Transcript The Theory of Evolution

Evolution
• Biology Honors
• By Gail Mayes
• Foothill High School
Biology Honors Objectives
The Theory of Evolution
Click on Tortoise for Intro
Evolution
• A. The process by which modern
organisms have descended from ancient
organisms.
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1. Charles Darwin (1809-1882) sailed
on the HMS Beagle to the Galapagos
Islands.
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2. This voyage sparked a curiosity
about how organisms came to be different
and survive on each of the islands.
Darwin’s Journey
Darwin’s Studies
• A. Studied to find out why species change
over time.
Malthus stated that human populations tend to
grow faster than Earth’s food supply.
Individuals struggle to compete in changing
environments.
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Compete for food and space
Escape from predators
Find mates
Locate shelter
Natural Selection
Evidence for Evolution
• A. “Adaptation”=Species survived because
they were better able to adapt to their
environment.
• Mole rats that live underground their
whole lives are blind. They have adapted
to their environment.
Can you find the katydid?
Lizard Adaptations
Video
• Lizards have adapted to their environment
over time. Click on the lizard to find out
how:
Mimicry- An adaptation
that enables one
species to resemble
another.
Camouflage- Species blend with their environment. They
can’t be easily seen by predators.
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CAMOUFLAGE
Find out more about snakes:
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Snakes
Click on the octopus to find out how
long they have survived through
evolution:
Vestigial structures- A
body structure in a
present-day organism
that no longer serves
its original purpose,
but was probably
useful to an ancestor.
(blind fish in the dark
deep sea).
Population Genetics and Evolution
A. How can a population’s genes change over time?
1. Gene pool- All of the alleles of the
population’s genes together on one pool.
2. Allelic frequency- The percentage of any
specific allele in the gene pool.
3. Genetic equilibrium- Alleles remain over
generations.
a. If a population is in equilibrium it is not
evolving.
b. Mutations results in favorable changes in a
species.
Hardy Weinberg Video
Evolution of Species
• A. Speciation- The evolution of new
species is called speciation.
– 1. Occurs when members of a similar
populations no longer interbreed to produce
fertile offspring within their natural
environment.
Speciation
• Convergent Evolution- Evolution in which
distantly related organisms evolve similar
traits.
• Different species can look alike:
Evolution Quiz Link
• http://www.unitedstreaming.com/stude
ntCenter/index.cfm?cdCode=8518D92B
Conclusion
• Evolution is a theory. There is evidence
that evolution has occurred. Speciation
occurs at a much quicker time scale and is
evident in bacterial mutations.