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Speciation

Speciation. Chapter 16-3. Review Standard 8a. Students know how natural selection determines the differential survival of groups of organisms. What is natural selection? In nature, certain animals are selected (survive) because they have traits and behaviors that benefit them.

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Speciation

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  1. Speciation Chapter 16-3

  2. Review Standard 8a • Students know how natural selection determines the differential survival of groups of organisms. • What is natural selection? • In nature, certain animals are selected (survive) because they have traits and behaviors that benefit them.

  3. Example - Peppered Moths There were two kinds of peppered moths that lived in England. One kind was black with white spots and the other kind was white with black spots. • There were more white ones with black spots. • Then the Industrial Revolution happened • Black Soot covered trees caused change in the population of the peppered moths • Now there were more black moths then white moths

  4. Standard 8b • Students know a great diversity of species increases the chance that at least some organisms survive major changes in the environment. • Diversity? • A variety of a species, or kind of organism

  5. Speciation For each animal, Write down • Describe the shape of each beak. • What do you think this bird eats? • Where (what environment) you think the bird lives in? 1 2 3 5 4

  6. Speciation • If all these birds lived in the same area, and a drought killed all the fish in a nearby lake, what do you think would happen? • What if a storm hit and the only thing that was left was small insects. Who would survive? What would the other birds need to do in order to survive? • Having different species ensures survival in the event of an environmental change.

  7. Back to Speciation • Now that we know the natural selection can change an allele frequency and change the way a population looks, but how does this lead to the formation of a new species? • Speciation: Process by which species can evolve from old ones. • Let’s find out the mechanism of how this occurs.

  8. Isolating Mechanisms • As different types of organisms change and evolve, populations become reproductively isolated from each other. • Wha? • Reproductive Isolation: When the members of two populations cannot interbreed and produce fertile offspring. • Wha? • How does this happen?

  9. Behavioral Isolation • Behavioral Isolation: Do not interbreed because of behavior differences in courtship rituals or other reproductive strategies. • Think of it like social customs…

  10. Geographic Isolation • Geographic Isolation: Populations are separated by geographic barriers (rivers, mountains, bodies of water)

  11. Temporal Isolation • Temporal Isolation: Populations are separated because of different mating times.

  12. Back to the Birds… • Remember the standards… Why is it good to have different species? • Peter and Rosemary Grant from Princeton went to the Galapagos to observe the finches and natural selection. • Noticed that during a drought, smaller-beaked finches died off. • What type of selection is this? [directional, stabilizing, disruptive]

  13. Back to the Birds • The hypothesis as to how the Galapagos finches evolved: • Founders arrive • Separation of populations • Changes in the gene pool • Reproductive isolation • Ecological competition

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