Download Evolution by Natural Selection

Darwin, Wallace, & Natural
Selection
• https://youtu.be/XOiUZ3ycZwU
Unit 6 Life Over Time
I. Theory of Natural Selection
https://youtu.be/0SCjhI86grU
A. Darwin
1. Naturalist aboard the ship HMS Beagle
2. Collected many different species and fossils
3. Visited the Galapagos Islands where he realized that species
change over time due to the environment
4. evolution= refers to the process by which
populations change over time
5. population= all of the individuals of a
species that live in an area at the same time
6. species= can mate and have fertile offspring
B. Darwin noted differences among species
1. Darwin was amazed that there were so many different types
of finches on different islands and mainland South America
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the beaks would be different because of the different available
food
2. The birds that had the beaks with the traits that could obtain
the most food survived, reproduced, and passed their
successful genes on
C. Artificial Selection
1. artificial selection= humans select plants or animals for
breeding based on desired traits wanted in the offspring
2. Darwin observed horse breeders and thought that this could
happen in nature
3. Today horse breeders, dog breeders, and farmers do this to get
the best animal or strongest crops
D. Acquired traits
1. Jean-Baptiste Lamarck that that the traits that a parent
acquired throughout their lives could be passed onto their
children
2. This thought was wrong and we now know that if
something is to be inherited it has to be passed through the
parents DNA
3. Darwin noticed that an organisms traits could help them to
survive
E. Earth Changes Over Time
1. Rock layers indicate that there have been changes on the
Earth over time
2. Charles Lyell hypothesized that small changes in rock
have collected over hundreds of millions of years
3. Darwin used this to prove that the Earth was very old
and that small changes over long periods of time add up
F. Struggle to Survive
1. Thomas Malthus stated that all populations are affected by
factors that limit growth
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disease
predation
competition
2. Darwin used this thinking to reason that survivors have traits
that have helped them to survive and these good traits will be
passed onto their children
G. Four parts to natural selection
http://study.com/academy/lesson/how-darwins-
observations-showed-the-process-of-natural-selection.html
1. Overproduction: when a plant or animals reproduces more
offspring than the environment can support to ensure that
some of their genes are passed to the next generation
2. Genetic variation: within a species there are natural
variation that help certain organisms survive and reproduce
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variation= differences in traits
mutation=a change in genetic material that is an important
source of variation
the more variations in a population the more chances that there
will be a trait that would be advantageous for the environment
3. Selection= traits that allow organisms to survive are
“selected” for and will become more common in the next
generations of offspring
4. Adaptation= an inherited trait that helps an organism survive
and reproduce in its environment
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this is a favorable trait that an organism is born with- not one
that that they acquire
adaptations become more common in a population with each
new generation https://youtu.be/5NdMnlt2keE
5. Genetic differences add up and even small differences can
change a population over time
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populations change with survivors reproducing & passing traits
on
6. Extinction= occurs when all members of a species have died
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greater competition, loss of habitat, & new predators are causes
of extinction
https://youtu.be/5NdMnlt2ke
E
Evolution of the Finch
Beak
https://youtu.be/mcM23M-CCog