1. Evolution
And Natural Selection

2. Early Earth Believed to be 4.5 billion years old
Thought to have had a very anaerobic atmosphere
Earliest organisms were able to survive primitive environments
Prokaryotes that resemble today’s bacteria
Endosymbiotic theory – says that eukaryotes arose from small prokaryotes living inside of larger prokaryotes
Lead to development of double membrane bound organelles like mitochondria and chloroplasts

3. Older theories of evolution… Darwin wasn’t the only one!
Jean Baptiste Lamarck
(early 1800’s) proposed:
“The inheritance of acquired characteristics”
He proposed that by using or not using its body parts, an individual tends to develop certain characteristics, which it passes on to its offspring.

4. .
Thomas Malthus
Reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone

5. Wallace Shared ideas with Darwin
Formulated his own theory of evolution that it resulted largely from competition among resources – he thought COMPETITION was the driving force behind evolution

6. Charles Darwin
Darwin set sail on the H.M.S. Beagle ( ) to survey the south seas (mainly South America and the Galapagos Islands) to collect plants and animals.
On the Galapagos Islands, Darwin observed species that lived no where else in the world. - These observations led Darwin to write a book.
“On the Origin of Species by Means of Natural Selection”

7. CHECKPOINT
Who believed that acquired characteristics were passed on or inherited?
Hand up – Darwin
Deuces up – Wallace
Thumbs up - Lamark

8. “Origin of Species” 2 Main points: NATURAL SELECTION
1. Species were not created in their present form, but evolved from ancestral species.
2. Proposed a mechanism for evolution:
NATURAL SELECTION
Individuals with favorable traits are more likely to leave more offspring better suited for their environment.

9. Natural Selection

10. Artificial Selection
The selective breeding of domesticated plants and animals by man
Humans select variations that are useful
Ex: a farmer only breeds his best livestock

12. CHECKPOINT For the following examples…
Thumbs up = natural selection
Thumbs down = artificial selection
Pesticide (pest killer) resistant insects
Dog breeding
Mating two quality race horses to get quality offspring
Galapagos islands finches
Talk to your neighbor and come up with one example of natural selection and one of artificial selection

13. Summary of Darwin’s Theory
1. Organisms differ; variation is inherited 2. Organisms produce more offspring than survive 3. Organisms compete for resources 4. Organisms with advantages survive to pass those advantages to their children (“Survival of the fittest”)

14. Evidence of Evolution Fossil record – fossils and the order in which they appear in layers of sedimentary rock
Absolute dating:
Relative dating:
Can determine a fossil’s relative age
Performed by estimating fossil age compared with that of other fossils
Can determine the absolute age in numbers
Is performed by radioactive dating – based on the amount of remaining radioactive isotopes

15. Evidence of Evolution Biogeography: Embryology:
Geographical distribution of living species
Similar animals in different locations
Embryology:
Study of structures that appear during embryonic development

16. Evidence of Evolution Vestigial Structures: Homologous structures:
Body parts of different organisms that have similar structures but may have different functions
Analogous structures:
Do NOT indicate shared ancestry
Body parts with similar functions but not structures
Vestigial Structures:
Body parts that serve no major or useful role in an organism’s life functions
Ex: human appendix

17. SUMMARY
Use the word EVOLUTION to create an acrostic using key words and phrases from our notes and discussions over the last couple days! E V O L U T I N