That's not really true: the fox and rabbit /are/ competing directly
for the same resource: the rabbit's body. The fox wants it for lunch,
the rabbit wants it for making more rabbits. That's just for this
one encounter, but such competitions among all kinds of organisms
over eons of time statistically wind up looking like competitions
between individual genes--but that's all, just statistical appearance.
The /only/ case in which two organisms compete for /exactly/ the
same resources over their lifetimes is two animals of the same
species and the same sex in the same area, and even then there may
be complications like different abilities. That just brings to the
fore that one-on-one models of competition are just simplifications
our mind uses to understand statistical effects that are caused by
complex interdependent armies of genes and memes fighting over
complex and overlapping resources. The fact that we can simplify
to understand should not blind us to the real complications.
-- Lee Daniel Crocker <lee@piclab.com> <http://www.piclab.com/lcrocker.html> "All inventions or works of authorship original to me, herein and past, are placed irrevocably in the public domain, and may be used or modified for any purpose, without permission, attribution, or notification."--LDC