Speciation PowerPoint PPT Presentation

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1. Speciation

2. Warm-Up 10/29 Which fish would be the most primitive? Knowing that whales have a vestigial pelvis and femur, would you say they evolved before or after mammals left the ocean?

3. Objective How do new species come about?

4. Natural Selection- Changes in Populations

5. The Process of Speciation – If animals continue to evolve and their genes change enough, they become a new species. Species- a group of organisms that breed with one another and produce a fertile offspring. If two animals cannot or do not breed with each other and produce a fertile offspring, they have created a new species. Reproductive Isolation

17. Causes of Speciation Behavioral Isolation- When two populations are capable of reproducing but have different courtship rituals or other reproductive strategies.

18. Bower Birds- Behavioral Isolation

19. Causes of Speciation Geographic Isolation Two populations are separated by geographic barriers

20. Causes of Speciation Temporal Isolation Two or more species cannot reproduce because they do not reproduce at the same time.

21. Question What type of isolation is seen in Darwin’s Finches? Had speciation occurred?

22. Wrap-up Speciation is when natural selection occurs to such an extent that the two groups can no longer mate. There are several things that cause speciation.

23. Warm-up (10/30) Define Speciation. What are 3 ways that 1 population can become 2 different species?

24. Objective How do scientists show evolutionary relationships between organisms? What is the difference between convergent and divergent evolution?

25. Examples of Cladograms

27. Phylogeny Phylogeny—the evolutionary history of a group of life forms. Phylogenetic tree—an evolutionary “family tree” that shows who evolved from whom. Can also be called a cladogram A cladogram can also show derived traits (characteristics) – “the checkpoints”

29. Patterns of Evolution Extinction Divergent Evolution (adaptive radiation) Convergent Evolution Coevolution

30. Extinction Why do species go extinct?

31. Extinction Natural selection, climate changes, and catastrophic events have caused 99 percent of all species that have ever lived to become extinct. Mass extinctions – caused by continents moving, sea level changing, volcano eruptions, large meteors

32. Predict what each ecosystem will look like after the event.

33. Question When a mass extinction happens, what do you think will happen next?

34. Divergent Evolution (adaptive radiation) Divergent evolution – natural selection causes 1 species to evolve into many species with many different adaptations (homologous structures) After mass extinctions, many environments will be open for inhabitation Species will migrate to that area and new environmental pressures will cause the population to change over time

35. Adaptive Radiation in honeycreepers

36. Convergent Evolution Convergent Evolution – when unrelated organisms come to resemble one another (analagous structures)

37. Coevolution When 2 species evolve in response to one another

38. Wrap-up Cladograms (phylogenetic trees) are used to show evolutionary relationships between different organisms Scientists use the evidence of evolution (homologous/analagous structures, fossils, biochemical comparison) to predict these evolutionary relationships Convergent vs Divergent Evolution

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