Evolution

2. Evolution • Evolution –process through which species change over time. The process by which modern organisms (multicellular) have descended from ancient organisms (unicellular) • Jean Baptiste de Lamarck was the first scientist to propose a model of how life evolves

3. Lamarck’ s theory of acquired characteristics • Lamarck said organisms acquired traits by using their bodies in new ways • These new characteristics were passed to offspring • Lamarck was unable to provide an evidence to support his ideas

4. Charles Darwin (1809-1882) Sailed around the world (1831-1836) Brainpop - Charles Darwin

5. What did Darwin’s travels reveal? • The diversity of living species was far greater than anyone had previously known!! • Darwin made observations on his voyage that later became the foundation for his theory of evolution by natural selection

6. How did the finches differ among the islands of the Galapagos? • Darwin noticed differences between the finches on the island and those of the nearby mainland • Each island had its own type of finch that were clearly different from the other islands • Darwin specifically noticed the differences in the shape of their beaks and in the food they ate

7. Darwin Thought Darwin wondered why the island finches were different from the mainland finches He hypothesized that perhaps some finches were blown to the island by a storm and over time the finches that survived adapted to different ways of living on the islandsDarwin Finches

8. Darwin’s Thoughts Continued • Darwin looked to selective breeding for clues • selective breeding - humans, not nature, select which traits will be passed along to the next generation (a farmer breeds only his best livestock)

9. Darwin’s Thoughts Continued • Darwin proposed that nature works somewhat in the same way… organisms that are better adapted are able to survive and reproduce • So they are somewhat “selected”bynature and pass their helpful trait to their offspring • Natural selection – members of a species that are best suited to their environment survive and reproduce at a higher rate than other members of the species

10. Brainpop - Natural Selection

13. Darwin’s Thoughts Continued • Mutation – change in the DNA - mutation causes no effect -mutation is harmful -mutation is beneficial Beneficial mutations allow organisms to survive and reproduce at a higher rate

14. Natural Selection Wins! • In 1859, Darwin published his results in his book called On the Origin of Species by Means of Natural Selection • Darwin theorized that evolution occurs through a process he called natural selection (survival of the fittest)

15. 1. Overproduction-each species produces more offspring than will survive to maturity. 2. Genetic Variation- the individuals in a population are slightly different from one another. Some traits increase the chances that the individual will survive and reproduce. Natural Selection in 4 Steps

16. 3. Struggle to Survive - a natural environment does not have enough food, water, and other resources to support all the individuals born. In addition, many are killed by other organisms. 4. Successful Reproduction- the individuals that are well adapted to their environment are more likely to survive and reproduce. Natural Selection in 4 Steps

17. Insecticide Resistance • Insects quickly develop resistance to insecticides because they produce many offspring and usually have short generation times. • A generation time is the period between the birth of one generation and the birth of the next generation. • In the 50 years that insecticides have been used, more than 500 species of insects have developed resistance to certain insecticides.

18. Formation of New Species • Natural selection can explain how a species can evolve into a new species. • Over time, two populations can become so different that they can no longer interbreed. This process is called speciation.

19. 3 Ways Speciation Can Occur • 1. Separation - a newly formed canyon, mountain range, or lake are a few ways that populations can be divided.

20. 2. Adaptation - if a population has been separated, the environment may also change. To live the species must adapt to the new environment.

21. 3. Division - over thousand or millions of generations, the two groups of a population may become so different that they can no longer interbreed. At this point, they are no longer the same species.

22. Peppered Moths of Manchester • Peppered moths spent most of their time resting on the bark of oak tree trunks. Most of the oak trees in England were light brown, speckled with green. • Most of the peppered moths at that time were light brown too. • Some dark ones around, but few.

23. Peppered Moths of Manchester • Pollution from Industrial Revolution stained London trees dark brown • Suddenly scientists noticed the population of dark moths increased, and the light moths population decreased

24. Peppered Moths of Manchester • Birds were the moths major predator • Birds can not see moths (prey) that blend in with tree trunks because they were camouflaged • The dark moths reproduced which increased the population of dark moths • Kettlewell- scientist who studied peppered moths

25. Fossils are evidence of Evolution! Fossil Rock Anthem

26. Paleontology- study of extinct life Fossils – remains of organisms preserved in the earth Mastadon Pterosaur

27. T-Rex • Fossils provide evidence about the history of life • Fossils show how organisms have changed over time • Fossil records are incomplete because most organisms die without leaving any trace! Brittle Star

28. Vestigial Structures • Vestigial Structures- body parts that are reduced in size and have no function • Whale evolution • Suggests that as the body part was no longer needed in the environment they were lost or reduced in size • Examples • hip and leg bones in snakes • pelvic and femur bones in whales suggest they once had back legs

29. Older fossils are usually found in the bottom geologic layer!