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How Natural Selection Happens
How Natural Selection Works
• How does the “fittest” organism happen?
How do we get organisms with the best traits?1. Lots of offspring
2. Differences or variations occur in those offspring (due to sexual reproduction or mutations)
3. Some variations are helpful, this results in a better chance of survival, reproduction, and passing on of those good variations.
4. Over time, individuals with new variations may become a new species. This is evolution.
Giraffes with long necks exist because…1. Mom and Dad giraffe had lots of
offspring2. Those offspring were each
different.3. Some had helpful variations
(longer necks) which meant better survival (more food) and more likely to reproduce.
4. Long neck genes get passed on to future offspring, eventually a new species of giraffe occurs.
• Mom and Dad bug had lots of offspring
• Those offspring were each different.
• Some had helpful variations (grey) which meant better survival (not eaten) and more likely to reproduce.
• Grey genes get passed on to future offspring, eventually a new species of bug occurs.
http://www.nysci.org/explore/ontour/charlieandkiwi/Charlies-and-Kiwis-Evolutionary-Adventure-Video
Adaptations are variations that make an organism better suited for its environment.
• Adaptations can be physical (on their body) or behavioral.
Adaptations can help an organism….
Warn predators
Hide from predators (camouflage)
http://www.youtube.com/watch?v=k8RlGbpuhgc
Imitate a more dangerous animal (mimicry)
mimicry
Geographic Isolation can allow some variations to appear in a species that might have been otherwise stayed hidden
Geographic Isolation
Geographically Isolated Animal Examples
Flightless birds and mouse lemurs
Speed of Evolution
• Gradualism- a continuous series of mutations and variations over time will result in a new species.
• Punctuated Equilibrium- rapid evolution that occurs when the mutation of a few genes results in the appearance of a new species over a relatively short time.
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http://www.youtube.com/watch?v=BwuL4J_jEyc&feature=related
The 0.1% of bacteria that survives, reproduces and
now is resistant to the spray
How many germs will survive?
20,000 single celled organisms, which are genetically different from the dead, will still
survive and continue to reproduce.
So what? Why does evolution matter?
http://www.youtube.com/watch?v=6jBD8xfbf4Y
http://www.nytimes.com/2013/04/12/world/asia/report-published-on-3-who-died-from-h7n9-bird-flu.html?_r=0
http://www.nytimes.com/2013/04/17/business/report-on-us-meat-sounds-alarm-on-superbugs.html?_r=0
April 16, 2013Report on U.S. Meat Sounds Alarm on
Resistant Bacteria
The End of Evolution….or is it?
http://www.youtube.com/watch?v=zGqae7vuUWo&feature=PlayList&p=60D07D9950E069A4&playnext_from=PL&playnext=1&index=16