To some degree, I am playing Devil’s advocate in supporting the split of Anolis – but I do think there are valid arguments that need to be considered.
There are a number of assumptions that, if proven to be false, weaken my argument:
- As a clade, anoles are older than the KT boundary – 65 million years. The estimates from Nicholson et al. are much older than that, but if you were to choose a date where splitting up vertebrate genera might make sense, 65 million years is not unreasonable. It is likely that coalescent methods will make the estimated age of anoles younger than the 95 million years in the paper, but I’m going to guess older than 65 million years. You may feel that clade ages are irrelevant, but I’m willing to bet that most people would have some age that they would say is too old for any genus (500 million years?)
- The Alfoldi et al. (2011) tree is pretty accurate and the following aspects of that tree will remain after adding taxa and more data. Starting with the Norops clade or genus (see below for a discussion of why Norops), there are 8 very well supported clades (black dots on the Supplemental figure). There are very short branches between 4 of those groups, representing a rapid radiation such that only 3 of 7 possible inter-group relationships are well supported. Anolis lucius and A. argenteolis were left in Anolis by Nicholson et al. because A. argenteolis represents the biggest conflict between mtDNA and nuclear DNA and is placed with high confidence with the Anolis clade in Alfodi et al. – I assume that the nuclear tree represents the correct placement of that species.
- If Anolis is split up, the usage of the word “anole” would increase and refer to all 8 genera to a degree that would minimize workers not knowing that these 8 genera are monophyletic.
One narrative that needs to be considered (see Rich Glor’s excellent post on the history) is that the impetus to split Anolis comes from those who have primarily worked in Central and South America, where the two most disparate (by time) clades of anoles co-exist. If there are non-systematists working on anoles on the mainland it would be useful if they recognized the deep split between two clades of species now in the same genus, especially if clade names fail to be used outside of those whose focus is phylogentic trees. The problem has been that if Dactyloa and Norops are used on the mainland, then a bunch of other generic names are needed for the Caribbean species that fall between the two genera on the tree, with 8 being the minimum number of very well supported groups (again with an assumption that the nuclear DNA framework is robust). To split Norops further might lose the great story of the reinvasion of the mainland from the Caribbean (Nicholson et al., 2005). From the perspective of those working on the mainland, 8 is a logical minimum number. Given the lack of resolution between the 8 groups, 8 clades is more information than 1 and not much is lost going to 8.
It is important to ask what workers on mainland anoles other than Nicholson et al. think about splitting Anolis. What does Laurie Vitt think, for example?
Another aspect of genera that hasn’t been touched on yet is morphological dissimilarity. Although there is no agreed upon (or necessary) level of dissimilarity needed to recognize a genus, my personal feeling is that if two species are in separate genera, it should not be difficult to tell them apart as species. I think that this is one reason that I am opposed to the excessive splitting of Bufo and Rana that have been proposed. (To really make this a really good argument, I would need to find some specific cases where the new Frost et al. 2006 genera are difficult to tell apart as species – I’m just assuming that this is true –). In any case, Anolis is not like Bufo – the species are distinct and there is plenty of morphological variation. Long before molecular phylogenies, workers on Anolis, knew (or at least strongly suspected) that ecomorphs were not monophyletic. This does not necessitate splitting Anolis, but it distinguishes it from other cases that may be oversplit.
It seems very likely, (particularly on the mainland) that some workers will use the revised taxonomy and some will not, leading to an increase in the mixture of name usage.
Unlike others, I don’t think that this fragmentation in usage is necessarily horrible because it will force anyone who works on this clade to consider phylogenetic relationships and to be cautious about applying any methods that blindly consider genera to be equivalent in any way (this includes any meta-analyses of squamates that use genera as a unit of measure).
In conclusion, even if I’m playing devil’s advocate to some degree, I have a real concern about the best way to encourage the use of phylogenetic information outside of research that is focused solely on taxonomy and the phylogenetic history itself.
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
Nicholson, K.E., Glor, R.E., Kolbe, J.J., Larson, A., Hedges, S.B. & Losos, J.B. (2005) Mainland colonization by island lizards. Journal of Biogeography, 32, 929–938.
- A Case For Splitting Up Anolis - October 2, 2012
Jason Knouft
From an ichthyologist’s perspective, I’m all for the break-up of Anolis…it immediately positions Etheostoma as a real contender for most diverse genus of vertebrates.
Thomas Sanger
And therefore I say, stay out of this Knouft! With a measly 140 species Etheostoma has millions of years to go before it catches up with Anolis.
Skip Lazell
All these arguments can be made for recognizing every clade as generic, so every species will be in its own genus: the pet-traders’ dream come true.
Kirsten Nicholson
Skip, you really need to let go of these references to the pet trade. None of us are involved in it, and no one is doing anything with the intention to facilitate it. None of this blog has anything to do with the pet trade.
Todd Jackman
A trend that I’ve noticed it that the degree to which you are passionate about name changes either way is proportional to the assumed lack of knowledge about the phylogeny of anoles. Let me explain with some random examples: —
Luke Mahler is concerned that changing names will result in people not knowing that anoles are monophyletic ( https://www.anoleannals.org/2012/09/27/whats-in-a-name-part-ii/#more-10694).
Advocating splitting Anolis is based to some degree on forcing those who don’t know about the phylogeny to increase the number of clades considered, and the idea that clade names will not be used widely (leaving people ignorant)
The argument of disruption is proportionally severe to the degree of ignorance about the taxonomy and phylogeny. I would say much of Jonathan Losos’ argument is based on the assumption that researchers ignorant about anoles will be confused and make mistakes.
I think we need to be more optimistic and/or demanding about researchers learning something about the phylogeny of the group they are going to publish about, even if they are not experts on the group.
If I were asked to be involved in a project about 50 genera of beetles which I know nothing about, it would not be too much to ask that I read a few papers and check all of the genera out and have some idea of the phylogenetic relationships of these beetles.
It is not too much to ask that people put a little effort into knowing some basic facts, the phylogeny being one. I was really annoyed (more than any of the other parts of this debate) when Luke Mahler said this in previous post
“As for whether people in the future would learn that these 8 genera are anoles, and were once called Anolis, I’m not so sure… A lot of people would be taught, but a lot of others might come across the group without any training at all. Harvesting and re-use of data is only becoming more prevalent with each passing year, and there are now countless papers that study big-picture questions using data on organisms that the authors know very little about (think, for example, of all the synthetic work that goes on in think tanks like NESCent and NCEAS). These are the folks that aren’t going to know one genus of lizards from another,..”
I wasn’t annoyed at Luke, but that he might be right.
If you work at NESCent, you should be intelligent enough to not be allowed to publish meta-analyses without having some minimal familiarity with the groups you are working with, regardless of your background. The attitude that phylogenetic trees are interesting, but specific trees are not interesting or worth knowing bout exists, but it shouldn’t be that way.
Kirsten Nicholson
I completely agree, Todd. We are all trained as scientists to be scholars and to do the proper due diligence to learn the back ground on our topics. With all of the online sources to helps us with both recent and ancient literature, there’s no excuse for not knowing all the details of your science. When I was an undergrad and graduate student, it was expected that you were to read EVEYRTHING on your species of concern and topic. These days, people just read the last two years worth of literature and seem to call it good…
Yoel Stuart
Respectfully, I’d like to point out that your argument cuts both ways, Kirsten. Anyone new to Anolis who was reading everything on the entire clade would quickly discover all the diversity that lies within it. They would find the Norops clade and the Dactyloa clade etc. nested within Anolis. They would see the diversity across the tree. So, the argument originally stated in your paper that we need to recognize all the diversity as new genera or otherwise people won’t know about it, actually shows little faith in your readers.
(I actually think it would be easier to find the diversity within a group than to zoom out to collate a bunch of genera into a bigger but undefined clade. Unless, of course, you’ve got a phylogeny [see all the comments during the last week])
Rhetoric and semantics aside, I think most of the arguments made on this site about this topic can cut both ways, all boiling down to the basic question of how do we decide what a genus is. This is not an easy question, as you know. Where do we stop the sliding scale on the arbitrary genus. The logical conclusion of your paper is that eventually all we’ll have are monotypic genera. The logical conclusion of the Losos/Glor lumping argument (I am in that camp) is to make bigger and bigger genera. Neither of these are tenable. Thus, I think the simplest and safest thing to do is nothing. Keep Anolis sensu lato.
Ambika Kamath
While it is perfectly reasonable to expect any biologist to find out what is known about the phylogeny of the taxa they work with, it seems unnecessary to have them contend with a series of reclassifications, running the risk of obscuring previous work on those taxa. If biologists are (and should be) expected to know the phylogenetics of the group anyway, why reclassify genera?
Luke Mahler
Todd, while I agree that it would be good to demand in-depth investigation of study organisms when people do large scale analyses, we’re not really in a position to make that demand when we taxonomize. All we can do is anticipate what will happen after we publish (and perhaps be grumpy about it when we’re old). Like it or not, taxonomic changes on big groups will inevitably lead to future research errors.
Ambika, I agree with you that it’s unnecessary to confront biologists with a series of reclassifications. It just makes research harder. I think this is especially true for students. I didn’t fully realize that scientific names changed frequently until sometime during my undergrad. The first time I saw a synonymy list, my immediate (and very natural) reaction was: “This is seriously messed up. What a broken system.”
I stand by this! When I learned how many days I was going to have to spend mastering the arcane and now completely irrelevant historical details of theropod dinosaur taxonomy before I could get rolling on my cool new project on tooth evolution, my heart sank. Some of that taxonomic change was necessary, I’m sure, but I guarantee lots of it wasn’t. I don’t think we should impose such punishing traditions on future generations just because of what we had to endure. If this sort of thing builds character, maybe students should also walk 10 miles to school every day in 10 feet of snow, uphill both directions, like our grandparents did.
Barnaby
Excellent post, Dr. Jackman. I agree strongly with your points, even if you’re just playing the devil’s advocate.
Liam Revell
@Todd –
To your point on morphological dissimilarity:
Although there is no agreed upon (or necessary) level of dissimilarity needed to recognize a genus, my personal feeling is that if two species are in separate genera, it should not be difficult to tell them apart as species.”
I think this actually serves as a persuasive argument to keep Anolis together. Sure, an anole specialist may be able to easily distinguish between (say) Anolis sheplani and Anolis (Deiroptyx) occultus; or (say) Anolis (Norops) sagrei and Anolis (Ctenonotus) cristatellus with the subjects in hand; but these species are, for all intents and purposes, highly similar. (I challenge the reader to distinguish female sagrei and cristatellus where the two species co-occur in south Florida without first having the animals in hand. Even males can be difficult.)
Anoles are phenotypically diverse, no doubt, but most (obvious) morphological and ecological diversity in anoles is within, rather than among, the clades of Nicholson et al. (2012). Morphological synapomorphies can be found, to be sure, but these subtle features of squamation and skeletal anatomy are much less apparent than the obvious gross morphological similarities between members of different clades.
Of course, I would not argue that we should retain the generic identifier Anolis based on symplesiomorphy and homoplasy, but I do provide this comment as a counterargument to the claim that there is “sufficient dissimilarity” in Anolis to warrant taxonomically subdividing the clade.
Furthermore, a number of features – highly apparent to the field worker – do serve as morphological synapomorphies uniting Anolis sensu lato. Anoles are always readily identifiable as such to a field biologist; much like Bufo sensu lato were all unmistakably toads.