1. "Nothing in Biology makes sense except in the light of evolution
"Nothing in Biology makes sense except in the light of evolution." ~Theodosius Dobzhansky

2. Evolution A scientific theory Subject to verification
Explains observed phenomena based on observable scientific facts
Continuously being tested as new evidence is found

3. Evolution is change over time

4. First theory of evolution proposed by Jean Baptiste de Lamarck (1744-1829)
He hypothesized that similar species descended from a common ancester
All living species were descended from similar extinct species evident in the fossil record
To support his hypothesis, he used acquired traits
Acquired trait-one that is not determined by genes-it arises during an organism's lifetime as a result of its experiences or behaviors
He was the first to propose that species change over time

5. Jean Baptiste de Lamarck and acquired traits

6. THEN 50 years later…
Charles Darwin and Alfred Wallace independently proposed the hypothesis that species were modified by natural selection

7. Darwin
Was 22 years old when he took a job as a naturalist aboard the H.M.S. Beagle
The Beagle traveled to South America and the South Pacific on a five year voyage

8. Darwin’s Voyage

9. During that time,
Darwin collected specimens and kept records of his observations
He look at 13 similar but different species of finches on the Galapagos Islands

10. On the islands, All the finches seemed to share a common ancester
All had bill differences

11. In 1858, Darwin Published his book The Origin of Species

12. Darwin’s Theories:
Descent with Modification: the newer forms in the fossil record are actually the modified descendants of older species
all living things probably descended from one (or a few) common ancestors
similar organisms arise in the same geographic locations

13. Cont. Modification by Natural Selection: how evolution occurs
natural selection-process by which organisms with favorable variations reproduce at higher rates than those without variations

14. Fitness The ability to reproduce successfully
The environment “selects” traits that will increase in a population

15. Adaptation
The ability of an organism to change in order to help the organism survive in a given environment
Unfavorable traits gradually disappear because the organisms die out

16. Factors that Affect Natural Selection
Overproduction- producing more offspring than can possibly survive
2. Competition – food and resources
are limited. (only the strongest survive)
Variations – slight differences among offspring

17. Organisms change over time through mutations and sexual reproduction