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Agenda

Explore Darwin's theory of natural selection, the Galápagos finches, and descent with modification. Understand how adaptation contributes to evolution and the process of artificial selection. Dive into observations, inferences, and examples of adaptation in various species.

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Agenda

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Presentation Transcript

  1. Agenda • Set Up DSJ / DSJ #2 • Stamp Homework (22.2 notes) • 22.2presentation • Group work - 22.2 concept check #1, 2 • Notebook Art • HW: Notes 23.1 and 23.3

  2. Agenda • Set Up DSJ / DSJ #2 • Stamp Homework (22.2 notes) • 22.2presentation • Group work - 22.2 concept check #1, 2

  3. DSJ #2 – DO ON PAGE 4 What is natural selection and how does it contribute to evolution?

  4. Chapter 22 Descent with Modification: A Darwinian View of Life

  5. Concept 22.2 • Essential knowledge: 1.a.1 Natural selection is a major mechanism of evolution

  6. England • EUROPE • NORTH • AMERICA • ATLANTIC • OCEAN • PACIFIC • OCEAN • Galápagos • Islands • HMS Beagle in port • AFRICA • SOUTH • AMERICA • Darwin in 1840, • after his return • AUSTRALIA • Cape of • Good Hope • Andes • Tasmania • Cape Horn • New • Zealand • Tierra del Fuego • Figure 22.5

  7. Darwin’s Focus on Adaptation • As Darwin reassessed all that he had observed during the voyage of the Beagle • He began to perceive adaptation to the environment and the origin of new species as closely related processes • Adaptations • New species

  8. From studies made years after Darwin’s voyage • Biologists have concluded that this is indeed what happened to the Galápagos finches • (a) Cactus eater. The long,sharp beak of the cactusground finch (Geospizascandens) helps it tearand eat cactus flowersand pulp. • (c) Seed eater. The large groundfinch (Geospiza magnirostris)has a large beak adapted forcracking seeds that fall fromplants to the ground. • Figure 22.6a–c • (b) Insect eater. The green warbler finch (Certhidea olivacea) uses itsnarrow, pointed beak to grasp insects.

  9. The Origin of Species • Darwin developed two main ideas • 1: Evolution explains life’s unity and diversity • 2: Natural selection is a cause of adaptive evolution

  10. Descent with Modification • The phrase descent with modification • States that all organisms are related through descent from an ancestor that lived in the remote past

  11. Sirenia • (Manatees • and relatives) • Loxodonta • africana • (Africa) • Elephas • maximus • (Asia) • Loxodonta • cyclotis • (Africa) • Hyracoidea • (Hyraxes) • the history of life is like a tree • Years ago • Stegodon • Mammut • Mammuthus • Deinotherium • Platybelodon • Millions of years ago • Barytherium • Moeritherium • Figure 22.7

  12. Observation #1: For any species, population sizes would increase exponentially • If all individuals that are born reproduced successfully • Figure 22.8

  13. Observation #2: Nonetheless, populations tend to be stable in size • Except for seasonal fluctuations • Observation #3: Resources are limited • Inference #1: Production of more individuals than the environment can support • Leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving

  14. Observation #4: Members of a population vary extensively in their characteristics • No two individuals are exactly alike • Figure 22.9

  15. Observation #5: Much of this variation is heritable • Inference #2: Survival depends in part on inherited traits • Individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals

  16. Inference #3: This unequal ability of individuals to survive and reproduce • Will lead to a gradual change in a population, with favorable characteristics accumulating over generations

  17. Artificial Selection • Lateral • buds • Terminal • bud • In the process of artificial selection • Humans have modified other species over many generations by selecting and breeding individuals that possess desired traits • Brussels sprouts • Cabbage • Flower • cluster • Leaves • Cauliflower • Kale • Flower • and • stems • Stem • Broccoli • Kohlrabi • Wild mustard • Figure 22.10

  18. Summary of Natural Selection • Natural selection is differential success in reproduction • results from the interaction between individuals that have different heritable traits and their environment

  19. (a) A flower mantidin Malaysia • Natural selection can produce an increase over time • In the adaptation of organisms to their environment • (b) A stick mantidin Africa • Figure 22.11

  20. If an environment changes over time • Natural selection may result in adaptation to these new conditions

  21. Group Work • In your groups, answer 22.2 concept check questions 1 and 2 in your notebook on pg. 7a

  22. Notebook Art • Using the textbook, find a chapter that seems interesting to you and copy one of the figures in that chapter

  23. Homework • take notes on 23.1 (454-458) and 23.3 (460-462) notebook pg. 8b • (yes you have an extra day to get these notes done! This does not happen often!!)

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