Lots of interesting papers coming out in Oikos in the next little while. I wanted to highlight a few that particularly caught my eye.
In the most recent (Feb. 2012) issue:
- Barto & Rillig on dissemination biases in ecology. This is a really important study. Barto & Rillig analyze the citation rates of almost 4000 papers included in over 50 ecological meta-analyses. Studies that report unusually strong effects (compared to other studies on the same topic) tend to be published first, published in higher-impact journals, and get cited more frequently–even though they also have the smallest sample sizes and so are objectively provide the least reliable estimates of effect size and direction. The overall picture is that we suffer from confirmation bias and theory tenacity–we tend to cite the studies that appear to confirm what we (think we) know, and that appear to support existing theory. I suspect the bandwagon effect also contributes here; everybody tends to cite the stuff everybody else cites. Which is an especially serious problem when, because of confirmation bias, those studies are the least-reliable ones. You wonder how zombies first arise? This is how! (UPDATE: Check out Mike Fowler’s discussion of this paper, including his own personal run-in with an anonymous reviewer who seems to be guilty of the sins Barto & Rillig quantify)
- Gotelli & Ulrich on null models. In an old post I argued that ecologists should refight the null model wars. I didn’t realize when I wrote that post that leading null model proponents Gotelli & Ulrich had already decided to fire the first shot! Although their title suggests a focus on purely statistical issues (such as testing for significant deviations from the null model), in fact the ms actually engages with deeper conceptual issues, such as how we figure out what our null expectation should be in the first place. I’ll try to do a longer post responding to Gotelli & Ulrich at some point, as I disagree with some of what they have to say. But it’s great that they’re bringing out into the open issues that were basically swept under the rug many years ago, and so aren’t familiar to many younger ecologists.
- Valladeres et al. on how forest fragmentation leads to food web contraction. The authors compile a truly massive set of plant-herbivore and host-parasitoid food webs for 19 Argentinian forest fragments of varying area. Smaller fragments harbor a subset of the food webs in larger fragments, specifically the highly-connected “core” species. This is interesting for a couple of reasons. First, it shows that extinction risk isn’t just a matter of a species’ own “traits”, it’s also a matter of the food web context in which the species is embedded. The same species could be more-connected (relative to others in the web), or less-connected, depending on which other species happen to comprise the web. Second, the results may have implications for the links between community stability and “complexity”. If “complexity”, in the form of high connectance, is destabilizing, then you might expect food webs to collapse by losing highly-connected species, the opposite of what these authors found. However, even their most highly-connected webs were still pretty-low connectance in absolute terms. For that and other reasons the results are merely intriguingly suggestive in terms of their implications for complexity-stability theory.
- Fox & Kerr on an extended Price equation partition. Yes, a shameless plug. In nature, species composition often exhibits turnover along environmental or spatial gradients. Ecosystem-level properties and “functions” also vary along those gradients. In this paper, Ben Kerr and I use Ben’s clever extension of the Price equation to partition between-site variation in ecosystem function into components attributable to different effects (e.g., changes in species richness vs. changes in species composition vs. environmental effects on the functioning of individual species). One interesting insight is that, when there is compositional turnover, there’s no single “species richness effect” and no single “species composition effect”. Rather, there are two of each. So all those arguments ecologists have had about how to separate “the” effect of species richness from “the” effect of species composition are badly framed.
We have many more interesting articles in the pipeline, so look for more “highlights” posts in the near future.