Posted by: Jeremy Fox | December 2, 2011

Food chain rewiring taken to absurd lengths

According to The Onion.

The accompanying food web diagram is very funny, and also rather uncomfortably close to the truth when it comes to how the links in food webs often are defined.

Related documentary evidence here and here.

Apparently the recent Oikos special issue on body size as a driver of food web structure and dynamics is already out of date. ;-)

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Responses

  1. Strangely relevant to some things that I’m working on…

  2. Thanks, Jeremy.
    I AM shocked. So this is what they mean by “global change”.
    I had to re-use this link at our blog: http://econetlab.tumblr.com

    • Well, to be serious for a minute, if body size was all that mattered, terrestrial insect herbivores wouldn’t exist! Neither would many of their parasitoids and hyperparasitoids. Together, those groups probably comprise the majority of species, and feeding “links”, on the planet. So I’ll admit that I’ve been a little bothered by the strong focus of recent food web theory on body size, because it would seem to write off the majority of the world’s species as unimportant or uninteresting “exceptions” to the “rules” of body size constraints. There are absolutely systems (primarily aquatic ones) in which body size is a useful predictor of (i.e. constraint on) who can eat who. I just worry that, if we focus exclusively on such systems just because they’re the easiest ones in which to figure out what the determinants of food web structure are, we risk ending up with a distorted view of how food webs work in general. Focusing on tractable model systems is great–just so long as we keep in mind the ways in which those model systems (here, systems in which body size determines who can eat who) are a biased sample of all systems.

      • I totally agree that a great number of feeding interactions are breaking the rules of allometry. However, I think, this is to be taken litterally: Parasitoids “broke” through the strong limiting constraints of body mass at some point in evolution. They evolved a way to feed on larger prey, trading off the risk of beeing crushed against the plenty of meaty food ressource. The same is true for eusocial insects or vertebrate pack hunters. It’s not about what’s the rule and what’s the exception. It’s about what is the primary mechanism and what came second in evolution.

      • Hmmm…I’m skeptical that large body size, relative to one’s prey, is always the ancestral condition. What evidence is there for this? I mean, was there ever a time in the evolution of insects when they were larger than terrestrial plants?

        Sorry, but sometimes even thinking of body size allometries as a “constraint” which can be broken, or as somehow “primary” in evolution, is misleading.

      • If they were, it was probably in the Carboniferous.

        e.g.:

        http://en.wikipedia.org/wiki/Meganeura

  3. Another one:
    Do you know the carnivorous giant mice of Gough Island?

    http://news.bbc.co.uk/2/hi/science/nature/4708899.stm

  4. to think of the starting point of eating and being eaten you have to go far beyond insects and trees. even further beyond multicellular organisms in general. although if this doesn’t help much in aswering the question (about the general importance of body size for trophic relationships in the living world) it helps as a starting point in formulating the right questions ;)


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