Lumpers vs. Splitters:
"Two Taxonomists, both alike in dignity."

“So, are you a lumper or a splitter?” I have been asked this question many times, by biologists working in both academia and the government. No, “lumpers” and “splitters” do not refer to baking mishaps. Instead, these terms are used to describe taxonomists. A taxonomist is a scientist that specializes in the categorization of living things. You may have heard of Carolus Linnaeus, who effectively created the discipline of taxonomy in the 1700s. In general, “lumpers” tend to combine taxa into larger systematic groups while “splitters” break systematic groups apart into more taxa. Recently, however, it seems like the terms could refer to rival gangs, and one runs the risk of being judged depending on their answer to the question above. A simple internet search reveals opinions from everyone from Science (Berg, 2018) to personal bloggers. There is even a blog called “Evolution is a Myth” that uses the existence of lumpers and splitters as evidence that evolution is a fabrication of scientists (“LUMPERS VS. SPLITTERS OF FOSSILS ENCOURAGE ‘NEW’ SPECIES – Evolution Is a Myth,” n.d.). So, with all this contention, what does the lumper-splitter debate mean for conservation? A recently publicized example of “lumping” may shed some light on that question.

In January of this year, a scientific article came out concerning the taxonomy of the Snail Darter, a small species of fish that became famous in 1975 for being the first species protected under the United States Endangered Species Act (ESA) (Ghezelayagh et al., 2025). The listing of the Snail Darter under the ESA was characterized by controversy. In 1967, the Tennessee Valley Authority began construction on the Tellico Dam, a project that already had many opponents, including farmers and members of the Cherokee Nation (Nark, 2025). Then, in 1973, Dr. David Netier discovered the new species that would be named the Snail Darter (Percina tanasi) in the Little Tennessee River. The Tellico Dam, being constructed on the Little Tennessee, would destroy the crucial habitat of the new species. Opponents of the dam petitioned that the dam construction be halted. To the dismay of the Tennessee Valley Authority and politicians, the Supreme Court upheld the protection of the species under the ESA, and the dam construction was halted (Nark, 2025).

Now, however, a group of scientists from Yale University, led by Thomas Near, postulate that the Snail Darter is not a distinct species after all. In a recent study they argued that it is simply a subpopulation of Percina uranidea, the Stargazing Darter (Ghezelayagh et al., 2025). Due to the Snail Darter’s historical relevance, the article was immediately picked up by news organizations, including The New York Times. The Times Article offers several quotes by Dr. Near and others that provide insight into how contentious the lumper-splitter debate can be. For example, Dr. Near implied that the researchers who initially discovered the Snail Darter may have hastily decided it was a distinct species solely to stop dam construction, stating they likely “squinted their eyes a bit” (Nark, 2025). On the other hand, Zygmunt Plater, a professor at Boston College accused Dr. Near of being a lumper and stated that lumping can undermine the power of the Endangered Species Act. In response, Dr. Near took offense to being called a lumper, arguing that the study actually aids conservation and that most of his papers result in new species (Nark, 2025). So, is there any truth to Plater’s assertion that lumping impedes the Endangered Species Act?

Technically, subspecies and even subpopulations can be listed under the Endangered Species Act (United States Geological Survey, 2006). There is no doubt, however, that taxonomic uncertainty hinders conservation efforts by making it difficult to pin down the definition of a species. One critique of the recent Snail Darter study is that it relied almost exclusively on genetic analysis. While DNA analysis is an important technology when it comes to describing species, there are other important factors to consider, including morphological traits. Morphology relates to the form or appearance of a species. While Dr. Near did include an analysis of some morphological traits, he only included “meristic” traits, which are those that can be counted, such as the number of fin spines on a fish (Ghezelayagh et al., 2025). Morphometrics, traits that concern the shape of body parts, were not included in the study at all (Ghezelayagh et al., 2025). Given the uncertainty surrounding the field of taxonomy, it is crucial to use all available data and indices to make decisions about species delimitation.

While it is true that the tug of war between lumpers and splitters increases taxonomic uncertainty, all hope is not lost. Researchers have found unique ways to address the inherent instability in the field of taxonomy. One group of researchers are tackling confusion within the class Aves (birds) using a system they call RANT (Reconciliation of Avian Taxonomy) (Hosner et al., 2022). They are doing the painstaking work of sorting through DNA sequences and other taxonomic data to reconcile the names and relationships between various species (Hosner et al., 2022). In addition, artificial intelligence (AI) may serve as a tool for reducing uncertainty. Using AI, scientists can integrate information from multiple sources (genetics, morphology, and ecology), allowing them to make more informed decisions about relationships between species. One can hope that with the advent of new technologies and changing perspectives, the terms “lumper” and “splitter” will be humorous remnants of the past. As for me, when I am asked where my allegiance lies, I simply decline to answer.