RNR 2101 Chapter : Ecology Exam 3 Study Guide
Document Summary
Ecology exam 3: natural selection should favor phenotypes that keep sympatric species distinct and reduce competition (phenotypes that reduce niche overlap [ ] with competitors, natural selection should also lead to niche expansion in the absence of competitors. Character displacement- divergence of realized niches of competing species when they occur together compared to where the species occur alone. Natural selection removes the individuals that compete the most with the other species, leading to directional selection: character displacement occurs because The result is an evolutionary battle between the interacting species: example of stabilizing selection- cicadas. Individuals hatching too early or too late have lower survival. In this case, the character under selection is timing of emergence: plant chemical defenses are called secondary chemicals. This means that they are modified from chemicals produced in normal metabolism (primary chemicals). Mutualisms are examples of coevolution: reciprocal evolutionary responses between interacting species.
