BIO 105 1st Edition Lecture 19Previous Lecture Outline1. Scaffolding (Key Terms)2. Evolutiona. Historical Contextb. Tenants of Evolutionc. Evidence for Evolutioni. Fossils ii. Anatomical recordiii. Molecular BiologyCurrent Lecture Outline1. Evolution CNTa. Mechanisms for Evolutioni. Microevolutionii. Macroevolution iii. Natural SelectionCurrent Lecture1. Evolution CNTa. Mechanisms for Evolutioni. Microevolution1. Changes in the genes (alleles) within a population2. Occurs between generations3. Causesa. Natural Selectioni. Stabilizingii. Directional iii. Disruptiveb. Genetic Drifi. Bottleneck effect1. IS NOT allele specifica. Caused by random effectsi. Ex. Floodsb. Smaller populations are affected more These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c. Losing genes matters not peoplei. Ex. In book: prairie chickensii. Founder Effect1. Few individuals restart the population2. Alleles will be different than starting population (species)c. Gene Flowi. Migration and immigrationii. Movement between a population1. Gene pool mixture2. Reduces differences between populationsii. Macroevolution 1. Accumulated changes (adaptations) in a population2. Can result in a new species entirelyiii. Natural Selection1. Nature chooses2. Variations in survival and reproduction3. Favored alleles are more commona. Key point to take away from hemoglobin example: alleles fitness completely rely on environment4. Many adaptations shape the species5. Also: artificial selection6. Requirements:a. Limited Resources- struggle to surviveb. Variationc. Advantages i. Survival and Reproduction7. Evolutiona. Nature chooses individualsi. Effect; populations evolveb. Only inherited traits effect evolutionc. Evolution isn’t perfect8. Genetic Varietya. Mutations occur b. Sexual reproduction is also an causei. Independent assortmentii. Crossing over (recombination)iii. Random mating9. TYPES of natural selection: phenotypesa. Stabilizing Selectioni. AGAINST extremesii. FOR middle/averageb. Directional Selectioni. AGAINST extreme on just one endii. FOR shif towards the opposite endc. Disruptive Selectioni. AGAINST average/ middleii. FOR extremes 1. This can lead to different species!10. Balancing Selectiona. Heterozygotes advantage can maintain diversity i. See ex. In book: hemoglobinb. Too much of a good thing?i. Frequency dependencec. Sexual Selectioni. Certain traits increase likelihood of matingii. Intrasexual selection (within)1. Competitioniii. Intersexual selection (between)11. Wrapping up. . . natural selectiona. Not randomb. Adaptive evolutioni. Organisms better than adapted ii. Increases fitnessc. Adaptation is not perfectioni. Nature can only select naturally occurring variationsii. Natural selection builds on what is there iii. Adaptation is a trade off1. 1 might be an advantage, the other trait a disadvantageiv. Evolution is complex1. Chance, natural selection, and the
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