1.) How might you add "Keystone species" to the concept map? A.) Keystone species increase competition among all populations in a community. B.) Keystone species are the most abundant members of communities. C.) Keystone species always live with other species in symbiosis. D.) Keystone species influence the diversity of communities. 2.) What is the correct relationship between the abiotic environment and trophic levels? (Select all that apply.) The resources available in the abiotic environment limit the number of trophic levels in a community. Fat soluble chemicals that organisms at low trophic levels obtain from the abiotic environment will decrease in concentration in the higher trophic levels. Organisms at the lowest trophic level of a community obtain nutrients directly from the abiotic environment. Some of the energy that producers obtain from the abiotic environment is lost at each trophic level. 3.) Herbivory has the same effect on species in a community as competition. mutualism. commensalism. parasitism.