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Bellwork: 02/13/2013

Bellwork: 02/13/2013. Using the following phylogenetic tree: What are the uses of a phylogenetic tree? What do the numbers on the chart represent? What are “ homologous characteristics? ” What is/are the homologous characteristic(s) between #1 and #2? #5 and #6?. Bellwork: 02/13/2013.

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Bellwork: 02/13/2013

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  1. Bellwork: 02/13/2013 Using the following phylogenetic tree: • What are the uses of a phylogenetic tree? • What do the numbers on the chart represent? • What are “homologous characteristics?” • What is/are the homologous characteristic(s) between #1 and #2? #5 and #6?

  2. Bellwork: 02/13/2013

  3. Groups of 4 or Less: 1) What is potentially problematic about a combination of the bottleneck effect & polygyny? 2) What are four conditions that favor fossilization? 3) How is homologous structures different than analogous structures? Give an example of each. 4) What is the driving force behind human founder effects? What aspects of human founder effects is incompatible with the definition of genetic drift? 5) What is adaptive radiation? During which time period would you expect the largest radiation event & why? (Keep in mind that extinction events end time periods)

  4. Before we start: What is a scientific theory? • It makes falsifiablepredictions with consistent accuracy across a broad area of scientific inquiry • It is well-supported by many independent strands of evidence, rather than a single foundation • It is consistent with pre-existing theories and other experimental results • It can be adapted and modified to account for new evidence as it is discovered, thus increasing its predictive capability over time. • It is among the most parsimonious explanations, sparing in proposed entities or explanations.

  5. Other Scientific Theories: • The Atomic Theory • Theory of Matter and Energy • Theory of Plate Tectonics • Theory of Quantum Mechanics • Theory of of Molecular Bonds • Theory of the States of Matter • Theory of Homeostasis • Theory of Gravity • Theory of Evolution (USA and Turkey are the only Westernize countries that still argues about this)

  6. Keep In Mind: • The theory of evolution and: • Creationism • Neo-creationism • Intelligent design • Creation science (“science”) • Are not equal on an scientific level.

  7. Humans, for example:

  8. Humans, for example: • (A) Pan troglodytes, chimpanzee, modern • (B) Australopithecus africanus, STS 5, 2.6 My • (C) Australopithecus africanus, STS 71, 2.5 My • (D) Homo habilis, KNM-ER 1813, 1.9 My • (E) Homo habilis, OH24, 1.8 My • (F) Homo rudolfensis, KNM-ER 1470, 1.8 My • (G) Homo erectus, Dmanisi cranium D2700, 1.75 My • (H) Homo ergaster (early H. erectus), KNM-ER 3733, 1.75 My • (I) Homo heidelbergensis, "Rhodesia man," 300,000 - 125,000 y • (J) Homo sapiens neanderthalensis, La Ferrassie 1, 70,000 y • (K) Homo sapiens neanderthalensis, La Chappelle-aux-Saints, 60,000 y • (L) Homo sapiens neanderthalensis, Le Moustier, 45,000 y • (M) Homo sapiens sapiens, Cro-Magnon I, 30,000 y • (N) Homo sapiens sapiens, modern

  9. Humans, for example:

  10. Evolution….After Darwin…

  11. Fossils

  12. Fossil Record • Fossil any preserved remnant or impression of an organism that lived in the past • Most form in sedimentary rock, from organisms buried in deposits of sand and silt. Compressed by other layers. • Also includes impressions in mud • Most organic matter replaced with minerals by Petrification • Some fossils may retain organic matter • Encased in ice, amber, peat, or dehydrated • Pollen

  13. Fossil Formation

  14. Conditions that Favor Fossilization: • Having Hard parts – shells, bones, cysts • Get buried, trapped • Marine species • Marsh, flooding areas • Abundant species (with many individuals) • Long lived species (as a species) • Avoid eroding away • Get discovered

  15. Limitations of Fossils record • Has to die in right place under the right conditions. Most things don’t get into the fossil record • Biased: Highly favors hard parts, abundant, long lived species organisms. • Lots of missing organisms • Hard to find, only certain areas highly researched (North America, Europe)

  16. Biogeography

  17. Biogeography

  18. Biogeography

  19. Biogeography • Study of geographic distribution • Use to study how lineages of animals evolved • History of earth • Patterns of adaptations for different environments

  20. Comparative Embryology • Compare developmental patterns to understand common ancestry

  21. Molecular biology • Study of DNA sequences to understand evolutionary relationships • Quantifiable relevant means of comparison • Compare degree of similarity • Uses conserved sequences of DNA • Mitochondrial DNA, RNA, proteins • Revolutionized our understanding of evolutionary biology

  22. Population Genetics • The study of genetic changes in populations over time • Quantify molecular differences within and among populations • Traits exhibit variation • Traits we have identified genes for • Population= group of individuals of the same species living in the same area at the same time • Gene pool= Genetic composition of a population (all alleles in a population at a given time)

  23. Microevolution How does it happen? • Mechanisms: • Gene flow • Genetic drift • Bottleneck effect • Founder effect • Mutations • Natural Selection • Artificial Selection

  24. Gene Flow • The loss or gain of alleles (genes) in a population due to migration of fertile individuals or gametes between populations • Migration • Immigration • Emmigration

  25. Genetic drift • Gene pool contains alleles available for the next generation • Genetic drift is a change in allele frequency due to random chance • Affect small populations • Limits alleles available to subsequent generations • Two types • Bottleneck • Founders effect

  26. Bottleneck Effect Genetic drift resulting from the reduction of a population, typically by natural disaster, surviving population does not represent the original population’s gene pool

  27. Bottleneck: 19th Century

  28. The northern elephant seal bottleneck • large US California and Baja California populations were hunted for oil and skins • by end 1800’s, ~ 20 individuals remained on Guadalupe Island off Baja California • population rebounded to ~120,000 by 1980 • Microunga angustirostris

  29. Inbreeding in California Sea Otters • Sea otters, once abundant along the west coast of the U.S., were almost wiped out by fur hunters in the 18th and 19th centuries.

  30. Inbreeding in California Sea Otters • California population reached a low of 50 individuals (now over 1,500). As a result of this bottleneck, the population has less genetic diversity than it once had.

  31. Inbreeding in California Sea Otters • Population is still at a low density and Lidicker and McCollum (1997) investigated whether this resulted in inbreeding. • They determined genotypes of 33 otters for PAP locus, which has two alleles S (slow) and F (fast)

  32. Bottleneck: 88,000 years ago

  33. Bottleneck: 43,000 years ago

  34. Bottleneck: dermal immunity

  35. Founder Effect • Genetic drift attributed to colonization by a limited number of individuals from a parent population

  36. Founder Effect • Examples • Islands • Mayflower • Amish

  37. Figure 18.5

  38. Before You Go: Groups of 2 or 3 1) What is potentially problematic about a combination of the bottleneck effect & polygyny? 2) What are four conditions that favor fossilization? 3) How is homologous structures different than analogous structures? Give an example of each. 4) What is the driving force behind human founder effects? What aspects of human founder effects is incompatible with the definition of genetic drift? 5) What is adaptive radiation? During which time period would you expect the largest radiation event & why? (Keep in mind that extinction events end time periods)

  39. Mutations

  40. Mutation • An error in replication of a nucleotide sequence (DNA), or any other alteration of the genome that is not due to recombination • Mutagens

  41. Natural Selection • Differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment • Results in adaptations

  42. Adaptation • A feature or characteristic that increases reproductive success (including survival) • Increases fitness relative to an alternate trait

  43. Natural SelectionHow Does it Happen? • Directional selection • 1 extreme is favorable • Diversifying selection • 2 extremes favorable • Stabilizing selection • Intermediate favored

  44. Mechanisms of Natural Selection

  45. Bellwork: 02/23/2012 • What is a mutagen & how are they associated with natural selection? • What is the importance of mitochondrial DNA to molecular biologists?

  46. Macroevolution • Grand scale • Form new species- speciation • Existing species go extinct- extinction

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