Download Mechanisms of Evolution

Mechanisms of Evolution
Natural Selection
IN
• Answer the following on your notes:
– What is natural selection and what impact does it
have on a population?
– Discuss with partner
– Share with class
Charles Darwin
• Who was Charles Darwin??
– Born in 1809
– A British Scientist who
studied the natural world.
– Considered the “Father of
Evolution”
– Studied the natural world
while traveling on the HMS
Beagle.
Darwin Continued
• Did extensive observations on the Galapagos
Finches.
• Proposed the idea that organisms that were
better suited for their environment were more
likely to survive and reproduce.
• Also known as “Survival of the Fittest”
HMS Beagle Voyage
Galapagos Finches
Natural Selection
• Individuals that are better adapted to their
environment survive, reproduce and pass on
their genes.
• Acts on populations of organisms, not
individuals.
Peppered Moths
• Discuss with your partner the following:
– What was the predominant color of Peppered
Moths before the Industrial Revolution?
– What happened to the Peppered Moth population
after the Industrial Revolution.
– Share with the class.
Natural Selection
• Acts on Populations, not individuals.
• Occurs because
– Individuals within a population vary.
– Some traits are better than others
– Those traits are inheritable
Antibiotic Resistant Bacteria
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Antibiotics are used to treat bacterial infections.
Bacteria with mutations can survive treatment.
They survive and reproduce.
Bacteria population changes over time to contain
more resistant bacteria than non resistant.
• Discuss with your neighbor the impact this could
have on humans.
Genetic Variation
• The measure of genetic differences within a
population.
• Mutations in DNA cause genetic differences.
• Populations that have more genetic variation
can adapt to their environment better than
populations with little genetic variation
Examples of Adaptations
• Mimicryresembling
another organism
• Camouflageblending into your
environment.
Elements of Natural Selection
Inherited Variation
• Genetic Variation within a population that can
be passed down to offspring.
• Typically caused by mutations in DNA
• Ex: Mimicry, Camouflage
Finite Supply of Resources
• The amount of resources available determines
the ability of organisms to survive and
reproduce.
Number of Offspring
• Organisms produce many offspring to ensure
the survival.
• More offspring equals higher chance of some
surviving which can pass on genes.
• Ex: Spiders produce large number of offspring.
Many will not survive, but the ones that do
will pass on their genes.
Reproductive Success
• The ability to reproduce and pass genes on to
future generations.
• Measured by the number of offspring an
organism produces.