Presentation on theme: "Chapter 16 Table of Contents Section 1 Genetic Equilibrium"— Presentation transcript:
1Chapter 16 Table of Contents Section 1 Genetic Equilibrium Population Genetics and SpeciationChapter 16Table of ContentsSection 1 Genetic EquilibriumSection 2 Disruption of Genetic EquilibriumSection 3 Formation of Species
2Chapter 16 Objectives Section 1 Genetic Equilibrium Identify traits that vary in populations and that may be studied.Explain the importance of the bell curve to population genetics.Compare three causes of genetic variation in a population.Calculate allele frequency and phenotype frequency.Explain Hardy-Weinberg genetic equilibrium.
3Variation of Traits Within a Population Section 1 Genetic EquilibriumChapter 16Variation of Traits Within a PopulationPopulation biologists study many different traits in populations, such as size and color.
4Variation of Traits Within a Population, continued Section 1 Genetic EquilibriumChapter 16Variation of Traits Within a Population, continuedCauses of VariationTraits vary and can be mapped along a bell curve, which shows that most individuals have average traits, whereas a few individuals have extreme traits.Variations in genotype arise by mutation, recombination, and the random pairing of gametes.
5Section 1 Genetic Equilibrium Chapter 16The Gene PoolThe total genetic information available in a population is called the gene pool.
6The Gene Pool, continued Section 1 Genetic EquilibriumChapter 16The Gene Pool, continuedAllele frequency is determined by dividing the total number of a certain allele by the total number of alleles of all types in the population.
7The Gene Pool, continued Section 1 Genetic EquilibriumChapter 16The Gene Pool, continuedPredicting PhenotypePhenotype frequency is equal to the number of individuals with a particular phenotype divided by the total number of individuals in the population.
8The Hardy-Weinberg Genetic Equilibrium Section 1 Genetic EquilibriumChapter 16The Hardy-Weinberg Genetic EquilibriumAllele frequencies in the gene pool do not change unless acted upon by certain forces.Hardy-Weinberg genetic equilibrium is a theoretical model of a population in which no evolution occurs and the gene pool of the population is stable.
9Section 1 Genetic Equilibrium Chapter 16Phenotype Frequency
10Chapter 16 Objectives Section 2 Disruption of Genetic Equilibrium List five conditions under which evolution may take place.Explain how migration can affect the genetics of populations.Explain how genetic drift can affect populations of different sizes.Contrast the effects of stabilizing selection, directional selection, and disruptive selection on populations over time.Identify examples of nonrandom mating.
11Section 2 Disruption of Genetic Equilibrium Chapter 16MutationEvolution may take place when populations are subject to genetic mutations, gene flow, genetic drift, nonrandom mating, or natural selection.Mutations are changes in the DNA.
12Section 2 Disruption of Genetic Equilibrium Chapter 16Gene FlowEmigration and immigration cause gene flow between populations and can thus affect gene frequencies.
13Section 2 Disruption of Genetic Equilibrium Chapter 16Genetic DriftGenetic drift is a change in allele frequencies due to random events.Genetic drift operates most strongly in small populations.
14Chapter 16 Nonrandom Mating Section 2 Disruption of Genetic EquilibriumChapter 16Nonrandom MatingMating is nonrandom whenever individuals may choose partners.
15Nonrandom Mating, continued Section 2 Disruption of Genetic EquilibriumChapter 16Nonrandom Mating, continuedSexual SelectionSexual selection occurs when certain traits increase an individual’s success at mating.Sexual selection explains the development of traits that improve reproductive success but that may harm the individual.
16Chapter 16 Natural Selection Section 2 Disruption of Genetic EquilibriumChapter 16Natural SelectionNatural selection can influence evolution in one of three general patterns.
17Natural Selection, continued Section 2 Disruption of Genetic EquilibriumChapter 16Natural Selection, continuedStabilizing SelectionStabilizing selection favors the formation of average traits.
18Natural Selection, continued Section 2 Disruption of Genetic EquilibriumChapter 16Natural Selection, continuedDisruptive SelectionDisruptive selection favors extreme traits rather than average traits.
19Natural Selection, continued Section 2 Disruption of Genetic EquilibriumChapter 16Natural Selection, continuedDirectional SelectionDirectional selection favors the formation of more-extreme traits.
20Chapter 16 Two Kinds of Selection Section 2 Disruption of Genetic EquilibriumChapter 16Two Kinds of Selection
21Chapter 16 Objectives Section 3 Formation of Species Relate the biological species concept to the modern definition of species.Explain how the isolation of populations can lead to speciation.Compare two kinds of isolation and the pattern of speciation associated with each.Contrast the model of punctuated equilibrium with the model of gradual change.
22Chapter 16 The Concept of Species Section 3 Formation of SpeciesChapter 16The Concept of SpeciesAccording to the biological species concept, a species is a population of organisms that can successfully interbreed but cannot breed with other groups.
23Isolation and Speciation Section 3 Formation of SpeciesChapter 16Isolation and SpeciationGeographic IsolationGeographic isolation results from the separation of population subgroups by geographic barriers.
24Chapter 16 Geographic Isolation Section 3 Formation of Species Click below to watch the Visual Concept.Visual Concept
25Isolation and Speciation, continued Section 3 Formation of SpeciesChapter 16Isolation and Speciation, continuedAllopatric SpeciationGeographic isolation may lead to allopatric speciation.
26Isolation and Speciation, continued Section 3 Formation of SpeciesChapter 16Isolation and Speciation, continuedReproductive IsolationReproductive isolation results from the separation of population subgroups by barriers to successful breeding.
27Reproductive Isolation Section 3 Formation of SpeciesChapter 16Reproductive IsolationClick below to watch the Visual Concept.Visual Concept
28Isolation and Speciation, continued Section 3 Formation of SpeciesChapter 16Isolation and Speciation, continuedSympatric SpeciationReproductive isolation within the same geographic area is known as sympatric speciation.
29Chapter 16 Rates of Speciation Section 3 Formation of SpeciesChapter 16Rates of SpeciationIn the gradual model of speciation (gradualism), species undergo small changes at a constant rate.Under punctuated equilibrium, new species arise abruptly, differ greatly from their ancestors, and then change little over long periods.
30Chapter 16 Comparing Punctuated Equilibrium and Gradualism Section 3 Formation of SpeciesChapter 16Comparing Punctuated Equilibrium and GradualismClick below to watch the Visual Concept.Visual Concept