1. Evolution

2. Origins of life
-Earth formed about 4.6 billion years ago -Early Earth had many active volcanoes. -These volcanoes released: 1. water vapor, which eventually led to formation of oceans 2. Gases, such as: methane, hydrogen, nitrogen, ammonia, carbon dioxide, and carbon monoxide -Earth’s early atmosphere had little to no oxygen.

3. Miller-Urey Experiments
Showed that organic molelcules, specifically, polypeptides (which are chains of amino acids) could be formed from elements present on Early Earth
These organic molecules of polypeptides could join together to create life

4. What were the first living organisms on Earth?
Fossil records show that the first living organisms appeared about 3.5 billion years ago and were simple, single-celled organisms.
The sequence of development is as follows:
Anaerobic prokaryotes  photosynthetic prokaryotes  unicellular eukaryotes  multicellular eukaryotes
*anaerobic means no oxygen is required

5. Where did oxygen first come from?
Most likely from photosynthetic bacteria, such as cyanobacteria
Anaerobic prokaryotes  photosynthetic prokaryotes  unicellular eukaryotes  multicellular eukaryotes

6. Where did oxygen first come from?
Most likely from photosynthetic bacteria, such as cyanobacteria
Anaerobic prokaryotes  photosynthetic prokaryotes  unicellular eukaryotes  multicellular eukaryotes
Review: What is the formula for photosynthesis?

7. Evolution
Question to think about: Do humans ‘come from’ monkeys? By the end of this Evolution unit, you will be able to answer this question correctly as a scientist!
The answer is no. Humans share a common ancestor with modern apes (chimpanzees and gorillas)

8. Evolution
Definition: a change in the genetic composition of a population of organisms over time. Summary: change in organisms over time.

9. Evolution
You may also see this definition: Descent with modification from common ancestors

10. How does evolution occur?
First hypothesis, which was incorrect (i.e. unsupported, was proposed by Jean-Baptiste Lamarck in 1809
Theory of acquired traits: physiological changes that an organisms acquires throughout its lifetime may be passed onto offspring
This idea was good in that it was a hypothesis on how evolution occurred, but it was bad in that there is no evidence to support it.

11. Theory of acquired traits: not a supported hypothesis for evolution
Actual results

12. Darwin’s Theory of Natural Selection
English naturalist
Sailed on the HMS Beagle in 1831to make natural history collections
His observations led to the theory of evolution by natural selection
Wrote a book titled, On the Origin of Species

13. Review: define evolution
a. an adaptation of an organism to its environment
b. a sudden replacement of one community by another
c. a geographic or reproductive isolation of organisms
d. a process of change in organisms over a period of time

14. Review: define evolution
a. an adaptation of an organism to its environment
b. a sudden replacement of one community by another
c. a geographic or reproductive isolation of organisms
d. a process of change in organisms over a period of time

15. Review: Which statement would most likely be in agreement with Lamarck’s theory of evolution?
a. Black moths have evolved in an area because they were better adapted to the environment and had high rates of survival and reproduction.
b. Geographic barriers may lead to reproductive isolation and the production of new species.
c. Giraffes have long necks because their ancestors stretched their necks reaching for food, and this trait was passed on to their offspring.
d. Most variations in animals and plants are due to random chromosomal and gene mutation.

16. Review: Which statement would most likely be in agreement with Lamarck’s theory of evolution?
a. Black moths have evolved in an area because they were better adapted to the environment and had high rates of survival and reproduction.
b. Geographic barriers may lead to reproductive isolation and the production of new species.
c. Giraffes have long necks because their ancestors stretched their necks reaching for food, and this trait was passed on to their offspring.
d. Most variations in animals and plants are due to random chromosomal and gene mutation.

17. Evolution by natural selection
Definition: a primary mechanism of evolution in which organisms with favorable traits are more likely to reproduce Summary: main process for evolution to occur

18. Components of natural selection
There are not enough resources (such as food) for all individuals in a population
There is variation of traits among individuals
These traits are heritable
Individuals with the ‘better’ trait will survive longer and reproduce more than those without the ‘better’ trait.
Important vocabulary words
Fitness: an organism’s relative ability to survive and produce fertile offspring.
Adaptation: feature that improves fitness. Example: camouflage

19. Guided Practice: beetles
There are lots of beetles, more than the environment can support
The beetles vary in color. Some are green, and some are orange.
The colors are inherited from parents.
Birds like to eat green beetles. So, being an orange color is a better trait because they are not eaten. Orange beetles are better at surviving and reproducing (have higher fitness)
Being orange is an adaptation!

20. Guided Practice: beetles
Did evolution occur? Why or why not?
How did evolution occur?

21. Guided Practice: beetles
Did evolution occur? Why or why not?
Yes, because there was change in the population over time. The beetles were both green and orange in the beginning, but at the end, all beetles are orange.
2. How did evolution occur?
Through natural selection. The orange beetles were better at surviving and reproducing.

22. Explain how giraffes evolved to have longer necks: Think-pair-share 5 minutes
Things to think about in your answer:
Should there be more or fewer individuals in a population than an environment can support? What resources do giraffes need to survive?
Is there variation in neck length amongst the giraffes in the population, or are they all the same?
Is neck length heritable or is determined by the environment?
Are certain giraffes better at surviving and reproducing than others? Why or why not?
Answers: there are more individuals in an environment than can be supported.
Individuals vary in neck length. Some short, medium and long.
Neck length should be influenced by genes & be heritable
Those with longer necks are better able to survive and reproduce because they can reach leaves better, their source of food.
Over time, those with longer necks have a higher fitness. Longer neck = adaptation!

23. Other mechanisms of evolution
Natural selection
Mutations
Genetic drift
Gene Flow
Nonrandom mating

24. Mutation
Change in genetic information Mutations that occur in gametes (sperm and eggs) are passed onto offspring May contribute to genetic variation

25. Genetic Drift
When genetic composition changes by chance More noticeable in smaller populations

26. Gene flow
Immigration or emigration of individuals

27. Nonrandom mating
Selective mating based on preferences

28. Phylogenetic trees
Hypotheses for the evolutionary relatedness of organisms

29. Cladograms
Diagrams used to show how organisms are related by descent from common ancestors

30. How to read a cladogram
Organisms that are closer to each other share a more recent common ancestor
Example: a chimp is more closely related to a mouse than a pigeon because the chimp & mouse share a more recent common ancestor

31. How to read a cladogram practice:
Is the lizard more closely related to a salamander or a hagfish?
Answer: Salamander

32. Evidences for evolution
Molecular
Anatomy
Vestigial structures
Comparative embryology
Fossils

33. Evidences for Evolution: Molecular
All organisms have the same 20 amino acids that make up proteins
2. All organisms use ATP
3. Organisms that share similar traits also show similar DNA base sequences
-Comparing DNA sequences is one of the best ways to understand evolutionary relationships

34. Yeast are unicellular fungi, rest of the organisms are multicellular

35. Evidences for Evolution: Anatomy
Homologous structures: structures among organisms that are similar structurally, but different in function.
Due to inheritance from a recent common ancestor

36. Evidences for Evolution: Anatomy
Analagous structures: structures among organisms that are different structurally, but appear and function similarly.
These occur when the organisms live similar life styles, not because of sharing a recent common ancestor

37. Evidences for Evolution: Vestigial structures
Structures that lost most or all of their ancestral function, but have been retained through evolution.
Examples:

38. Vestigial Structures Example:
Pelvic bones in whales
Whales don’t walk. So, why do they need
pelvic bones?!?!?!
Answer: These pelvic bones have been reduced
and are not used. This vestigial structure
suggests inheritance from a recent common ancestor

39. Vestigial Structures Example:
Pelvic bones in whales
Whales don’t walk. So, why do they need
pelvic bones?!?!?!
Answer: These pelvic bones have been reduced
and are not used. This vestigial structure
suggests inheritance from a recent common ancestor
Did you know that: whales are mammals??

40. Vestigial structure example:
You can feel your tailbone! It’s the tiny bone right where your buttcheeks start….you can test this at home.
Human embryos have tails, which later moves into the body, but retains much of its bone structure in the coccyx

41. Evidences for Evolution: Comparative Embryology
Embryos of animals with backbones (vertebrates) look very similar
This indicates that the rules of embryonic development are similar among vertebrates, meaning that all vertebrates share a common ancestor

42. Evidence for Evolution: Fossils
-Fossils are preserved remains of animals, plants, and other organisms. -When fossils are arranged according to age, a progressive series of changes (i.e. evolution) can be observed
Wasp fossil
Evolution of horse forefoot

43. Stop and jot: 4 minutes
In your notes, list and explain four evidences of evolution.

44. Speciation Speciation is a process by which species evolve
A species is a group of organisms that can interbreed and produce fertile offspring
How do species form?
1. Geographic isolation
2. Behavioral isolation

45. Geographic isolation
Populations separated by geographic barriers (rivers, mountains, bodies of water, etc.)
Doesn’t always lead to new species.

46. Behavioral isolation
Capable of interbreeding, but have different courtship rituals.

47. Patterns of evolution Adaptive radiation Convergent evolution
Coevolution

48. Patterns of Evolution Adaptive Radiation
Small group of species evolve into different forms that live in different ways.

49. Patterns of Evolution Convergent Evolution
Unrelated organisms begin to resemble each other.
Similar environmental demands. Produces analagous structures

50. Patterns of Evolution Coevolution
Two species evolve in response to changes in each other.
Hawkmoth visiting orchid. Long tongue (proboscis) which moth uses to get nectar. This orchid and moth have coevolved such that this moth drinks nectar from this plant, and in return, the plant gets cross-pollinated.

51. Evolution over a larger time scale
Punctuated equilibrium: periods of quick evolution followed by periods of stasis.
Gradualism: evolution that occurs gradually, or slowly over time.

52. Classification https://www.youtube.com/watch?v=F38BmgPcZ_I
Crash course video & worksheet
Answers:
1. Carl Linnaeius