In the coniferous forests of oregon, eight species of woodpeckers coexist. four species select their nesting sites based on tree diameter, while the fifth species nests only in fir trees that have been dead for at least 10 years. the sixth species also nests in fir trees, but only in live or recently dead trees. the two remaining species nest in pine trees, but each selects trees of different sizes. this pattern is an example of
(a) resource partitioning.
(b) commensalism.
(c) predation.
(d) predator-mediated competition.
(e) a keystone species.

The correct answer is a. resource partitioning

Explanation:

Resource partitioning is a strategy that species employ to avoid competition. It is based on the selection of different nutrition sources by different organisms that coexist in the same ecological niche, so there is no conflict between them. In the present case, each one of the eight species of woodpeckers feed on different trees, it means that each one select a different tree´s species or, if they select the same species, they use trees of different diameters.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.