1. Evolution and Adaptation Notes
**** Don’t talk about Lamarck specifically just who influenced Darwin, and not specific relative and radioactive dating just broad of this is how you can tell how old fossils are****
Do talk about gene flow, genetic drift, recombination (sexual reproduction and crossing over), and mutation, convergent and divergent evolution ADD – the stabilizing, directional and disruptive selection and add cladograms introduction
Good flow: Darwin and who influenced him then Evolution with natural selection then Evolution of populations (divergent vs convergent and include genetic drift, etc) then the Evidence of Evolution then the time gradualism and punctuated equilibrium
Performance task – use the homer simpson video and see what 5 misconceptions are and suggest alternatives:
- video 7

2. What is Evolution??

3. Grab Notebook Don’t get comfortable.

4. Evolution
Evolution - Change in a kind of organism over time; process by which modern organisms have descended from ancient organisms.

5. What is a Theory versus a Hypothesis?
An educated guess that has to be testable by scientific methods
Has to be well- supported and has been tested over and over and has occurred
Is an explanation of a phenomena that has occurred in the natural world

6. Origins of Evolutionary Thought
James Hutton: Proposes that earth is shaped by geological forces that took place over extremely long periods of time (gradualism). He estimates Earth to be millions – not thousands – of years old.
1798 – Thomas Malthus: Predicts that the human population will grow faster than the space and food supplies needed to sustain it.

7. Origins of Evolutionary Thought
1809 – Jean-Baptiste Lamarck: Proposed that changes in environment caused an organism to have greater use or disuse of a structure/organ. His ideas are flawed, but he is one of the first to propose a new mechanism explaining how organisms change over time (inheritance of acquired traits).
1833 – Charles Lyell: Observed processes that made small changes in Earth’s features are uniform through time and have shaped Earth’s geological features over long periods of time.

8. Charles Darwin
In 1831, Darwin joined the crew of the Beagle and set sail from England for a voyage around the world.
Darwin made numerous observations and collected evidence (fossils) that led him to propose a revolutionary hypothesis about the way life changes over time.
That hypothesis, now supported by a huge body of evidence, has become the theory of evolution.

9. The Galápagos Islands: Adaptation and Variation
Although they were close together, the islands had very different climates.
Darwin observed that the characteristics of many animals and plants varied noticeably among the different islands of the Galápagos.

10. Darwin Presents His Case
Eighteen months later, in 1859, Darwin published the results of his work, On the Origin of Species.

11. Darwin’s Conclusions Evolution Occurs by Natural Selection
Struggle for existence exists in nature
Competition among members of a species exist for food, living space, and the other necessities of life.
Survival of the Fittest – Individuals that are better suited to their environment – that it, with adaptations that enable fitness – survive and reproduce more successfully; Darwin referred to this as natural selection
Fitness - Ability of an organism to survive and reproduce in its environment.

12. Adaptation
Over time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species' fitness in its environment.
Takes place without human control or direction.
Natural selection cannot be seen directly; it can only be observed as changes in a population over many successive generations.

13. Descent with Modification
Darwin proposed that over long periods, natural selection produces organisms have different structures, establish different niches, or occupy different habitats.
As a result, species today look different from their ancestors.
Each living species has descended, with changes, from other species over time.
Darwin referred to this principle as descent with modification
Talk about why we have wrinkled fingers

14. How Common Is Genetic Variation?
Many genes have at least two genes or alleles.
Animals such as dogs, horses, and mice often have several alleles for traits such as body size or coat color.
All organisms have additional genetic variation that is “invisible” because it involves small differences in biochemical processes.
An organism can be heterozygous for many genes.
An insect can be heterozygous for as many as 15% of its genes.
Individual fishes, reptiles, and mammals are typically heterozygous for between 4–8% of their genes. Hh

15. Biodiversity Another word for variety is diversity.
Biodiversity – Biological diversity; Sum total of the genetically based variety of all organisms in the biosphere.

16. Notebook warm-up Take out notebook
Review of Darwin Agree vs. Disagree and make any changes
Write a short explanation of why for each statement. 

17. Evidence of Evolution comes primarily from these sources…. http://www
Evidence of Evolution comes primarily from these sources…. - video 3
Fossil record
Geographical distribution of living species
Structural similarities of related life forms
Chemical similarities in DNA
Embryology

18. Age of Fossils
Paleontologists determine the age of fossils using two techniques:
Relative dating
Radioactive dating
Relative Dating
Radioactive Dating

19. Relative Dating
In relative dating, the age of a fossil is determined by comparing its placement with that of fossils in other layers of rock.
Paleontologists estimate the age based on the age of other fossils found near it.
It’s not absolute and doesn’t tell the age in years..
The rock layers form in order by age:
The oldest layers on the bottom
More recent layers on top (closer to Earth's surface)

20. Radioactive Dating
Scientists use radioactive decay to assign absolute ages to rocks.
Radioactive elements decay, or break down, into nonradioactive elements at a steady rate, which is measured in a unit called a half-life

21. Radioactive Decay
A half-life is the length of time required for half of the radioactive atoms in a sample to decay.

22. Evidence of Evolution: The Geographical Distribution of Living Species
Similar, but unrelated species exist. Similar animals in different locations were the product of different lines of evolutionary descent.

23. Evidence of Evolution: Structural Similarities of Living Things
Homologous Structures
Analogous Structures
Vestigial Structures

24. Homologous Structures of Living Organisms
Researchers had noticed striking anatomical similarities among the body parts of animals with backbones.
Example: The arms of reptiles, wings of birds, and legs of mammals vary greatly in form and function. Yet, they are all constructed from the same basic bones.

25. Homologous Structures
Homologous Structures - Structures that have different mature forms in different organisms but develop from the same embryonic tissues.
Same development - different function.
Provide strong evidence that all four-limbed vertebrates have descended, with modifications, from common ancestors.

26. Vestigial Organs
Vestigial Organs – Organ that serves no useful function in an organism; Traces of homologous structures.
Examples:
Hip bones found in whales, salamanders, and pythons
Eye bulbs of blind, cave-dwelling creatures, such as the grotto salamander.
Human coccyx bone (tail bone) – lost original function of a tail but now serves as places for bones to attach
A surgeon can remove an appendix from someone, and there doesn't seem to be any noticeable effect, but a healthy appendix is beneficial (acts as a filter and removes bacteria and protects the intestines from infection. Antibodies are also made there).
Appendix – used to help digest cellulose when we were herbivores but not anymore
Coccyx – remnants of tail – lost original function of tail but serves now for places bones to attach
Wisdom teeth –

27. Analogous Structures
Analogous Structures - Structures that evolve separately to perform a similar function.
Different development – same function.
Provides evidence for convergent evolution because they have very similar structures even though they were completely independently derived to fill a similar purpose.
Examples: Wings of birds, bats, and insects (have different embryological origins but are all designed for flight).

28. Evidence of Evolution comes primarily from these sources…. http://www
Evidence of Evolution comes primarily from these sources…. - video 3
Fossil record
Geographical distribution of living species
Structural similarities of related life forms
Chemical similarities in DNA
Embryology

29. Evidence of Evolution: Chemical Similarities
All of the tens of thousands of types of proteins in living things are made of only 20 kinds of amino acids.
Despite the great diversity of life on our planet, the simple language of the DNA code is the same for all living things.
This is evidence of the fundamental molecular unity of life.
New technologies, such as DNA fingerprinting, have helped to fill in gaps in the fossil record.

30. Amino Acid Comparison http://www. pbs
Amino Acid Comparison - video 5
The more closely related two species are, the more amino acid sequence similarities should be seen.

31. Evidence of Evolution: Similarities in Embryology
The early stages, or embryos, of many animals with backbones are very similar.
Many embryos look especially similar during early stages of development.
The same groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates.

32. Try to guess which embryo is the:
A B C D E F G H
Try to guess which embryo is the:
Chicken?
Rabbit?
Fish?
Human?

34. Evolution of Populations
Turn in Homework in the tray up front
Grab Notebook
Go around the room and record the number of all the butterfies you can find

35. Variation and Gene Pools
Genetic variation is studied in populations.
A population is a group of individuals of the same species that interbreed.
Because members of a population interbreed, they share a common group of genes called a gene pool.
Gene Pool - Consists of all genes, including all the different alleles, that are present in a population.

36. Sources of Genetic Variation
The two main sources of genetic variation are:
Mutations – Any change in a sequence of DNA.
Can occur because of mistakes in the replication of DNA or as a result of radiation or chemicals in the environment.
Recombination - The natural formation in offspring of genetic combinations not present in parents.
Independent assortment occurs during the production of gametes – each homologous pair moves independently during meiosis. As a result the 23 pairs of chromosomes found in humans can produce 8.4 billion different combinations of genes.
Crossing over during meiosis further increases variation.

37. Natural Selection on Single-Gene Traits
Natural selection on single-gene traits can lead to changes in allele frequencies and thus to evolution.

38. Natural Selection on Polygenic Traits
When traits are controlled by more than one gene, the effects of natural selection are more complex.
The action of multiple alleles on traits such as height produces a range of phenotypes that often fit a bell curve.

39. Natural Selection on Polygenic Traits
Natural selection can affect the distributions of phenotypes in any of three ways:
Directional Selection
Stabilizing Selection
Disruptive Selection

40. Directional Selection
Directional Selection – Takes place when individuals at one end of the curve have higher fitness than individuals in the middle or at the other end.
The range of phenotypes shift as some individuals fail to survive and reproduce while others succeed.

41. Stabilizing Selection
Stabilizing Selection – Takes place when individuals near the center of the curve have higher fitness than individuals at either end of the curve.
This situation keeps the center of the curve at its current position, but it narrows the overall graph.
Example: The weight of human infants – smaller than average babies are likely to be less healthy and larger than average babies are likely to have difficulty being born.

42. Disruptive Selection
Disruptive Selection – Takes place when individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle.
In such situations, selection acts most strongly against individuals of an intermediate type.
If the pressure of natural selection is strong enough and lasts long enough, this situation can cause the single curve to split into two (can create two distinct phenotypes).

43. Genetic Drift
Natural selection is not the only source of evolutionary change. In small populations, an allele can become more or less common simply by chance.
Genetic Drift - Random change in allele frequencies that occurs in small populations.
The smaller a population is, the farther the results may be from what the laws of probability predict.
Unlike natural selection because:
It happens by chance - such as random mating or a natural disaster (fire, landslide or lightning strike).
Doesn’t work to produce adaptations like natural selection does.

44. How Does Genetic Drift Occur?
In each generation, some individuals may, just by chance, leave behind a few more descendants (and genes, of course) than other individuals.
The genes of the next generation will be the genes of the “lucky” individuals, not necessarily the healthier or “better” individuals.
It happens to all populations – there’s no avoiding the vagaries of chance.

45. Gene Flow
Gene Flow - The transfer of alleles or genes from one population to another; also known as gene migration.
Affected by:
Mobility
Barriers

46. Gene Pools and Evolution
The relative frequency of an allele is the number of times that the allele occurs in a gene pool, compared with the number of times other alleles for the same gene occur.
In genetic terms, evolution is any change in the relative frequency of alleles in a population.

47. Evolution vs. Genetic Equilibrium
To clarify how evolutionary change operates, scientists often find it helpful to determine what happens when no change takes place.
So biologists ask: Are there any conditions under which evolution will not occur?
The answers to those questions are provided by the Hardy-Weinberg principle.

48. The Hardy-Weinberg Principle
Hardy-Weinberg Principle – Allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change.
Genetic Equilibrium - Situation in which allele frequencies remain constant.
If the allele frequencies do not change, the population will not evolve.
Hardy Weinberg Equation: p2 + 2pq + q2 = 1
p + q = 1

49. Hardy-Weinberg Principle
Five conditions are required to maintain genetic equilibrium from generation to generation:
There must be random mating.
All members of the population must have an equal opportunity to produce offspring, which ensures that each individual has an equal chance of passing on its alleles to offspring.
The population must be very large.
Genetic drift has less effect on large populations than on small ones.
There can be no movement into or out of the population.
Individuals may bring new alleles into a population.
There can be no mutations.
If genes mutate from one form into another, new alleles may be introduced into the population, and allele frequencies will change.
There can be no natural selection.
No phenotype can have a selective advantage over another.

50. The Hardy-Weinberg Equation
p2 = Frequency of AA
2pq = Frequency of Aa
q2 = Frequency of aa
p = Frequency of A
q = Frequency of a
For example: If the frequency of two alleles in a gene pool is 90% A , and 10% a, what is the frequency of individuals in the population with the genotype Aa?
Solve: p = frequency of A, which is .9 (90%)
q = frequency of a, which is .1 (10%)
2pq = frequency of Aa = 2(.9)(.1) = .18
Therefore, the frequency of individuals with genotype Aa would be .18

51. Cladogram
Cladogram – Diagram that shows the evolutionary relationships among a group of organisms.
Is constructed using derived characters, which are characteristics that appear in recent parts of a lineage but not in older members.

52. Phylogeny
Phylogeny - Study of evolutionary relationships among organisms.
Biologists now group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities.

53. The Process of Speciation
Factors such as natural selection and chance events can change the relative frequencies of alleles in a population.
But how do these changes lead to the formation of new species, or speciation?
Species - Group of organisms that breed with one another and produce fertile offspring

54. Speciation & Reproductive Isolation
The gene pools of two populations must become separated for them to become new species.  
As new species evolve, populations become reproductively isolated from each other.
Reproductive Isolation - When the members of two populations cannot interbreed and produce fertile offspring.

55. Reproductive Isolation
Reproductive isolation can occur in a variety of ways, including:
Behavioral Isolation
Geographic Isolation
Temporal Isolation

56. Behavioral Isolation
Behavioral Isolation - Two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior.
Example: Eastern and Western Meadowlarks
Members of the two species will not mate with each other partly because they use different songs to attract mates.
Eastern meadowlarks will not respond to western meadowlark songs, and vice versa.

57. Geographic Isolation
With geographic isolation, two populations are separated by geographic barriers such as rivers, mountains, or bodies of water.
Example: The Abert & Kaibab Squirrel
About 10,000 years ago, the Colorado River split the species into two separate populations.
Two separate gene pools formed.
Natural selection worked separately on each group and led to the formation of a distinct subspecies, the Kaibab squirrel.

58. Temporal Isolation
Temporal Isolation - Form of reproductive isolation in which two populations reproduce at different times.
Example:
Three similar species of orchid all live in the same rain forest.
Each species releases pollen only on a single day.
Because the three species release pollen on different days, they cannot pollinate one another.

59. Patterns of Evolution
Some large-scale evolutionary patterns and processes that occur over long periods of time are:
Extinction
Convergent Evolution
Divergent Evolution
Gradualism
Punctuated Equilibrium

60. Extinction
More than 99% of all species that have ever lived are extinct.
Extinctions happen because species compete for resources, and environments change. Some species adapt and change. Others gradually become extinct in ways that are often caused by natural selection.
Each disappearance of species left habitats open and provided ecological opportunities for those organisms that survived. The result is often the burst of evolution that produces many new species.
The extinction of the dinosaurs cleared the way for the evolution of modern mammals and birds.

61. Convergent Evolution
Convergent Evolution – Process by which unrelated organisms come to resemble one another. (analogous structures)
Examples:
Natural selection may mold different body structures, such as arms and legs, into modified forms, such as wings or flippers. The wings or flippers function in the same way and look very similar.
The similar nature of the wings of insects, birds, pterosaurs, and bats. All four serve the same function and are similar in structure, but each evolved independently and not from a common winged ancestor.

62. Divergent Evolution
Divergent Evolution – The process of two or more related species becoming more and more dissimilar. (homolougous structures)
A single species or a small group of species have evolved, through natural selection and other processes, into diverse forms that live in different ways.
The vertebrate limb is one example of divergent evolution. The limb in many different species has a common origin, but has diverged somewhat in overall structure and function

63. Gradualism vs. Punctuated Equilibrium
How quickly does evolution occur?
Gradualism – Long time with gradual change.
Punctuated Equilibrium - Long, stable periods interrupted by brief periods of more rapid change.
Gradualism example –
Punctuated equilibrium example -

64. Think about this…How did a tiger get its stripes
Think about this…How did a tiger get its stripes? Gradually or with a huge, quick change?

65. Adaptations
Adaptation – Inherited characteristic that increases an organism’s chance of survival.
Can be either physical or behavioral.
Animals have evolved their adaptations.
A long period of slow change resulted in an animal’s adaptations.
Example: The spots on the snow leopard did not emerge overnight. Instead, this process took generation upon generation of snow leopards physically adapting to their environment for characteristic spot patterns to evolve. Those leopards with spot patterns were able to hide more successfully, therefore surviving longer than those without spots. This allowed the longer surviving snow leopards to reproduce and create more snow leopards with spot patterns like their own.
This process of change over time is the key to how many organisms develop adaptations.
Some adaptations can arise quickly through genetic mutations as well. But some mutations can be deadly as well.

66. Common Misconceptions
Humans did not come from monkeys. Instead, humans and primates share a common ancestor.
Darwin is not the only evolutionary theorist. Darwin utilized evidence from other evolutionists to draw his conclusions.
Evolution does not happen quickly – it occurs over generations of time.
Change does not occur at the individual level – it occurs in populations.

67. Now watch the Homer Simpson video again…..
aRlFsYmkeY
Why is this cartoon inaccurate? Use the information that you’ve learned about evolution in this unit!

68. Adaptions
Catepillar that looks like a snake