What’s In A Name?: Scientific Name Use For Anoles, By The Numbers

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.

Here’s what I found for anoles vs. geckos:

Anole                       844
Anolis                      9,155
Dactyloidae            3
Polychrotidae        200
Gecko                      8,877
Gekko                      1,199
Gekkonidae            1,516

Here are the eight genera proposed by Nicholson et al. (2012). All of the non-Anolis names have a previous history of use, but they’re relatively minor compared to Anolis. Obviously, we don’t expect them to compare to Anolis, but I did want to give some numbers on their present “searchability”:

Anolis                        9,155
Audantia                  0
Chamaelinorops     22
Ctenonotus               6
Dactyloa                   12
Deiroptyx                 3
Norops                      146
Xiphosurus              2

Finally, here are numbers for some more inclusive groups. I find it remarkable that “Anolis” returns more records than “Squamata”! We can eventually beat “Anolis” if we continue to widen the circle though, and I’ve included some examples:

Iguanidae                1,209
Iguania                    299
Squamata                8,409
Squamate                1,135
Lizard                      64,591
Reptilia                   249,702
Reptile                    250,569

In addition to showing that the Anolis literature is extraordinarily rich, I think the numbers bear out the common intuition that the genus name “Anolis” is the de facto name for this group of lizards within the scientific community. If your undergraduates would like to learn about anole community ecology for their upcoming term paper, they’d be much better off searching for “Anolis community ecology” (135 hits) than “anole community ecology” (23 hits). Furthermore, there’s overlap in the use of these terms, with “Anole” being largely nested within “Anolis“: 79% of the “Anole” results also come up in a search for “Anolis” – you can ignore the term completely, and still recover nearly 80% of the records that use it. Conversely, only 7% of “Anolis” results come up if you search for just “Anole”. The opposite general pattern exists for geckos. For that group, Linnean names are less widely used than the common name “Gecko” to communicate to other scientists. One might argue that this isn’t a fair comparison, since we’ve always had different names for various gecko lineages, but I think this is beside the point, which is that “Anolis” is an incredibly communicative and scientifically useful handle, and that we can’t simply replace it by using a common name or higher taxonomic name when we wish to refer to the entire group in the future. If we’re to adopt the Nicholson et al. classification for anoles, should we put “Anolis” in the keywords of all future papers on Deiroptyx or Xiphosurus, so that the group continues to have a useful, searchable name? Alternatively, should we make efforts to ensure that newcomers learn the taxonomic histories of these other genera, so that they can carry out their research effectively? My hunch is that neither approach would work well – historical taxonomic details quickly become arcane, and I think it would be too much to ask for non-specialists to remain aware of these.

Anoles have become a model system in biology, and for whatever reason – historical, idiosyncratic, legitimate, or perverse – the name “Anolis” is what we use for them, and the name has come to serve the community well. Several other model systems are also known primarily by genus names, in some cases despite being old and diverse lineages, as Thom Sanger very recently discussed. Although we all know what “fruit flies” are, we tend to refer to them as “Drosophila,” and because of the history of use of that name, there would be many costs to significantly redefining it (see the references linked near the bottom of Thom’s post for a very interesting discussion of debated proposals to split up Drosophila). For what it’s worth, the genus and common names for Anolis and Drosophila return similar ratios of records on Web of Knowledge: “Drosophila” yields 331,074 results, while “fruit fly” returns 33,532. Just as in anoles, the genus name returns roughly ten times more results than the common name. As Thom mentioned, the genus name “Drosophila” has been maintained by that community despite proposals to carve it up. Given the similarities of these groups (both are model organisms studied by huge communities, and both are primarily referred to by a genus name), it’s worth considering why that community decided to maintain a more inclusive name.

I think that for anoles, there’s much to lose by abandoning the primary name used for this group for the past century. I’m skeptical of the proposal that “the single genus concept can be a hindrance to scientific communication regarding evolutionary events and directions of future research” (Nicholson et al. 2012, p. 13). The numbers show that the name “Anolis” has been the handle of choice for communicating all sorts of findings about anoles for many decades, and scientific communication about anoles has been, if anything, exceptional during this period. If progress resolving the phylogenetic relationships of anoles seems late in coming (and I would argue that we still have a ways to go), I think it’s because it’s a legitimately difficult problem rather than because we don’t recognize enough lineages within the current Linnean taxonomy. I’d certainly be interested in seeing any data that might support Nicholson et al.’s criticism of the single genus concept, but even if that argument can be buttressed empirically, I think we need to carefully weigh the impact of dramatically redefining a genus name like “Anolis” before adopting a radically different taxonomy.

KIRSTEN E. NICHOLSON, BRIAN I. CROTHER, CRAIG GUYER & JAY M. SAVAGE (2012). It is time for a new classification of anoles (Squamata: Dactyloidae) Zootaxa, 3477, 1-108

21 thoughts on “What’s In A Name?: Scientific Name Use For Anoles, By The Numbers

  1. Luke, what is the difference between the number of research groups that use Drosophila versus the number the use Anolis? I ask as a devil’s advocate because it’s possible that a relatively small number of extremely productive labs use a name out of habit or ease-of-use, a sort of “Founder Effect” in terminology. With Drosophila, you have almost 100 years of research produced by probably hundreds of groups. It might be an apples-and-oranges comparison.

    1. Hi Marc,

      That’s a great question, and it would be a really interesting comparison. There are probably clever ways to quantify this, but I’m not aware of anything simple. Rich – is this something you’ve ever looked into?

      While there are undoubtedly some pretty big “lineage signatures” in the anole literature, I bet they’re becoming less pronounced. The green anole has been a pretty widely used as a lab model since the early 20th century, but new work on anoles is occurring worldwide as a result of the recent sequencing of the genome of Anolis carolinensis.

      1. The lineage-specific signature in anole taxonomy that is most evident in the literature is the persistent use and advocacy for Norops by Jay Savage and his students. Over the past 30+ years three papers have introduced taxonomic revisions that recognize Norops and all of them were written by Savage and his students (Savage and Talbot 1978, Guyer and Savage 1986, Nicholson, Crother, Guyer, and Savage 2012). Meanwhile, members of numerous academic lineages have advocated continued recognition of a single large genus of anoles within which diversity is recognized informally (e.g., Etheridge [PhD with Hartweg at U. Michigan], Williams [PhD with Gregory at Columbia], Hedges [PhD with Highton at Maryland], and Poe [PhD with Cannatella and Hillis at UT Austin]). I haven’t gone back in these people’s lineages more than one generation or considered who they trained with outside of their PhDs (e.g., Poe worked with Williams as an undergraduate), but I think the pattern is clear.

  2. I’ve done a similar exercise using full-text searches of the JSTOR database and have obtained similar results. No question about the fact that Anolis has a very long history of use and that this term is far more widely used than any other formal taxonomic term to refer to anoles.

  3. Luke, this is a great argument for not changing Anolis, except that the history of usage should not necessarily be the main consideration.
    Look at the fungal genus Candida.
    51,024 results in Web of Science, nearly beating out lizards.
    Except Candida is two unrelated genera (with a common ancestor over 100 million years ago).
    The reason the names haven’t changed, is the enormous amount of literature using Candida to represent both unrelated clades of fungi (who both happen to be human parasites) – changing the genus would cause too much disruption.
    Anolis is monophyletic, and that could end the comparison, but if you agree that name changes are needed in some cases in spite of historical disruption – the argument has to be that any potential benefit of accurately representing phylogeny with new names are outweighed by the disruption of usage in the case of Anolis (rather than a general disruption argument)
    The disruption would be great in the case of Anolis, and thus my mixed feelings –
    Ignoring rules of nomenclature, I also dislike using Chamaelinorops for a large clade, and I dislike getting rid of A. etheridgei.
    However, I would like anyone who is working on (at any level) Hispaniolan crown giants to be always aware of their membership in a clade that includes big Cuban oddballs and Cuban crown giants.
    Using clade names would be great, if there were some good ideas for broad usage in ecology, physiology and other non-systematic disciplines.

    1. As you recognize in your comment, its not fair to compare the situation with Anolis to the situation you mention involving Candida. I don’t think any of use would argue against breaking up genera or other named taxa that are demonstrably non-monophyletic (and that cannot be rendered monophyletic by including additional species belonging to genera with younger generic epithets), regardless of how dramatic the required changes might be. I believe most systematists would characterize these types of changes as “necessary.” However, changes like those proposed by Nicholson et al. that involve breaking up a widely studied and demonstrably monophyletic genus into a set of smaller genera can easily be characterized as “unnecessary.”

  4. That’s a really interesting comparison Todd. As you mentioned though, the Candida situation is much more unfortunate, since those species are apparently polyphyletic, unlike Anolis. We’d be faced with a tougher choice if anoles were shown to be non-monophyletic, but I’m taking it as a given that they’re not. I think that if a taxonomy doesn’t violate monophyly, history of usage (a key component in assessing impacts on stability) is indeed one of the primary factors of consideration when the ICZN arbitrates taxonomic disputes (in fact, their motto is “standards, sense, and stability for animal names in science”: http://iczn.org/).
    As for your point about considering the balance between a “benefit of accurately representing phylogeny with new names” and the cost of “the disruption of usage in the case of Anolis“, I think we’re stepping into dangerous territory here for a couple reasons. First, I think it’s important to be clear that simply maintaining “Anolis” is in no way phylogenetically inaccurate, since this name has long been applied to all members of a monophyletic clade. The alternatives on the table differ not in accuracy, but in the phylogenetic scale of information content. “Anolis” accurately depicts our understanding of phylogeny, and communicates valuable information about the phylogenetic affinities of nearly 400 pad-bearing small-to-medium-sized neotropical lizards with dewlaps. These are organismally and phylogenetically informative traits, and we’re fortunate to be in a situation that, for anoles, all of this information is contained within the genus name applied to all of the species. That said, we might be able to carve Anolis up and still accurately represent phylogeny. But it would involve a tradeoff in the type of phylogenetic information expressed in the names of genera, and I think that’s the key distinction (i.e., scale of informativeness, not anything to do with phylogenetic accuracy). Let’s assume for a moment we know the phylogeny with certainty: If we were to divide the anoles into 8 genera, the Latin binomials for anoles would gain information about phylogenetically shallower affinities and distinctions, but lose information about phylogenetically deeper affinities (and distinctions from other groups). Since neither treatment is more accurate than the other, it must be decided whether the cost to stability is outweighed by any benefits that might come from favoring one type of phylogenetic informativeness in the binomials. Ultimately, how much phylogenetic information “should” go into names is completely subjective, and I don’t think the ICZN has rules or even best practices on this for this reason (please correct me if I’m wrong!). I think the ICZN has tended to be conservative (i.e., favoring stability) when changes involve subjective costs and benefits, but ultimately, it probably rests in the hands of the community at large.

    1. Lots of people writing posts and commenting on Anole Annals seem to have the wrong idea about what the ICZN does and seem concerned that the ICZN is going to start policing anole taxonomy or forcing the community to formally accept Nicholson et al.’s proposed generic revisions. I’m not expert on the ICZN, but I think I know enough to clear up some of this confusion. The ICZN does not govern taxonomy and doesn’t want to have any role in dictating taxonomic practice to systematic biologists. The ICZN only governs nomenclature (i.e., the application of names to taxa). See my other comments on this that appear under this post and this other post. Perhaps a stand-alone post on this is warranted, but maybe we can get a real expert on the ICZN to do this?

      1. I agree Rich. I suspect this distinction (governing only the nomenclature of taxa, and not other taxonomic issues) seems like a subtle one to a lot of folks (myself included), and it would be great to clarify things. I’ll be reading up on this stuff over the next few days, but I’d certainly welcome a post by someone who really knows what they’re talking about.

  5. As most of you know, I am not a systemacist and I don’t work on Anolis…..however, as an outsider, I am struck by the large number of species in this one genus (~400!). How typical is this? Does is matter?

    1. Among vertebrates Anolis is very large, but it is far from the largest genus out there. Wikipedia maintains a list of 57 angiosperm genera with over 500 species. There are over 600 Conus species and over 1,000 Drosophila. Personally, when I see large genera I think they are the result of one of two things: (1) unknown or uncertain phylogenetic relationships in the group is – these “trashcan” genera and are likely to be split later due to a lack of monophyly or (2) large, monophyletic groups which represent remarkable radiations of species. I think nearly all anole biologist would agree that the latter is the case for anoles.

  6. The text below is quoted from: The Destabilization of North American Colubroid
    Snake Taxonomy by Burbrink, Crother and Lawson (Herpetological Review, 2007, 38(3), 273–278).

    “By eliminating the subfamily classification, Collins (2006) has
    effectively reduced the phylogenetic information inherent in the
    taxonomy proposed by Lawson et al. (2005). The arrangement of
    the NA Colubroidea in Collins (2006) simply elevates seven subfamilies
    to familial level while discarding interfamilial relationship.
    Retaining these as subfamilies nested within families, as suggested
    by Lawson et al. (2005), reveals information concerning
    relationships among these subfamilies (Table 1; Fig. 1). For example,
    it is not clear in Collins (2006) that the Elapidae and
    Hydrophiidae share a more recent common ancestor with each
    other than any of the other NA families of the Colubroidea (i.e.,
    Colubridae, Natricidae, etc.).”

    Would not such a criterion argue for the use of subgeneric taxa within the monophyletic genus Anolis? Or is my small mind just haunted by a hobgoblin?

  7. So “Anolis” is a well used name because it represents a group of lizards that have been well studied and used by the scientific community. But the reason that the term Anolis is used is because that name has been around a long time, and because few changes have been proposed OR accepted by the herpetological community. Guyer and Savage made one attempt, Hedges et al also made another, but at a time when their methods were not largely embraced. The Guyer and Savage proposal was not accepted by many in part because the genera they were proposing were not monophyletic; I, too, did not use those names in my papers. However, the accumulated evidence in the literature, as well as in our paper, supports many large clades to which we apply generic names. The point of a classification is to facilitate communication. I understand that folks are pounding the pulpit for “stability”, but if you agree that our classifications should mirror our phylogenetic knowledge, then you won’t have taxonomic stability until you have phylogenetic stability. Of course, if you think classifications should not mirror phylogenetic knowledge and are just useful ways for some folks to “pigeon-hole” groups of taxa, well then never mind, but those types of classifications won’t be useful to the majority of people. Our paper reviews what we know regarding these large clades within the Dactyloidae and we apply names towards those well supported clades. They are all monophyletic with the exception of a very few taxa that move around, and we address those and how we proposed to handle them in our paper. Each of those large groups within the Dactyloidae represents an evolutionary lineage with specific molecular and morphological characters unique to them and their independent evolutionary histories. In our view, our classification serves to make those evolutionary histories clear, and in some ways, serves to further highlight the exceptional diversity exhibited by these lizards. For those that are not systematists, and I rather think those are the ones BEST served by classification schemes because they don’t know the details of the phylogenetic research, these names serve to highlight for them what taxa are most closely related to others. I do think it will be interesting to try to apply the PhyloCode to the anoles as a test case, because while I think the Code might satisfy some of you, there are some aspects that I suspect no one will embrace, which might explain why it hasn’t been embraced by everyone.

  8. Hi Kirsten,

    Thanks for weighing in! As Rich said, it’s great to have you join the discussion.

    In the spirit of keeping things going, I’ve written a bit more (well, more like a lot more) to expand on some of the thoughts that prompted me to post last week. I originally put these in a comment here, but have moved them to a new post, since (1) I think this thread is worth continuing, but is becoming buried in the historical depths of Anole Annals, and (2) it’s hard to see the figures I made when they’re inserted in a comment. Hopefully we can pick up the discussion here.

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