1. How does evolution happen? LAMARCK vs DARWIN
Inheritance of Acquired Traits
Natural Selection

2. REMEMBER: DARWIN and LAMARCK DIDN’T KNOW ABOUT DNA or GENES

3. LAMARCK Inheritance of Acquired Traits
Ancestor giraffes had shorter necks than modern giraffes.
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4. What do Giraffes eat?
- Prefer flowers and fruit when in season MAJORITY OF DIET COMES FROM eating: - leaves and buds on trees and shrubs In lesser amounts: - Herbs and climbing vines - small amounts of grass

5. LAMARCK Inheritance of Acquired Traits
If a giraffe repeatedly reached for food high up in tall branches its neck would stretch longer and when it reproduced its offspring would have a longer neck, too.

6. LAMARCK Inheritance of Acquired Traits
Over time more giraffes will have longer necks
Result of INDIVIDUALS changing by acquiring new traits
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7. WHAT’S WRONG WITH LAMARCK’s INHERITANCE OF ACQUIRED TRAITS IDEA?
- Giraffes can’t make necks longer by stretching.
- Individuals can develop some characteristics over their lifetime, (increasing muscle size, learning a skill) but these developments are NOT passed on to their offspring - DNA carries the genetic code; Inheritance is based on GENES
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8. DARWIN- NATURAL VARIATION “Everyone is different”
Ancestor giraffes all have different sizes of necks
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9. DARWIN- NATURAL SELECTION
Some individuals ALREADY HAVE TRAIT. They have an advantage in that environment and survive.
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10. DARWIN - “Struggle for Existence” Competition for resources
Giraffes must compete with each other to get the food and other resources they need

11. DARWIN- NATURAL SELECTION “Survival of the Fittest”
“Winners“
“Winners“
“Winners“
“Winners“
Giraffes in population with longer necks will be able to reach more food, survive long enough to reproduce, and pass on their long neck trait to offspring.
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12. DARWIN- NATURAL SELECTION “Survival of the Fittest”
“Losers“
“Losers“
“Losers“
Giraffes in population with shorter necks have harder time getting food. Some will die.
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13. DARWIN- NATURAL SELECTION
Over time the number of giraffes with longer necks increases in population.
INDIVIDUALS DON’T CHANGE. POPULATION CHANGES.
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14. MISCONCEPTION: Evolution DOES NOT INVOLVE “needing something” OR ‘trying’ to adapt.”

15. MISCONCEPTION: Evolution DOES NOT INVOLVE “needing something” OR “trying to adapt.”

16. Either an individual has genes that are good enough to survive and reproduce, or it does not—but it can’t get the right genes by “trying.”
Nature is selecting for individuals that ALREADY HAVE THE GENE/TRAIT.