1. Charles Darwin and Natural Selection Evolution Primer #2 – Evolution Primer #2 – Who was Charles Darwin? Who was Charles Darwin?

2. Theory of Acquired Characteristics  Gain or lose features based on overuse or non-use of them. Would pass this trait onto offspring. Lamarck

3. Example  Giraffes have long necks because they stretched them to reach food in high places.  Characteristic then passed onto offspring.  Other Examples?

4. Theory Discarded  Lamarck’s theory proved to be illogical…  Car Accident/Amputation Example

5. Charles Darwin  HMS Beagle  Galapagos Islands  Suspected that small gradual changes might lead to new species over time.

6. Natural Selection  Individuals in a population show differences, or variation.  Variations can be inherited.  Some competition would lead to the death of some individuals while others will survive.  Individuals that have advantageous variations will be more likely to survive and reproduce.

7. 1. Individuals in a population show differences, or variation.

8. 2. Variations can be inherited.

9. 3. Some competition would lead to the death of some individuals while others will survive.  REVIEW ALERT! –What are some factors that organisms compete for?

10. 4. Individuals that have advantageous variations will be more likely to survive and reproduce.

11. Interactive Activities: Natural Selection  Visualizing Natural Selection Visualizing Natural Selection Visualizing Natural Selection  Basic Principles of Natural Selection Basic Principles of Natural Selection Basic Principles of Natural Selection  Virtual Peppered Moth Simulation Virtual Peppered Moth Simulation Virtual Peppered Moth Simulation  Natural Selection video clip Natural Selection video clip Natural Selection video clip

12. Darwin’s Galapagos Island Observations  Species on the Galapagos Island closely resembled species found on mainland South America even though the environments were not very similar.  Why is this the case?

13. Darwin’s Finches  Observation: –Finches of Galapagos Islands looked very similar except for shape of their beak.

14. Darwin’s observations  Organisms were originally from South America  Organisms began to change after leaving South America and arriving at the Galapagos.

15. Darwin’s Finches  Conclusion: –Finches came from common ancestor. –EXPLANATION: Different shape of beak was adaptation for eating a particular food source.

16. Adaptations and Evolutionary Strategies  A trait shaped by natural selection that increases an organism’s reproductive success.  Fitness: measure of the relative contribution an individual trait makes to the next generation. –How many viable offspring does an organism provide to the next generation?

17. Types of Adaptation  Camouflage

18.  Mimicry Compare Mimicry and Camouflage.

19.  Antimicrobial Resistance –For almost every antibiotic, at least one species of resistant bacteria exists.

20. Cannibalism

21. Feathers http://notesfromatransitionalfossil.blogspot.com/2008/10/its- all-over-but-crying-and-burial.html http://www.mvsd21.org/~abrown/

22. Mechanisms of Evolution  EVOLUTION OCCURS AT THE POPULATION LEVEL, WITH GENES AS THE RAW MATERIAL.

23. Hardy-Weinberg Principle  If allele frequencies do not change, the population will not evolve.  In order for this to happen, 5 conditions need to be met.

24. 1. No Genetic Drift!  Genetic Drift – change in allelic frequencies in a population that is due to chance. –Founder Effect –Bottleneck

25. 2. No Gene Flow!  No new genes can enter the population and no genes can leave the population.  Migration increases genetic variation within a population and reduces differences between populations.

26. 3. Mating must be random  This rarely ever happens…. Why?

27. 4. No mutations  Mutation – random change in genetic material.  Mutations can change the alleles in a population (sometimes even for the better).

28. 5. No natural selection.  HW requires that all individuals in population be equally adapted to their environment and thus contribute equally to the next generation.  Does this happen!?!?

29. Types of Natural Selection  Stabilizing Selection  Directional Selection  Disruptive Selection

30. Stablilizing Selection  Eliminates extreme expressions of a trait when the average expression leads to higher fitness.  Example: baby weight

31. Directional Selection  An extreme version of a trait makes an organism more fit.  Example: Peppered moth

32. Example

33. Disruptive Selection  Splits population into two groups:  Removes individuals with average traits, but retain individuals expressing extreme traits.

34. Example

36. Speciation  A population diverges and then is reproductively isolated. – can no longer interbreed or produce fertile offspring with one another  Different “species” result  TWO MAIN TYPES –Allopatric Speciation –Sympatric Speciation

37. Allopatric Speciation  A physical barrier divides one population into two or more populations.  Examples: mountain ranges, channels, wide rivers, lava flows  Grand Canyon Speciation? – Kaibab and Albert Squirrels

39. Sympatric Speciation  A species evolves into a new species without a physical barrier. They live side by side.  Examples: apple maggot flies diverging based on fruit they eat

40. Patterns of Evolution  Divergent Evolution –Two or more related species become more and more DIFFERENT as a result of new habitat or opportunity. Red Fox Kit Fox

41. Patterns of Evolution  Convergent Evolution –Unrelated species become more and more alike in appearance as they adapt to the same kind of environment

42. Co-evolution  The relationship between two species is so close that the evolution of one species affects the evolution of the other.  Ex: Moth’s foot long tongue

43. Rate of Speciation  Traits may change rapidly or slowly.  Rates of Speciation: –Gradual Equilibrium –Punctuated Equilibrium

44. Rates of Speciation

46. Gradual Equilibrium  Evolution proceeds in small, gradual steps.  Supported by a great deal of evidence.  HOWEVER, fossil record contains instances of abrupt transitions.  Example: snail shells

47. Punctuated Equilibrium  Rapid spurts of genetic change cause species to diverge quickly; these periods punctuate much longer periods when species show little change.  Accounts for abrupt changes in fossil record.