Final answer:
Pioneer species initiate the first stage of ecological succession while climax communities represent the stable final stage. Pioneer species alter the environment to enable other species to follow, and climax communities maintain a stable balance of well-adapted organisms unless disrupted.
Step-by-step explanation:
The statement that best contrasts pioneer species and climax communities is:
Pioneer species are involved in the first stage of succession, and climax communities are involved in the final stage of succession.
Pioneer species are the hardy plants and organisms that are the first to colonize previously disrupted or damaged ecosystems. They begin the process of ecological succession by establishing themselves in the environment and altering it in such a way that allows other, more delicate species to follow. Climax communities, on the other hand, represent the final, stable stage of succession in an ecosystem. They form a balanced community where no single species is expected to become dominant or change significantly, unless disturbed by an external event. Climax communities consist of a characteristic assortment of plant and animal species that are well-adapted to the climate and geology of the area.