1. Honors Biology Unit 7 Powerpoint #2 2011-2012
Patterns of Evolution
Honors Biology
Unit 7
Powerpoint #2

2. Macroevolution
Large-scale evolutionary patterns and processes that occur over long periods of time
Key Concept: 6 important patterns of macroevolutions

3. 1) Mass Extinction
When many different species of organisms go extinct at the same time.
End of Paleozoic: 95% of complex life (both plants and animals on the land and in the sea) went extinct.

4. Causes of Mass Extinction
Climate Change: rapid changes in yearly weather patterns. Example: Ice Age
Volcanism: the sudden oozing of millions of cubic meters of lava from the earth that release gasses poisoning the atmosphere
Impact Events: Meteors or asteroids impacting the earth

5. The Future of Mass Extinction
E.O. Wilson of Harvard University predicts that man’s destruction of the biosphere will lead to the extinction of 50% of the species on earth in the next 100 years.
70% of biologists agree

6. Example of Mass Extinction: 65 Million years ago (very recent)
50% of all species went extinct including dinosaurs
Thought to be caused by the Chicxulub Meteor which hit the Yucatan Peninsula in Mexico.

7. Chicxulub Crater

8. Chicxulub Crater Made by a meteor 6 miles in Diameter
Equivalent to exploding 190,000 gigatons of TNT

9. Tsar Bomba: By comparison: The most powerful nuclear bomb ever tested (Russia 1961) was only 0.05 gigatons

10. 2) Adaptive Radiation
A single species, or small group, evolves, through natural selection into diverse forms.
Example:
Darwin’s Galapagos Finches

11. 3) Convergent Evolution
When unrelated organisms come to resemble each other due to environmental demands.
Example:
Placental v. Marsupials

12. 4) Coevolution
When two species evolve in response to changes to each other over time
Example:
Insects and flowers

13. 5) Punctuated Equilibrium
Long stable periods interrupted by periods of rapid change.
Example:
Darwin’s Galapagos Finches

14. 6) Developmental Genes & Body Plans
Small changes in the activity of control genes can produce large changes in adult animals
Example:
HOX genes

15. Fossil Evidence of Mass Extinction
Fossilization does not happen very often.
Mass Extinctions also do not occur very often.
Scientist believe that there are more fossils to be found around the time of mass extinctions than any other time.

16. Strata Layers of dirt and stone from different time periods on earth.
Form bands of rock layers.

18. Geologic Time
Based Upon major changes in the fossil record in the rock strata
ERAS are longer time divisions than PERIODS
There are four eras:
Precambrian (4.6 billion – 544 million years ago)
Paleozoic ( million years ago)
Mesozoic (245 – 65 million years ago)
Cenozoic (65 million – Present)

20. Dating of Fossils (p )
Relative Dating: estimates a fossils age compared with other fossils but no info about age in years
Index Fossils: distinctive fossil used to compare the relative ages of fossils
Radioactive Dating: Calculate the age of a sample based on amount of remaining radioactive isotopes it contains
Half-life: length of time required for half of the radioactive atoms in a sample to decay