1. Warm-Up #39 Answer questions #1-4 on Text page 372 Section Assessment.
Answer questions #1-4 on Text 377 Section Assessment

2. Voyage of the Beagle (1839 - 1844)
Darwin’s Voyage - During his travels, Darwin made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time.

3. Galapagos Islands
During his travels Darwin was amazed how different organisms were so well adapted to many different environments.
He saw patterns of diversity
Not just in living organisms, but also in fossil records.
The Galapagos Islands were a microcosm of Evolution

4. Vocab
Evolution - change in a kind of organism over time; process by which modern organisms have descended from ancient organisms
Theory - well-tested explanation that unifies a broad range of observations

5. Questions
Key Concept What two ideas from geology were important to Darwin’s thinking?
Key Concept According to Lamarck, how did organisms acquire traits?
Key Concept According to Malthus, what factors limited population growth?
Why has Lamarck’s theory of evolution been rejected?

6. Idea’s that shaped Darwin’s Thinking
James Hutton and Charles Lyell helped scientists recognize that Earth is many millions of years old, and the processes that changed Earth in the past are the same processes that operate in the present.
Jean-Baptiste Lamarck proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. Over time, this process led to change in a species
Thomas Malthus (English Economist) - reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone.

7. Lamarck (His theory is wrong)
Tendency Toward Perfection
Innate tendency toward complexity and perfection
Birds acquired the urge to fly
Kept trying to fly
Use and Disuse
Using a trait (wings) causes them to become stronger and larger
Disuse causes it to disappear
Inheritance of Acquired Traits
Passing acquired traits from one generation to the next

8. Lamarck

9. Daily Quiz #26 1. Define evolution. Define natural selection.
What are structures that have different mature forms, but develop from the same embryonic tissue called?

10. Charles Darwin and Natural Selection
Evolution
Charles Darwin and Natural Selection

11. Two things to know before talking about Natural Selection
In our world there is:
Natural Variation - differences among individuals of a species
And in order to understand Natural Selection you need to understand
Artificial selection - selection by humans for breeding of useful traits from the natural variation among different organisms

12. Vocab
struggle for existence - competition among members of a species for food, living space, and the other necessities of life
Fitness - ability of an organism to survive and reproduce in its environment
Adaptation - inherited characteristic that increases an organism’s chance of survival (increases an organism’s fitness)
survival of the fittest - process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection

13. Natural Selection
is the process by which individuals that are better suited to their environment survive and reproduce most successfully; also called survival of the fittest
In order for natural selection to occur there must be:
Natural Variation
Struggle for existence
An adaptation that increases the fitness of one organism over another

14. Descent With Modification
Darwin’s proposed that over long periods natural selection produces organisms that:
Have different structures
Establish different niches
Or occupy different habitats
As a result species have descended, with changes from other species over time.
Darwin’s principle of Descent with modification

15. Evidence of Evolution

16. The Fossil Record

17. Geographic Distribution of Living Species
Darwin’s Finches—descended from a common ancestor on South American mainland—each species adapted to its specific environment.
Similar environments on different continents can lead to different species evolving some common features even though they descend from different ancestors. (beaver and capybara)

18. Darwin’s Finches

19. Geographical Distrib. of Species
Common Descent

20. Homologous and Analogous Structures
1.Different ancestors
2.“analogy”=like
3.Different underlying structures
4.Same Function
5.Similar Environments
1.Same ancestor
2.“homo”=same
3.Same underlying structures
4.Different Functions
5.Different Environments

21. Homologous and Analogous

22. Vestigial Structure
Structures or Organs that serve no purpose or function.

23. Homologous Body Structures
vestigial organ--organ that serves no useful function in an organism

24. Vestigial Organ
organ that serves no useful function in an organism

25. Embryological Similarities
Many embryos of vertebrates look especially similar during early stages of development.
Same groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates.
These features develop into homologous structures.
Figure 15-17

26. Similarities in early development

27. Comparative Biochemistry
Similar DNA sequences=
Similar Gene segments of the DNA
Code for similar traits
In closely related species
Amino Acid Lab Today

28. Plate Tectonics Geological theory:
Continental masses were one land mass that explains
Closely related species have common ancestors on now separated continents

29. Summary of Darwin’s Theory
There is variation (genetic…)between organisms which can be inherited.
Organisms in nature produce more offspring than can survive, and many of those that survive do not reproduce.
Because more organisms are produced than can survive, members of each species must compete for limited resources.
Because each organism is unique, each has different advantages and disadvantages in the struggle for existence.
Individuals best suited to their environment survive and reproduce most successfully. The characteristics that make them best suited to their environment are passed on to offspring. Individuals whose characteristics are not as well suited to their environment die or leave fewer offspring.
Species change over time. Over long periods, natural selection causes changes in the characteristics of a species, such as in size and form. New species arise, and other species disappear.
Species alive today have descended with modifications from species that lived in the past.
All organisms on Earth are united into a single tree of life by common descent.

30. Amino Acid Sequencing Lab

31. Homework—Due Friday 1/14 Complete Amino Acid Sequencing Lab
Read Text Page
Study Guide

32. Warm-Up #40
Compare your answers on the Amino Acid lab with your partner’s answers.
Write a conclusion that summarizes how Biochemical Evidence provides support for evolution.

33. Daily Quiz #27
The number of times that a specific allele occurs in a gene pool compared to other alleles is called what?
What is gene shuffling?
How many phenotypes result from single-gene traits?

34. Chapter 16
GENES and VARIATION

35. Darwin’s Ideas Revisited
Darwin’s ideas had to be integrated with our new found information on Genetics.

36. Genes and Variation
Gene Pools - combined genetic information of all the members of a particular population
Relative Frequency - number of times an allele occurs in a gene pool compared with the number of times other alleles occur

37. Sources of Genetic Variation
Mutations—any change in the sequence of DNA.
Mistakes in replication
Radiation or chemicals in the environment
Gene Shuffling
Independent Assortment of homologous chromosomes during Meiosis
Crossing Over

38. Genes and Variation There are two main sources of genetic variation:
Mutations –
What are the two main types of mutations?
Gene shuffling –
When and how does gene shuffling occur?
Big question: Do mutations and gene shuffling cause evolution? In other words do mutations and gene shuffling change the relative frequencies of alleles in a gene pool?

39. Genes and Variation
single-gene trait - trait controlled by a single gene
How
many phen-
otypes are
produced?

40. Genes and Variation
polygenic trait - trait controlled by two or more genes
How many pheno-
types are produced?

41. Genetic Change (Evolution)
Big Question Since mutations and gene shuffling does not change the relative frequencies of alleles in a population, what causes the change of allele frequencies in a population? Natural Selection

42. Single-gene Trait (Natural Sel.)
Natural selection on single-gene traits can lead to changes in allele frequencies and, thus, to evolution.

43. Homework
Handout 16-1 and 16-2
Thursday

44. What two processes can lead to inherited variation in populations
What two processes can lead to inherited variation in populations? How does the range of phenotypes differ between single-gene traits and polygenic traits?

45. Polygenic Traits (Natural Sel.)
Natural selection can affect the distributions of phenotypes in any of three ways:
directional selection – form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve
stabilizing selection - form of natural selection by which the center of the curve remains in its current position; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end
disruptive selection - form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle

46. Directional Selection

47. Stabilizing Selection
Stabilizing selection takes place when individuals near the center of a curve have higher fitness than individuals at either end. This example shows that human babies born at an average weight are more likely to survive than babies born either much smaller or much larger than average.

48. Disruptive Selection
What will Disruptive Selection result in?

49. Peppered Moths Lab
Microevolution of a moth population in England in response to a change in environment.

50. Homework—Due Tuesday 1/18
Read Text and
Complete Study Guide

51. Genetic Drift
Genetic Drift - random change in allele frequencies that occurs in small populations
In small populations, individuals that carry a particular allele may leave more descendants than other individuals do, just by chance. Over time, a series of chance occurrences of this type can cause an allele to become common in a population.
founder effect - change in allele frequencies as a result of the migration of a small subgroup of a population

52. Genetic Drift and Founder Effect

53. Does Evolution occur all of the time?

54. Hardy-Weinberg principle
The principle that allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change
If there are no factors causing allele frequencies to change then the population is in……..
genetic equilibrium - situation in which allele frequencies remain constant

55. Genetic Equilibrium
Five conditions are required to maintain genetic equilibrium from generation to generation:
random mating
the population must be very large
there can be no movement into or out of the population
no mutations (that filter into the gene pool)
no natural selection

56. Homework
Studyguide 16-3
Test Chapter 15 and 16 on Tuesday

57. Describe how natural selection can affect traits controlled by single genes.
Describe three patterns of natural selection on polygenic traits. Which one leads to two distinct phenotypes?
How does genetic drift lead to a change in a population’s gene pool?
What is the Hardy-Weinberg principle?

58. When evolution DOES OCCUR
The process of SPECIATION - formation of new species
Speciation has occurred when – population have become reproductively isolated from one another
reproductive isolation - separation of species or populations so that they cannot interbreed and produce fertile offspring
Reproductive isolation can develop in a variety of ways, including behavioral isolation, geographic isolation, and temporal isolation.

59. Behavioral Isolation
form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding
Examples
Mating calls
Mating dances

60. Geographic Isolation
form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water

61. Temporal Isolation
form of reproductive isolation in which two populations reproduce at different times

62. Speciation of Darwin’s Finches
Speciation in the Galápagos finches occurred by the:
founding of a new population
geographic isolation
changes in the new population’s gene pool
reproductive isolation
ecological competition