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The number of species-level food webs, or variations of the community (such as the web shown in the previous post) that can be derived for the Miocene marine community, comprising 130 heterotrophic species grouped into 25 guilds (plus for autotrophic guilds) is:
1.354169406609263 \text{x}10^{1213}

That’s much larger than the paltry 10^{72} or 10^{87} particles estimated to make up the known Universe! I can feel the weight of my Hindu ancestry here. A very nice discussion of large numbers can be found in The Biggest Numbers in the Universe. Therein is listed an old favourite of mine from The Hitchhiker’s Guide to the Galaxy: “Space is big. Really big. You just won’t believe how vastly hugely mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist, but that’s just peanuts to space.”

So just how meaningful is all the possible community network variation? One caveat to the answer is that primary productivity is specified in the network as units of productivity, and not actual species. So there are actually a total of 1320 nodes representing primary production in the network, and those certainly contribute significantly to the huge number. But let’s say we reduce those nodes to simply one for each producer guild, resulting in substantially smaller species-level networks. The number of possible networks is now
1.07583\text{x}10^{237}
That’s still pretty big!

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