT a sink, and that there is NO selection against hybrids. In this case, I disagree strongly with the authors who proposed to split these subspecies into distinct species. That is inconsistent with any lineage species concept…there is a huge area where these two forms intergrade, with no evidence of any loss of fitness. Thus, the two forms are geographical, intergrading races, or subspecies.

I think we will soon see a backlash against the splitting off of geographic races as species as well. Frank Burbrink (who was an author on the copperhead example I mentioned above) and I plan to write a pro/con article about this together, each arguing our respective points of view. Hopefully, this will re-kindle the conversation about subspecies.

Subspecies are unpopular right now because they were long abused in several ways. Inappropriate uses include (1) to describe non-geographic “varieties”; (2) to arbitrarily break up clines; and (3) to describe distinct, isolated lineages that clearly are species. But used in proper context to designate a geographically distinct race, they are certainly reasonable and often useful. They are rarely used in some groups, for several reasons: Groups like freshwater fishes have discrete ranges, so taxa don’t interbreed over broad areas. And many groups are too poorly studied to understand geographic variation. But in well-studied terrestrial groups (like herps), subspecies are perfectly reasonable and useful taxa to designate intergrading geographic races.

Over the last several years, ever since Nicholson et al. proposed dividing Anolis into eight genera, the topic of taxonomic splitting has periodically been discussed in these pages (for example, this post, its comments, and links to other posts).

The general question of when to split taxa recently has been revisited in several comments in AA. A week ago, David Hillis wrote:

“Anolis is a valid name for a monophyletic group on the Tree of Life. It is “special” as a genus only in that the genus name is used as part of a binomial for particular species. It doesn’t make sense to change the scope and application of generic names unless the names are actually misleading about phylogeny (e.g., if Anolis were polyphyletic, then that problem should be fixed). But splitting a valid, monophyletic genus into a bunch of smaller genera, and thereby needlessly changing the names of many species, without fixing any phylogenetic problems with the existing taxon names, is not science. It is just playing around with names. If someone wants to name the groups within genera, then do so…but there is no reason to change the meaning of a existing name (or the names of the all the affected species) in doing so. That is the kind of silliness that gives taxonomists such a deservedly bad reputation among biologists.”

Elswhere, David posted a flowchart on his recommended decision-making process about whether and how to divide recognized genera:

Ivan Prates, in line with comments he made in a recent paper on A. punctatus, then remarked:

“This seems more like a sociological matter.

During the ‘taxonomic revolution’ of the amphibians, about 10 years ago, the (perhaps?) most influential (or faster?) group was the splitter one, and their taxonomic scheme prevailed. Currently, nobody is upset about which species were once named as Bufo, Hyla or Rana. A few do care about Dendrobates – like Anolis, a sexy group with a body of dedicated investigators.

It seems that a single genus makes sense for the community that investigates dactyloid lizards more closely. On the other hand, those who deal with overwhelming levels of herpetological diversity in the tropics (waaaay beyond lizards) see benefit in more partitioned schemes, which correlate more closely to morphology and geography.

So, when we discuss names, it may be healthy not to forget about our diversity as investigators as well. About science, splitting Anolis is not science, but well, not splitting Anolis isn’t science either.”

Photo by Karen Cusick

From Daffodill’s Photo Blog.