Domain 1: Evolution

1. Domain 1:Evolution

2. Evolution "In the broadest sense, evolution is merely change, and so is all-pervasive; galaxies, languages, and political systems all evolve. Biological evolution ... is change in the properties of populations of organisms that transcend the lifetime of a single individual. The ontogeny of an individual is not considered evolution; individual organisms do not evolve. The changes in populations that are considered evolutionary are those that are inheritable via the genetic material from one generation to the next. Biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population (such as those determining blood types) to the successive alterations that led from the earliest protoorganism to snails, bees, giraffes, and dandelions.“ - Douglas J. Futuyma in Evolutionary Biology, Sinauer Associates 1986

3. ULTIMATE RESULT OF EVOLUTION Change in the genetic composition (gene pool) of a population.

4. MICROEVOLUTION VS. MACROEVOLUTION Microevolution: survival through the inheritance of favorable characteristics mutations selection Macroevolution: progression of biodiversity through geological time speciation extinction

5. MICROEVOLUTION Evolutionary Mechanisms Types of Natural Selection Hardy-Weinberg Equilibrium

6. WHAT IS MICROEVOLUTION? Traces generational changes in a population of organisms Changes eh? Allelic frequency changes within a gene pool!

8. WHAT LEADS TO CHANGES IN THE GENE POOL OF A POPULATION? SMALL POPULATION SIZE small pop  frequencies (toss a coin to prove it)

9. MECHANISMS OF EVOLUTION GENETIC DRIFT Random/chance events that change the gene pool of a small population examples: natural disasters

10. 2 TYPES OF GENETIC DRIFT MECHANISMS Genetic Bottleneck Dramatic decrease in pop size due to : ~ catastrophes ~ predation ~ disease, etc.

13. 2 TYPES OF GENETIC DRIFT MECHANISMS Founder Effect Migration leads to changes in allele frequencies from population of origin

17. WHAT ELSE CAUSES GENE POOL CHANGES ? GENE FLOW ~ immigration ~ emigration

18. EX OF GENE FLOW IN HUMANS Frequency of Rh - allele among Africans: 63% Frequency of Rh - allele among African-Americans 45% Frequency of Rh - allele among White European population 3%

19. MUTATIONS may produce a selective advantage may produce deleterious effects may be harmless WHAT ELSE CAUSES GENE POOL CHANGES ?

20. NATURAL SELECTION! increases/decreases allele frequencies due to environmental impact. Ex: English Peppered Moths WHAT ELSE CAUSES GENE POOL CHANGES ?

21. NON-RANDOM MATING individuals choose based upon traits (vertebrates) individuals “choose” based upon physical proximity (invertebrates) WHAT ELSE CAUSES GENE POOL CHANGES ?

22. OTHER FORMS OF NON-RANDOM MATING: INBREEDING Proximity issues SEXUAL SELECTION: Male competition: # offspring  fitness Female choice: quality offspring  fitness WHAT ELSE CAUSES GENE POOL CHANGES ?

23. SEXUAL SELECTION Picky females, show-off males…

24. MICROEVOLUTION REVIEW Changes in the GENE POOL! Caused by: Gene Flow Natural Selection Mutations Non-Random Mating Sexual Selection Inbreeding

25. THE SIGNIFICANCE OF SELECTION Selection increases the adaptive qualities of a population for the environment in which it lives. Types of Selection: Natural Selection determined by phenotype selection toward phenotypes that improve fitness

26. SUBDIVISIONS OF NATURAL SELECTION… Stabilizing Selection Eliminates individuals with extreme traits. Results in decreased variation

27. Directional Selection Favors traits at ONE extreme ex: resistance to insecticides

28. DIRECTIONAL SELECTION

29. Disruptive Selection Selection toward BOTH extremes. Extreme traits are favored, common traits are NOT! Results in major divisions in population! What might result?

30. DISRUPTIVE SELECTION

31. ARTIFICIAL SELECTION Directional selection determined by humans

33. CAUSES OF VARIATION Mutation is the ultimate source of variation Two major types of mutations: Gene mutations Chromosome mutations

34. GENE MUTATIONS Addition / Insertion Deletion Substitution Inversion

36. SPECIFIC EXAMPLES OF MUTATIONS Gene mutations PKU (phenylketonuria) CF (cystic fibrosis) Chromosome mutation Klinefelter syndrome (male with 47,XXY karyotype)

37. ONCE MUTATIONS HAVE ARISEN, FURTHER VARIATION RESULTS FROM: Recombination of alleles during meiosis Recombination of alleles during fertilization

38. ONCE GENETIC VARIATION HAS ARISEN, THERE IS ALSO PHENOTYPIC VARIATION. Recall that, according to Darwin’s Theory, due to competition within populations, there is … Differential Reproduction of Selected Phenotypes

39. GREAT EXAMPLE OF DIFFERENTIAL REPRODUCTION OF SELECTED PHENOTYPES:

40. ULTIMATE RESULT OF EVOLUTION Change in the genetic composition (gene pool) of a population.

41. RELATED CAUSES OF GENETIC VARIATION Sexual Reproduction! Diploidy Outbreeding

42. MINORITY ADVANTAGE… 50/50 Sex Ratio Predation (more common phenotype preferred by predator) The Lefty Hypothesis 10-15 % general population >50% contact sports (esp. males)

43. REPRODUCTIVE ISOLATION Prezygotic Temporal isolation Behavioral isolation Mechanical isolation Ecological isolation Gametic isolation Postzygotic Hybrid inviability Hybrid sterility Hybrid breakdown

44. ALLOPATRIC SPECIATION

45. SYMPATRIC SPECIATION

46. GRADUALISM Species A evolves to become species B. LONG, GRADUAL process!

47. PUNCTUATED EQUILIBRIUM Evolution is Slow with brief periods of rapid development of new species.

49. THE HARDY WEINBERG LAW If allele frequencies for a population do not change… NO EVOLUTION IS OCCURRING! Genetic Equilibrium Hardy Weinberg Equilibrium

50. GENETIC EQUILIBRIUM OCCURS ONLY IF THERE IS… A large breeding population Random mating No change in allelic frequency due to mutation No immigration or emigration No natural selection