24 January 2007

Want to be big and strong?

Contradicting traditional assumptions, it seems that the big tip is lay off the meat. It seems that carnivory is very expensive as you get larger:

We show that the transition from small to large prey can be predicted by the maximization of net energy gain; larger carnivores achieve a higher net gain rate by concentrating on large prey. However, because it requires more energy to pursue & subdue large prey, this leads to a 2-fold step increase in energy expenditure, as well as increased intake. Across all species, energy expenditure & intake both follow a three-fourths scaling with body mass. However, when each dietary group is considered individually they both display a shallower scaling. This suggests that carnivores at the upper limits of each group are constrained by intake & adopt energy conserving strategies to counter this. Given predictions of expenditure & estimates of intake, we predict a maximum carnivore mass of approximately a ton, consistent with the largest extinct species.

So says Andrew P. Dobson, Princeton University.

The graphs look interesting.

We won’t be seeing a return to Indricothere & the like, at 15 tons apiece. Anybody running a dino-burger joint had better expect some stiff support costs, because even a 15t vegetarian would (literally) mow through tonnes of food every day.

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