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Lecture #30: POPULATION & EVOLUTION

Lecture #30: POPULATION & EVOLUTION. Ms. Day Honors Biology http://glencoe.mheducation.com/sites/9834092339/student_view0/chapter20/animation_-_mechanisms_of_evolution.html. Population & Evolution. Population :

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Lecture #30: POPULATION & EVOLUTION

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  1. Lecture #30: POPULATION & EVOLUTION Ms. Day Honors Biology http://glencoe.mheducation.com/sites/9834092339/student_view0/chapter20/animation_-_mechanisms_of_evolution.html

  2. Population & Evolution • Population: • Group of the same species living in the same place at the same time that can interbred • Species: • a group of populations whose individuals can to interbreed and produce living offspring that can reproduce themselves • Gene pool: • ALL of the genes (alleles) in a population at any one time

  3. “Individuals are selected, but populations evolve.” • Populations = smallest unit of evolution

  4. A change in the gene pool of a population over many generations There are 5 reasons why populations can evolve. Causes of Microevolution

  5. #1: Small Populations How can this happen? Genetic Drift • Genetic drift: changes in the gene pool of a SMALL population due to chance (reduces genetic variability) • http://highered.mcgraw-hill.com/sites/0072835125/student_view0/animations.html# • 2nd to last video

  6. Genetic Drift Example #1 Bottleneck Effect • Caused by a natural disaster • Leaves surviving population with less genetic variation than original population

  7. Ex: NORTHERN ELEPHANT SEAL

  8. Genetic Drift Example #2 Founder Effect: • a result of colonization by a few individuals from a parent population finding a new place to live http://nortonbooks.com/college/biology/animations/ch16a01.htm http://bcs.whfreeman.com/thelifewire/content/chp24/2402002.html

  9. Cause #2: Migration of Alleles Gene Flow: • alleles/genes migrate (move) between populations (reduces differences between populations)

  10. Cause #3: Mutations Mutations: • a change in an organism’s DNA • original source of genetic variation (raw material for natural selection) • Mutations can immediately lead to NEW variation in a population

  11. Cause #4: “Picky” Mating Nonrandom mating • “picky” mating • Unequal chances of each egg getting fertilized • Assortative mating - choosing individuals more like self

  12. results in sexual dimorphism differences between the sexes in secondary sexual characteristics Sexual Selection

  13. Cause #5: Natural Selection • Different survival and reproductive success due to variation https://highered.mheducation.com/sites/9834092339/student_view0/chapter20/animation_-_mechanisms_of_evolution.html

  14. LIGHT/DARK ROCK HABITAT DARK ROCK HABITAT MEDIUM COLOR ROCK HABITAT

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