1. Evolution & Natural Selection What does it mean to evolve? What causes evolution? What evidence do we have for evolution?VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

2. GSE’s  Genetic variations are passed on through reproduction. LS3–9a  Evidence for evolution illustrates how organisms are related. LS3-9b  Natural selection leads to evolution. LS3-9d  Our understanding of evolution has changed over time. LS3-9eVocabulary Evolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

3. Evolution The theory that organisms change (evolve) over time. What is a theory?VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

4. Why have thoughts about evolution changed?  We used to think the earth was a few thousand years old  We now know it is billions of years old from looking at rock samples.  We used to think the planet and its inhabitants have not changed since the beginning of time.  We now know the planet and its inhabitants have changed, from observing fossils.VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

5. Jean Pierre Lamark  His theory was that organisms could change their traits during their lifetime by using them or not using them.  These new traits were passed on to offspring and over time the species evolved.  Example:VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils We now know this is not possible!

6. Charles Darwin (1809-1882)  Proposed the theory of evolution by natural selection  Voyage of the HMS Beagle  Five-year journey to various places across the world  Went to South America and the south pacific collecting specimens and making observationsVocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

7. Charles Darwin (1809-1882)  Kept a journal of his findingsVocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

8. Observation: Galapagos Finches  The finches on each island had different types of beaks. Why do you think that might be?  Beaks correspond to the food the birds eat.VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

9. Darwin’s Hypothesis  Organisms had a common ancestor but had adapted to their particular environments and changed over time. What is an ancestor?  Evolution is due to a process called natural selection.  Published his theory in On the Origin of Species in November, 1859VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

10. Natural Selection Organisms best adapted to their environment have a better probability (chance) of surviving and reproducing. Organisms best adapted to their environment survive and reproduce. This can cause evolution.VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

11. Adaptation A trait or behavior that helps an organism survive in its environment. What two traits do humans have that help us adapt?  Thumbs  Language SkillsVocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

12. Example of Adaptation  How are cactuses different from most other plants?VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

13. VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils Natural selection leads to evolution! Here’s how...  Overproduction  Competition  Variations

14.  Overproduction  Too many offspring are produced.  Competition  Offspring compete for resources such as food, water, mates, and living space.  Variations  Differences in individuals of the same species.  They are passed on through reproduction. Important! Important! Variations can make some individuals more adapted to their environment than others. These individuals are more likely to survive and reproduce.VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils

15. NATURALSELECTION (best adapted are able to survive and reproduce)NATURALSELECTION OVERPRODUCTION OVERPRODUCTION COMPETITION 1. 2. 3. 4. VARIATIONS EVOLUTION_____________________________________________EVOLUTION_____________________________________________

16. VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils Evidence of Evolution  Common Ancestry  Homologous Structures  Vestigial Organs  Embryo Development  Fossils

17. VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils Common Ancestry If two species evolved from a common ancestor, then they should share some common traits with each other. Hawaiian Honeycreeper: Family of birds in Hawaii. They have similar skeletons but each species has a different beak for eating specific foods. Just like the finches Darwin observed!

18. VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils Homologous Structures Structures that are similar in two different species. They suggest that the organisms evolved from a common ancestor. What do you notice about these 6 structures?

19. VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils Body organs that do not serve a purpose. They may have served a purpose to the ancestors of a species.

20. VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils Examples of Vestigial Organs  Kiwi, a flightless bird, has wings that serve no known purpose.  Humans have a tailbone. Some scientists suggest that early humans had tails like some other mammals.

21. VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils Embryo Development What do you notice about these embryos? List two observations.

22. VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs FossilsFossils Remains of organisms preserved in rock. They give us clues about what organisms looked like in the past, and allow us to show how a species may have evolved.

23. VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils ONE LAST THING! Darwin said that variation in organisms was a factor of natural selection. But he could not explain what caused variation! What is DNA?

24. VocabularyEvolution Natural Selection AdaptationOverproductionCompetitionVariationsCommonAncestryHomologousStructures Vestigial Organs Fossils DNA is what it’s all about! We now know about DNA, the code which determines an organism’s genes. Mutations in the code (DNA) lead to variation. Mutations are changes in DNA that can be passed on to offspring. DNA from different species can be analyzed to see how related they are.

25. Combining Evidence:

26. What does it mean to evolve? What causes evolution? What evidence do we have for evolution?