Re: Why are Muslims against Evolution?!?
Survival of the fittest is a rule generally. Those animals that can survive do so, and those that cannot, do not. That isnt to say that all animals survive. The vast majority of species that ever have existed, have gone extinct.
Im not quite sure what your asking as far as the food chain.
If I understand what you asking, as far as how survival of the fittest can apply to the food chain, gradual changes in habitat for example, creates challenges that either animal, sheep or wolf, would have to adapt to. The fitness of either species, that being the ability to survive and reproduce a viable population, would depend on the nature of the challenge, and the capacity of each species to meet those challenges. A loss of grass may require the Sheep to vary its diet, or the loss of sheep would force a wolf to change its diet. The one that is most successful will be the one that has the most capacity to adapt.
In the short term, as within our life times, there is a balance, and a symbiosis. But over the long term, that symbiotic relationship may break down and force either to have to adapt or die. Accumulated adaptatins over Millions of years can produce a huge amount of variation.