The slow, gradual change in a population of organisms over time

Transcription

1 The slow, gradual change in a population of organisms over time SB5. Students will evaluate the role of natural selection in the development of the theory of evolution.

2 acquired characteristics inherited characteristics variation fossil record embryology geographic distribution biochemistry homologous structures analogous structures vestigial structures evolution evidence comparative anatomy

3 Jean Baptiste Lamarck Believed that organisms had changed over time Idea of use and disuse You either use it or you lose it like your appendix! Inheritance of ACQUIRED CHARACTERISTICS Giraffe necks

4 Charles Darwin Father of modern evolution *Darwin disagreed with Lamarck! Sailed around the world on the HMS Beagle Most important stop was in the Galapagos Islands, 1000 km off the coast of South America Believed in Descent with Modification You can only pass on genes to your offspring Jointly published the Theory of Evolution by Natural Selection (1858) with Alfred Russell Wallace

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6 Adaptations: characteristics that help organisms survive and reproduce Physical Behaviors Species: group of organisms that can mate and reproduce

7 Scientists have observed: Variations (changes) in species Changes in inherited characteristics in populations As populations change over time, new species form.

8 There are 7 different methods that scientists use to prove evolution: 1. Fossil Records 2. Homologous Structures 3. Analogous Structures 4. Vestigial Structures 5. Embryology 6. Geographic Distribution 7. Biochemistry

9 7 Evidences for Evolution Looking at organisms from long ago and comparing them to modern species

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12 7 Evidences for Evolution Any structure that is similar among organism due to a common ancestor Type of comparative anatomy

13 Modern Whale Dorudon-40 mya Ambulocetus-49 mya Pakicetus-50 mya

14 7 Evidences for Evolution Structures that are similar NOT due to a common ancestor but instead a common environment or habitat Type of comparative anatomy

15 7 Evidences for Evolution Structures that are no longer used by the organism that have decreased in size and/or function Examples: whale leg, ostrich wing, human appendix

16 7 Evidences for Evolution Organisms that are of a common ancestry will develop in a similar fashion Ontogeny Recapitulates Phylogeny MEANS Embryonic Development helps to explain our evolutionary history

17 7 Evidences for Evolution The distribution of fossils will tell you where they once lived or if they went extinct

18 7 Evidences for Evolution Comparison of DNA and RNA similarities

19 competition fitness natural selection Sexual selection Disruptive selection Stabilizing selection Directional selection

20 More organisms were produced than the environment could support There was always a struggle for resources (COMPETITION) Water Food Shelter Mates Only a fraction of the offspring survive. This is called SURVIVAL OF THE FITTEST. What does the word FIT mean?

21 FITNESS the ability to survive and reproduce Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals This is Natural Selection

22 The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection)

23 1. How are Lamarck s views different from those of Darwin & Wallace? 2. Name 2 types of evidence for natural selection and describe HOW scientists use it. 3. Describe the difference between homologous and analogous structures. 4. What is meant by fitness?

24 : organisms with the best adaptations will survive and reproduce

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29 1. Sexual 2. Disruptive 3. Stabilizing 4. Directional

30 Traits are increased or decreased in a population due to mate choice Usually the female does the choosing Males need to: be more attractive Provide shelter for young Fight for feminine approval

31 Natural Selection is favoring both extremes of a trait Leads to 2 new species after a LONG period of time

32 Natural selection is favoring the intermediate (heterozygote) trait

33 Natural selection is favoring one extreme of the trait