Chapter 8 Summary Natural Selection

1.

Adaptive evolution is driven by natural selection through the propagation of beneficial traits.

How can all three phenotypes of lizards exists in one population?

Frequency-dependent selection allows for a distribution cycle, where all forms are selected for.

What influence does he sexual sexual dimorphism of the tail have on a peacock's ability to mate successfully?

Larger, heavier tails in males signify the male is more fit; therefore, a better mate for the female

What are the differences and similarities between directional and stabilizing selection?

Stabilizing selection results in a decrease of a population's genetic variance when natural selection favors an average phenotype and selects against extreme variations. In directional selection, a population's genetic variance shifts toward a new phenotype when exposed to environmental changes. Diversifying or disruptive selection increases genetic variance when natural selection selects for two or more extreme phenotypes that each have specific advantages. In diversifying or disruptive selection, average or intermediate phenotypes are often less fit than either extreme phenotype and are unlikely to feature prominently in a population.

Which type of selection cause a shift in a population's genetic variation due to environmental change?

directional selection

Which of the following is not a limitation on natural selection?

the sum of selective forces driving evolution