Final answer:
The ecological species concept stresses the role of disruptive natural selection in keeping species distinct in different but nearby environments, even amid substantial gene flow.
Step-by-step explanation:
The species concept that emphasizes the importance of disruptive natural selection in maintaining species boundaries, particularly when similar species are found in different but proximate environments, is the ecological species concept. This concept is based on the role of natural selection rather than gene flow in maintaining the distinctiveness of species. The ecological species concept holds that even where there is substantial gene flow, as seen in hybrid zones, natural selection can preserve the integrity of distinct species. Examples include the moor macaque and the Tonkean macaque, which despite interbreeding, remain separate species due to natural selection maintaining their species boundaries.