When the phenotype of a given species is different when it is living in a habitat alone compared to when it is interacting with a competing species is evidence for:disruptive evolution.
Extreme values of a trait are preferred above intermediate values in population genetic alterations known as disruptive selection, also known as diversifying selection. In this situation, the phenotype variation rises and the population is split into two clearly defined groups.
When extreme phenotype outperform more intermediate phenotypes in terms of fitness, disruptive selection takes place. When selection maintains a population under a disruptive regime, the phenomena is particularly intriguing.
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