Nicholson et al. (2014) provide two reasons that Anolis should be divided into eight genera. The first is simply that this is what modern systematists do, breaking up big groups into little groups. But this is not really a very compelling argument in its own right. As your mother used to tell you, “just because everyone else is jumping into a lake doesn’t mean you should, too.”
Their second reason is more specific. They argue that more finely divided groups are essential for understanding patterns of evolution and diversity:
“When new monophyletic structure is revealed in groups for which such structure was previously unrecognizable, taxonomy should change to incorporate that new information. This process does reveal constructs inherent to the natural world and, therefore, forces us to change the way we train future generations of biologists, design future comparative analyses, and interpret new data.”
But let’s take apart this argument. First, have Nicholson et al. revealed “new monophyletic structure” that was “previously unrecognizable”? The authors themselves point out that these groups have been found in all recent systematic studies and, indeed, the community has been well aware of them. One only needs to go back to Jackman et al. (1999) to see recognition of 17 clades, and discussion of these clades has continued ever since. Nicholson et al. would have readers believe that we thought that Anolis was one big, unstructured group of 400 species, but that is a very incorrect portrayal of the widespread understanding of anole phylogeny.
More importantly, second, has our understanding of anole evolution and diversity suffered because we have considered anoles as one genus instead of eight? This is a pretty hard argument to make. For a quarter of a century, work on anoles has been an exemplar of how to incorporate phylogenetic information into studies of evolutionary diversity. For example, anoles are now known as a model case of convergent evolution—it’s not like we’ve failed to recognize that convergence just because they’re all called “Anolis.” It’s striking in this regard that the sole paper cited by Nicholson et al. (2014) to support their contention that a single genus is problematic is nearly 30 years old! Thirty years of copious anole research shows that recognition of a single, large genus has not hindered anole research in the slightest.
Indeed, it is thought-provoking to compare the contributions made by research on anoles in the Caribbean and on the mainland. Workers on Caribbean anoles almost without exception adhere to the single genus framework, and work on Caribbean anoles has been extensive and is now well-known by the community at large. In contrast, mainland anole researchers are more divided, some favoring a single genus, others favoring multiple genera. It would be hard to compare the quantity and impact of work on Caribbean and mainland anoles and argue that recognizing multiple genera has accelerated research.
Finally, we might take a step back and ask: Is it still the case that big monophyletic groups must be broken up into little monophyletic groups to foster evolutionary research? This viewpoint may have been correct in the 1980’s when the cladistics revolution occurred, but is it really true, in this day and age, that researchers look to taxonomy to derive their evolutionary thinking? I would suggest that this is no longer true: with the huge explosion of phylogenetic thinking, modern researchers no longer look at taxonomic classifications to identify evolutionary groups; rather, they go straight to the phylogenies themselves. To see that this is true, pick up any journal and look at the evolutionary analyses. No one is basing their research on taxonomies; they are basing them on the phylogenies themselves, regardless of the binomial names appended to the terminal taxa. The argument that splitting up clades ever more finely to enhance research is old-fashioned, a hold over from the days when phylogenetic thinking was uncommon and many recognized groups were not monophyletic.
Still, Nicholson et al. are correct: it is the trend to ever more finely split up clades into smaller genera. Why should anoles be different? The answer is that there is an enormous, half-century of literature on these lizards that extends far beyond the fields of herpetology and systematics. Researchers in areas as disparate as physiology, cell biology, development and functional morphology, as well as evolution, ecology, and behavior, have conducted important work on anoles. And this work has been published using the name “Anolis.”
Nicholson et al. (2014) don’t even address the point raised by Poe and many others, that such name changes are more than disruptive, but truly damaging to scholarly research. In the herpetology course I teach, students are given a number of assignments that require them to go into the literature. And they have great trouble tracking down information on species whose names have changed. That’s not even accurate–usually they are simply unaware that there is a literature on a species under its former name. It would be nice to think that they would consult online resources that provide lists of the different names a species has had, but the students usually aren’t savvy enough (even though they are instructed to do so). In this regard, molecular biologists, physiologists and ethologists are no better than undergrads. If they read a paper on Anolis cristatellus from 1983, they will not know to connect that paper to a species now known as Ctenonotus cristatellus. Proponents of name changes tend to brush this under the rug, saying that people are adaptable and will cope, but this view is unrealistic.
Some day, all scholarly resources will be digital and species names will be automatically hyperlinked to their previous identities, but we are a long way from that point. And until that day, there are real costs to changing names, particularly for well-known groups with a long history of research. Given that research on Anolis is vibrant and phylogenetically informed, there is nothing to be gained and a lot to be lost by division into multiple genera.