Aspecies of fish evolved over thousands of years to have gills that allowed the fish to swim deep in the sea. what’s the effect of this development on deep-water resources? the fish developed the gills because . because the fish are now able to swim in deep water, their in shallower water will have less food. likewise, competition for food among deep-water fish that eat the same types of food will 1. a. genetic modification b. hybridization c. natural selection 2. a . competitors b. predators c. prey 3 a .increase b. decrease c. not change