Biodiversity bias? The relationship between taxon diversity and research publications
Yesterday I was doing some background reading on the insect order Strepsiptera (twisted-wing parasites), of which there are about 600 described species. In contrast, the order Carnivora (Mammals, bears and the like) has about half that number of described species. This resulted in a bit of discussion on twitter about whether there might be any relationship between the number of species described for an order and the number of publications on that order. Stated another way, is there a publication 'biodiversity bias'?
In an ideal world of biodiversity science (and in my opinion...), I would like to think that there should be more publications on taxon that have more described species. Hyper-diverse orders of insects or arachnids ought to have more publications than, say, the species-poor cetaceans. To address this question, I haphazardly selected 5 orders from each of the dominant Arthropod classes (Arachnida, Crustacea, and Insecta) and 5 orders from the main chordates: Aves, Mammalia, and (Amphibia + Reptilia). Therefore, there was a total of 15 orders of arthropods and 15 orders of chordates. Using web of science, I searched for the number of publications in which the order was found under the 'topic'. A simple approach, I admit... but perhaps it will give some indication of whether or not a bias exists.
Here is the result:
At first glance, this looked great! Researchers are studying animals in the proportion to their total diversity. However, I did have to use a log-log scale in that presentation, and the overall pattern is certainly affected by a few hyper-diverse arthropod Orders (in this case, Hymenoptera [wasps, bees, ants] and Araneae [spiders]). Next, I thought it would make sense to look at the total number of papers published per species.
The winner? Carnivora has about 7 publications per species.
The loser? Pseudoscorpiones has about 0.05 publications per species.
Graphically, the results are as follows:
Clearly, species with backbones (especially furry ones) see more publications.
What is even more interesting is that the bias is even stronger when common names are used instead of the scientific name of an order. "Falcons" for example, receives an order of magnitude more hits on web of science than using "Falconiformes". The same is not true of researchers publishing on arthropods - their use of the scientific name of the order is far more common. Clearly, more digging into this topic is needed.... (a future blog post perhaps). And, interested readers should certainly look at this publication by Simon Leather. (He's done a far more careful job than I did here)
In sum, there appears to be some taxonomic bias in publication. I realize that I have my own biases, and it's not all about the diversity - there are clearly other considerations which I have largely ignored. I also recognize that "orders" are themselves are not necessarily a good taxonomic category to use for this kind of study, and many are in continual flux. And, my methods were not overly rigorous. At first glance, however, folks working on arthropods have some catching up to do. Especially the pseudoscorpionologists.