One of the most fraught questions in ecology is whether or how ecologists should seek generalities. Debates over this broad question crop up in many contexts and take on many forms. Think of debates over whether ecology has “laws” analogous to the laws of physics. Debates over whether ecologists ought to focus on producing information relevant to management or conservation of specific species or locations, rather than on less-useful generalizations. Debates over whether we should give up on doing community ecology because every community is an idiosyncratic special case. Etc.
In an old post, I tried to partially resolve some of these debates by suggesting that there are many different sorts of “generality” that ecologists might seek. I argued that they’re all valuable in their own way, though some might be more achievable and/or valuable than others depending on the goals and interests of the investigator.
But it’s my anecdotal impression that ecologists as a group value some forms of generality over others. And that different sorts of ecologists tend to seek, and value, different sorts of generality. To get some data, I hope you’ll take the short poll below (just four questions). It asks you about your opinions about, and own use of, various sorts of “generality” in ecology and ways of seeking generality. Here’s a brief summary of each of them:
- Universal or nearly-universal patterns or “laws”. Think of quarter-power body size allometries, the latitudinal species richness gradient, the species-area curve, Bergmann’s Rule, etc. They provide generality because many different systems/species/cases fit the same pattern, or obey the same rule or “law”. (EDIT: as Brian points out in the comments, Bergmann’s Rule turns out to be more of a purported pattern or law than an actual one. It has too many exceptions to be a pattern or law. But I’m leaving it here as an example, because sometimes when you set out to study a purported universal pattern or law, you find that it’s not a pattern or law at all. But you still set out to study a (purported) pattern or law, so your research still falls in this category.)
- Meta-analysis. That is, statistical summaries of the results of different studies of the same phenomenon. They provide generality in the sense that they tell us what’s statistically “typical” or common, and how much variation there is around what’s “typical”.
- Simple theoretical models. I’m thinking here of theoretical models that are intended to “capture the essence” of the phenomenon being modeled, “sharpen our intuitions” about the phenomenon being modeled, or identify some general “principle” about the phenomenon being modeled. These models aren’t intended as realistic, exact descriptions of any particular system, in part because they assume away or make very simple assumptions about other phenomena besides the one being modeled. But these simple models are thought to provide generality because they apply in an approximate way to many different systems, or act as a simplified “limiting case” for many different systems. Think of the Lotka-Volterra competition model, the Rosenzweig-MacArthur predator-prey model, Tilman’s R* model of resource competition, the marginal value theorem of optimal foraging, etc.
- Statistical attractors. Think of MaxEnt-type phenomena: empirical patterns that are common because they’re hard to avoid. The pattern is commonly observed (and so “general” in that sense) because many different ecological processes/mechanisms/scenarios would give rise to the pattern, and few would give rise to any other pattern. The pattern is thus a statistical “attractor”–a statistical inevitability. For instance, the fact that species-abundance distributions always have a lognormal(ish) shape may indicate that that shape is a statistical attractor. That shape is common because population growth is always a multiplicative stochastic process, and system-specific ecological details have little or no effect on the overall lognormal(ish) shape of the distribution.
- “High level” theoretical frameworks. Think of modern coexistence theory, the Price equation, and the “four fundamental forces” framework of population genetics (selection, drift, mutation, migration). These “high level” frameworks provide generality in the sense that they unify and subsume various models as special cases.
- Fruitful analogies. I think of this as the Tony Ives approach to generality. For instance, lots of different ecological systems have been hypothesized to exhibit alternate states, with stochastic perturbations occasionally flipping the system from one state to the other. In the linked post, Tony Ives talks about how his previous experience with alternate states in other systems helped him recognize and model the possibility of alternate states in the population dynamics of Icelandic midges. That is, there are analogies one can draw between those midges, and other systems (including even non-living systems!) that exhibit alternate stable states. Those analogies are a form of generalization–they allow us to reinterpret our knowledge of one system so that it applies to another, analogous system. As another example, think of how Steve Hubbell’s neutral theory, and Mark Vellend’s theory of ecological communities, both start by drawing an analogy between community ecology and evolutionary biology.
- Model systems. A model system is one that has features that make it particularly tractable to address the question of interest. Studies in model systems often are thought, hoped, or assumed to apply to other systems as well. Sometimes because the question of interest isn’t tractable to address in any non-model system.
- Distributed experiments. That is, experiments that run simultaneously at many sites, using the same methods everywhere, so as to facilitate cross-site generalization. One could consider this a special case of meta-analysis, but I split it out because I feel like many ecologists tend to think of it as its own thing. Think of NutNet, for example.
- Long-term studies. A long-term study should capture a greater range of temporal variation than a short-term study, and so should provide insights and conclusions that can be applied in a greater range of circumstances.
- Other. No doubt my list of forms of generality and ways of seeking generality is incomplete, at least in the eyes of some of you!
Looking forward to your responses!