SLUH – Bio 431/AP Bio – Pham

Reading Guide 15

RG 15 – Mechanisms of Evolution*

*Adapted and modified from Robbyn Tuinstra’s work

Section 15.1 – Evolution is both factual and the basis of broader theory

  1. Jean-Baptiste Lamarck was one of the first to assert that evolution occurs. What was the mechanism he proposed?
  1. Summarize Darwin’s theory of evolution by natural selection.
  1. Explain the statement “Natural selection acts on individuals, but populations evolve.”

Section 15.2 – Mutation, selection, gene flow, genetic drift, and nonrandom mating result in evolution

  1. What is the source of genetic variation? Explain.
  1. Define adaptation.
  1. Explain how artificial selection shed light on Darwin’s understanding of natural selection.
  1. What is the difference(s) between natural selection and adaptation?
  1. Why is genetic drift more apparent in small populations?
  1. Explain population bottleneck.
  1. Explain founder effect.
  1. Define fitness. How is fitness determined?

Section 15.3 – Evolution can be measured by changes in the allele frequencies

  1. What is the significance of Hardy-Weinberg equilibrium?
  1. Summarize the 5 conditions that must be met for a population to be at Hardy-Weinberg equilibrium.
  1. Why is the concept of Hardy-Weinberg equilibrium important even though the assumptions on which it is based are never completely met in nature?
  1. Although the stringent assumptions of Hardy-Weinberg equilibriumare never met completely in real populations, the genotype frequenciesof many populationsdo not deviate significantly from Hardy–Weinberg expectations. Explain why.
  1. Summarize the effect of each of the following on allele frequencies in a population.

Mutations
Gene Flow
Genetic Drift
Non-Random
Mating
Natural
Selection

Section 15.4 – Selection can be stabilizing, directional, or disruptive

  1. Why do phenotypic variations in a population generally resemble a bell-curve?

Type of Natural Selection / Effect and Example
Stabilizing
Selection
Directional
Selection
Disruptive
Selection
  1. Summarize how each of the following act to maintain genetic variation or contribute to evolutionary change in populations.

Neutral Mutations
Sexual Recombination
Gene Duplication
Heterozygote Advantage

Section 15.6 – Recombination, lateral gene transfer, and gene duplication can result in new features

  1. What are some of the potential advantages of lateral gene transferto the organismsthat gain new genesby this mechanism?
  1. Why is gene duplicationconsidered important for long-term evolutionary change?
  1. Why is sexual reproductionso prevalent in nature, despite its having at least three short-term evolutionary disadvantages?

______

Page 1 of 2