Mechanisms of Evolution

1. Mechanisms of Evolution Changing the frequencies of genes in populations Reading: Chapter 15.2

2. Genes • The basic unit of heredity in a living organism

3. Gene or Allele Frequency Proportion of genes/alleles in a population that are of a particular type These genetic differences are heritable and can be passed on to the next generation Both alleles for each individual trait are accounted for

4. Gene Pool or Population • A group of organisms living close to one another that interbreed with one another and do not breed with other similar groups • May occupy greater or smaller geographic regions

5. Allelic Frequency Lab • Define: • Homozygous • Heterozygous • Co-dominant • Recessive • Lethal alleles • Paste the table

6. Allelic Frequency Lab

7. Allelic Frequency Lab Brown beans = brown allele BB and Bb = brown bunny White beans = white allele bb = white bunny

8. Allelic Frequency Lab • Count out 50 white beans (b) and 50 brown beans (B) • Put them all in a bag and shake them up • Pull two beans out at a time making genotype pairs until the bag is empty • All recessive pairs (2 white) represent individuals who die (100% selection against) • Count the number of heterozygous and homozygous dominant pairs remaining and divide by 4. Remove that number of pairs to show 25% selection against the dominant phenotype • Count the number of brown (B) beans and white (b) beans left. • Percentage of “B” = (B/B+b) x 100 and “b” = (b/B+b) x 100 must be recorded on the data table • Write the number of brown beans (B) and the number of white beans (b) that will start the next generation (in the first column) • Put the new percentages of white and brown beans back in the bag • Repeat 4 more times

9. Hypothetical Data (do not copy) After the end of the 1st round… How many brown beans would I put in the bag? How many white? 68 32

10. Allelic Frequency Lab Analysis • Graph your data. • Title • X-axis: generations of bunnies • Y-axis: frequency of alleles • Key: B ---- and b-.-.-. • Did either allele disappear? Why or why not? • What does your graph show about allelic frequencies and natural selection? • What would happen to the allelic frequency if the predators declined? • Justify the life and death of organisms based on their allele combinations.

11. Learning Log #16 • Lethal Alleles Read the article and then explain how lethal alleles can be maintained in a gene pool.

12. Genetic Variation When individuals are genetically different from others Some of the basic mechanisms of evolutionary change cannot operate without it

13. Sexual Recombination Crossing over and random chromosome segregation For thousands of eggs, only one matures; for thousands of sperm, only one succeeds

14. Mutation • A random change in DNA • DNA fails to copy right • External influences like radiation • Only germ cell mutations matter to evolution

15. Migration or Gene Flow • Movement of genes between populations • Immigration • Emigration • Provides variation if those genes previously did not exist in that area

16. Genetic Drift • Some individuals may, just by chance, leave behind a few more descendents (and genes, of course!) than other individuals • Genes of the next generation will be the genes of the "lucky" individuals, not necessarily the healthier or "better" individuals

17. Learning Log 13 • Bottleneck Effect Read the article, then explain the consequence of the bottleneck effect on the diversity of the population discussed.

18. Learning Log #14 Genetic Drift Perform the simulation, then answer the questions found at Beeson Science.

19. Natural Selection Variation in traits Differential reproduction Mating rituals Mate selection Not everyone gets to breed Heredity If you get to breed you pass on your genes More advantageous trait becomes more common in the population

20. Learning Log 9 • Natural Selection, Variation, and Survival After the lecture on standards 7d, 8a, and 7a (go to page 245 in the PDF document to review these standards), write a journal about what was discussed. You can also check out the first link to read more on the concept of natural selection.

21. Darwin’s Theory of Evolution by Natural Selection • Overproduction – In good times, lots of offspring are born • Variation – No two organisms in a population are identical • Competition – organisms within populations compete to survive • Survival of the fittest – those with a selective advantage (are best adapted) survive • Reproduction – survival leads to passing on genes = fit organism • Speciation – populations change because some traits are passed on and others are not

22. Survival of the fittest

23. Oh, deer! 1 2 3 2 1 3 2 3 1 3 2 1 3 1 3 3 1 2 3 2 Count off students 1-4 • 1= water • 2= food • 3 = shelter • 4 = deer Deer who get what they want survive and reproduce. The Habitat they get will represent the offspring the next year. Deer Deer Deer Deer Deer Deer Deer

24. Oh, Deer! Natural Selection in Action • Overproduction – In good times, lots of offspring are born • Variation – No two organisms in a population are identical • Competition – organisms within populations compete to survive • Survival of the fittest – those with a selective advantage (are best adapted) survive • Reproduction – survival leads to passing on genes How are each of these represented by the “Oh, deer!” game?

25. Speciation • Physical barrier – geographic isolation • Mountain • Stream • Canyon • Reproductive isolation • Breeding seasons • Courtship rituals • Different chromosomes

26. The Rate of Speciation Gradualism Punctuated Equilibrium Species evolve slowly Small changes over long periods of time Many intermediate (transitional) species Species remain relatively unchanged for long periods of time Environmental change occurs Speciation happens relatively rapidly FEW transitional forms in fossil record

27. Learning Log #10 & Project #5 • Kettlewell's Theory: Explain Kettlewell's idea and then explain how it just might be wrong. • Peppered Moth Lab - Answer the questions on Beeson Science and perform the lab as instructed through the link.

28. Hardy-Weinberg Principle • The frequency of a trait’s alleles in a population can be described mathematically as p + q =1 • p = the dominant allele • q = the recessive allele • The frequency of genotypes can also be described • p2 + 2pq + q2 = 1 • Homozygous dom + 2 ways to get heterozygous dom + homozygous recessive • Read page 416 in the textbook • What are the three reasons the Hardy Weinberg principle is useful?

29. H-W Equilibrium = No evolution • A large breeding population • Random mating • No change in allelic frequency due to mutation • No immigration or emigration • No natural selection • Explain how each one of these conditions does NOT occur.

30. Project #3 • Population Genetics - Perform the lab online. Take notes over each concept and answer all questions. Put all information in your comp book.

31. Learning Log 12 • Hardy-Weinberg Equilibrium Explain the theory of equilibrium of populations. You can do the Practice Quiz at the end of the article to make sure you understand the article and can explain the theory. Then try to do some of the problems yourself.

32. Webliography • http://www.biology.arizona.edu/evolution • http://evolution.berkeley.edu/evolibrary

33. Great Transformation Video PROJECT 6 1)How do we know that whales came from land? 2)what evidence do we have that shows the transformation into whales? 3) How did fish get on land? 4) What evidence did the Burgess Shale provide that lead scientists to recognize that all animals have the same body plan? 5) What evidence was collected to confirm that the same genes control all body plans? (Day Two viewing-optional) 6) What role does the lemur play in scientists understanding of the evolution of man? 7) What evidence was provided to explain how humans developed bipedal walking?

34. Adaptation Lab Activity • Perform the tasks • Enter data on the data table • Graph ONE task assigned to you

35. Identify the following elements of the Adaptation Experiment • Control Group: In an experiment, the group of test subjects left untreated or unexposed to some procedure and then compared with treated subjects in order to validate the results of the test • Experimental Group: In an experiment, the group of test subjects that is treated • Independent Variable: A variable that is manipulated in an experiment in order to observe the effect on another variable • Dependent Variable: A variable that is observed due to the manipulated variable

36. Questions for Adaptation Activity • 2 discussion questions • Conclusion • Error Analysis

37. Adaptations Genetic variation maintained by natural selection

38. Adaptation not adaption! • A feature that is common in a population because it provides some improved function • Are well fitted to their function and are produced by natural selection • Adaptations can take many forms

39. Identifying Adaptations • A behavior that allows better evasion of predators • A protein that functions better at body temperature • An anatomical feature that allows the organism to access a valuable new resource

40. Desert Adaptations • Camel Rete – air breathed in through nostrils cools blood. Blood flows over brain cooling it. Therefore, no fried brains!

41. Desert Adaptations Hare ears – surface area allows heat to escape through the capillaries

42. Desert Adaptations • Kangaroo rat: doesn’t drink water, just eats and has concentrated urine. Also, hibernates during the day.

43. Desert Adaptations • Spade foot toad: digs a hole with big foot and stays in the burrow therefore keeps cool and conserves water

44. Desert Adaptations • Desert Trees: Limbs angle into roots (directs water to the roots), Little leaves angels in a V directs water. Narrow, long leaves prevent water loss. Stomata angle away from the sun and a waxy cuticle on the top also prevent water loss.

45. Learning Log #17 • Adapting to Survive Mutations are said to be the fuel of evolution. List the adaptations of the organisms in this article and what they are used for. Find other adaptations, for a total of 10 organisms, at least one adaptation per organism and what it is used for. Go to other sites as needed.

46. Speciation A species is a group of organisms living together that can reproduce viable offspring Speciation is a lineage-splitting event that produces two or more separate species

47. Domains

48. Linnaean system of Classification Kingdom Phylum Class Order Family Genus Species Animalia Chordata Aves Passeriformes Turdidae Turdus T. migratorius http://en.wikipedia.org/wiki/American_Robin

49. Linnaean system of Classification http://animaldiversity.ummz.umich.edu/site/resources/jerry_gingerich/84nilecroc-5alt.jpg/view.html Kingdom Phylum Class Order Family Genus Species Animalia Chordata Reptilia Crocodilia Crocodylidae Crocodylus C. niloticus

50. Phylogenic Classification System • Names only clades - groups of organisms that are all descended from a common ancestor • Birds are not reptiles • Birds share a common ancestor with some reptiles http://evolution.berkeley.edu/evosite/evo101/IIDClassification.shtml