1. Introduction to Evolution and the Origin of Life
Mrs. Stewart
Biology
Stewarts Creek High School

2. Standards:
CCSS ELA
I can trace the historical development of the theory of evolution
I can summarize the evidence for the theory of evolution
CCSS ELA
I can critique and evaluate competing evolutionary arguments based on scientific knowledge, empirical evidence and logical arguments regarding relevant factors.

3. Can You… Define Evolution
Differentiate between Charles Darwin and Jean-Baptiste Lamarck
Explain the idea of “natural selection”
Evaluate how “fitness” leads to adaptations which lead to evolution?

4. Choose… But choose wisely.
Decide which partner is the bird and which is the cat.

5. Scientific Theory
Theory - a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment.

6. How did it all start? Abiogenesis:
The process by which life arises from non- living matter, such as organic compounds
Happened on earth approx billion years ago in the ocean
Enough organic compounds bound together and were able to conduct energy processes more efficiently until life was created

7. Early Beliefs of How New Life Formed
Abiogenesis / Spontaneous Generation: Living organisms could arise from nonliving matter
Example: Cheese wrapped in a rag and left in a corner would produce mice
Disproven by Redi and Pasteur
Biogenesis:
All living things come from other living things

8. Miller/Urey Stanley Miller and Harold Urey (1950s)
simulated early earth conditions in the lab and created a “spark”
created amino acids

9. Archaebacteria
The earth’s earliest life forms were prokaryotes

10. Endosymbiosis Where/how did mitochondria get their own DNA?
How did chloroplasts become so specialized?
Theory of Endosymbiosis:
Aerobic prokaryotes were engulfed by eukaryotic cells evolved into mitochondria (which perform aerobic respiration)
Photosynthetic prokaryotes were engulfed by plant cells and evolved into chloroplasts (where photosynthesis occurs)

11. How did we go from bacteria to mammals? Evolution

12. What is Evolution?
Evolution of Dance
Evolution of Hip Hop Dancing

13. Evolution
The process of organisms CHANGING OVER TIME as a result of changes in heritable physical or behavior traits.
In general: how new species develop from preexisting species

14. What does it explain? Does NOT attempt to explain the origin of life
DOES explain how the most basic early life forms became the complex ecosystem we know today

15. Cats
Define evolution for your bird

16. Jean-Baptiste Lamarck
French Naturalist ( )
Developed an early theory of evolution based on two principles:
By selective USE OR DISUSE of organs, organisms can acquire or lose certain traits.
Characteristics acquired during an organisms lifetime could then be passed on to their offspring (INHERITANCE OF ACQUIRED TRAITS).

17. Lamarck’s Hypothesis

18. Importance of Lamarck’s Hypothesis
Use and disuse – If a part of the body is used extensively, it can grow larger and stronger, while those that are not used deteriorate.
Inheritance of acquired traits - Organisms can pass on those altered body parts/organs to their offspring.
Lamarck recognized that species evolve, but his explanatory mechanism was flawed.

19. Birds
What did Lamarck get right?

20. Cats
What did Lamarck get wrong?

21. Lamarck the Loser First to develop a hypothesis of evolution
First to realize organisms adapt to their environment
But, Behavior has no effect on inheritable characteristics

22. Charles Darwin
1809 – 1882
Naturalist – study of nature and the natural world
Sailed on the HMS Beagle in 1831
Every time the ship docked, Darwin went ashore to collect plant and animal specimens

23. Darwin’s observations piqued his interest in the diversity of life he observed.
Darwin even found evidence that suggested species once present on earth had vanished.
Researchers today speculate that 99.9% of all species that ever inhabited earth are now extinct.

24. Galapagos Islands
The islands were close together, but had very different climates
Smallest and lowest islands = hot, dry & barren
Hood Island = sparse vegetation
Higher islands had greater rainfall and a different assortment of plants/animals
Isabella Island = rich vegetation
Land Tortoise shell shapes could be used to identify which island it inhabited

25. What observations can YOU make about these species of land tortoise?
Hood Island Tortoise
Pinta Island Tortoise
What predictions can YOU make about the island environment for each tortoise?
What observations can YOU make about these species of land tortoise?
Isabella Island Tortoise

26. Which island would you predict has only low-lying vegetation?
Hood Island Tortoise
Pinta Island Tortoise
Which island would you predict has only low-lying vegetation?
Isabella Island Tortoise

27. Darwin’s Idea
Darwin observed that the plants and animals varied noticeably among the different Galapagos Islands.
However, Darwin wondered if animals living on different islands had once been members of the same species – originating from the same South American ancestor.
Did exposure to different environments lead to different traits?

28. Darwin’s Finches
Darwin observed many different types of “finch” and noticed several different beak shapes.
Why?
He began to notice different shaped beaks were “adaptations” for different food sources

29. Darwin’s Mechanism of Evolution
Based on his observations on the HMS beagle, Darwin proposed a new hypothesis for the mechanism of evolution.
Darwin’s hypothesis: all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce.

30. Darwin and Religion Darwin was a devout Catholic
He knew that his ideas, based on what he observed would provoke the catholic church
He debated over whether or not to publish his results for 25 years.
An essay from Alfred Wallace in convinced him to publish his findings

31. Darwin’s Theory – Descent With Modification
The Origin of Species by Means of Natural Selection – 1858
Every species – living or extinct – descended by reproduction from preexisting species
AND
Species must be able to change over time in response to selective environmental pressures

32. Do you think like Lamarck?
Many students tend to think like Lamarck (an organism can create a new variation if the need arises).
Remember: Natural Selection can only ACT UPON THE VARIATION THAT IS ALREADY PRESENT WITHIN A POPULATION.
Natural selection DOES NOT CAUSE THE VARIATION.

33. Natural Selection

34. Review What was Lamarck’s hypothesis? What did Darwin believe?
Use and disuse & Inheritance of acquired traits
Common descent with modifications by means of natural selection

35. Standards:
CCSS ELA
I can trace the historical development of the theory of evolution
I can summarize the evidence for the theory of evolution
CCSS ELA
I can critique and evaluate competing evolutionary arguments based on scientific knowledge, empirical evidence and logical arguments regarding relevant factors.

36. Objective (Today I will…)
Explain the idea of “natural selection” and determine “fittest”
Examine how adaptations help animals survive better

37. Sources of Genetic Variation That Lead to Evolution
Sexual Reproduction
Crossing Over
Random Independent Assortment of Chromosomes
Mutations

38. Darwin’s reasoning for Natural Selection
Overproduction – more offspring are produced than can survive due to competition for resources
Genetic Variation – within a population, individuals have different traits. New traits may appear spontaneously.
Struggle to survive – constant competition may cause some variations/traits to be advantageous
Differential Reproduction – Organisms with the best adaptations will survive and reproduce, thus the advantageous adaptations will become most prevalent in the population.

39. Evolution by Natural Selection
Struggle for existence – each member of a species competes regularly for food, water, living space and the ability to reproduce.
Who wins?

40. Think – Pair – Share
How can we describe Natural Selection in just 4 words?

41. Survival of the Fittest
How well suited an organism is to it’s environment
Does fittest mean strongest?
Does fittest mean in the best shape?
Fitness = the ability of an individual to both survive and reproduce
Best traits are the result of adaptations

42. Adaptations
Characteristics that enhance an organisms ability to survive and reproduce (fitness) in specific environments.
Example: Desert foxes have large ears which radiate heat. Arctic foxes have small ears which conserve body heat.
The characteristics that are most advantageous in a specific environment, give an individual a better chance to survive and reproduce more than other individuals without those traits.

43. Heritable Adaptations
The individuals with the most beneficial traits will survive and reproduce more offspring.
This means, the DNA coding for those traits will be passed down to more future members of the population.
Over time, the frequency of traits in the population shift toward the most beneficial versions, increasing the match between organisms and their environment.

44. Why were the medium size fish disappearring?
Fitness Example:
Why were the medium size fish disappearring?

45. Fitness Example:
Peppered Moth evolution
Peppered moth virtual lab

46. What determines fitness?
The Environment!
EVERYTHING IN AN ORGANISM’S SURROUNDINGS
Anything that helps the organism survive and reproduce better within the specific environment they inhabit increases an organisms fitness

47. Fitness leads to evolution
After an environmental pressure selected against green, the population became more brown than green beetles
Began with equal amounts of brown and green beetles

48. Evolution: Change in the frequency of traits over time
Natural selection on single-gene traits can lead to a change in allele frequencies and thus to evolution
Example: Red lizards are more visible to predators. Black lizards warm faster which allows them to be active sooner. They get food first and reproduce first and more because food needs are met.

49. Survival of the Fittest
Fittest – the individuals most capable to survive and reproduce for multiple generations
Natural Selection accounts for Descent with Modification as species become better adapted to different environments.

50. Birds
Explain to your cat how the environment can determine fitness – use a specific plant or animal as an example.
(Not one Mrs. Stewart gave you)

51. What is a Population?
A group of organisms of the same species, that live in the same area, AND can successfully interbreed

52. Adaptation vs. Acclimation
Adaptation - Changes in frequency of traits within a POPULATION over time
Example: White moth population becoming a black moth population after 5 generations.
Acclimation – INDIVIDUAL organism changes physiologically to environment
Example: humans that live in moderate/hot environments use mostly white fat. But when moving to colder climates, begin to make brown fat instead.

53. Adaptations
Inherited characteristic that increase an organism’s ability to survive and reproduce, are therefore, passed down more often to offspring.
Anatomical or structural characteristics
Porcupine quills - protection
Longer necks in giraffes – find food
Physiological processes
How a plant performs photosynthesis
Instinctual Behaviors
Hunting in packs
Living in burrows

54. Key Distinction! INDIVIDUAL organisms ACCLIMATE.
POPULATIONS ADAPT and therefore, EVOLVE over time.
Individuals DO NOT ADAPT OR EVOLVE.

56. Can You…
Differentiate between Charles Darwin and Jean-Baptiste Lamarck
Explain the idea of “natural selection”
Can you explain how “fitness” leads to adaptations which lead to evolution?