Textbook Question
Explain the role of heritable variations in Darwin's theory of natural selection.
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1. Introduction to Biology
Natural Selection and Evolution
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Which is the best definition of directional selection?
A
A process where intermediate phenotypes are favored, reducing variation in the population.
B
A process where one extreme phenotype is favored over others, causing a shift in the population's trait distribution.
C
A process where genetic drift causes random changes in allele frequencies.
D
A process where both extreme phenotypes are favored, leading to a bimodal distribution of traits.
Verified step by step guidance1
Understand the concept of directional selection: Directional selection is a type of natural selection that favors one extreme phenotype over other phenotypes, leading to a shift in the population's trait distribution.
Compare the given definitions: Analyze each option to determine which one aligns with the concept of directional selection.
Option A describes stabilizing selection, where intermediate phenotypes are favored, reducing variation.
Option C describes genetic drift, which involves random changes in allele frequencies, not directional selection.
Option D describes disruptive selection, where both extreme phenotypes are favored, leading to a bimodal distribution. Therefore, the correct definition of directional selection is the one that describes favoring one extreme phenotype over others.
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