EvolutionLesson 2 of 3 in the course The Evolution of Populations

Population Genetic Variation and Evolutionary Forces

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Populations contain individuals with different traits. Understanding which differences are inherited helps explain how populations can evolve.

Individuals in a population may show different phenotypes, the observable characteristics of organisms. A population is polymorphic when it has two or more forms of a particular characteristic. For example, individuals may have different colors or may express different alleles of a gene.

All flashcards

What is phenotypic variation?
The distribution of phenotypes among individuals in a population.
What is heritability?
The fraction of phenotypic variation in a population attributable to genetic differences among individuals.
What is genetic drift?
A change in allele or genotype frequencies caused by chance.
What is gene flow?
The movement of alleles into or out of a population through migrating individuals or gametes.
What is a cline?
A gradual change in a characteristic across a geographic or ecological gradient.

Quiz questions

  1. What distinguishes genetic drift from natural selection?Answer: Drift changes frequencies through chance rather than trait-linked reproductive advantage.
  2. What defines a bottleneck effect?Answer: A sharp population reduction leaves survivors as a chance sample of the original group.
  3. How does a founder effect arise?Answer: A small founding group carries only part of the source population's genetic variation.
  4. What role do mutations play in population variation?Answer: They can create new alleles and thus add genetic variation.
  5. What is assortative mating?Answer: A mating pattern in which individuals prefer partners with similar phenotypes.

Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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