1. Evidence for Evolution
EQ: How do the various forms of evidence support the theory of evolution?

2. Evidence for Evolution
Biogeography
The distribution of plants and animals world wide follows a set pattern
Isolated islands have similar plants and animals as the mainland
Fossils of the same animal are found on different continents

3. Biogeography

4. Evidence for Evolution
Comparative Anatomy
Homologous structures exist in different species
These are structures that are similar in form but different in function
Embryological similarities exist
The developmental stages of closely related organisms are similar
Molecular Biology
Compare the DNA of two different species
The more similarities that exist the more related the organism are to each other

7. Homologous Structures

8. Evidence of Evolution includes The fossil record
Geographic distribution of living species
Homologous body structures
Similarities in early development
which is composed of
which indicates
which implies
which implies
Physical remains of organisms
Common ancestral species
Similar genes

9. Natural Selection Theory Assumptions
More offspring are born than can survive
There is phenotypic variation within a population
Variations are caused by changes or mutations in the DNA
Mutations occur by random chance
All organisms struggle to survive
Nature selects those variations that are best fit for the environment

10. Evidence for Evolution
Fossils are the remain of ancient organisms preserved in the different layers of rocks
The law of superposition states that the fossils in the top layers of the earth are younger than the fossils found in the lower layers of the earth
Often shows how species changed over time

14. Age of Things
In 1778 a scientist named Hutton brought up the idea that the earth was very old
The rocks, mountains and valleys were all shaped over time by erosion
Finally have agreed upon the age of ~ 4.6 billions years
Geologic Time Scale
The rocks on the bottom are older than the rocks on top of any land feature
Allowed scientists to place the age of fossils found in the rocks through relative dating
Called the law of superposition

15. Radioactive Dating
Used to date rocks and fossils with more accuracy than relative dating
Rocks and bones contain radioactive elements
A radioactive element is one that is unstable in its current form and eventually breaks down into a more stable form releasing heat
The amount of time for half of the element to break down is its half – life
The amount of time it takes for half of the elements to go from unstable to stable

16. Radioactive Dating
Different elements have different half lives allowing scientists to fairly accurately pinpoint when the organism died
This is done by comparing how much of an element is still unstable with how much is stable
Old form used C14 but it has a large margin of error
New form uses K40

19. Geologic Time Periods Precambrian Life on earth begins – we think
Is it possible that life began before this?
Earliest fossils of life are dated to 3.5 billion years ago
Some evidence suggests it started around 3.8 billion years ago
Early animals were single and multicellular
Some show evidence of cellular organization like modern jellyfish

20. Paleozoic Time of major evolution
Organisms with shells and skeletons appear
Size of individuals increased
First invertebrates like the trilobites
First jawless fish
First fish and forests
The earth became inhabitable by organisms much like the ones we see today
Ends in mass extinction
90% of all marine species
66% of all reptile and amphibians
30% of all insects

21. Mesozoic Age of the dinosaurs First mammals and flowering plants
The dinosaurs came and went in the mesozoic
Were only on the planet for 70 million yrs
First mammals and flowering plants
Rocky mountains appeared
Ended with a major extinction
Most likely caused by a meteor crashing in the Gulf of Mexico
Changed the climate

22. Cenozoic Age of the mammal Humans evolved during this time
Grasses become abundant
First early horses appear
Whales and other large mammals appear
Humans evolved during this time
Variable climates
Sea life very similar to today

23. Age of Civilization Early man appears 2.5 million years ago
Many different species of man exist before our present state is reached
Possible that more than one species of man was present at any given time

25. Athropocene Age of Man New geologic Epoch
Defined by man’s influence on the environment
Started approximately 8000 years ago
This is the time in which man began using agriculture to create food
38% of the land is now used for farming
Actual start is being debated
First purposed in 1870
First scientific papers published using it as an official time period were published in the early part of this century