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Catalyst:

Catalyst:. Which of the choices below is an appropriate representation of commensalism ? +/+ c. -/- +/- d. +/0 How were the activities yesterday connected to evolution? What is the difference between microevolution and macroevolution?. Evolution: A Darwinian View of Life.

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Catalyst:

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  1. Catalyst: • Which of the choices below is an appropriate representation of commensalism? • +/+ c. -/- • +/- d. +/0 • How were the activities yesterday connected to evolution? • What is the difference between microevolution and macroevolution?

  2. Evolution:A Darwinian View of Life

  3. Overview: Darwin Introduces a Revolutionary Theory • A new era of biology began on November 24, 1859 • The day Charles Darwin published: On the Origin of Species by Means of Natural Selection

  4. Figure 22.1 • The Origin of Species • Focused biologists’ attention on the great diversity of organisms

  5. Darwin made two major points in his book • He presented evidence that the many species of organisms presently inhabiting the Earth are descendants of ancestral species • He proposed a mechanism for the evolutionary process, natural selection

  6. The Origin of Species • Shook the deepest roots of Western culture • Challenged a worldview that had been prevalent for centuries

  7. Darwin:from childhood to publication • As a boy and into adulthood, Charles Darwin • Had a consuming interest in nature • Soon after Darwin received his B.A. degree • He was accepted on board the HMS Beagle, which was about to embark on a voyage around the world

  8. 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 • Darwin’s interest in the geographic distribution of species was kindled by the Beagle’s stop at the Galápagos Islands near the equator west of South America

  9. (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. (b) Insect eater. The green warbler finch (Certhidea olivacea) uses itsnarrow, pointed beak to grasp insects. Figure 22.6a–c • 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

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

  11. The phrase descent with modification • Summarized Darwin’s perception of the unity of life • States that all organisms are related through descent from an ancestor that lived in the remote past

  12. Sirenia (Manatees and relatives) Loxodonta africana (Africa) Elephas maximus (Asia) Loxodonta cyclotis (Africa) Hyracoidea (Hyraxes) Years ago Stegodon Mammut Mammuthus Deinotherium Platybelodon Millions of years ago Barytherium Moeritherium Figure 22.7 • In the Darwinian view, the history of life is like a tree • With multiple branchings from a common trunk to the tips of the youngest twigs that represent the diversity of living organisms

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

  14. Observation #2: Nonetheless, populations tend to be stable in size • Except for seasonal fluctuations

  15. Observation #3: Resources are limited

  16. 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

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

  18. Observation #5: Much of this variation is inheritable

  19. 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

  20. 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

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

  22. Lateral buds Terminal bud Brussels sprouts Cabbage Flower cluster Leaves Cauliflower Kale Flower and stems Stem Broccoli Kohlrabi Wild mustard Figure 22.10 • Humans have modified other species over many generations by selecting and breeding individuals that possess desired traits, this is called artificial selection

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