1. Evolution Intro: A bit about Darwin Biology 12

2. Joke of the day:

3. Evolution  Is the process by which modern organisms have descended from ancient organisms over time  Involves significant changes to the genetic make up a species over time

4. Charles Darwin  1809 -1882  He was an English naturalist.  A keen observer of the natural world and collected many different species  He kept meticulous notes of his observations.  Darwin published his theory of evolution with compelling evidence in his 1859 book On the Origin of Species

5. Voyage of Beagle  Date: Feb 12th, 1831  Captain: Charles Darwin  Ship: H.M.S. Beagle  Destination: Voyage around the world.  Findings: evidence to propose a revolutionary hypothesis about how life changes over time

6. Where did he go?

7. What did Darwin observe and do?

8. 1. Noted Patterns of Diversity  Darwin visited Argentina and Australia which had similar grassland ecosystems. Those grasslands were inhabited by very different animals. Neither Argentina nor Australia was home to the sorts of animals that lived in European grasslands.  Darwin posed challenging questions: Why were there no rabbits in Australia, despite the presence of habitats that seemed perfect for them? Why were there no kangaroos in England?

9. 2. Collected Fossils  Darwin collected the preserved remains of ancient organisms (fossils). Some of those fossils resembled organisms that were still alive today. Others looked completely unlike any creature he had ever seen.  As Darwin studied fossils, new questions arose: Why had so many of these species disappeared? How were they related to living species?

10. Example:  Fossils of extinct animals that resembled animals present today

11. 3. The Galapagos Islands  Darwin noted that the different islands had plants and animals with traits unique to each island

12. 3. The Galapagos Islands  Giant tortoises varied in predictable ways from one island to another, the shape of a tortoise's shell could be used to identify which island a particular tortoise inhabited.

13. 3. The Galapagos Islands  He noted different species on each island

14. More of Darwin's observations:  Homologous structures: common origin but different functions  Analogous Structures: similar function but different origin

15. Homologous Structures  Homologous structure are structures that share a common origin but may serve different functions in modern species. These structures are evidence that organisms with similar structure evolved from a common ancestor.  Examples include the forelimbs of a variety of mammals. For example, human, cat, whale and bat. These species show the same skeletal elements. Is in the humerus, radius and ulna. However these skeletal elements have been modified over time to suit the different functions suitable for the type of mammal.

16. Homologous structures

17. Analogous Structures  They serve the same function between organisms but are different in internal anatomy.  Such as the wings of birds and butterflies or the eyes of lobsters and fish. These structures are of no use in classifying organisms or in working out their evolutionary relationships with each other.

18. Analogous Structures

19. Vestigial Organs  Rudimentary and non-functioning structures that are homologous to fully functioning structures in other species Vestigial organs provide further evidence for evolutionary change Examples of these include: o The human external ear muscles. o The tail bone. o Wisdom teeth. o Some snakes have skeletal limbs.  Sometimes vestigial organs may be adapted for new uses Examples: penguin winds can’t be used for flight, yet they are adapted for swimming.

20. Theory of Natural Selection  Observations: 1. Individuals within a species vary 2. Some variability can be inherited 3. More individuals are born than can survive 4. Populations of species tend to remain stable in size  Inferences: 1. Members of same species compete for survival 2. Individuals with favorable traits are more likely to survive and mate 3. These individuals will contribute more offspring to future generations therefore increasing favorable trait

21. To do :  Read pages 529-533 (section 11.6)  Answer questions 6 -9 (on page 533)  Looking for Homologies Activity  Peppered Moth Activity

22. Looking for Homologies Activity