1. Theory of Evolution Just how do species change over time????
Early atmosphere, evidence, natural selection and disease agents influence natural selection.

3. Introduction Evolution “ simple” definition: change over time
Evolution helps us to understand the history of life.

4. Central idea
The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother

5. Evidence for Evolution
Adaptations
Fossil Record
Comparative Anatomy
Embryological Development
DNA Similarities

6. Adaptations
All organisms have adaptations which help them survive in their particular environment
Adaptation: a structure or behavior that helps an organism better survive in its environment
Examples: Mimicry, camouflage and physiological

8. Mimicry
Mimicry: a structural adaptation that enables one species to resemble another species
E.g. A harmless species might mimic a poisonous one

12. Camouflage
Camouflage: a structural adaptation that allows a species to blend in with its surroundings

17. Physiological Adaptations
Many bacteria have evolved resistance to antibiotics in the last 50 years
Pests have evolved resistance to pesticides

18. Pathogens can influence natural selection by weeding out the weaker ones
Organisms with stronger immune systems are more likely to survive pathogens.
Eventually, the species that builds up antibodies for this particular pathogen will thrive.          

19. Bacteria are also affected by Natural Selection.
The bacteria that build up a resistance the antibiotics survive.
The ones that do not also die, just like in animals and plants.

20. https://www.youtube.com/watch?feature=pla yer_embedded&v=zjR6L38yReE
10/4/quicktime/l_104_03.html

21. Variation in Populations
Evolution by natural selection happens in populations, not individuals. A single organism cannot evolve. Populations evolve.
Populations evolve because there is variation
Variation causes some organisms to be better fit than others. These better fit organisms are more likely to survive and pass their genes to the next generation

23. Evolution by Natural Selection
Evolution is the gradual change in a population over time
Darwin was the first scientist to realize that evolution can work by natural selection.
Natural Selection – Organisms with traits well suited to an environment are more likely to survive and produce more offspring than organisms without these favorable traits
“Survival of the fittest”
E.g. Thicker fur is a favorable trait in cold environments

27. Charles Darwin (1809 – 1882)
English naturalist who proposed the theory of evolution by natural selection

28. HMS Beagle Voyage
Darwin sailed around the world on the HMS Beagle and carefully studied thousands of different plants and animals

29. The Galapagos Islands
On the Galapagos Islands Darwin found very strange plants and animals that don’t exist anywhere else in the world!

31. Darwin’s Finches
Different islands have different types of finches not found on any other islands. This is where species all deriving from a common ancestor have over time successfully adapted to their environment via natural selection.

32. Two Types of Evolution
Convergent evolution: distantly related organisms evolve to become more similar
Happens when unrelated species adapt to similar environments, possibly in different parts of the world

34. Two Types of Evolution
Divergent evolution: species that once were similar become increasingly different
Happens when populations adapt to different environments

36. Galapagos Giant Tortiose

37. Blue-footed Booby

40. Natural Selection There are 3 basic types of natural selection
Directional Selection
Stabilizing Selection
Disruptive Selection

41. Directional Selection
Directional selection: favors one of the extreme variations of a trait
E.g. Male peacock tail feathers: Females favor larger tail feathers. Therefore males with larger feathers reproduced more often. Over many generations tail feathers grow larger and larger

44. Stabilizing Selection
Stabilizing selection: favors average individuals in a population
E.g. Human infants: Too small = bad; too large = bad; average = good

46. Disruptive Selection
Disruptive selection: favors individuals with either extreme of a trait but intermediate individuals have a disadvantage
E.g. Cuddlefish (a type of squid): Being large is an advantage because females prefer larger males. Being small is an advantage also. Small males impersonate females trick the females into mating.

48. Early Atmosphere conditions
Atmosphere contained all of the following gases:
Nitrogen
Ammonia
Methane
Carbon Dioxide
Water
Hydrogen
No oxygen….oxygen came later with photosynthesis.

50. How did the first cells evolve?
Experiment conducted by Miller and Urey proposed simple- organic molecules could have been synthesized in the atmosphere of early Earth and rained down into the oceans.

51. Fossil Evidence Fossil: Any trace of a dead organism
Fossils show the evolution of species over the past millions of years
Fossil evidence proves that modern species have evolved from ancient species

52. Puijila the walking seal

53. Tiktaalik

54. Archaeopteryx

56. Comparative Anatomy
Homologous structures: Body structures on different organisms that are similar in structure (same bones) and evolved from a common ancestor

57. Homologous Structures

58. Comparative Anatomy
Analogous structures: Body structures on different organisms that are similar in function but did not evolve from the same ancestor (bird wing and butterfly wing)

59. Moth (insect)
Pterodactyl (reptile)
Bat (mammal)
Bird
Analogous Wing Structures

60. Comparative Anatomy
Vestigial structure: body structure in an organism that no longer serves its original purpose but was useful to an ancestor (useless wings on the African ostrich)

64. Embryological Development
Early in development, human embryos and embryos of all other vertebrates are very similar, which suggests that all vertebrates are related

66. DNA Similarities
Nearly all organisms have DNA, ATP, and many of the same proteins and enzymes
The DNA (genes) of closely related organisms looks very similar

67. What Drives Evolution? Mutations Genetic Drift Gene Flow
Natural Selection

68. Gene Pool
Gene pool: collectively, all of the alleles of the population’s genes
Allelic frequency: the percentage of any specific allele in the gene pool
Genes can enter and leave a population’s gene pool for many reasons
Populations in which the gene pool is not changing are said to be in genetic equilibrium

70. Mutations
New genes can be added to the population by errors in DNA copying called mutations
Most mutations are neutral or bad!

72. Mutations
Very very rarely a mutation might come along that improves an organism’s chance at survival or reproduction
These mutant genes will be passed along to offspring and become more common in the gene pool over time
If the mutation offers a large advantage, eventually (after many generations) all members of the population will have the beneficial mutation

75. Evolution by Artificial Selection
Artificial Selection: Humans choose individuals with certain traits for breeding
After many generations of selection, dramatic evolutionary changes can result
Dogs
Fruits/Vegetables
Livestock

78. Gene Flow Gene flow: the transport of genes by traveling individuals
When an individual leaves a population, its genes are lost from the gene pool
When an individual enters a population, its genes are added to the gene pool

79. Genetic Drift
Genetic drift: when allelic frequencies are changed by random events in a isolated population
Example: diseases, natural disasters, mating habits

80. Speciation-the evolution of a new species
A certain population may become isolated and evolve to fit new or different environmental conditions
The isolated population may change so much that it can no longer mate with the original population
Similar to the evolution of new languages

83. How Fast Does Speciation Occur?
Gradualism: idea that species originate through a gradual change of adaptations (longer than 10,000 years)
E.g. Fossil evidence shows that sea lilies evolved slowly and steadily over time
Punctuated equilibrium: idea that species originate in rapid bursts (10,000 years or less) with long periods of genetic equilibrium in between
Global ice age causes rapid adaptation of thick fur
Both gradualism and punctuated equilibrium are known to occur