Ch23(revised) - Chapter 23 The Evolution of Populations...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 23 The Evolution of Populations
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Study guide Genetic Variation, the Substrate for Natural Selection Explain the statement “It is the population, not the individual, that evolves.” Explain how quantitative and discrete characters contribute to variation within a population. Distinguish between average heterozygosity and nucleotide variability. Explain why average heterozygosity tends to be greater than nucleotide variability. heterozygosity Advantage .Define neutral variations. Explain why natural selection does not act on these alleles. Mutation and Sexual Recombination Explain why the majority of point mutations are harmless. Explain why mutation has little quantitative effect on allele frequencies in a large population. The Hardy-Weinberg Principle Define the terms population , species , and gene pool . Explain why meiosis and random fertilization alone will not alter the frequency of alleles or genotypes in a population. List the five conditions that must be met for a population to remain in Hardy-Weinberg equilibrium. Write the Hardy-Weinberg equation. Use the equation to calculate allele frequencies when the frequency of homozygous recessive individuals in a population is 25%. Natural Selection, Genetic Drift, and Gene Flow Explain the following statement: “Only natural selection leads to the adaptation of organisms to their environment.” Explain the role of population size in genetic drift. Distinguish between the bottleneck effect and the founder effect. Describe how gene flow can act to reduce genetic differences between adjacent populations. Distinguish among directional, disruptive, and stabilizing selection. Give an example of each mode of selection. Distinguish between intrasexual selection and intersexual selection. List four reasons why natural selection cannot produce perfect organisms.
Background image of page 2
Overview: The Smallest Unit of Evolution One misconception is that organisms evolve, in the Darwinian sense, during their lifetimes Natural selection acts on individuals, but only populations evolve Genetic variations in populations contribute to evolution Microevolution is a change in allele frequencies in a population over generations
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Microevolution Microevolution is simply a change in gene frequency within a population. Evolution at this scale can be observed over short periods of time between one generation and the next E.g mosquitoes evolving resistance to DDT whiteflies evolving resistance to pesticides gonorrheal bacteria strains evolving resistance to penicillin HIV strains evolving resistance to antiviral medicines . There are a few basic ways in which
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/18/2010 for the course BIO SCI 104 taught by Professor Lin during the Spring '09 term at UC Davis.

Page1 / 78

Ch23(revised) - Chapter 23 The Evolution of Populations...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online