evolution: a change in a kind of organism over time. the process of modern organisms coming from...
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Evolution is a scientific theory. There is much evidence to support evolutionTRANSCRIPT
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Evolution: A change in a kind of organism over time. The process of
modern organisms coming from ancient organisms
Evolution and Natural Selection
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Hairstyles
Computer
Music
Change over time
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EvolutionEvolution is a
scientific theory. There is much
evidence to support evolution
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Lamarck (1809)First suggested
changes overtime Stated that changes
are adaptations acquired in one’s lifetime due to selective use or disuse of certain traits
These traits would then be passed on to their offspring, but not through genes; forces
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Desire to do something led to adaptations
Example: Giraffes kept stretching their necks over generations until they could reach the leaves.
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DarwinJoined the crew of
the HMS Beagle for a 5 year survey adventure. (1831-1836)
Naturalist; wanted to study and observe different species.
http://www.youtube.com/watch?v=E2y1DJ1rhck
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During his travels , Darwin made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes
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Galapagos Island TortoiseDarwin noted that the
island were very small and varied greatly
Some hot, dry and nearly barren
Other islands had greater rainfall and had more diverse vegetation
He noted the tortoises’ shape of their shell corresponded to their different habitat
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FinchesStudied finches on
each island Noticed similar
types of finches had small beak adaptations depending on available food sources
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1859- “The Origin of Species by Means of Natural Selection”
Stated that organisms evolved Mechanism for evolution called Natural
SelectionPresented evidence that evolution has been
taking place for millions of years – and continues in all living things
Darwin
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1-Variation: Each organism has it’s own variations in it’s struggle for existence
2-Competition-Organisms compete for natural resources
3- Pop. Growth-Organisms produce more offspring than can survive
4- Differential reproduction- Those organisms best suited to the environment will survive and pass along their genes to their offspring
Darwin’s 4 main points of Natural Selection
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Results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in its environment
Natural selection is one of the basic mechanisms of evolution, along with mutation, migration, and genetic drift.
Natural Selection
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Natural Selection ObservedPeppered moths -
England1850’s - light color (few
were dark)Early 1900’s - pollution
darkened tree trunksLight moths eatenDark moths camouflaged
- increasedRecently - pollution
controls - trees lightenLight moths increase in
number again
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In artificial selection, nature provided the variation, and humans selected those variations that they found useful
Ex. Dogs, Vegetables, Cows
Artificial Selection
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Common descent- principle that all living things were derived from common ancestors
Fossil recordFossils show the links between species Radioactive dating can tell how old the
fossils are Scientists calculate the half-life of certain
isotopes, like Carbon-14, in the fossil to determine the age in years.
Evidence of Evolution
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Evidence From StructureSimilar structures are evidence of a common
ancestor.
Selection causes modifications for different environments.
Homologous structures - different functions but common ancestry.
Vestigial organs - small or incomplete organs with no apparent function.
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Comparative Anatomy
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Vestigial OrgansImplication: the vestigial organ
served a function in the ancestor of the organism, but not its present holder
Examples
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Evidence from EmbryologyEmbryo - developing
organismEarly stages of
development are similar
More closely related organisms have more similar embryological patterns
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Evidence From BiochemistryUniversal genetic code
- evidence of evolution.All living things are
made up of the same 4 nucleotides: A,G, C, T
Many of the same DNA sequences, or genes, are exact or similar depending on how closely related we are
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The evolutionary process by which new species arise.
Arise for different reasons, but reproductive isolation and geographic isolation are the most common
Reproductive isolation is when no mating occurs between species for so long that sexual selection changes or having offspring
Geographic occurs when species are separated by a barrier, such as a mountain range or a river
Speciation
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Geographic IsolationAbert squirrel and Kaibab squirrel - used to
be same population.About 1 million years ago - Colorado river
changed course and split population.Kaibab is a subspecies of the Abert squirrel.
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Reproductive Isolation Washington- two populations of
sockeye salmon became established
One spawning in a river and one along a lake beach.
Sockeye salmon bury their eggs and spawn in different kinds of locations, and in a variety of environments, even in a small system such as this.
When new populations become established at different sites, you'd expect them to evolve different adaptations, and that's in fact what happened. Body depth in males Size of breeding females
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Convergent EvolutionDefinition: when the
environment puts similar selective pressure on different species.
Results in similar adaptations for organisms that are not closely related.Example: fish do not
have same immediate ancestor as whales.
Bird wing vs. insect wing