What’s the greatest ecology experiment in history?

A while back, Rich Lenski did a nice post summarizing and commenting on a classic evolutionary experiment: Luria and Delbrück 1943. This is the famous “fluctuation test” experiment showing that mutations in E. coli occur at random with respect to their fitness effects, rather than being caused by selection pressures. The experiment was based on simple but subtle reasoning, was very elegant, and the results were both clear and profound. It provided the basis for a massive body of research, including the cracking of the genetic code. It was also ahead of its time, in that evolutionary biologists at the time were mostly uninterested in microbes, so that the paper’s immediate influence was much greater in molecular biology. And it had a big personal effect on Rich himself. Rich calls it “for me, the single greatest experiment in the history of biology.”

So, here’s the question: what’s the single greatest experiment in the history of ecology?

I ask this question mostly for fun. “Greatest” is too broad, multifaceted, vague, and subjective a concept to expect that we’ll all agree on an answer. But questions like this are a fun way to force us to think about what really matters in science, and force us to step outside the inevitably-narrow boxes of our own personal interests and subfields. And I’m hopeful that students in particular will find the answers to be interesting entry points into the history of ecology.

Just to keep things semi-focused, I am going to ask that you pick a single experiment. Not a series of related experiments*, or an entire line of research like the Hubbard Brook Ecosystem Study, or all the work of an individual, team, or facility. And by “experiment” I mean a planned manipulation. “Natural experiments” like Brooks & Dodson 1965, comparative studies, theoretical studies, etc. don’t count (merely because they’re different than manipulative experiments; again, I’m just trying to keep things semi-focused here). The experiment need not be well-designed according to modern standards. It’s up to you to decide if, say, an unreplicated experiment can still be the greatest ecology experiment ever. And it doesn’t have to be a field experiment. Microcosms, mesocosms, etc. are fair game.

Some obvious candidates, just off the top of my head:

I’ll note in passing that, great as all of the above are, I don’t think any of them are as great as Luria and Delbrück 1943. I don’t think any of the above experiments are serious candidates for the title of greatest experiment in all of biology, as Rich suggests Luria and Delbrück 1943 is. It’s interesting to consider whether that says something about ecology or ecologists**. Ecologists aren’t great experimentalists? (unlikely!) Ecology isn’t as conceptually central or foundational for biology as are evolutionary biology and genetics? (probably something to that) No single experiment can ever greatly advance ecology? (maybe, but if not, why not?) Or maybe it just illustrates that ecology is a young-ish field (and especially young in terms of its use of experimentation)? So that the greatest ecological experiment is yet to come?

*I admit that the line between “related experiments” and “one big experiment with several treatments” can be unclear, especially when considering work from earlier decades. For instance, is Huffaker’s famous work on mite metapopulation dynamics a series of several experiments, or one big experiment with several treatments?

**Or maybe it just says something about me.

29 thoughts on “What’s the greatest ecology experiment in history?

  1. I’m not aiming for “the greatest”, but want to mention the work by John Drake (Ecol Lett 2004, Plos Bio 2005, Ecology 2006) on different aspects on extinction dynamics in Daphnia. These studies were the first (?, or one of the first) attempts to experimentally try to test theoretical results from population models, with “confirmations” of some results but also many interesting deviations from what was expected. We need many more studies like these.

    • Yeah, I really like those Drake papers testing models of extinction risk for small populations. For a while I’ve been thinking about doing a “great microcosm experiments” post, and that work would be on the list.

      Your comment kind of gets to another post I’ve thought about writing, too–asking people to name great *underrated* experiments in ecology. But I’m a little worried that that would be too long a list–ecology’s a big field, and everyone’s interests are sufficiently unique that I suspect we’d get as many answers as we have readers!

  2. Isn’t this sort of like asking who the greatest high school basketball player was when you have the NBA? I don’t think manipulative experiments have been very important in ecology, compared to natural experiments and simulation modeling, so I’m not sure of the point.

  3. I would like to mention an elegant experimental study, although it’s one that most ecologists don’t know. Given that fact alone, I’m sure it doesn’t qualify as the greatest ecology experiment ever since it hasn’t had the necessary impact on the field. Nevertheless, it’s a real beauty.

    The paper is by Lin Chao and Bruce Levin (1981, PNAS). It’s a laboratory-based microcosm study that lies at the interface of ecology, evolution, and behavior. It provides compelling demonstrations of several interesting and related phenomena including interference competition, tradeoffs, stable and unstable equilibria, and the difference between physically structured versus mass-action environments.

    I’ve blogged about it here, in case you want to read more: http://telliamedrevisited.wordpress.com/2013/09/08/chao-and-levin-1981-pnas/

  4. In terms of a field experiment, and one that is well known to ecologists, let me suggest Daniel Simberloff’s experimental test of the theory of island biogeography using mangrove islands of various sizes and distances from the mainland.

    • That was the top of my list too.

      I would also add Parker and Birch’s work on flour beetles. And probably not as classic but more up to date, the work by Costantino, Cushing, Desharnis, Dennis et al on flour beetles and chaos.

      • Yeah, 5 minutes after I hit post I thought “Oh, I probably should’ve listed Simberloff’s mangrove island experiment among the obvious candidates for greatest ecology experiment ever.”

        Constantino, Cushing, Desharnais, & Dennis’ flour beetle work is indeed brilliant, definitely a candidate for greatest experimental population ecology in history if not greatest in all of ecology. Several of their results are so clean, and quantify such subtle effects, that even a fellow microcosmologist like me reads them and goes, “Oh, now you’re just showing off!”🙂 (You detected *lattice effects*?! Are you freakin’ kidding me?! [jaw drops]) Though it’s hard to pick a single experiment from that body of research.

  5. In the same vein as the classic papers by Connell and Paine, another of my favorites is Jane Lubchenco’s “Plant Species Diversity in a Marine Intertidal Community: Importance of Herbivore Food Preference and Algal Competitive Abilities.” Link: http://www.jstor.org/stable/info/2460135

    One reason I especially like Lubchenco’s paper is that it emphasizes the importance of a tradeoff, namely between competitive ability and resistance to predation. In terms of the field of ecology, tradeoffs are, of course, critical to understanding the maintenance of species diversity.

    At a more personal level, understanding the tradeoff between competitive ability and resistance to predation — in my work, studying bacteria preyed upon by viruses — has been a topic that I’ve really enjoyed thinking about and studying.

  6. I think I would cast my vote for Schindler’s eutrophication experiment at the ELA for several reasons. First, it opened the door for a lot of great work on stoichiometric limitation in aquatic systems by identifying P as a limiting nutrient, it did so using a large-scale ecosystem manipulation (incredibly complex, yet elegantly simple in its design and interpretation), and it was responsible for swift and sweeping regulatory actions to curb eutrophication. A single picture from that experiment (who needs data?) was enough to change how the world thought about phosphorus inputs to freshwater systems, and I think thats rather amazing.

    Probably not the most theoretically eye-opening and groundbreaking experiment in ecology, and I am slightly biased because of my interests and background, but man do I love that paper.

  7. It’s been noted on Twitter that 2/5 of the experiments I listed are from the rocky intertidal. That’s partially an accident, but only partially, I think. I do think rocky intertidal ecologists were among the pioneers of field experimentation in ecology. Which arguably is part of what makes Connell & Paine’s work great: it influenced a lot of people to start doing field experiments, both in rocky intertidal systems and in other systems.

    • I was an unusual Paine student who didn’t work in the intertidal. One feature of the intertidal that Bob has mentioned is how it is easy to see patterns, which makes experimentation easier. I’m a fan of the Pisaster experiment, although I’m probably biased.

  8. I would second the Experimental Lakes nutrient addition work and also put in a plug for Likens and Bormann’s work with the Hubbard Brook Experimental Forest on clearcutting and nutrient losses.

  9. Perhaps the Biological Dynamics of Forest Fragments Project started in 1979? (Lovejoy et al) According to Wikipedia it generated 562 publications, and 143 graduate theses as of 2010.

    • Wendell, I was late to the party and glad to see this nominated. Undereplicated, but unmatched in scale and ambition by just aboutanything but the lake-scale manipulations. PS Lovejoy deserves the credit he gets, but role of Philip Fearnside and other INPA scientists underapprciated.

  10. I can think of a few really good ones that haven’t been mentioned so far. I think it is hard to quantify “best”, but these have certainly had big impacts on the way we do experiments in ecology now. Jim Brown’s Portal site, David Tilman’s prairie experiment (and his plankton/diatom work), Os Schmitz’s experiments with grasshoppers and spiders, Charles Krebs’ experiment on predator-prey dynamics (even though there was no replication), the Nutrient Network (NutNet), and Nick Haddad’s corridor project.

    • It’s interesting that the commenters are all thinking along the same lines as me! When originally writing this post I was thinking of including a list of experiments that might not be the “greatest” ever, but that are certainly close or at least in the conversation. And on that list would’ve been Jim Brown’s desert granivore experiment at Portal, Dave Tilman’s long term N enrichment experiment (though my own obviously-subjective definition of “greatness” would put that one a bit behind Park Grass), and possibly NutNet (I say possibly because it’s early days and I’d kind of like to see more of what comes out of it and how long it lasts before it goes in the Hall of Fame).

  11. I’m biased, and it might not be the greatest ever. But Biodiversity I and Biodiversity II at Cedar Creek are two experiments that have been hugely influential for the subfield of biodiversity-ecosystem functioning. They were both started in 1994 (http://cedarcreek.umn.edu/research/biodiversity.html), and are good runner-ups. Single experiments that have resulted in long lists of publications.

    • Yeah, I thought of those. Certainly those two plus Biodepth and Naeem et al.’s Ecotron work would have to be considered the greatest BDEF experiments, I think. But that topic is sufficiently narrow that I’d be reluctant to list any of those as among the greatest ecology experiments ever. I’d say the same for, say, the work of Yoshida, Ellner, Hairston Jr. etc. on eco-evolutionary dynamics of rotifers and their algal prey (or the flour beetle dynamics work mentioned by Brian). Wonderful work, which I hugely admire (and am quite jealous of!), but I’m not sure the question or range of questions addressed is quite broad or fundamental enough for it to be the greatest ecology experiment ever.

      Which of course probably just reveals something about my own subjective way of defining “greatest”. That’s part of what’s fun about this comment thread–hearing what others think makes an experiment really “great”.🙂

  12. I’m completely on board with Dr. Chaoborus – first because it was so ambitious and second, as was already mentioned because it had a profound impact on how we regulate phosphorus inputs. Best, Jeff H

    • I think it’s great, but I think it suffers perhaps a bit more than some of the others mentioned here for having been unreplicated. I think it’s quite possible that Huffaker got the result he got through luck. Showing my own biases, I tend to think of Huffaker and the properly replicated and controlled version (Holyoak & Lawler, in protist microcosms rather than mites and oranges) as a sort of great pair.

  13. Two that nobody’s mentioned yet that deserve to be in the conversation are Nicholson’s blowflies (another candidate for greatest population ecology experiment ever) and Thomas Park’s competing flour beetles. Though those are two more where it’s a little difficult to say where one experiment stops and the next one begins.

  14. I’m not voting, but I think Root’s collards experiment deserves a nomination for foundational work in understanding how diversity affects multi-trophic communities.

  15. Very interesting topic, post, and comments. I’m surprised not to see any work by Bertness mentioned, e.g.

    Bertness, M. D. and S. D. Hacker (1994). “Physical stress and positive associations among marsh plants.” American Naturalist 144: 363-372.

    Bertness, M. D. and G. H. Leonard (1997). “The role of positive interactions in communities: lessons from intertidal habitats.” Ecology 78: 1976-1989.

    Or in fact, ANY work on positive species interaction. Are we still stuck in that old competition-predation rut? There is so much more going on out there.

    I also would have included this or several other Silliman experiments.

    Silliman, B. R. and M. D. Bertness (2002). “A trophic cascade regulates salt marsh primary production.” PNAS 99: 10500-10505.

    Or countless papers by Hay, Stachowicz, Menge, etc. Yes all marine peeps. Field experimentation is still alive and well in the ocean. And for mess / micro-cosm work. NOBODY does work that comes close to what Emmett Duffy has done in plastic tubs, e.g.

    Duffy, J. E. and M. E. Hay (2000). “Strong impacts of grazing amphipods on the organization of a benthic community.” Ecological Monographs 70: 237-263.

    Duffy, J. E., et al. (2005). “Ecosystem consequences of diversity depend on food chain length in estuarine vegetation.” Ecology Letters 8: 301-309.

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