Category: All Posts Page 140 of 153

httpv://www.youtube.com/watch?v=LVdLNIXujL8

My vain attempt at alliteration with the title, here’s a news story on those pesky lizards mucking about with electrical power (sorry I don’t know how to avoid you watching the ad at the beginning).

From Dustracks on the Web.

Janson Jones has a binder full of anoles.

In the latest issue of Copeia, Eric Pianka provides the latest positive review of Lizards in an Evolutionary Tree.  Its easy to understand why this review appears more than three years after the book’s publication when you remember that Pianka has been a busy dude who most recently gained attention for recovering from the dead.  Anole Annals also has archived links to other reviews of the book for those interested.

Three weeks ago, I initiated discussion of Nicholson et al.’s recent monograph by noting that it is the most important paper on anoles published in recent years. We’ve had a lot of interesting discussion of many aspects of the paper since then, but we should keep in mind, even in the light of this discussion, that regardless of what one thinks about the various issues debated on our pages, this paper certainly represents a comprehensive compendium of knowledge about anole taxonomy, systematics, biogeography and ecology, and as such will remain an important resource for years to come.

Having said that, I wanted to use this last post of mine to synthesize what I see as the conclusions of the past three weeks’ discussion concerning the “bold hypothesis” of anole biogeography and evolution presented by Nicholson et al. Their hypothesis can be boiled down to three main points: Anolis is much older than previously recognized; divergence into eight major clades of anoles (which this paper raises to generic status) occurred when the geological blocks that now form the Caribbean islands separated from their previous, connected position where they had served as a landbridge connecting North and South America (and, hence, anole biogeography is primarily the result of vicariance, rather than dispersal); and the history of anole habitat use is primarily one of change from a large, crown-inhabiting species to smaller species found on or near the ground. How does this scenario stand up in light of discussion on AA?

Anolis Is Much Older Than Previously Recognized

Nicholson et al. conclude that the ancestor of anoles diverged from their nearest relative 95 million years ago (mya) and that diversification to produce the eight major clades occurred 72-87 mya. These dates are far older than other estimates; three recent studies have pegged the split between Anolis and its sister taxa as occurring 25-80 mya.

Nicholson et al. molecular phylogeny with their dates of divergence and with dates corrected assuming a younger date for the Mexican amber anole, A. electrum in parentheses. The arrow points to the phylogenetic position where A. electrum was placed by Nicholson et al.

This proposed antiquity of anoles is surprising, but is almost surely mistaken.

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I have followed the controversy over anole classification with interest.  Amphibian taxonomists faced a similar issue with the reclassification of Bufo and Rana, among many lesser-known genera.  I discovered that most herpetologists quickly accept new taxonomies (with the exception of extreme and ill-founded taxonomies, like those proposed by Hoser).  So attempts to resist will likely fail.  However, there is an intermediate option that is being used successfully for some taxa and I think it could be profitably pursued for anoles.  That is, use subgenera.  In short, keep using Anolis as you have historically, but if you think the phylogenetic analysis of Nicholson et al. meets your standards of quality, treat their genera as subgenera.  Anolis is the oldest valid taxon and so it has priority. I argue that the name Anolis (Dactyloa) latifrons is more informative taxonomically, phylogenetically and biogeographically than is the name Dactyloa latifrons.  What are the arguments against using subgenera? I can think of none.  I advocate doing this for Bufo and Rana (making certain that each is monophyletic, of course).  The argument against this move is that some relatively well-known names of genera would be lost, but I do not think that is the case.  For anoles nothing is lost if one uses subgenera.  Subgenera are being used successfully for salamanders.  Hydromantes is a well-known group of salamanders, admittedly small in relation to Anolis.  It is clearly a clade based of substantial DNA sequence data and osteological-myological data.  Yet some wanted to break it up because it occurred in Europe and North America.  To me this is one of the best reasons for keeping it a single genus.  So I have advocated a three-subgenera classification: Hydromantes (Hydromantes) for the American species and Hydromantes (Speleomantes) and Hydromantes (Atylodes) for the European species.  This highlights the fact that Hydromantes is monophyletic (no-one questions this) and also reminds us of the extraordinary distribution.  With colleagues I have proposed seven subgenera for the 121 species of Bolitoglossa, three subgenera for the 36 species of Oedipina, and two subgenera each for the 22 species of Batrachoseps and the 55 species of Plethodon.

Why not use subgenera for anoles?

Last week, I wrote a post on how the new classification for anoles proposed by Nicholson et al. 2012 might affect long term taxonomic stability for this group. That post generated some discussion, including, most recently, commentary by Kirsten Nicholson herself, explaining some of the reasons her group decided it was time to split up the anoles. Because that conversation is quickly becoming buried in the depths of Anole Annals, I wanted to continue it here on the main page. Also, I wanted to write some more to expand on some of the thoughts that prompted me to post last week, and I hope folks will continue to weigh in (note, the rest of this post will make a lot more sense if you first read my previous post, and the ensuing commentary). I’d like to make several general points:

1 – I think we can all agree that taxonomies should reflect accurate phylogenetic knowledge (I don’t think anyone here would disagree with this – let’s take it as a given that Linnean taxa should not be paraphyletic or polyphyletic).

2 – Beyond accuracy, I’m pretty sure there aren’t any rules governing the type or level of phylogenetic information that “should” be included in a binomial classification. Whether binomial names should reflect deep phylogenetic knowledge or shallow phylogenetic knowledge is a matter of opinion – I’d propose it’s completely subjective.

3 – The amount of phylogenetic information you can communicate in a binomial classification is trivial. It’s hard enough to represent phylogenetic structure across the depths of the entire Linnean hierarchy, and there’s almost no such information in Genus+species epithets. The goal of communicating finely resolved phylogenetic information probably should not be our main concern when dealing with genus names (so long as they are not phylogenetically inaccurate).

4 – Given that no one’s to say who’s right about what the appropriate phylogenetic scale of a genus is, and that Latin binomials are ineffective at communicating much of anything about phylogenetic information anyway, issues of stability are comparatively very important. It’s no small thing to propose a change for 88.6% (n = 343) of the scientific names of a group of species studied by thousands of people.

Since I think we can all agree that Linnean names should be applied solely to monophyletic groups, I’ll start with my second point, which is that there’s no “right amount” of phylogenetic knowledge that should be expressed in binomial names. Kirsten suggested we might all agree that “our classifications should mirror our phylogenetic knowledge.” I certainly agree with this statement in general, but I suspect I might disagree on some of the details. What sort of classification, exactly, would mirror our knowledge best? Should we assign genera to the smallest phylogenetic units about which we can be reasonably certain of monophyly, and continue to split them up into additional genera as we work towards resolving the entire bifurcating history of anoles? If so, we’ll probably eventually end up with a taxonomy that’s as finely parsed as that of the non-avian dinosaurs, where the genus:species ratio is 1:2 (I’m not even kidding – check it out…)! At this point, we’d have all sorts of cool binomials, like Nicholsonolis annectans and Mahlerolis gorgonae, but the genera would be functionally equivalent to species names (as they are in dinosaurs). This sort of reasoning (taxonomy should reflect ever-improving phylogenetic knowledge) is implied in the very title of the Nicholson paper, which seems to suggest that periodically, when the progress of systematics has advanced enough, “it is time” to reclassify everything (I think this contradicts the founding purpose of Linnean classification, but that’s another point). Anyhow, if this isn’t what it means for a taxonomy to mirror phylogenetic knowledge, then what exactly does that mean? Why 8 genera, and not 60, 16, or 4?

My main point here is that it’s a matter of opinion what kind of phylogenetic knowledge should be in a Latin name. One person might think that a genus should apply to the MRCA and all descendants of any two species similar enough to be confused by an experienced herpetologist (e.g., Anolis fraseri and A. biporcatus; see Williams 1966 for details). Another person might maintain that a genus should have 20 species max, no exceptions. Both are entirely matters of opinion, and such opinions abound when it comes to systematics. But since there are no official guidelines on the matter, I don’t think that such opinions can suffice to justify a disruptive taxonomic change.

I next wanted to criticize the logic of amending genus names to reflect systematic developments. The reasons are that (a) there’s very little phylogenetic information in Latin binomials, and (b) any change in the names of genera will result in a gain of some phylogenetic information (shallower information) at the expense of other phylogenetic information (the deeper stuff).

Linnean binomials contain next to no phylogenetic information. When we look at a list of scientific names, all we know is that congeners are more closely related to one another than they are to members of other genera, and other than that, they don’t tell us anything about phylogeny. To illustrate this, I created “binomial phylogenetic trees” for the Iguanidae (or Iguania, depending on who you follow..). I included all species in “Iguania” from the Reptile Database. Here’s what the traditional classification looks like, with Anolis highlighted in red:

Binomial “phylogenetic tree” of iguanian genera, following the traditional classification.

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That’s right, it says so right here!

No surprise to us at AA, but greenies apparently provide yeoman service as garden pest control. And the wonderful folks at www.getmypestout. com provide all kinds of good advice about how to foster a healthy anole population in your garden. Good on ’em!

We’ve already received a lot of great entries, but there’s room for more! We’re reprinting the announcement below. Deadline is September 30, so submit today!

Last year we had an Anolis photo contest and produced a 2012 anole calendar. Both were wildly successful. Today, Anole Annals is pleased to announce it is combining both. We herewith announce the 2012 Anole Photo Contest. The goal of the contest is to identify 12 winning photos.  The grand prize winner will have her/his photo featured on the front cover of the 2013 Anole Annals calendar and will receive an autographed copy of Karen Cusick’s lovely book, Lizards on the Fence. The second place winner will receive a copy of the calendar and have her/his photo featured on the backcover of the calendar.

As should be evident from several recent Anole Annals posts and comments, Nicholson and colleagues published a paper last week proposing that “It is time for a new classification of anoles.” Among a number of arguments in favor of splitting up the genus Anolis, Nicholson et al. (2012) argue that use of a single genus name hinders scientific communication about these animals. This argument has generated a lot of discussion (e.g., a post by Sanger, and two different threads of comments found here and here), and I thought it might be useful to continue the discussion with a bit of information about the usage of anole names in the scientific literature.

In a comment on an earlier post, Duellman argued that a genus name does not simply exist to reflect systematic knowledge – it’s a (hopefully stable) handle that conveys information about identity to a very wide audience, from laypersons to college students to ecologists, conservationists, and systematists.  My impression has always been that this is especially true for Anolis – more so that for many other groups of organisms. For example, geckos are commonly known, even to scientists, by their common name “gecko,” and we find this term in paper titles and abstracts. I don’t think this is true for anoles – it seems to me that we more often simply call them “Anolis“.

To see if this is actually the case, I decided to pull some numbers from Web of Knowledge. I conducted a series of “Topic” searches for various taxonomic names, such as “Anole”, “Anolis“, “Gecko”, etc., and recorded the numbers of matching records for each search. Records include instances in which a term is found in the title, keywords, or abstract of any book or article recorded in the Web of Knowledge academic database. The numbers returned are reflective of my university’s library holdings (University of California), and will be different if conducted elsewhere; I also didn’t spend any time processing the results, but I don’t think that should qualitatively affect any results.

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