1. 48

2. 49

3. 50
Speciation
Macroevolution

4. Evolution: change in the allelic frequencies in a population51
Macroevolution
Speciation
How do we get new species?
Where do new species come from?
Species: population whose members can interbreed in nature and produce viable, fertile offspring
Evolution: change in the allelic frequencies in a population

5. 52
Speciation
In the physical world, natural barriers form and cause the breakup of populations to form smaller populations.
Volcanoes, sea-level changes, and earthquakes are a few examples of natural occurrences that affect populations

6. Speciation Mechanisms53
Speciation Mechanisms
Geographic Isolation
Separated by bodies of water or mountains.
Temporal Isolation
Reproduction takes place at different times of the year
Different Mating seasons
Overtime they can change so much that they become unable to breed as they adapt to their environment.

7. 54
Behavioral Isolation
Populations are capable of interbreeding, but have different courtship rituals or other type of behavior.
Do not recognizes another species as a mating partner.
Sexual Selection
Brightly colored male- drab female
video clip: Dressing fro desire

8. 55
VOCAB CHECK

9. Combined genetic information of a particular population. 56
Gene Pool
Combined genetic information of a particular population.
All the genes present with in a population
Can change
A population is a localized group of individuals that belong to the same species.

10. Changes in allele frequency with in a population
Genetic drift— along with natural selection, mutation, and migration—is one of the basic mechanisms of evolution. 57
Changes in allele frequency with in a population
Genetic drift
Random changes in allele frequency that occurs in small populations
“Lucky” individuals leave more offspring.
Also known as the “Founder Effect”

11. Gene Flow
Immigration
Emigration

12. Start Packet #2
Review Clip

13. 58
Patterns of
Evolution

14. Divergent Evolution 59
Divergent evolution is the process of two or more related species becoming more and more dissimilar.
The red fox and the kit fox provide and example of two species that have undergone divergent evolution.
As they adapted to different environments, the appearance of the two species diverged.

15. Two or more related species becoming more and more dissimilar
Divergent Evolution 60
Two or more related species becoming more and more dissimilar

16. Convergent Evolution 61
Independent development of similar structures
Convergent evolution is the emergence of biological structures or species that exhibit similar function and appearance but that evolved through widely different evolutionary pathways.
examples include the multiple origins of wings (bats, birds) and eyes.

17. Convergent Evolution 62
Independent development of similar structures

18. Coevolution Predators and their prey Parasites and their hosts63
Predators and their prey
Parasites and their hosts
Plant-eating animals and the plants upon which they feed
One example of coevolution is between plants and the animals that pollinate them.
Coevolution is the joint change of two or more species in close interaction.

19. Coevolution 64
Bumblebees & the flowers they pollinate have coevolved so that both have become dependent on each other for survival.
Some Central American Acacia species have hollow thorns and pores at the bases of their leaves that secrete nectar. These hollow thorns are the exclusive nest-site of some species of ant that drink the nectar. But the ants are not just taking advantage of the plant—they also defend their acacia plant against herbivores.

20. Evolution at the species level is called microevolution.
It results from genetic variation and natural selection within a population of organisms.
Small Changes
Macroevolution is evolution that occurs between different species. 65

21. 66

22. Evolution is the change in a species over time.67
Evolution is the change in a species over time.

23. 68

24. 69

25. 70

26. 71
Rates of Evolution

27. Gradualism & Punctuated Equilibrium72
Two ways in which the evolution of a species can occur.
A species can evolve by only one of these, or by both.
CLIP
Species with a shorter evolution evolved mostly by punctuated equilibrium, and those with a longer evolution evolved mostly by gradualism.

28. Punctuated equilibrium73
Gradualism
Very gradually, over a long time... Over a short period of time it is hard to notice.
Slow Changes
Small variations that fit an organism slightly better to its environment are selected for: a few more individuals with more of the helpful trait survive, and a few more with less of the helpful trait die.
Change is slow, constant, and consistent.
Punctuated equilibrium
change comes in spurts. There is a period of very little change, and then one or a few huge changes occur, often through mutations in the genes of a few individuals.

29. 74

30. STOP HERE>>>>>>>>>>>>>

31. Biological Resistance75
Biological Resistance
When organisms are no longer affected by a drug.
First documented around 1952
Causes: Natural consequence of selective pressures in the environment.

32. Resistance in Bacteria76
Read page p403.

33. Bacteria- Antibiotic resistance 77
Bacteria- Antibiotic resistance
Many insects have developed a resistance to insecticides. (simple point mutations)

34. 78

35. The Effects of Selection on Populations79
The Effects of Selection on Populations

36. Types of Selective Processes in Natural Selection80
Types of Selective Processes in Natural Selection
Stabilizing Selection
Directional Selection
Diversifying Selection
Balancing Selection
Heterozygote Advantage
Frequency-dependent

37. Stabilizing Selection81
Intermediate forms of a trait are favored and alleles that specify extreme forms are eliminated from a pop.
Ex: Human birth weight stay between 6-8 lbs. Lower or higher has higher mortality.

38. Directional Selection82
Changing environmental conditions give rise to directional selection, where one phenotype replaces another in the gene pool.
Can produce rapid shift in allelic frequencies.
Ex: Peppered moth
– peppered moths, pesticide resistance,
antibiotic resistance
Occur in response to:
* directional change in the environment
* one or more new environmental conditions
* a mutation that appears and proves to be adaptive

39. Diversifying (Disruptive) Selection83
Diversifying (Disruptive) Selection
Increases the extreme types in a population at the expense of the intermediate forms.
One population divided into two.
(bill size in seedcrackers)

40. Diversifying selection can result in balanced polymorphism.
For example, two distinct bill types are present in black- bellied seedcrackers in which larger-billed birds are more efficient when feeding on hard seeds and smaller-billed birds are more efficient when feeding on soft seeds. 84

41. Heterozygote Advantage
Exists when a heterozygote (Aa) has a higher fitness than either homozygote (AA, aa).
ex: Sickle Cell 85

42. Frequency dependent 86
The term given to an evolutionary process where the fitness of a phenotype is dependent on its frequency
Can arise in systems of mimicry
ex: Butterflies
ex: Maintenance of a 50:50 sex ratio: If one sex becomes more common, some of its members will not be able to mate

43. Adaptation is a key concept in natural selection. 87
Adaptation is a key concept in natural selection.
Natural selection can change the inherited characteristics in a population and possibly even result in a new species.

44. Two main sources of genetic variation88
Two main sources of genetic variation
Mutations
Genetic Shuffling (by sexual reproduction)

45. 89
EOCT- It is important that you are able to explain how the concepts of genetics provide the basis for explaining natural selection and evolution. This will help you answer questions like this:
What is the end result of natural selection?
A increased number of offspring of a given phenotype that survive
B changes in the frequency of alleles in a population
C fossil formation through extinction
D environmental changes of a habitat

46. A acquired traits during their lifetimes that contributed to survival 90
Although the Arctic fox and the kit fox are closely related, they look very different because the individuals
A acquired traits during their lifetimes that contributed to survival
B with traits most suited to their environments reproduced most successfully
C migrated long distances to environments that most suited their traits
D passed on to their offspring acquired behaviors that were helpful

47. A. birds and reptiles have a common ancestor
Fossils of Archeopteryx show that this animal had feathers, like a bird. It also had a bony tail, teeth, and claws on its wings, like a reptile. This fossil is evidence that supports the idea that
A. birds and reptiles have a common ancestor
B. birds have changed very little over 150 million
years
C. reptile species are more advanced than bird
species
D. reptiles are warm-blooded like birds 91

48. B convergent evolution C DNA hybridization D natural selection
Horses and tapirs have a common ancestor, but now look very different. Horses now are grassland animals adapted for grazing on grass and shrubs. Tapirs are jungle animals that live in dense forests and eat fruit, leaves and aquatic vegetation. Which of the following led to the development of such differences in the two species?
A selective breeding
B convergent evolution
C DNA hybridization
D natural selection 92

49. 93

50. Adaptation is the key concept in natural selection. Review CLIP94