Evolution & Natural Selection

EVOLUTION is defined as species or populations of species going through changes over a period of time

Important People

• Charles Darwin
• Jean Baptiste Lamarck

Pre-Darwin Thoughts

• Earth was only a couple thousand y.o.
• Inhabitants had never changed

Pre-Darwin Thoughts (Lamarck)

• Jean Baptiste Lamarck
• Believed organisms could change their traits
• This was called the ACQUIRED CHARACTERISTICS theory

Characteristics, or traits, developed during a parent organism’s lifetime are inheritable, and passed down to its offspring

#hewaswrong

Charles Darwin

• English Naturalist (1809-1882)
• Disproved Lamarck's theory
• Creator of the Theory of Evolution by Natural Selection
• Voyage to South America was key 

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• Sailed on the HMS Beagle
• Stopped at spots along S.A
• Collect Samples of specimens
• Galapigos Islands most famous stop

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The Galapagos Islands

• Darwin's Finches
• Studied BEAK shape
• Found all different types

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Hypothesized that organisms could come from a common ancestor, but had went through adaptions based on environment

Evolution by Natural Selection

• Variations passed on through reproduction
• Natural Selection leads to Evolution
• Understanding of Evolution has changed over time
• Evolution helps us understand relationships

POPULATIONS can Evolve...not Individuals

For Evolution to occur there must be VARIATIONS in populations

VARIATIONS are the differences in genes within a population in a species

NATURAL SELECTION is the term that describes the process that organisms who are better adapted to their environment have a better chance of surviving and reproducing

Natural Selection

• Must be variation in a species
• Process that drives Evoluton
• Example: Peppered Moth

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Speed of Evolution

Gradualism

• Selection and variation that happens more gradually. Over a short period of time it is hard to notice. Small variations that fit an organism slightly better to its environment are selected for:
• Over a short period of time it is hard to notice. Small variations that fit an organism slightly better to its environment are selected for
• Small variations that fit an organism slightly better to its environment are selected for
• Over a short period of time it is hard to notice. Small variations that fit an organism slightly better to its environment are selected for

Punctuated Equilbrium

• Change comes in spurts.
• There is a period of very little change, and then one or a few huge changes occur
• Result of mutations in the genes of a few individuals