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Evolution & Natural Selection What does it mean to evolve? What causes evolution?

Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils. Evolution & Natural Selection What does it mean to evolve? What causes evolution? What evidence do we have for evolution?.

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Evolution & Natural Selection What does it mean to evolve? What causes evolution?

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  1. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils Evolution & Natural Selection What does it mean to evolve? What causes evolution? What evidence do we have for evolution?

  2. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • 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. LS3-9e

  3. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • Evolution • The theory that organisms change (evolve) over time. • What is a theory?

  4. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • 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 knowthe planet and its inhabitants have changed, from observing fossils.

  5. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • 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: We now know this is not possible!

  6. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • 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 observations

  7. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • Charles Darwin • (1809-1882) • Kept a journal of his findings

  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. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures 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, 1859 Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils

  10. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • 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.

  11. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • 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 Skills

  12. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • Example of Adaptation • How are cactuses different • from most other plants?

  13. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • Natural selection leads to evolution! Here’s how... • Overproduction • Competition • Variations

  14. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • 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! Variations can make some individuals more adapted to their environment than others. These individuals are more likely to survive and reproduce.

  15. OVERPRODUCTION NATURAL SELECTION (best adapted are able to survive and reproduce) VARIATIONS COMPETITION 1. 2. 3. 4. EVOLUTION _____________________________________________

  16. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • Evidence of Evolution • Common Ancestry • Homologous Structures • Vestigial Organs • Embryo Development • Fossils

  17. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures 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. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures 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. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils • Vestigial Organs • Body organs that do not serve a purpose. • They may have served a purpose to the ancestors of a species.

  20. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures 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. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils Embryo Development What do you notice about these embryos? List two observations.

  22. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures Vestigial Organs Fossils Fossils 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. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures 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. Vocabulary Evolution Natural Selection Adaptation Overproduction Competition Variations Common Ancestry Homologous Structures 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?

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