1. How Populations Evolve CHAPTER 13
Darwin's Voyage and Origin of Species
Lamarck's and Lyell's Contributions
Descent with Modification
Evidence of Evolution
Fossils, Biogeography, Comparative Anatomy, Comparative Embryology, & Molecular Biology
The Theory of Natural Selection
Artificial Selection: A Model for Natural Selection
Overproduction, Variation, Competition, and Differential Reproduction
Modern Synthesis: Darwin and Genetics
Populations are Evolutionary Units
Sources of Genetic Variation
Gene Pools and Evolution
Mechanisms of Evolution
Genetic Drift, Gene Flow, Mutation, and Natural Selection

2. Charles Darwin and The Origin of Species
Charles Darwin’s On the Origin of Species by Means of Natural Selection
Was published on November 24, 1859.
Darwin argued that contemporary species arose from ancestors
Through a process of “descent with modification,” with natural selection as the mechanism.
The basic idea of natural selection is that
Organisms can change over generations.
Individuals with certain heritable traits leave more offspring than others.

3. The result of natural selection is evolutionary adaptation.
Seahorse Camouflage

4. How Populations Evolve CHAPTER 13
Darwin's Voyage and Origin of Species
Lamarck's and Lyell's Contributions
Descent with Modification
Evidence of Evolution
Fossils, Biogeography, Comparative Anatomy, Comparative Embryology, & Molecular Biology
The Theory of Natural Selection
Artificial Selection: A Model for Natural Selection
Overproduction, Variation, Competition, and Differential Reproduction
Modern Synthesis: Darwin and Genetics
Populations are Evolutionary Units
Sources of Genetic Variation
Gene Pools and Evolution
Mechanisms of Evolution
Genetic Drift, Gene Flow, Mutation, and Natural Selection

5. An Early Proposal of Evolution: Theory of Acquired Characteristics
Jean Baptiste Lamarck (~ 1800) : Theory of Acquired Characteristics
Use and disuse alter shape and form in an animal
Changes wrought by use and disuse are heritable
Explained how a horse-like animal evolved into a giraffe

6. The earth is now considered to be about 4.6 billion years old
Earth Process Are Constant and Have Been Going On For Billions of Years
Lyell’s Gradualism or Uniformitarianism
The laws have science have not changed over time
Natural geological processes occurring today are the same ones that operated in the past
Natural process effect the earth gradually over long periods of time
The earth must be much older than 6,000 (according to Biblical interpretations of human generations since Adam and Eve)
Charles Lyell
In Principles of
Geology, 1830
The earth is now considered to be about 4.6 billion years old

7. The Voyage of the Beagle
Figure 13.4

8. Darwin was intrigued by he fact that Galápagos Island organisms resembled those in South America.
Figure 13.5

9. Descent with Modification
Darwin made two main points in The Origin of Species:
Organisms inhabiting Earth today descended from ancestral species.
Natural selection was the mechanism for descent with modification.

10. How Populations Evolve CHAPTER 13
Darwin's Voyage and Origin of Species
Lamarck's and Lyell's Contributions
Descent with Modification
Evidence of Evolution
Fossils, Biogeography, Comparative Anatomy, Comparative Embryology, & Molecular Biology
The Theory of Natural Selection
Artificial Selection: A Model for Natural Selection
Overproduction, Variation, Competition, and Differential Reproduction
Modern Synthesis: Darwin and Genetics
Populations are Evolutionary Units
Sources of Genetic Variation
Gene Pools and Evolution
Mechanisms of Evolution
Genetic Drift, Gene Flow, Mutation, and Natural Selection

11. Evidence of Evolution Biological evolution has left observable marks.
1. Fossils
Are preserved remnants or impressions left by organisms that lived in the past.
Are often found in sedimentary rocks.

12. reconstructions from fossils
Progression of Modification Through Time Seen in Fossil Remains
Primitive horse foot
reconstructions from fossils

13. Biogeography 2. Biogeography
The of the geographic distribution of species.
First suggested to Darwin that today’s organisms evolved from ancestral forms.
Organisms that are related to each other in structure and appearance tend to occur in the same geographical area
Organisms that are more distantly related tend to be found in distant geographical areas

14. Related Animals Descended From a Common Ancestor
Figure 13.10

15. Comparative Anatomy 3. Comparative anatomy
Is the comparison of body structure between different species.
Confirms that evolution is a remodeling process.
Homology
Is the similarity in structures due to common ancestry.
The more recently two species diverged from one another, the more similar their homologous structures

16. Homologous Structures Are Derived From the Same Parts
of a Common Ancestor
Figure 13.11

17. Dolphins and Whales are Related to Land Mammals By Homologous Pelvis and Feet

18. Comparative Embryology
Organisms with common ancestors share certain developmental structures as they grow into adults
One would expect unrelated organisms to share little similarity in embryological growth

19. Comparative Embryology Suggests Common Ancestry
and Modification By Descent

20. Molecular Biology
5. Evolutionary relatedness can be discerned through molecular comparisons
Compare genes and proteins of different organisms
Only 5% difference in DNA sequences between humans and chimpanzees

21. How Populations Evolve CHAPTER 13
Darwin's Voyage and Origin of Species
Lamarck's and Lyell's Contributions
Descent with Modification
Evidence of Evolution
Fossils, Biogeography, Comparative Anatomy, Comparative Embryology, & Molecular Biology
The Theory of Natural Selection
Artificial Selection: A Model for Natural Selection
Overproduction, Variation, Competition, and Differential Reproduction
Modern Synthesis: Darwin and Genetics
Populations are Evolutionary Units
Sources of Genetic Variation
Gene Pools and Evolution
Mechanisms of Evolution
Genetic Drift, Gene Flow, Mutation, and Natural Selection

22. Natural Selection Darwin’s finches
Are an excellent example of natural selection and adaptive evolution.

23. Varieties of maize (corn)
Examples of Artificial Selection
Varieties of maize (corn)
New species from wild mustard
Dog breeds
Varieties of chili peppers

24. Observations That Led Darwin to the Theory of Natural Selection
Overproduction
All species tend to produce excessive numbers.
This leads to a struggle for existence.
Individual variation
Variation exists among individuals in a population.
Much of this variation is heritable.
Population with varied inherited traits
Competition
Struggle to get food, mates, shelter, escape from predators
Some variations are more successful than others and those organisms with those variations are the “fittest”
Elimination of individuals with certain traits
Reproduction of survivors
Differential reproductive success
Those individuals with traits best suited for the local environment leave more fertile offspring.
Successful variations become more common
Modification: Increased frequency of traits that
enhance survival and reproductive success

25. Natural Selection in Action
Examples of natural selection include
Pesticide resistance in insects.
Drug-resistant strains of HIV.
The development of antibiotic-resistant bacteria.
1. Selection of resistant forms
under incomplete antibiotic treatment (selection)
2. The few surviving resistant cells divide and repopulate with all resistant offspring

26. How Populations Evolve CHAPTER 13
Darwin's Voyage and Origin of Species
Lamarck's and Lyell's Contributions
Descent with Modification
Evidence of Evolution
Fossils, Biogeography, Comparative Anatomy, Comparative Embryology, & Molecular Biology
The Theory of Natural Selection
Artificial Selection: A Model for Natural Selection
Overproduction, Variation, Competition, and Differential Reproduction
Modern Synthesis: Darwin and Genetics
Populations are Evolutionary Units
Sources of Genetic Variation
Gene Pools and Evolution
Mechanisms of Evolution
Genetic Drift, Gene Flow, Mutation, and Natural Selection

27. The Modern Synthesis: Darwinism Meets Genetics
The modern synthesis is the fusion of genetics with evolutionary biology.
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

28. Populations as the Units of Evolution
A population
Is a group of individuals of the same species living in the same place at the same time.
Is the smallest biological unit that can evolve.

29. Genetic Characteristics of Populations
Population genetics
Focuses on populations as the evolutionary units.
Tracks the genetic makeup of populations over time.
Individual variation abounds in populations.
Not all of this variation is heritable.
Only the genetic component of variation is relevant to natural selection.
A population is said to be polymorphic for a characteristic if two or more morphs, or forms, are present in noticeable numbers.
Genetic Variation from Sexual Recombination

30. Polymorphism in Color and Pattern of Garter Snakes
Figure 13.19

31. How Populations Evolve CHAPTER 13
Darwin's Voyage and Origin of Species
Lamarck's and Lyell's Contributions
Descent with Modification
Evidence of Evolution
Fossils, Biogeography, Comparative Anatomy, Comparative Embryology, & Molecular Biology
The Theory of Natural Selection
Artificial Selection: A Model for Natural Selection
Overproduction, Variation, Competition, and Differential Reproduction
Modern Synthesis: Darwin and Genetics
Populations are Evolutionary Units
Sources of Genetic Variation
Gene Pools and Evolution
Mechanisms of Evolution
Genetic Drift, Gene Flow, Mutation, and Natural Selection

32. Sources of Genetic Variation
Mutations and sexual recombination
Produce genetic variation.
Mutations
Are changes in the DNA of an organism.
Sexual recombination
Shuffles alleles during meiosis.

33. Analyzing Gene Pools The gene pool
Consists of all alleles of all individuals making up a population
Gene occurance usually expressed as a gene frequency (percentage of occurrence in population)

34. Mechanisms of Microevolution
Microevolution is defined as
A generation-to-generation change in a population’s frequencies of alleles.
The main causes of microevolution are
Genetic drift
Gene flow
Mutations
Natural selection
Causes of Evolutionary Change

35. How Populations Evolve CHAPTER 13
Darwin's Voyage and Origin of Species
Lamarck's and Lyell's Contributions
Descent with Modification
Evidence of Evolution
Fossils, Biogeography, Comparative Anatomy, Comparative Embryology, & Molecular Biology
The Theory of Natural Selection
Artificial Selection: A Model for Natural Selection
Overproduction, Variation, Competition, and Differential Reproduction
Modern Synthesis: Darwin and Genetics
Populations are Evolutionary Units
Sources of Genetic Variation
Gene Pools and Evolution
Mechanisms of Evolution
Genetic Drift, Gene Flow, Mutation, and Natural Selection

36. Two categories of genetic drift
Is a change in the gene pool of a small population due to chance.
Two categories of genetic drift
Bottleneck Effect
Death of most of population leaves only a few survivors and their genes to rebuilt the population
Founder Effect
Small group randomly removed from a larger population begins a new colony

37. Genetic Drift: The Bottleneck Effect
Is an example of genetic drift.
Results from a drastic reduction in population size.
Bottlenecking in a population usually reduces genetic variation.

38. Genetic Drift: The Founder Effect
Is genetic drift in a new colony
Can lead to a high incidence of genetic disease in a colony population
By chance, 7 q alleles and 3 Q alleles are carried by this subgroup

39. Asian/Latino/Black/Caucasian/Native American
2. Gene Flow
Gene flow
Is genetic exchange with another population.
Tends to reduce genetic differences between populations.
Asian/Latino/Black/Caucasian/Native American

40. 3. Mutation Mutations Are changes in an organism’s DNA.
Alone do not have much effect on a large population.
Can have significant cumulative effects on a population.
Produces new gene forms

41. How Populations Evolve CHAPTER 13
Darwin's Voyage and Origin of Species
Lamarck's and Lyell's Contributions
Descent with Modification
Evidence of Evolution
Fossils, Biogeography, Comparative Anatomy, Comparative Embryology, & Molecular Biology
The Theory of Natural Selection
Artificial Selection: A Model for Natural Selection
Overproduction, Variation, Competition, and Differential Reproduction
Modern Synthesis: Darwin and Genetics
Populations are Evolutionary Units
Sources of Genetic Variation
Gene Pools and Evolution
Mechanisms of Evolution
Genetic Drift, Gene Flow, Mutation, and Natural Selection

42. 4. Natural Selection
Of all causes of microevolution, only natural selection promotes adaptation.
Three results of natural selection
Directional selection
Shifts the phenotypic “curve” of a population.
Selects in favor of some extreme phenotype.
Disruptive selection
Can lead to a balance between two or more contrasting morphs in a population.
Stabilizing selection
Maintains variation for a particular trait within a narrow range.

43. Three Types of Natural Selection
Figure 13.28

44. Biology and Society: Persistent Pests
Mosquitoes and malaria
In the 1960s, the World Health Organization (WHO) began a campaign to eradicate the mosquitoes that transmit malaria.
It used DDT, to which some mosquitoes have evolved resistance.

45. How Populations Evolve CHAPTER 13
Darwin's Voyage and Origin of Species
Lamarck's and Lyell's Contributions
Descent with Modification
Evidence of Evolution
Fossils, Biogeography, Comparative Anatomy, Comparative Embryology, & Molecular Biology
The Theory of Natural Selection
Artificial Selection: A Model for Natural Selection
Overproduction, Variation, Competition, and Differential Reproduction
Modern Synthesis: Darwin and Genetics
Populations are Evolutionary Units
Sources of Genetic Variation
Gene Pools and Evolution
Mechanisms of Evolution
Genetic Drift, Gene Flow, Mutation, and Natural Selection