Competition between members of a species ("intraspecific") for resources such as food, water, territory, and sunlight may result in an increase in the frequency of a variant of the species best suited for survival and reproduction until its fixation within a population. However, competition among resources also has a strong tendency for diversification between members of the same species, resulting in coexistence of competitive and non-competitive strategies or cycles between low and high competitiveness. Third parties within a species often favour highly competitive strategies leading to species extinction when environmental conditions are harsh (evolutionary suicide).