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….

Attract a mate

http://www.youtube.com/embed/REP4S0uqEOc

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.

+

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