In General, P- and S-Wave Velocities Increase Abruptly as the Waves

question 106

True/False

In general, P- and S-wave velocities increase abruptly as the waves pass downward across the crust-mantle boundary.

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Definitions:

Genetic Drift

A mechanism of evolution involving random fluctuations in the frequency of alleles within a population, which can cause genetic variation to decrease over time.

Bottleneck

A sudden decrease in a population size caused by adverse environmental factors; may result in genetic drift; also called genetic bottleneck or population bottleneck.

Directional Selection

A type of natural selection that favors one extreme phenotype over another, causing the allele frequency to shift in one direction.

Disruptive Selection

A form of natural selection where extreme values for a trait are favored over intermediate values, potentially leading to the evolution of distinct forms within a population.