Introduction to Evolution and the Origin of Life

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

2. Standards: • CCSS ELA 9-10.2 • I can trace the historical development of the theory of evolution • I can summarize the evidence for the theory of evolution • CCSS ELA 9-10.8 • 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. 3.8 - 4.1 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 • www.ucsd.tv/miller-urey/

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 (1744-1829) • 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. 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. 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 1858 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 ISALREADY 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 9-10.2 • I can trace the historical development of the theory of evolution • I can summarize the evidence for the theory of evolution • CCSS ELA 9-10.8 • 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. 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)