Practice Questions

Neo-Darwinism combines Darwinian selection with Mendelian genetics, defining evolution as a change in allele frequencies within a population's gene pool over generations.

Selective pressure (e.g., predators, climate, disease) is the environmental force that drives natural selection by favoring certain phenotypes over others.

The rapid development of resistance in bacteria and pests is a documented, direct observation of natural selection occurring in contemporary times under strong selective pressures.

The drought alters the environment, making the brown phenotype more advantageous. Brown insects will survive predation better, reproduce more, and increase the frequency of the brown allele.

Darwin argued that complex structures evolve via the gradual accumulation of many slight, heritable modifications, with each step improving the organism's fitness compared to the previous state.

Individuals do not adapt by mutating their own genomes in response to environmental demands. Mutations are random; natural selection simply filters pre-existing genetic variations.

Natural selection requires a choice of variants to "select" from. If all individuals are genetically identical, any differential survival is due to chance, and no evolutionary adaptation can occur.

Because both phenotypic extremes (very long and very short tails) are selected against, stabilizing selection acts to maintain intermediate tail lengths.

The inheritance of acquired characters is a postulate of Lamarckism, which Darwinism does not rely on (although Darwin did occasionally speculate on soft inheritance, it is not a core tenet of natural selection).

Natural selection only acts on traits that influence differential reproductive success. If a trait is completely neutral with respect to fitness, natural selection does not influence it directly.