What’s In A Name? Perhaps A Rose Is A Rose Is A Rose, But Is An Anolis A Dactyloa?

ResearchBlogging.orgA half century ago my graduate research was stimulated and influenced by the important unpublished Etheridgean thesis (Etheridge, “1959”, 1960).  As an E.E. Williams student, I was an  adopter, user, and later coiner of informal names for seemingly natural evolutionary groups in the diverse genus Anolis.  In most cases, I was building upon (sometimes tweaking) the foundation of Etheridge’s classification.  I believed then and believe now that the use of informal names for natural groups worked well for communicating evolutionary hypotheses both to specialists in our field, and to a broader audience of professional and amateur biologists who are likely not well informed about the nomenclatural history of these lizards.

Nicholson et al. (2012) believe otherwise. Here is their overview, page 13:

“The role of systematics is to advance our understanding of biological diversity in the natural world. Its practitioners are the guardians of the knowledge produced by past generations and responsible for the rational interpretation of new data and their implications. Within this framework, phylogenetic inference has consequences that we think bind its practitioners to produce a systematic classification of the studied organisms. Such a classification must be founded on the inferred evolutionary relationships and dictated by the canon of monophyly.”

I support that.

This note, then, is neither about the role of systematics, nor the  interpretation of phylogenetic analyses (the Nicholson et al. presentation is comprehensive and extremely valuable).  Rather it concerns their conclusion to the cited paragraph about the use of Anolis, as the generic name for the entire clade. They write:

“the single genus concept can be a hindrance to scientific communication regarding evolutionary events and directions of future research.”

I believe exactly the opposite. Specifically, I believe that the single genus concept enhances scientific communication and suggests directions of future research.

Historical Perspective On Anole Genera

Anole taxonomists: Richard Etheridge, Jay Savage, Ernest Williams, S. Blair Hedges, Craig Guyer, Steve Poe

Anolis has been recognized as an extraordinarily large genus for decades, but Nicholson et al. (2012) are not the first to propose recognition of multiple anole genera.  Indeed, all of the generic epithets used in Nicholson et al.’s new classification were coined in 1934 or earlier and most are from the early 19th century.  This early proliferation of generic epithets resulted primarily from the fact that a comprehensive systematic treatment of anoles did not appear until the mid-20th century.  My purpose here is to review the history of generic level anole classification in the years following Richard Etheridge’s pioneering PhD thesis of 1959/60.  I believe that this historical perspective provides necessary context for evaluation of Nicholson et al.’s proposed revisions, and helps explain why the genera in their revised classification appear so rarely in the literature relative to Anolis (see Mahler’s recent post on the topic of genus name usage).

To briefly summarize the history of anole genera, the vast majority of work published over the past half century has formally assigned all, or nearly all, anole species to Anolis.  The only noteworthy exceptions to this include (1) assignment of a small number of morphologically unusual species from the mainland, Cuba, or Hispaniola to PhenacosaurusChamaelinorops or Chamaeleolis into the 1990s and (2) assignment of species belonging to Etheridge’s β section of Anolis to Norops by some anole biologists working primarily in Central America during the 1990s through the 2000s.

Etheridge’s dissertation, which was completed in 1959 but not available until 1960.

In 1959, Richard Etheridge, a PhD student with Norman Hartweg at the University of Michigan, submitted a thesis that relied on remarkably thorough analyses of skeletal morphology to revise anole classification.  At the beginning of this study, Etheridge recognized Anolis as a diverse genus containing over 200 species, but also identified ten other anole genera that contained only one or a few species: Chamaeleolis, Phenacosaurus, Chamaelinorops, Tropidodactylus, Audantia, Mariguana, Diaphoranolis, Xiphocercus, Deiroptyx, and Norops.  Etheridge found the first four genera listed above to be “so unusual” morphologically that they warrant continued recognition, but the rest were synonomized with Anolis because his morphological analyses found them “to be not at all separable from Anolis, or to be based on characters so trivial that they are here considered as identical with Anolis.”

Etheridge left the large genus Anolis intact in spite of the fact that, at the beginning of his study, he “thought it very likely that the great number of species in the genus Anolis might be dividied into several groups, and that each of these might reasonably be accorded generic status.”  His reason for leaving Anolis intact was that “the relationships of the various species of Anolis have proven to be far too complex to be treated in so simple a manner as the proposal of formal generic groupings.”  Rather than naming new genera, Etheridge informally characterized sets of species at “several different hierarchical positions between the genus and species” as “groups,” “complexes,” “sections,” or “series.”  The aspect of Etheridge’s classification that drew the most attention was his division of Anolis into α and β sections distinguished primarily on the basis of basis of a striking difference in the morphology of tail vertebrae (see figure above from Etheridge’s disseration).

The Code Does Not Compel Anole Biologists To Accept Nicholson et al.’s New Classification

We’ve already had lots of discussion about Nicholson et al.’s (2012) recent proposal that Anolis be fragmented into eight genera.  Throughout the course of this discussion, several posts and comments have suggested that anole biologists might be compelled to implement Nicholson et al.’s proposed generic revision by the International Committee on Zoological Nomenclature (ICZN) and its rules for nomenclature (a.k.a. the ICZN* or The Code) (see comments on recent posts by Losos and Sanger).

Although I must admit at the outset that I am not an authority on The Code or its implementation, I will argue below that the belief that the code compels anole biologists to accept Nicholson et al.’s proposed taxonomic revision is completely false.  The ICZN has neither the authority, nor the interest in, policing taxonomic practice and will have no role in determining whether Nicholson et al.’s (2012) new generic classification is accepted or rejected by the community of researchers who study anoles.  I believe that the reasons for this are fairly straightforward and uncontroversial, but they do require us to think a little about our taxonomic philosophy and the difference between taxonomy and nomenclature.

Let’s start with some basics for the non-systematists.  According to the ICZN, the goal of taxonomy is “the identification and interpretation of natural groups of organisms (i.e., taxa) based on characters (such as morphology, genetics, behaviour, ecology).”  One piece of good news for anole biology is that everyone involved in debate over Nicholson et al.’s new classification shares the same fundamental taxonomic philosophy – namely, that taxa should be diagnosed using phylogenetic trees and should correspond with monophyletic groups.  We may debate whether certain taxa are supported as monophyletic by the available data, but we all agree that recognition of monophyletic groups is a primary objective of any taxonomic scheme for anoles.

More good news: The Code has no interest in getting involved with taxonomic decisions.  I realize that the The Code can be really boring to read, but you don’t have to read more than the first two paragraphs of the introduction to get this message (in a few cases I’ve added my own emphasis by bolding text):

“The 4th edition of the International Code of Zoological Nomenclature … has one fundamental aim, which is to provide the maximum universality and continuity in the scientific names of animals compatible with the freedom of scientists to classify animals according to taxonomic judgments.  The Code consists of Articles … [that] are designed to enable zoologists to arrive at names for taxa that are correct under particular taxonomic circumstances. The use of the Code enables a zoologist to determine the valid name for a taxon to which an animal belongs … There are certain underlying principles upon which the Code is based. These are as follows: (1) The Code refrains from infringing upon taxonomic judgment, which must not be made subject to regulation or restraint…

Rather than concerning itself with taxonomy, which inevitably involves subjective decisions made by systematists that specialize on particular groups of organisms, The Code focuses exclusively on nomenclature, or “the system of scientific names for taxa (such as species, genera, or families) and the rules and conventions for the formation, treatment, and use of those names.”  The Code, therefore, merely provides “a set of rules for the naming of taxa that follows an internationally agreed, quasi-legal procedure.”

With this background, we can return to a consideration of Nicholson et al.’s classification and the role that The Code may have in its implementation.  Nicholson et al. argue that in order to appreciate and study the phylogenetic diversity of anoles we must formally recognize the taxon that includes all anoles not as a single genus, but rather as a number of related genera.  Although determining whether to proceed with the traditional classification involving a single genus or the Nicholson et al. classification that recognizes eight genera might seem to be a distinction between two alternative systems of nomenclature whose outcome is dictated by the The Code, this is not the case.  Instead, both alternatives are perfectly compatible with The Code, and the decision about which classification to adopt moving forward is a subjective taxonomic decision that must be made by the community of biologists who study anoles.

All The Code says is that if we anole biologists want to recognize the taxa that Nicholson et al. have diagnosed as genera, we must use the names they have resurrected from the historical literature and applied to these taxa.  If I wrote a paper tomorrow that gave a new generic epithet to the same taxon that Nicholson et al. have named Ctenonotus, this new name would be rejected under the rules of priority outlined in The Code.  However, The Code respects the right of anole biologists to make the subjective taxonomic decision about whether we want to recognize the taxa diagnosed by Nicholson et al. as genera, or instead recognized them informally as series or species groups, as anole biologists have done for decades.  Recall from our earlier passage from The Code that its rules for nomenclature only apply “under particular taxonomic circumstances.”

My fellow anole biologists, we have a taxonomic decision to make and the ICZN is not going to make it for us.  It seems that the worst outcome would be fragmentation of the community of anole biologists, with some researchers using the traditional approach and others applying Nicholson et al.’s revised generic classification.  More readings and notes are after the fold.

Day Geckos Eating Cheerios

httpv://www.youtube.com/watch?v=gPti2cm2ypw&feature=player_embedded

Those darn faux anole day geckos are out-cuting our boys again. The title of this post is self-explanatory, but the link to anoles isn’t completely tenuous–the gene that encodes for taste receptors that are sensitive to sweet things isn’t posssessed by all animals (e.g., cats lack it), but it has been found in the anole genome and, Matthew Cobb guesses based on this video, in geckos as well.

Color-Changing, Water-Cruising Anoles

Check ’em out on dust tracks on the web. Who says green anoles perch high up when in areas where brown anoles don’t occur (check out this recent post and especially the comments  to find someone who says they do, at least in North Carolina).

Anolis Carolinensis Named “Invasive Species Of The Week”

The Invasive Species Specialist Group, a Species Survival Commission (SSC) of the International Union for the Conservation of Nature and Natural Resources (IUCN), recently gave the weekly top honor to our favorite greenie. We love ’em here in the U.S., but as we’ve documented many times, they can be a problem elsewhere. A pdf of the picture above is available at the ISSG site.

Dietary Data For Anolis Capito In Costa Rica

AA contributor Dave Steinberg is in Costa Rica filming anoles. He’s posted his first report over on Chipojolab, featuring information on the diet of a juvenile A. capito he caught, with a surprising twist.

How Often Do Anoles Lose Their Tails In Intraspecific Fights?

Male A. pogus fighting. Photo from http://www.lesfruitsdemer.org/wp-content/gallery/anolis-pogus-battle-03-01-2010/DSC_7573.jpg

Recently, our lab group was discussing what can be inferred from calculating tail loss rates in anole populations. It was pointed out that tail loss doesn’t necessarily result from predators and that, in fact, males may bite off the tails of other males in fights,  and the victor or vanquished may even eat the tail. Someone pointed out that the older literature certainly pointed this out with examples*, but we haven’t seen much of this in more recent literature. So, we then asked, has anyone ever actually seen a tail lost in a fight? No one had. I then got online to look for photos. I could find plenty of males fighting, usually locking jaws or sometimes biting the body or a limb, but I found no photos of an anole biting another’s tail, much less biting off a tail. So, I ask you, fair AA reader, have you ever seen this? Can you provide a photo?

*By earlier literature, we were thinking 1960’s and 1970’s, but here’s a quote from the 1870’s, referring to A. cristatellus. Can you name the author? “During the spring and early part of the summer, two adult males rarely meet without a contest. On first seeing one another, they nod their heads up and down three or four times, and at the same time expanding the frill or pouch beneath the throat; their eyes glisten with rage, and after waving their tails from side to side for a few seconds, as if to gather energy, they dart at each other furiously, rolling over and over, and holding firmly with their teeth. The conflict generally ends in one of the combatants losing his tail, which is often devoured by the victor.”

 

A Week Of Discussion On Anole Taxonomy, Biogeography, And Ecomode Evolution

Nicholson et al.’s proposed re-classification of anoles is now a few weeks old and we’ve already had numerous posts on the topic as well as some great discussion.  Given the interest in this topic, we’ve decided to dedicate all of next week to discussion of this paper.  We invite contributions from all members of the anole community.  Because we have mostly heard people speaking out against, we are particularly interested in hearing those who support this new arrangement.  Anole Annals is a community forum and we do not edit content of posts from our contributors, but we do expect all contributors and commenters to use their real names (like many blogs, we’ve found that anonymity leads to problems that we’d like to avoid).

Here are some of the topics and posts slated for next week. More are welcome!

Monday: Background Information
Historical Perspective on Fragmentation of Anoles into Multiple Genera – Glor
Does The Code Compel Us to Change Anole Classification? – Glor

Tuesday: Thoughts on the New Taxonomy
It is NOT Time for a New Classification of Anoles – Losos
A Rose is a Rose, but is an Anolis a Dactyloa? – Gorman

Wednesday: Calibration and Biogeography
Evaluating Support for the Hypothesis that Anoles are 90+ Million Years Old – Glor
Mitochondrial Estimates for the Age of Anole Radiations – Scantlebury

Thursday: Anole Ecomodes
Is It Time to  Replace Ecomorphs with Ecomodes? – Losos

Friday: Loose Ends and Discussion

What’s In A Name?, Part II

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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