Rethinking models of mutualism

I saw an article brief posted at PhysOrg, entitled "Maths experts question key ecological theory," and (apart from triggering my desire to write yesterday's post), I immediately thought of a particular xkcd strip, specifically, this panel:

And then I read the post, and there seem to be some interesting points:

By carefully examining previous analytic results, and applying computational and statistical methods to 59 empirical datasets representing mutualistic plant-pollinator networks, they say they disprove the accepted theory of nestedness. Instead, they contend that the number of mutualistic partners a species has is a much better predictor of individual species survival and community persistence.

...

Co-author Dr Alex James, of the Department of Mathematics and Statistics at Canterbury, said: "It is a well-used phrase but correlation does not imply causation. Although a cursory glance at real networks can make it appear that nestedness is correlated with survival, you need to delve deeper to realise this is a secondary correlation. The stronger and more causal relationship is between the number of mutualistic partners a species has and its survival."

If this all proves to be true and usable, then it will be a good addition to our understanding of mutualisms in nature.