2. Evolution

4. Lamarckian vs. Darwinian Evolution Darwinian evolution states that an organism had a genetic adaptation to environments, though it is actually Lamarck who first conceived of such a concept Difference? Darwin had a population emphasis

5. Descent with Modification 1.All organisms are related to ancestors that lived in the past and as they moved into different habitats, they acquired new traits to adapt to that new habitat 2.Darwin used Linnaeus’ classification system and saw that some species were more related to each other than to others

6. Natural Selection & Adaptation  Organisms are capable of producing large numbers of offspring  These offspring vary and some of these variations are inheritable  Environmental resources are limited and these varied offspring must inherit characteristics that allow them to compete for resources AND they must leave more offspring  Example- the finch beaks in the Galapagos; finches adapted different beaks for the food available at different times of the year. ( seeds, nuts, insects, nectar)

7. Example Example

8. Artificial Selection: Various Animals Darwinism got his ideas that organisms change with time by observing artificial selection

9. Biogeography Closely related species found in similar geography look similar

10. BIOGEOGRAPHY BIOGEOGRAPHY Very different but similar looking species are found in different regions marsupial placental

11. Homology- similar structure, different function

12. Paleo Homology (whale legs) Fossil record can give rise to transitional species

13. Vestigial Structures

14. Homologies: Vertebrate Embryos

15. Molecular Homologies

16. Developmental Error The genes for tail formation presumably are still with us, just not normally expressed (that is, they are vestigial).

17. EVOLUTION IN ACTION Examples from the AP test:  Antibiotic resistance in bacteria  Antiviral resistance in viruses (including HIV)  Insecticide resistance in insects  Industrial Melanism- dark and light moths  Guppy-cichlid changes in size- Some cichlids eat young guppies so these guppies mature faster. Other cichlids eat mature guppies so these young guppies mature slower

18. Industrial Melanism

19. Practice Questions

20. Population Evolution and Speciation

21. Gene Pools A population is a localized group of organisms of the same species A gene pool is the sum of alleles within a population

22. To assume Hardy-Weinberg equilibrium all of the following must be true: 1.The population must be very large (no sampling error/genetic drift) 2.There must be no mutation 3.There must be no natural selection 4.No migration between populations 5.Random mating Hardy-Weinberg Equilibrium

23. Hardy-Weinberg Equations p=frequency of one allele (A); q=frequency of the other allele(a); p+q=1.0 p=1-q q=1-p  p 2 =frequency of AA genotype; 2pq=frequency of Aa genotype; q 2 =frequency of aa genotype  frequencies of all individuals must add to 1 (100%) p 2 + 2pq + q 2 = 1

24. Population of cats n=100 16 white and 84 black bb = white B_ = black Can we figure out the allelic frequencies of individuals BB and Bb? Hardy Weinberg Equilibrium

25. Using Hardy-Weinberg equation q 2 (bb): 16/100 =.16 0.4 q (b): √.16 = 0.4 0.6 p (B): 1 - 0.4 = 0.6 q 2 (bb): 16/100 =.16 0.4 q (b): √.16 = 0.4 0.6 p (B): 1 - 0.4 = 0.6 population: 100 cats 84 black, 16 white How many of each genotype? population: 100 cats 84 black, 16 white How many of each genotype? bbBbBB p 2 =.36 2pq=.48 q 2 =.16

26. If only 6% of the population displays pale eyes (recessive gene e), what is the frequency of genotype Ee in this population? Hardy Weinberg Ex 1 q 2 = 0.06 ---> q = 0.24 p + q = 1 ---> p = 0.76 Ee = 2pq = 2(0.76)(0.24) = 0.36

27. If the statistics for people who have PKU is 1 in 10,000, what percentage of the US population carries the gene but does not exhibit the disease? Hardy Weinberg Ex 2 q 2 = 0.0001 ---> q = 0.01 p + q = 1 ---> p = 0.99 2pq = 2(0.99)(0.01) = 0.0198 or 1.98%

28. Genetic Drift Genetic drift is random fluctuation in allele frequency between generations.

29. A Genetic Bottleneck is a Form of Genetic Drift In a genetic bottleneck, allele frequency is altered due to a population crash. Once again, small bottlenecked populations = big effect.

30. Genetic Bottleneck – A Historical Case Other animals known to be affected by genetic bottlenecks include the cheetah and both ancient and modern human populations. A severe genetic bottleneck occurred in northern elephant seals.

31. Founder Effect- new habitat The South Atlantic island of Tristan da Cunha was colonized by 15 Britons in 1814, one of them carrying an allele for retinitis pigmentosum. Among their 240 descendents living on the island today, 4 are blind by the disease and 9 others are carriers.

32. Gene Flow genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations) seed & pollen distribution by wind & insect migration of animals

33. Mutations Mutation creates variation a change in an organism’s DNA (gametes; many generations); original source of genetic variation (raw material for natural selection)

34. Nonrandom Mating Inbreeding assortive mating- choosing a mate with either similarities or differences (both shift frequencies of different genotypes)

35. Sexual selection It’s FEMALE CHOICE, baby!

36. Genetic Variation Polymorphism- 2 or more distinct forms (morphs) within a single population of organisms

37. Geographic Variation-cline Differences in genetic structure between populations This was on the AP test 2 years ago

38. Mutation and Sexual Recombination -random changes to DNA errors in mitosis & meiosis environmental damage -Recombination mixing of alleles new combinations= new phenotypes

39. Balanced Polymorphism Heterozygote advantage (hybrid vigor; i.e., malaria/sickle- cell anemia);

40. Modes of Selection Stabilizing Selection- favors the middle and eliminates the extremes in a population Directional Selection- natural selection or evolutionary changes in the population Disruptive Selection- favors the two extremes creating polymorphism.

41. Modes of Selection

42. What is a species? Biological species concept: a population whose members have the potential to interbreed and produce viable, fertile offspring

43. Other Species’ Concepts  Biological Species Concept Reproductive Isolation Not necessarily easy to apply  Morphological Species Concept Phenotypic differences  Paleontological Species Concept Fossil species  Ecological Species Concept Filling of ecological niches  Phylogenetic Species Concept Evolutionary lineages/genetic history

44. Reproductive Isolation (isolation of gene pools) Pre-zygotic barriers: impede mating between species or hinder the fertilization of the ova Habitat (snakes; water/terrestrial) Behavioral (fireflies; mate signaling) Temporal (salmon; seasonal mating) Mechanical (flowers; pollination anatomy) Gametic (frogs; egg coat receptors)

46. Reproductive Isolation Post-zygotic barriers: fertilization occurs, but the hybrid zygote does not develop into a viable, fertile adult Reduced hybrid viability (frogs; zygotes fail to develop or reach sexual maturity) Reduced hybrid fertility (mule; horse x donkey; cannot backbreed) Hybrid breakdown (cotton; 2nd generation hybrids are sterile)

48. Modes of speciation (based on how gene flow is interrupted) Allopatric: populations segregated by a geographical barrier; adaptive radiation – diversification due to habitat change (Darwin’s finches) Sympatric: reproductively isolated subpopulation in the midst of its parent population

49. Sympatric Speciation Polyploidy-more than 2 paired chromosomes Allopolyploidy- infertile hybrid Sexual selection- intraspecies competition

50. Tempo of speciation Gradualism- species diverge more and more as they adapt Punctuated Equilibrium- periods of apparent stability and then a sudden change

51. Evolutionary Novelties Exaptation- structures becomes better adapted for another function- bird feathers originally kept the bird warm but later were better suited for flight Paedomorphosis- retaining some juvenile characteristics

52. Convergent Evolution Analogies are products of convergent evolution