1. Chapter 7 Human variation (and population genetics)

2. Population: Individuals within a species that can mate with each other in nature. Biological variation (like Darwin saw) exists: within a population. between different populations.

3. Some traits differ over a wide range with lots of variation in between… We describe the population in terms of distributions …continuous variation height

4. Figure 7.1 Fig 7.1 Average continuous variation

5. Some traits differ over a wide range with lots of variation in between… height …continuous variation Other traits follow the dominant/recessive pattern we discussed earlier (blood type, Tay Sachs disease, etc.)… …discontinuous variation

6. Other traits follow the dominant/recessive pattern we discussed earlier (blood type, Tay Sachs disease, etc.)… …discontinuous variation We describe a population in terms of allele frequencies. …….e.g., 41% of the population has type A blood

7. The study of genetic variation of populations is called…. We have gotten away from a morphological definition of species (like Aristotle used). Evolution cannot work unless there is variation within a population. …..population genetics The textbook has two asides here:

8. Traits with continuous variation often are controlled by multiple genes as well as the environment. (the distribution may differ) The average for one population may be different than the average of another population.

9. fig 7-2

10. Traits with discontinuous variation may also vary from one population to another... “race”% with 0 blood e.g.,U.S. Caucasian47% African-American49% U.S. Asian40%

11. Race What does it mean?

12. Figure 7.3c Race Based on culture: conquerer’s (us) vs. conquered (them) dominateoppressed World prior to ocean travel… …very little mixing of cultures

13. Figure 7.3c Race Based on culture: Based on morphology (appearance): subspecies (races) skin color, hair texture, etc.,

14. Linnaeus:four “races” WhiteEuropeans YellowAsians BlackAfricans RedNative Americans

15. Figure 7.3c Race Based on culture: Based on morphology (appearance): Based on genetics:

16. Intelligence Is there a genetic basis for “race”? What is it? How do you measure it? (see page 212)

17. Figure 7.3c Is there a genetic basis for “race”? Look at a single trait in different populations What percentage of people have the trait? Look at population genetics

18. Figure 7.3c Is there a genetic basis for “race”? shows only indigenous people (original inhabitants) Blood typing maps (pg. 214) (clines) geographic variation

19. Figure 7.3a fig 7-3

20. Is there a genetic basis for “race”? There are no unique genetic markers for “race” Changes are gradual Doesn’t correlate with “morphological races” Great variability between A, B, o “no race” concept used to suppress others, e.g., “racism” slavery, Hitler’s Germany, anti-immigration

21. Population genetics: Blood typing Injured soldiers on the battle field (mid 1800’s) A B O not compatible with each other

22. Population genetics: Blood typing A and B are antigens (cause the immune system to attack) “A” carbohydrate on red blood cellsA Landsteiner (early 1900’s) “B” carbohydrate on red blood cellsB NeitherO Both(codominant)AB

23. fig 7-4

24. Other blood groupings: ABO system Rh system C, D, E: close on same chromosome Dominant/recessive C, D, or ERh positive ccddeeRh negative

25. fig 7-5

26. Other blood groupings: ABO system Rh system MN, Duffey, others, …

27. Back to population genetics: How do we keep track of the genetic make-up of a population? IF: Hardy-Weinberg principle no migration no selection large population (with sexual reproduction)

28. Hardy-Weinberg principle (equation) Allele frequencies will stay the same, if… large population (with sexual reproduction) no selection no migration Box 7.2 pp 222, 223 AAAaaa p 2 + 2pq+q 2 = 1

29. Fig 7-6

30. German Baptist Brethren (Dunkers) If they were genetically typical 18th century Germans... Strict rules (no marriage outside group) Started colony in Pennsylvania Fled Germany in 1719

31. If they were genetically typical 18th century Germans... (and Hardy Weinberg applies)... then they should have similar genetic make-up to other populations descended from 18th century Germans.

32. If they were genetically typical 18th century Germans... then they should have similar genetic make-up to their neighbors in PA. (and if natural selection was working in Pennsylvania)

33. The Dunkers: Other traits: more German “looking” than Native American or African No Fy a blood type (like Africans) (Europeans are mostly Fy a ) no type B blood (like Native Americans) (Germans and Pennsylvanians have 6-8%)

34. fig 7-6

35. Sequence and compare mitochondrial DNA Construct a tree to show relationships Look for similarities and differences

36. fig 7-7

37. What is the origin of differences in these different people groups? Remember the dark / light moths? They have lived in different places (environments) and have been subjected to different selective pressures.

38. What natural events help “select” humans? Remember sickle cell anemia? One of them is disease.

39. fig 7-10

40. fig 7-9

41. Genetics of sickle-cell anemia Hb S Hb S sickle-cell disease (often die young) Hb A Hb S sickle-cell trait (some symptoms) Hb A Hb A normal normaldiseased Hb A and Hb S

42. Genetics of sickle-cell anemia WHY? In some parts of Africa the frequency of the HB S allele is over 25% So… check in Africa In the US and Caribbean, most people with sickle-cell problems were of African descent.

43. Another disease: Malaria

44. Figure 7.8 fig 7-8

45. fig 7-11

46. Is there a connection? Hb A Hb S individuals infected with Plasmodium Hb A Hb A individuals infected with Plasmodium -severe symptoms -less severe symptoms (and fewer bites) (normal) (carrier)

47. Is there a connection? Having the sickle-cell gene protects against Malaria

48. Other genetic diseases also protect against Malaria: Thalassemia G6PD deficiency

49. More Human differences: There were differences between “groups” cold hot and dry heat and humid Tolerance of different conditions: pg. 236 african european native american

50. More Human differences (geographic variation): Protruding parts (arms, legs) are shorter and thicker in cold areas and longer and thinner in warm areas. body size is larger in cold areas and smaller in warm areas Allen’s rule Bergmann’s rule

51. Protruding parts (arms, legs) are shorter and thicker in cold areas and longer and thinner in warm areas. Allen’s rule rabbits and ears

52. Figure 7.12 fig 7-12

53. More differences (geography and climate): Sunlight (UV) is needed to make Vitamin D Vitamin D is needed for normal growth darker in warmer (sunnier) regions Species are paler in colder regions Gloger’s rule Too much UV- cancer and folate deficiency

54. Figure 7.13 fig 7-13