Evolution journals publish more (and different) theory papers than ecology journals

A little while back, commenter Holly K shared an interesting view on theory papers in evolution vs. ecology journals:

I am someone very interested in ecological theory in the pure data-free sense. But I think often strategic (general) theory is in the realm of evolutionary ecology, or even just evolution (behavior or speciation theory, for example). Truthfully, I read Am Nat, Evolution, JEB and Proc B much more faithfully than Ecology because I have noticed they tend to publish more insightful theory (including my own, admittedly I am biased!).

Which led to a little discussion in which a couple of people suggested that there’s greater appreciation for theory in evolutionary biology than in ecology. I’m mostly a dabbler in evolutionary biology, but I share the impression that theory in evolution isn’t seen as some separate subfield the way it often is in ecology. I share that impression in part because it seems like evolution journals publish a mix of theory papers and data papers, whereas ecology journals publish one or the other.

But rather than rely on possibly-erroneous impressions, I decided to compile a bit of data. I went through the Jan. 2015-May 2015 issues of two top evolution journals (Evolution and J. Evol. Biol.), five top ecology journals (Ecol. Lett., Ecology, JAE, J. Ecol., and Oikos), and a top journal publishing in both fields (Am Nat).* I counted up the number of theory papers. “Theory” was operationally defined as a paper based largely or entirely on one or more mathematical models. I didn’t count statistical models, things like Leslie matrices or or integral projection models, or papers that manipulated empirical data to simulate some hypothetical scenario (e.g., randomly deleting species from an observed food web in order to study extinction cascades). I kept a separate count of papers which developed a theoretical model, but also tried to parameterize or test it with quantitative data from some specific system or other. Fortunately, there were only two or three papers in the whole set for which I was in any doubt about how to classify them.

Here are the results, along with some brief comments. I didn’t bother expressing the results as a proportion of all papers, because the trends are totally obvious and wouldn’t be qualitatively altered by correcting for number of papers published by each journal.

  • Evolution: 13 theory papers. Many but not all were population genetics models.
  • J. Evol. Biol.: 10 theory papers, including 2 which used data to parameterize or test the model. One of those two was kind of borderline as to whether it was a theory paper.
  • Am Nat: 14 theory papers in ecology, 11 in evolution (counting anything with evolution in it as evolution, which didn’t lead to any weird categorizations to my eye). Six of those 25 used data to parameterize or test the model.
  • Ecol. Lett.: 5 theory papers, 2 of which involved data. One of those two was actually evolutionary, despite appearing in an ecology journal.
  • Ecology: 1 theory paper. It involved data.
  • Oikos: 1 theory paper. But note that I didn’t count the Jan. 2015 issue of Oikos, a special issue devoted to a single topic, which included several theory papers.
  • JAE: 1 theory paper.
  • J. Ecol.: 1 theory paper, and it’s actually an evolution paper.

The conclusions as I see them:

  1. Evolution journals really do publish a lot more theory than ecology journals. This is striking to me. They’re sister fields with a lot in common–but they differ greatly in this respect.
  2. The difference is even starker if you restrict attention to theory papers lacking any data. Only 2/21 theory papers in evolution journals involved data; 3/9 theory papers in ecology journals involved data.
  3. The differences would be starker still if you didn’t count the two theoretical evolution papers published in ecology journals.
  4. Am Nat is an outlier in terms of its mix of papers. Much more theory than any other journal on this list, but by no means exclusively theory. A mix of ecology and evolution. And an intermediate fraction of theory papers that involved data.

It’s interesting to speculate on the underlying reasons for these differences.** It would also be interesting to go back a decade or two (or more) and do the same exercise.*** But I think it’s most interesting to speculate on the consequences and implications of the differences.

For instance, which do you think is a symptom of a healthier theory-data interface in a scientific field: leading journals in the field publish both data papers and data-free theory, or leading journals in the field publish little theory, but the few theory papers they publish often include data? I’d probably stump for the former. After all, it’s not as if the data papers in Evolution and J. Evol. Biol. omit or ignore theory–many of them test theoretical predictions. As do papers in ecology journals, of course. So ecology journals are publishing a narrower range of stuff than evolution journals. That suggests to me a greater separation between the theoretical and empirical sides of the field.

This little exercise also reminded me what a precious outlier Am Nat is. I know that some empirically-minded folks think of Am Nat as a theory journal, but I don’t think they should. I think Am Nat fulfills a pretty vital role as the one leading ecology journal where theory and data papers both show up on a consistent basis. Because like it or not, publication venues do still matter. They reflect as well as shape our choices of where to publish and (crucially) what to read. As long as Am Nat exists, it means that empirical and theoretical ecologists still have something in common, because they’re still reading and publishing in the same shared space.

*Yes, of course there are lots of other journals I could’ve looked at. You get the background research you pay for on this blog. 🙂 I didn’t consciously choose journals so as to try to skew things one way or the other, I just haphazardly picked the first few journals that occurred to me. But if you think my results are way off because I didn’t look at Functional Ecology or Ecography or whatever, by all means go compile the data and share it in the comments!

**Presumably part of the reason is the perception on the part of many ecologists that ecology journals other than Am Nat only want to publish “realistic” theory.

***But I’m too lazy to bother. 🙂

16 thoughts on “Evolution journals publish more (and different) theory papers than ecology journals

  1. Very interesting point. I think the difference largely reflects the difference in the value of theory for ecologists and evolutionary biologists. For any basic evolution class, students learn population genetics and that theory is foundational to the students understanding of evolutionary change. Does that happen in basic ecology classes? I would argue not. Sure, some courses may cover Lotka-Volterra models but are likely to do so in a way that leaves students with a feeling that ecology has a collection of models that are, at best, loosely connected to one another. But I suppose that is a topic for a different blog post. This has at least been my experience both as an undergrad and grad student,

    • I think you’re right.

      Which connects up with the previous post too. A big reason philosophers of science have given much more attention to evolution than ecology is that evolution has a core theory whereas ecology doesn’t.

      • It’s my general feeling that this issue will continue to stifle the progress of ecology until ecologists collectively adopt a consistent core theory.

  2. Coming out of UChicago, our ecology labs fall on a nice data-centric (Price) to theory-centric (Allesina) spectrum with the Pfister-Wooten and Dwyer labs being a hybrid of both.

    I wonder how much of this is historical. Both Ecology and Evolution have deep roots in observation-based natural history, but Evolutionary Biology in the modern (synthesis) sense really got started by theoreticians/experimentalists (Sewall Wright, Fisher etc) working before we even knew that genes were housed in DNA.

    Basically, I think that theory has been at the core of evolutionary biology since it began to separate from natural history, and that history still reflected today in both Nick’s point about classes today and the distinct publishing patterns you observed.

    • “I wonder how much of this is historical. Both Ecology and Evolution have deep roots in observation-based natural history, but Evolutionary Biology in the modern (synthesis) sense really got started by theoreticians/experimentalists (Sewall Wright, Fisher etc) working before we even knew that genes were housed in DNA.”

      I think that’s probably right.

      An interesting question is whether it could’ve turned out differently. Once Darwin happened, was it more or less inevitable that evolutionary biology would end up as a well-defined field with a clear conceptual “core” that’s expressed mathematically? That is, Fisher/Haldane/Wright/et al. were “merely” using math to flesh out a coherent set of ideas that Darwin had already laid down. Whereas ecology doesn’t have a single founding father; it’s been designed by a committee, as it were. So perhaps having mathematics as a core part of your discipline’s toolbox goes hand in hand with your discipline having a well-defined conceptual core (see also: physics). And maybe having a well-defined conceptual core goes hand in hand with your field having a single founder.

      So ironically, maybe evolution is a well-defined field with a theoretical core because it didn’t evolve–it had a creator.

      /end wild speculation and gross overstatement 🙂

      • Hah, I like that!

        It’s worth noting that without the horizontal idea transfer of Mendelian genetics it’s not clear if it would’ve had the early opportunity to go theoretical…

        A potential example for “could things turning out differently” would be paleobiology.

        As a discipline, paleo was definitely designed by committee. There’s no real founder. GG Simpson laid out a lot of evolutionary theory in a verbal sense, but it wasn’t until decades later did Raup/Sepkoski/Vrba/Van Valen/etc start building formal theoretical models.

        And today almost all theoretical papers in paleo are published either in a single specialist journal (Paleobiology) or in mainstream Evolution journals (e.g., Journal of Systematic Biology), while most paleo journals publish pure data papers (Journal of Paleontology, Palaeontology, etc.).

      • “A potential example for “could things turning out differently” would be paleobiology. ”

        I had the same thought!

        Which hints at the disconnect/tension between paleontology and the rest of evolutionary biology. See, e.g., Maynard Smith’s remark about paleontology not sitting at the “high table” of evolutionary biology…

      • I believe part of the effect mentioned also involves philosophies of methods. Medicine, for example, had no one founder and it brings together many scientific disciplines. While the combining of chemistry, physics, biology, social science and so on could have given rise to the hodge-podge of approaches we see in ecology, it didn’t. And that comes from a definitive focus on standardization of methodologies. Thus, a physician in Vermont is likely to use the same blood panel during a routine physical as a physician in Taiwan or the UK. Alternatively, when it comes to something equivalent in ecology, like assessing populations, the guy on the west end of Denver is using Whittaker plots while the guy on the east end is using point intercepts. It is very difficult, but not impossible, to arrive at unifying concepts when cottage industries dominate the landscape.

      • I will wander out on a limb and speculate that the Synthesis was able to happen not just because Darwin laid out a conceptual core, but because of the decades-long debate, like Jon touched on – there were real questions about how evolution actually happened (gradualist versus saltationist). Fisher/Haldane/Wright showed that the two pieces can go together. The breeder’s equation and Hardy-Weinberg are completely separate formulas, and come from different schools of thought, but both are important parts of the mathematical basis of evolutionary theory.

        So no, I guess I don’t think that it’s the fact that evolutionary biology comes from a single source that is the reason it is so theoretical. I also don’t think there’s fewer than two sources – Darwin and Mendel – and that evolutionary biology was enormously influenced ‘by committee.’ It’s just that it’s a very precise committee made of a finite number of people who were active at about the same time and interacted with each other. In fact, proponents of overhauling the evolutionary synthesis talk a lot about how oligarchic (my word) it was and that therefore X or Y got left out / overemphasized / etc.

      • “It’s just that it’s a very precise committee made of a finite number of people who were active at about the same time and interacted with each other. In fact, proponents of overhauling the evolutionary synthesis talk a lot about how oligarchic (my word) it was and that therefore X or Y got left out / overemphasized / etc.”

        Hmm, you could well be right. Your comments reminded me of an old series of posts by a science writer who read the Origin of Species and blogged about it. He remarked that there are two schools of thought in evolutionary biology: the “lean and mean” school exemplified by folks like Fisher, Price, Hamilton, and Maynard Smith, with its focus on simple mathematical models, and the “let a thousand flowers bloom” school exemplified by Stephen J. Gould, which is non-mathematical. The writer commented that both schools could legitimately claim Darwin as their intellectual ancestor.

        I think that’s right, and so I’ll walk back my earlier wild speculations in favor of yours.

      • Yes, I would concur with Abigail on the notion of having a critical mass of scholars in the right place, at the right time as it concerns this phenomenon. We saw the very same occurrence in the early 20th century with Bohr, Podolsky, Einstein, Heisenberg, Schrodinger & Rosen as it concerned quantum physics. Is it not curious how things like this coalesce?

  3. I never paid attention to the trends you note, Jeremy, but I have noticed I consistently find really good theory papers in Am Nat, and I have always been impressed with the quality of the journal.

  4. As my name has been mentioned, I will point out that ecology does have a core theory: Scheiner, S. M. and M. R. Willig. 2011. A general theory of ecology. In: S. M. Scheiner and M. R. Willig (eds.) The Theory of Ecology. University of Chicago Press, Chicago. pp. 3-18.

    The point that we make in that chapter and the previous paper is not that we somehow invented something new. Rather, we simply codified a set of principles that were already well known. Sort of like how at the end of the Wizard of Oz, when the wizard is recognizing the brain, heart and courage of the Scarecrow, Tin Woodman and Cowardly Lion :-).

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