When two species evolve to be more different over time due to competition, e.g., beak sizes to process different-sized seeds, this process is known as convergent evolution competitive exclusion niche compression character displacement A niche occupied by a given species in the absence of any competition from other species will be its realized niche primary niche fundamental niche expressed niche What is the name for the pattern where more-drought-tolerant ecological communities tend to occur on the sides of mountains that are on the down-wind side from the prevailing winds? Allee effect potential evapotranspiration (PET) commensalism rain shadow