1. 15 – 3 Darwin Presents His Case
Biology
Pgs
Baker

2. The Findings – The Origin of Species by Means of Natural Selection#6
Published in 1859 – 30 years after Darwin’s voyage on the HMS Beagle.
In Darwin’s book he assembled the evidence supporting evolution and he proposed a hypothesis to explain how evolution occurs.

3. Of Farmers and Pigeons
Upon Darwin’s return from his voyage he extended his thinking about organisms to observations of farm animals and agricultural crops in England.
No Two Alike
Artificial Selection

4. No Two Alike
Plant and animal breeders told Darwin that no two plants or no two animals were exactly alike.
Some plants produced more fruit and some cows made more milk.

5. Artificial Selection #7
Farmers were doing this by picking only the largest hogs, fastest horses and the cows that gave the most milk to breed.
Nature provided variation and in artificial selection the humans intervene and decide which organisms will produce offspring.

6. Selection in Nature Variation in Nature Struggle for Existence
Natural Selection

7. Variation in Nature
The variation in nature that Darwin observed was not linked to Gregor Mendel’s principles on genetics until later since Mendel’s work was not published until 1866.
Variation is common in nature and in areas where humans control the reproduction.

8. Competition & Fitness
Competition is present among members of the same species.
Those that are able to win in this struggle survive to reproduce offspring.

9. Struggle for Existence (fitness)#8
Darwin related Malthus’ thinking regarding high birth rates and decreasing resources to the struggle for existence.
The fastest predators catch the most prey and the best camouflaged prey escape being hunted.

10. Natural Selection Survival of the fittest.#9
Survival of the fittest.
The animals that are the most fit will survive to reproduce.
Over time generations become better suited to survive in their environment.

11. Descent with modifications?
#10
Each living species has descended, with changes, from other species over time.

12. Common Descent
#11
Darwin proposed that organisms were not spontaneously produced as we know them.
If you were able to trace back far enough all living things share a common ancestors.

13. Evidence of Evolution #12
Fossil Records – different species have been present at different times.
Geographic Distribution of Living Species – Places with similar ecological conditions have animals that share common features.
Homologous Body Structures – Different types of body parts sharing the same basic structure.
Embryology – Patterns at which various embryonic cells appear in various vertebrates.

14. #13 Charles Darwin’s theory of evolution:
Variation – Individuals are different.
Overproduction – Organisms produce more than can survive.
Struggle for existence – compete for resources.
Species change – Individuals best suited for their environment live to reproduce and others die off.
New species form – All organisms came from a common ancester.

15. Evolutionary Theory
#14
Strengths – insight into biological & biomedical sciences.
Weakness – mechanism by which a new species may arise is unknown.

16. Common Misconception: