Practice Questions

Stabilizing selection favors the intermediate phenotype (medium-sized wings) and selects against both extreme phenotypes (very short and very long wings).

Special Creation is a non-evolutionary concept proposing that species are fixed, unchanging entities created in their current forms, whereas Darwinism emphasizes descent with modification.

The selective pressure (predation) favors the faster extreme of swimming speeds, causing a directional shift in the average speed of the prey population over time.

Darwin's 1859 book went beyond speculating about evolution; it presented a vast array of evidence and proposed natural selection as the functional mechanism of evolutionary change.

Without pre-existing genetic variation, natural selection has no raw material to work with. If the environmental change is lethal to all identical individuals, the population will go extinct.

Because both extreme phenotypes (white and dark brown) are favored in their respective micro-habitats, while intermediate colors are less fit in both, disruptive selection is at play.

Wallace independently co-discovered the theory of natural selection, prompting Darwin to quickly publish his own extensive findings in "On the Origin of Species" in 1859.

Differential reproductive success is the core of natural selection; it means that individuals with traits better suited to the environment leave more offspring behind than less-suited individuals.

Artificial selection demonstrates the power of selective breeding to dramatically modify organisms, suggesting that a similar process (natural selection) operates in nature over longer periods.

Directional selection shifts the phenotypic distribution toward one extreme (larger beaks), typically in response to a directional change in environmental conditions.