1. Evidence of Evolution Part 2

2. Biology Chapter 12 Section 1b
Objectives:
Recognize that various lines of evidence for evolution exist
Apply knowledge of evolution to organisms (both modern and extinct)

3. Evidence of Evolution
In addition to fossils, other evidence supports the theory of evolution
Comparative anatomy: study of the structures of different organisms
Remember, a theory in science means:
The idea has been tested repeatedly and so far not disproven

4. Homologous Structures
Homologous structures: body parts similar in origin and structure
Homologous: from the ancient Greek meaning “to agree”
Homologous structures developed from the same body part in a common ancestor
Homologous structures are the result of divergent evolution

5. Homologous Structures
From and Monroe and Wicander, The Changing Earth, 3rd Edition

6. Homologous Structures
Not necessarily similar in function
Homologous structures indicate organisms are related (have a common ancestor)
The greater the number of homologous structures, the more closely related

7. Homologous Structures
Homologous structures the result of having the same structural genes
Structural genes control the presence of a particular part

8. Homologous Structures
Regulatory genes control the shape and form of the structures made by structural genes
When the structure begins growth
Rate of growth
When the structure stops growing

9. Homologous Structures
From

10. Vestigial Structures
Suppose a structure becomes unnecessary— the genes making it don’t just disappear
Vestigial structures: structures an organism has that are like those another organism has, but which are not used
Vestigial structures indicate similarities and common ancestors in organisms because they are created by similar structural genes

11. Vestigial Structures Examples of vestigial structures:
Flightless birds have wings

12. Vestigial Structures

13. Vestigial Structures Examples of vestigial structures:
Hind leg bones in whales
Human tail bone (coccyx)
Human appendix
Pig toes (the little ones)

14. Vestigial Structures

15. Vestigial Structures

16. Vestigial Structures

17. Vestigial Structures

18. Vestigial Structures