SETI public: Fw: Palaeobiology - The Cambrian smorgasbord

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Source: Nature
http://www.nature.com/news/2008/080604/full/453717a.html

Published online 4 June 2008 | Nature 453, 717-718 (2008) |
doi:10.1038/453717a
Palaeobiology: The Cambrian smorgasbord
Animal behaviour is an endless challenge to mathematical modellers. In the
first of two features, Mark Buchanan looks at how a mathematical principle
from physics might be able to explain patterns of movement. In this, the
second, Arran Frood asks what current models can teach us about ecological
networks half a billion years old.
>>>>>>>>>>>>>>>
Ecosystems on other planets would be a great help in sorting out the
necessary from the contingent, but remain stubbornly undiscovered. Mimicry
in the lab can't capture the necessary subtlety. Food webs from the fossil
record might thus be the closest to something completely different that
contemporary researchers can ever hope to get their hands on. And the
Burgess Shale fauna from British Columbia, Canada, were the obvious choice.
>>>>>>>>>>>>>>>>>>>>>>
In the years after that original lunch, Dunne and Erwin mined existing
databases and compiled, reviewed and revised the two Cambrian food webs.
"Our first surprise was that we could put these data together," says Dunne.
With the food webs ready, the team then analysed them according to the
'niche model' first promulgated by Richard Williams and Neo Martinez1..
In the niche model, each predator is constrained to eating from one
'dimension', and is expected to eat everything in that dimension. So if a
dolphin eats tuna and sardines, it is presumed to eat everything between the
two on that dimension. In practice, such a dimension maps closely to body
size, but that's not how it is defined; it is a statistical creation that
represents many traits, of which body size simply happens to be a
significant one in most systems.
>>>>>>>>>
Just three of the 17 properties of the Burgess Shale web that they measured
fell outside the predictions of the niche model. "Most palaeobiologists
would assume that these half-billion-year-old food webs should look really
different from modern food webs," says Dunne. "But it looks like in most
ways, at least that we characterize, the organization looks really
similar."2

• Previous message: LARRY KLAES: "SETI public: Searching for ETI in the ecliptic plane"

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