F. DARWIN’S EVIDENCE FOR EVOLUTION

1. F. DARWIN’S EVIDENCE FOR EVOLUTION

2. 1. Fossils - fit a pattern

3. 2. Homologous structures similar structures doing very different functions a. bones in adults

4. Tiktaalik was discovered in 2006

5. fish salamander turtle chicken pig mouse dog human b. structures in embryos

6. fish salamander turtle chicken pig mouse dog human

7. fish salamander turtle chicken pig mouse dog human

8. 3. vestigial features [pg 525] structures with no function in one organism but have a function in similar organisms eg human appendix, The appendix of the gorilla is massive, accounting for its ‘fat’ stomach. This appendix houses bacteria that breakdown cellulose

9. whale pelvis A whale pelvis has the same bones as land animals, but is not attached to the spine and so is useless.

10. 4. artificial selection a. dogs All of these dogs have a recent common ancestor.

11. b. pigeons Darwin kept pigeons and was familiar with their breeding and how almost any trait could be selected for by the breeder..

12. the key is that artificial selection happens much faster as humans discard the unsuitable breeders

13. Note the differences among these kittens. 5. Mechanisms of Darwinian Evolution by Natural Selection ASSUMPTIONS 1. offspring vary

14. Setters produce setter pups, not retriever pups. 2. some of this variation is heritable

15. If all of these baby spiders survived, the world would be overrun! 3. more offspring are born than cansurvive

16. 4. populations generally do not increase in size

17. INFERENCES 1. individuals of the same species will compete 2. the survivors will pass on their ‘favourable’ traits to the next generation 3. over time, there will be more traits from the survivors in the population

18. many species arising from one common ancestor 6. Macroevolution vs Microevolution Macroevolution – change to form new species eg Darwin’s finches this takes a very longtime [10,000’s millions of years]

19. all were sprayed with herbicide but one remains green Microevolution - change within a species this takes only a short time [10’s 1000’s of years] eg. bacteria antibiotic resistance and weeds herbicide resistance

20. In this one species, there are two forms of moths eg. peppered moths light-coloured pre-Industrial trees Prior to industrialization, the light form was most common

21. light-coloured pre-Industrial trees dark-coloured post-Industrial trees prior to industrialization, the light form was most common after industrialization, the dark form became the most common Studies showed that predators selected the easier to find moths

22. Darwin’s explanation for the longer necks in giraffes? He knew that some baby giraffe’s are born with slightly longer necks. There is limited food and so these longer-necked giraffes might get more food and do better. Over time, more of the population would consist of loner necked giraffes. But Darwin was wrong!!

23. Neck length is giraffes has nothing to do with food Giraffes spend most of their time eating low, not high And bending down to get a drink is very awkward So why do giraffes need long necks? For fighting!!

24. EVIDENCE OF EVOLUTION # 1-7 time to work on these questions now