(This is a repost from the previous version of this blog)
Inspired by a recent post by Brian McGill at the (highly recommended) blog Dynamic Ecology about the changes in ecological sciences over the last 25 years, I have conducted a similar survey on how much research in amphibian ecology and evolution has changed over the last 20 years.
I first selected all the papers included in ISI Web of Knowledge “Ecology” and “Evolutionary Biology” categories for 1993 and 2013, filtered by searching for “amphibian* or anuran* or frog* or toad* or urodel* or newt* or salamander* or tadpole*”. I manually checked later all the abstracts to eliminate a few not exactly focused on amphibians, or the ones lacking in an abstract. For the selected papers, I included all the words in the abstracts into a Wordle, and looked for the 75 most used words (after removing common English ones). I consciously avoided the “Zoology” category where the pure herpetological journals are, since I was not interested here in the taxonomic/natural history aspects of amphibian research that constitute a big proportion of the papers published in these journals.
The first clear trend is a notable increase in the number of papers on amphibians published in “Ecology” and “Evolutionary Biology” journals during this period. From merely 121 papers published in 1993, to 562 in 2013 (4.6-fold increment). Although there is a general trend in Science towards publishing more papers, when considering all scientific disciplines this increment was only of a 1.3-fold during the 1993-2013 period. Looking e.g. at the “Zoology” journals, the increment in the total number of published papers was higher (2.1-fold) but still smaller than the increment in papers on amphibian evolutionary ecology research. So, it looks like there is a real trend for people working (and publishing) more on general questions in Ecology and Evolution using amphibians as study models.
Regarding the changes in the more common research topics in amphibian ecology and evolution during 1993-2013 it is easy to see some clear trends (see figures below). In 1993 studies were focused in core ecological concepts such as “growth”, “density”, “metamorphosis” or “competition”. Studies also looked in great detail to “size” issues too, mostly associated to factors affecting size at metamorphosis (“larvae” also appears as a highly relevant word). Some other words such as “fish” or “pH” reflect some of the conservation issues at that time. To add some context, concern over worldwide amphibian declines was pretty recent, the 1989 World Congress of Herpetology in Canterbury, UK, being considered as the starting point of the global concern on the amphibian conservation crisis. Furthermore, the chytrid fungus Batrachochytrium dendrobatidis (Bd) was not identified as a potential cause of mortality for amphibians until late-90’s (Berger et al. 1998).
Looking at 2013 data, it is easy to notice the increase on the role of genetics in amphibian evolutionary research (both “gene” and “genetic” appear as key topics in 2013). Also noticeable is the relevance that topics such as “models”, “patterns”, “structure”, “occupancy” or “diversity” had on current research. As expected, “Bd”, “declines” and “conservation” are common research topics nowadays, reflecting the great concern over amphibian disease-prone declines worldwide. The role of “habitat” and “sites” are still pretty relevant.
What are your thoughts?