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Evolution

Evolution. Content. 1. An introduction to evolution 2. Historical view (the evolutionary thinking) 3. Genetic variation 4. Mechanisms: the processes of evolution 5. Microevolution vs Macroevolution 6. Speciation 7. Issues on evolution. Evolution. Evolution = Change.

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Evolution

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  1. Evolution

  2. Content 1. An introduction to evolution 2. Historical view (the evolutionary thinking) 3. Genetic variation 4. Mechanisms: the processes of evolution 5. Microevolution vs Macroevolution 6. Speciation 7. Issues on evolution

  3. Evolution • Evolution= Change. • Biological Evolution= Change in the intrinsic qualities of life over time. • NOT progressive change. • What can change? Characteristics of species Number of species

  4. Evolution • Microevolution= Change in the genetic qualities of populations within a species over time. • Macroevolution= Change in the number of species and the formation of groups of species. • Speciation = formation of species

  5. Results of Evolution Anagenesis = change within a species lineage(number not increase) Cladogenesis = change and diversification

  6. History: Early 1800’s • Natural Theology Discover God’s plan, study nature. • Essentialism=Organisms are imperfect reflections of perfect eternal “essences.” (invariant) • Natural groups reflect the essential groups in the mind of God.

  7. History: Early 1800’s • Paleontology= study of fossils. • Fossil=preserved remnant of an organism that lived in the past Certain fossils only found in certain rock strata (layers). Some organisms are extinct! • Earth = VERY OLD • Sedimentary Rocks = layered rocks formed by settling particles.

  8. youngest layer oldest layer Sedimentary Rocks & Fossils

  9. Sedimentary Rocks & Fossils Dead Thing

  10. Sedimentary Rocks & Fossils Fossil (Dead Thing)

  11. Sedimentary Rocks & Fossils Fossil (Dead Thing)

  12. Sedimentary Rocks & Fossils EROSION Fossil (Dead Thing)

  13. Sedimentary Rocks & Fossils Fossil (Dead Thing)

  14. Sedimentary Rocks

  15. Geologic Time Scale • Geologic scale based on the fossil record. (time divisions UNequal) • Eras =four largest time periods (Precambrian -->Paleozoic -->Mesozoic -->Cenozoic) • Periodssubdivide eras. • Mass Extinction = extinction of a large proportion of existing species. They separate many eras or periods.

  16. Cenozoic extinction of dinosaurs first flowering plants Mesozoic first dinosaurs & mammals “fern” forests form coal Paleozoic first land plants & animals first vertebrates near present oxygen levels Precambrian Geologic Time Scale

  17. Eons = hundreds of millions of years in duration(บรมยุค) Eras(มหายุค) Eons period(ยุค) epochs. Biostratigraphy: The organisation of sedimentary rocks into units on the basis of the fossils they contain

  18. Biostratigraphy:

  19. Charles Darwin

  20. Mid-1800’s, Charles Darwin • Studied medicine & theology • Traveled on H. M. S. Beagle • Bred pigeons • The Origin of Species, 1859 • TWO big ideas Common Descent (old idea) Natural Selection (new idea)

  21. Natural Selection • Mechanism of change within one species. (Proposed by Darwin.) • Microevolutionary process. • First evidence from plant and animal breeding by humans to create domestic forms.

  22. Natural Selection • Populations can grow tremendously. • In nature, populations remain stable in size due to limited resources (K). • THEREFORE, there is a struggle to survive and reproduce within species. • Organisms vary in inheritable characteristics (genetic). • THEREFORE, reproduction varies based on differences in inherited traits.

  23. Natural Selection DEFINITION Differential reproduction (survival) based on differences in inherited characteristics. NOT “survival of the fittest”

  24. Population

  25. Population

  26. Population

  27. Population

  28. Population

  29. Population

  30. Population

  31. Fitness • FITNESS=the relative contribution of an individual to the next generation • More fit = more surviving offspring • Less fit = fewer surviving offspring • “Survival of the fittest” = circular, non biological statement

  32. แฟคเตอร์ที่มีอิทธิพลต่อ fitness

  33. Adaptation • Adaptation= characteristic that results from natural selection also... a trait that enhances the reproductive success of the bearer. • Not ALL characteristics of organisms are “adaptations.” • Difficult to provide evidence that a characteristic is truly an adaptation.

  34. Laboratory Selection ลายจุดบนตัวปลาหางนกยูงส่วนใหญ่ถูกควบคุมด้วยพันธุกรรม ลายจุดนี้ช่วยในการพรางตัวให้เข้ากับสิ่งรอบข้างเพื่อป้องกันการถูกจับกินโดยปลาใหญ่ แต่ลายจุดนี้ก็ช่วยให้ดูเด่นกว่าตัวที่ไม่มีลายจุด จึงดึงดูดคู่ผสมพันธุ์

  35. Microevolution

  36. Sexual Selection

  37. “Special” Kinds of Selection • Natural Selection=differential reproduction (survival) based on differences in inheritable characteristics (different alleles). • Sexual Selection= natural selection based on mate choice. • Artificial Selection= natural selection due to conscious human choice. (e.g., dogs, wheat)

  38. Sexual Selection

  39. Artificial Selection

  40. Artificial Selection p. 399

  41. Population Genetics • Population= localized group of individuals of the same species • Population genetics= studies the genetic variation within populations • Genotype= the genes (alleles) possessed by an organism • Phenotype= the physical characteristics of an organism

  42. Genetics “Review” • Genes (DNA) in cells direct cell activities. • Most cells have TWO copies of every gene. (DIPLOID) • One copy from each parent. • Sperm or egg have ONE copy of every gene. (HAPLOID)

  43. Genetics “Review”

  44. Genetics “Review” • The same gene can have different forms (Alleles). E.g., blue iris allele and brown iris allele of eye color gene • Diploid individual with the same 2 alleles = homozygote. • Diploid individual with 2 different alleles = heterozygote.

  45. Genetics • Gene “A” has 2 alleles, “A” and “a.” • AA or aa = homozygotes. • Aa =heterozygotes. • AA, Aa,and aa = genotypes. • Calculation of allele frequencies.

  46. Population Genetics • Gene pool=all the alleles in a population • Genetic structure= frequencies (%) of alleles and genotypes in a population. • Mendelian population= interbreeding group within a population.

  47. Hardy Weinberg • Hardy-Weinberg Theorem = describes a population that is NOT evolving. p2 + 2pq+ q2 = 1 p=frequency of A in the pop. q=frequency of a in the pop. p + q = 1

  48. Random mating P(A)=p P(a)=q P(A)=p AA=p2 Aa =pq aA=pq aa=q2 P(a)=q AA + 2Aa + aa = p2 + 2pq+ q2 = 1 (p+q) 2 = 1 p+q = 1

  49. Hardy Weinberg p2 + 2pq + q2 = 1 p2 =frequency of AA in the pop. 2pq =frequency of Aa in the pop. q2 =frequency of aa in the pop.

  50. Hardy-Weinberg p2 + 2pq + q2 = 1 Thefrequency of AA in a population at H.-W. equilibrium is 0.25. What is the frequency of Aa in this population?

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