1. 15-3 Darwin Presents His Case

2. I. Inherited Variation & Artificial Selection

3. Desired traits are selected for human use.
Artificial Selection- humans take advantage of the genetic variation that already exists in plants & animals.
Desired traits are selected for human use.
From a single ancestral plant breeders selected for different traits

4. II. Evolution Happens As A Result of Natural Selection

5. Evolution happens because organisms:
Struggle for Existence- members of species (plants, animals, bacteria, etc.) compete for food, water, shelter, & mates
These bears fight for food, mates, and territory

6. Adaptation- An inherited trait that helps an organism survive & reproduce.

7. Survival of the fittest- Fitness is the ability of an organism to survive in its environment that results from inherit traits (adaptations)
Cheetahs that are the faster runners catch more food and survive to reproduce and pass their genes to the next generation

8. The traits are inherited which slowly changes a population over time
Natural Selection- nature selects traits that are best suited for survival.
The traits are inherited which slowly changes a population over time
In this cartoon, darker colored birds are more successful at surviving and reproducing than lighter colored birds, and so they increase their proportion in the population in later generations.

9. Natural selection can’t be seen directly, it can only be observed as a population slowly changes over many generations.

10. Descent w/ Modification- All living species have descended from a common ancestor w/ changes (modification) over time
Evolution of the Camel

11. III. Evidence For Evolution
These bones that are similar in all of these animals is evidence that they have a common ancestor

12. Prehistoric “Ice Man” in Andes Mountains
The fossil record- All of fossilized artifacts & how they are placed w/i the earth's rock layers or sedimentary rocks.
provides information about the history of life on earth
Strata of rock w/ fossils

13. Biogeography- the way species are spread around the world
Darwin used this to explain how species evolved from common ancestors
Lizards on different islands of
the Galapagos

14. Homologous Structures- structures that have different mature forms but develop from the same embryonic tissues

15. Discuss w/ Partner:
Discuss w/ partner: What do you have in common w/ the cat, whale, & bat.

16. Whales evolved from mammals that
Vestigial Organ- organ that has no useful function in an organism.
Left-overs of homologous organs in other species
Whales evolved from mammals that
lived on land

17. Ex: legs of skinks, a type of lizard
Coccyx (tailbone) in humans

18. Similarities in Embryology- the study of structures that appear during the development of different organisms
Tortoise
Pig
Lizard
Human

19. What do these embryos have in common?
Discuss w/ Partner:
What do these embryos have in common?

20. Molecular Biology- the study of the molecular basis of genes and gene expression

21. Discuss w/ Partner:
Which two organisms have the most amino acids in common?
Which two organisms have the least amino acids in common?

22. Answers:
Which two organisms have the most amino acids in common? Humans and the Rhesus monkey
Which two organisms have the least amino acids in common? Humans and the lamprey

23. The genetic code is nearly universal in all organisms on earth
All organisms use the same 20 amino acids to make proteins
The Genetic Code is the 20 amino acids that makes proteins