said a professor on a competition involved theory

said a professor on a competition involved theory, that if similar types of animals live in the same area, will be the same food as prey, which led to one of less than the competition for food species extinction, the professor that this some one-sided theory, she made an example, that a bird has three types, but they are one, under the co-existence of the phenomenon of removal, because they plant a tree different places to eat foods, such as A Bird, eat the above book, B Bird, eat the middle, and then c Bird eating the following, and because they eat each other as the season does not have survived so, then this is a student asked a question, it is more like cooperation, not symbiotic, that example is not sufficient, then the teacher said, a few times then put them in the same place at the same time to eat, it does not produce competitive pressures, and later added an element for the impact of organism, like nitrogen, I did not understand, that even if because of competition, but its back to the evolution of animals, such as two species compete for water, but the game play will evolve into the species who need very little water species.