Jim wrote that my speculation that rabbits might have a poor digestive
system to make them ideal for the bottom of the food chain was a just
so story:
>Just so story. You could equally well argue that he would design them
>with efficient digestive systems, so that more of them could be
>supported in the ecosystem, and so provide more food for other animals.
Thinking about this, I realized he was exactly wrong. An animal that
has a poor digestive system but can eat its own feces has the best system
possible for a creature on the bottom of the food chain.
Consider a drought year, food is scarce and rabbits cannot find the
amount of food they are used to. What do they do? They eat their own
feces and plants or insects that depend on their feces for fertilizer
go without for a year. The rabbit population remains about the same
and doesn't starve away as quickly as it would if they couldn't eat
their feces (i.e. In bad years the poor digestive system plus capability
of eating their own feces combo acts equivalently to a good digestive
system)
In a good year, rabbits don't eat their feces but forage for what they
need. Their feces are available for ecological purposes and they are
outside exposed to predators for long periods of time.
Rabbits with a bad digestive system that can eat their feces have the
best of both worlds. The poor digestive system useful for keeping
their population in check and feeding the predators in the food chain
and the good digestive system required during lean times.
(i.e. good digestive system = bad digestive system + capability of eating
feces)
In Christ
robert van de water
associate researcher
UCLA