1. Zebra Mussels (An Invasive Species)

2. Lamarck: Review
Important because he was one of the first to study how a population changes over time.
Use and Disuse Theory: if an organism wants something badly enough (desire), it can acquire a new trait by use or disuse.
Inheritability of Acquired Traits = if an organism acquires (gets) a trait it did not have before, it can then pass the trait on to its offspring.

3. Lamarck: Examples Giraffes Human Flying Blacksmith Muscles Mouse Tails
Moths
Finch Beaks

4. Reasons Lamarck is Wrong
Changing the phenotype does not change the genotype.
Cannot pass on traits that you acquire throughout life; must be in your DNA
Now know more about genetics, especially mutations and variability in POPULATION.

5. Evolution and Natural Selection

6. I. Charles Darwin Charles Darwin is the father of evolutionary theory.
What question is he trying to solve?
Why do populations change over time?

7. Darwin on HMS Beagle
It took Darwin years to develop his theory of evolution; eventually published ideas in book entitled On the Origin of Species
He began in 1831 at age 22 when he took a job as a naturalist on the English ship HMS Beagle, which sailed around the world on a five-year scientific journey.

8. A map of Darwin’s voyage

9. Darwin on HMS Beagle
As the ship’s naturalist, Darwin studied and collected biological and fossil specimens at every port along the route.
After Darwin went to the Galapagos islands, the animals and plants he studied there helped him create his theory of evolution by natural selection.

10. Evolution
Evolution is when a POPULATION of organisms changes over time
Darwin proposed the idea that evolution happens through natural selection.
Developed from his idea of artificial selection = nature provides variation and HUMANS select variations they find useful

11. II. Natural Selection
Natural selection is the way evolution happens. That is, natural selection is how organisms change over time.
Natural selection is when nature selects
organisms with good genes to live and pass on their genes and…
organisms with bad genes to die out

12. II. Natural Selection
In any population, there are differences between species.
For example: These fish are different sizes, shapes and speeds.
What causes these differences?
Mutations (alterations in DNA sequences)

13. II. Natural Selection
Organisms with helpful traits, such as being fast, survive better in their environment, compared to being slower.

14. II. Natural Selection
Over time, only the organisms with the good genes (in this example, fast fish) will survive and the new population of fish will look very different from their ancestors:
Ancestors (Great-Grandparents)
New population of fish

15. Natural Selection Sometimes called “Survival of the Fittest”
Fitness: the physical traits and behaviors that enable organisms to survive and reproduce in their environment - Common Descent: the idea that all species have common ancestors

16. Darwin’s Theory of Natural Selection
1. Organisms reproduce organisms like themselves
2. There are variations in individuals in a given population & these traits can be passed on. (caused by mutations)
3. Whether an individual will survive to breed depends upon the interaction between these variations & the environment.
Some variations will be favorable  increases fitness
Variations will become more common from one generation to the next.
This is called natural selection (nature is selecting favorable traits that already exist in a population)
4. In time, natural selection will produce different groups of organisms (speciation)

17. What makes a variation favorable?
One that makes it more likely for you to:
Get food
Not get eaten
Have children
Thermal conservation

18. Giraffes (again)!! Remember:
There is variation in traits in a population due to mutation (Giraffe's necks).
More individuals are born than can survive: called the "Struggle for Existence”

19. C Giraffes with longer
necks get better food,
have more babies
(greater fitness)
C Longer necks give birth to
longer necks
(trait is passed on in genes)

20. Results:
Over time,
average neck
length increases

21. Thus, what has happens?

22. PEPPER MOTHS pre-industrialization
Which moth would be more fit? WHY???

23. PEPPER MOTHS post-industrialization
01. Now, which moth would be more fit?
WHY???
02. Explain how this happened as if you were
Darwin (in terms of natural selection).

24. You are Darwin. Explain why and how this change could happen.

25. Finch Beak Size These two finches came from the same ancestor.
According to Darwin, how did they come to look different?
What would Lamarck had said?