Changes in the eyes of species 1 after species 2 became established illustrate which ecological concept?

• A. Coevolution
• B. Adaptive radiation
• C. Character displacement
• D. Resource partitioning

Answer: (C)

Character displacement occurs when competing species evolve differences in traits to reduce overlap in resource use. If species 2 is established and species 1 subsequently shows changes in its eyes, it suggests selection favors a different sensory specialization to avoid direct competition for similar resources or cues. This kind of divergent evolution in sympatry helps the two species coexist by partitioning their niches. It’s not about reciprocal changes in both species (coevolution), nor about a single lineage giving rise to many species (adaptive radiation), and it isn’t just the outcome of niche use (resource partitioning) but the evolutionary change that reduces direct competition.