Should Anolis be split into several genera, and why is this is the wrong question? The battle over anole classification is not about splitting Anolis into several genera; it is about changing the content of a well-understood taxon, by pointing the name Anolis to a different branch or node of the tree. The war, then, is about the failure to connect taxonomy to phylogeny in an evolutionarily meaningful way, which is that taxon names should be associated with evolutionary lineages (clades) and not with ranks. If one accepts this, then it is rarely necessary to change the association of a name with its taxon, as proposed by Nicholson et al. (2012) in the case of Anolis.
Below I respond to several misconceptions about taxonomy, some with reference to anoles. I am not claiming that Nicholson et al. (2012) espouse these explicitly, but they are germane to anole taxonomy.
Misconception 1. Taxonomic stability is ignorance. Put another way, stability in taxonomy is not necessary, or even desirable. In contrast, I argue that stability should be a basic characteristic of taxonomy.
Taxonomies become unstable when the association between a name and its taxon changes, i.e., when the name points to a different taxon. However, stability does not mean that taxonomies do not change at all. Stable taxonomies can change, that is, improve, by adding more information about hierarchy. That is, as new nodes are discovered, names are progressively applied to those nodes. The existing associations between names and taxa need not change.
Misconception 2. Taxonomies are primarily for systematists. Unfortunately, some systematists view taxonomy as a personal sandbox. Rather, taxonomies are reference systems that are fundamentally important to the community of non-systematists. If not conservative, taxonomies are confusing for those who need stable reference lists. Witness the controversy about Bufo, Rana, etc.
Misconception 3. Some people don’t like change. Two types of change are at issue: (a) change in taxonomy, and (b) change in the practice of taxonomy. We who prefer a conservative taxonomy that maintains name-taxon stability are considered old-fashioned. Those who prefer taxonomy that breaks name-taxon stability, as has been proposed for anoles, are often considered progressive (see Misconception 1), under the assumption that any change is progress.
Ironically, a stable, “conservative” taxonomy requires a radical change in mindset about how taxonomy is done. Simply put, one maintains the association between name and clade, and applies new names when as needed to newly uncovered taxa. This approach reflects a growing understanding of the relationship between taxonomy and phylogeny. de Queiroz (1988) called attention more than 20 years ago to the failure of taxonomists to integrate taxonomy into the Darwinian Revolution.
A focus on ranks—arguing that eight genera of anoles are preferable to one—is inherently non-evolutionary. Thus, those who prefer to split a ranked taxon into several of equal rank are the resistors of change.
Misconception 4. Changes in stability between name and taxon are inevitable, especially in cases of paraphyly. De-stabilizing changes are not inevitable, and only result if one places primacy on rank-based taxonomy rather than taxonomy based on ancestor-descendant (evolutionary) relationships. N. B., I am not advocating that ranks should not be used, only that the emphasis on ranks is the cause of the controversy.
Elimination of paraphyly was the battle-cry of early cladists, but in reality the arguments about paraphyly were a distraction from the real issue. The Reptilia-Aves controversy was fundamentally about ranks, not paraphyly. Should Reptilia and Aves both be ranked as classes? If yes, then Reptilia is paraphyletic, because paraphyly follows from the use of ranks. The solution to the controversy was acknowledgement that Aves is nested within Reptilia, giving primacy of phylogeny over ranks. As Neil Shubin articulated, we all have an Inner Fish.
Paraphyly has consistently been a motivation for dismantling Anolis beginning with Guyer and Savage (1986). However, that the genus Norops (for example) is nested within the genus Anolis does not require splitting Anolis into several genera. One simple solution is to treat Norops as a subgenus within Anolis. The name of the species sagrei can then be written as Anolis (Norops) sagrei. The elegance of this is that Norops and Anolis, as nested taxon names, continue to refer to their traditional clades.
A second, more general solution is to use multiple levels of unranked clade names as done by Castañeda and de Queiroz (2013). They recognized as formal unranked taxa the clade Dactyloa; and within Dactyloa, clade Megaloa for the latifrons series, and clade Phenacosaurus for the heterodermus series. Because these are expicitly used as unranked names, they are not regulated by the International Code of Zoological Nomenclature (the Code).
As Cannatella and de Queiroz (1989:68) responded to Guyer and Savage (1986): “A phylogenetic taxonomy could have been effected by reorganizing sections, subsections, and series within Anolis, without generic level re-arrangements.”
Misconception 5. Subgenera are not used much in herpetology. Even if this were true, it is not a reason to reject the use of subgenera. Regardless, the data don’t support this claim; the use of subgenera is rising. They are a very useful tool, but have constraints imposed by the Code (these can be easily fixed).
Misconception 6. The most recent classification must be used as the standard. To recognize this fallacy one need only read the first Principle of the Code, which embraces taxonomic freedom. A common question from the community-at-large is, Which classification is the “correct” one? The answer is of course that there is no “correct” classification, and taxonomists who claim this do a disservice to the general community.
It is, in fact, time for a new classification of anoles, but one that truly integrates evolutionary principles with taxonomy, reflecting progress and not just change.
Acknowledgements. This essay is strongly influenced by Kevin de Queiroz, who articulated many of these ideas >25 years ago. David Wake engaged in helpful discussions.
Cannatella, D. C., and K. de Queiroz. 1989. Phylogenetic systematics of the anoles: is a new taxonomy warranted? Syst. Zool. 38:57-69.
de Queiroz, K. 1988. Systematics and the Darwinian revolution. Phil. Sci. 55:238-259.
del Rosario Castañeda, M., and K. de Queiroz. 2013. Phylogeny of the Dactyloa clade of Anolis lizards: New insights from combining morphological and molecular data. Bull. Mus. Comp. Zool. 160:345-398.
Guyer, C., and J. M. Savage. 1986. Cladistic relationships among anoles (Sauria: Iguanidae). Syst. Zool. 35:509-531.
Nicholson, K. E., Crother, B. I., Guyer, C., and J. M. Savage. 2012. It is time for a new classification of anoles (Squamata: Dactyloidae). Zootaxa 3477:1–108.