Which stage is the last stage of speciation?

The populations become adapted to different environments and eventually become so different that they cannot imterbreed to produce fertile of spring.

Speciation is the evolution of one species into two different kinds , and when they become isolated , that is the final step , since they cannot interbreed any longer .

Explanation:

Hope it helps

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.

radon is correct hope this