Evolution

1. Evolution A Change in a species over time

2. Fossil Evidence • Fossils show that organisms are different today than they were in the past

3. What fossils show • More complex organisms came from simpler ones • The older the fossil the simpler the organism

4. Homologous structures • Same basic structure in different species • Human arm and Whale fin

5. Vestigial structures • No apparent function or purpose – left over from an earlier time • Human tail bone – no purpose now, once a tail

6. Embryos as evidence • Many animals look the same as embryos showing all descended from a common ancestor • Chimps are the most closely related to humans • 99% same DNA

8. Charles Darwin • Evolution through Natural Selection

9. Variations and mutations • Organisms in the same species have variations • Mutations happen within a species most are bad

10. Evolution through natural selection • The fittest or best suited to the environment will survive to pass their traits on to their offspring • Short necked giraffes – long necked giraffes • The long necked were better suited to the environment and survived and passed the long neck gene to future generations

11. Natural selection

13. adaptations • Come from variations and beneficial mutations • (Thumbs were a mutation) • Some mutations are harmful, those organisms will not survive and that trail will not be passed on to the offspring variations and mutations that are beneficial to surviving allow the organism to pass the trait to their offspring

14. Divergent evolution • When one species becomes two different species • A species gets separated due to earthquake or forest fire or some natural event. • Gene pools is closed to only those individuals and over time they develop through differently through variations

15. All these finches were the same species – the birds few to different islands and evolved into different species – notice the different beaks, each beak evolved to eat different kinds of seeds