evolution by natural selection
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Evolution by Natural Selection. Scientific Theory. An explanation of natural phenomenon supported by a large body of scientific evidence obtained from many different investigations and observations. Evolution. A gradual change in a species (populations) through adaptations over time. - PowerPoint PPT PresentationTRANSCRIPT
Evolution by Natural Selection
Evolution by Natural Selection
Scientific TheoryScientific Theory
An explanation of natural phenomenon supported by a large body of scientific evidence obtained from many different investigations and observations.
An explanation of natural phenomenon supported by a large body of scientific evidence obtained from many different investigations and observations.
EvolutionEvolution
A gradual change in a species (populations) through adaptations over time.
Adaptation = some phenotypic feature or trait that improves an organism’s likelihood of survival and reproduction.
In Georgia, there is a popular hunting area of forest called the Poopycack forest, where the Poopy Deer lives. This species of deer has 6 ears. How might this adaptation have occurred and how is it
beneficial? What would you expect to happen to the Poopy Deer
population in the next 1000 years?
A gradual change in a species (populations) through adaptations over time.
Adaptation = some phenotypic feature or trait that improves an organism’s likelihood of survival and reproduction.
In Georgia, there is a popular hunting area of forest called the Poopycack forest, where the Poopy Deer lives. This species of deer has 6 ears. How might this adaptation have occurred and how is it
beneficial? What would you expect to happen to the Poopy Deer
population in the next 1000 years?
Charles Darwin“Theory of Evolution by Natural Selection”
Charles Darwin“Theory of Evolution by Natural Selection”
Proposed that new species could develop through a process called Natural Selection
During his travels aboard HMS Beagle, made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time
Proposed that new species could develop through a process called Natural Selection
During his travels aboard HMS Beagle, made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time
Darwin’s VoyageDarwin’s VoyageDarwin studied animal species in the Galapagos
Islands and found they each had unique adaptations
Darwin studied animal species in the Galapagos Islands and found they each had unique adaptations
Darwin’s StudiesDarwin’s Studies
Galapagos finches demonstrate different adaptations to eat different kinds of foods
Galapagos tortoises are the biggest in the world
Galapagos finches demonstrate different adaptations to eat different kinds of foods
Galapagos tortoises are the biggest in the world
Natural SelectionNatural Selection Acts on Phenotype rather than Genotype Those better suited for their environment will survive Those least suited to their environment will die
faster, leaving fewer offspring
Acts on Phenotype rather than Genotype Those better suited for their environment will survive Those least suited to their environment will die
faster, leaving fewer offspring
Genetic variation is essential!
Genetic variation is essential!
_________ promote genetic variation, which helps ensure a species survival Like crossing over!
_________ promote genetic variation, which helps ensure a species survival Like crossing over!
Mutations
How does a great number of species ensure that at
least some organisms survive major changes in
the environment?
How does a great number of species ensure that at
least some organisms survive major changes in
the environment?
Those who are better at adapting will survive major changes in the environment
Those who are better at adapting will survive major changes in the environment
Natural SelectionNatural Selection
A mechanism for change in a population
Natural Selection (NS) is responsible for most evolutionary change by selectively changing genetic variation through differentiated survival and reproduction.
Goal - To be fit enough to survive and reproduce
Three types of NS
A mechanism for change in a population
Natural Selection (NS) is responsible for most evolutionary change by selectively changing genetic variation through differentiated survival and reproduction.
Goal - To be fit enough to survive and reproduce
Three types of NS
Stabilizing SelectionStabilizing Selection
Favors average individuals in a population
Those individuals have a “selective advantage”.
Reduces variation in a population
Favors average individuals in a population
Those individuals have a “selective advantage”.
Reduces variation in a population
Directional SelectionDirectional Selection
Favors one of the extreme variations of a trait
Can lead to rapid evolution of a population
Favors one of the extreme variations of a trait
Can lead to rapid evolution of a population
Disruptive SelectionDisruptive Selection
Favors both extreme variations of a trait
Leads to evolution of two new species
Favors both extreme variations of a trait
Leads to evolution of two new species
SpeciationSpeciation
A process of producing two individual species from one Members of the
population no longer interbreed within their natural environment
A process of producing two individual species from one Members of the
population no longer interbreed within their natural environment
Evidence for Evolution:Evidence for Evolution: 1. Fossil record
A piece of organism or imprint left behind. Fossils show that species have changed over time.
2. Vestigial structures Body structures that have shrunken and are not used
anymore. 3. Homologous structures
Structures that share a common ancestry and look/behave similarly.
4. Embryology 5. DNA homology, Amino Acid homology,
Mitochondrial DNA, Photosynthetic Plant cells
1. Fossil record A piece of organism or imprint left behind. Fossils show that species have changed over time.
2. Vestigial structures Body structures that have shrunken and are not used
anymore. 3. Homologous structures
Structures that share a common ancestry and look/behave similarly.
4. Embryology 5. DNA homology, Amino Acid homology,
Mitochondrial DNA, Photosynthetic Plant cells
Evidence For EvolutionEvidence For Evolution
Fossils Provide a
record of early life and evolutionary history
Fossils Provide a
record of early life and evolutionary history
Geologic Strata (sedimentary layers) and Carbon Dating
Geologic Strata (sedimentary layers) and Carbon Dating
Carbon-14 (remember isotopes?) Used to date any
object composed of carbon
Radioactive carbon decays over time check amount of C14
left in sample, enabling you to tell age of object
Carbon-14 (remember isotopes?) Used to date any
object composed of carbon
Radioactive carbon decays over time check amount of C14
left in sample, enabling you to tell age of object
Defining age of fossils!
Did you know that whales have feet? Well, sort of….
Did you know that whales have feet? Well, sort of….
Fossils help us determine whale evolution
Fossils help us determine whale evolution
60 million years ago
50 million years ago
40 million years ago
Yesterday
Human tail-bone, wisdom teeth, appendix (they have no purpose)
Snake feet,
Whale feet
Human tail-bone, wisdom teeth, appendix (they have no purpose)
Snake feet,
Whale feet
Vestigial StructuresVestigial Structures
Homologous Structures (derived from a common ancestral feature)Homologous Structures (derived from a common ancestral feature)
Limb adapted to function
means the same!
Analogous
Structures-similar in function but not structure
Analogous
Structures-similar in function but not structure
Evidence For EvolutionEvidence For Evolution
Embryology Similarities
among the young embryos suggest evolution from a distant, common ancestor
Biochemistry Comparing DNA
and RNA
Embryology Similarities
among the young embryos suggest evolution from a distant, common ancestor
Biochemistry Comparing DNA
and RNA
How do we know what happened when?
How do we know what happened when?
Radiometric dating relies on half-life decay of radioactive elements to allow scientists to date rocks and materials directly
Stratiography provides a sequence of events from which relative dates can be extrapolated
Molecular Clocks allow scientists to use the amount of genetic divergence between organisms to extrapolate backwards to estimate dates.
Radiometric dating relies on half-life decay of radioactive elements to allow scientists to date rocks and materials directly
Stratiography provides a sequence of events from which relative dates can be extrapolated
Molecular Clocks allow scientists to use the amount of genetic divergence between organisms to extrapolate backwards to estimate dates.
DNA/Amino Acid Homology
DNA/Amino Acid Homology
Human 5’A-T-C-T-T-A-C-G-A-A-T-C-A-T-G-C-C-C-T-A-A-C-T-T-C-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’
Whale 5’A-C-C-T-T-A-C-C-A-A-T-C-A-T-T-C-C-C-T-A-A-C-T-T-A-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’
Frog 5’A-C-C-A-T-G-C-G-T-G-T-C-A-T-C-C-C-C-G-A-G-C-T-T-C-G-G-T-A-T-T-A-C-G-C-A-A-G-C-3’
Gorilla 5’A-T-C-T-T-A-C-G-A-A-T-C-A-T-G-C-C-C-T-A-A-C-A-T-C-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’
Human 5’A-T-C-T-T-A-C-G-A-A-T-C-A-T-G-C-C-C-T-A-A-C-T-T-C-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’
Whale 5’A-C-C-T-T-A-C-C-A-A-T-C-A-T-T-C-C-C-T-A-A-C-T-T-A-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’
Frog 5’A-C-C-A-T-G-C-G-T-G-T-C-A-T-C-C-C-C-G-A-G-C-T-T-C-G-G-T-A-T-T-A-C-G-C-A-A-G-C-3’
Gorilla 5’A-T-C-T-T-A-C-G-A-A-T-C-A-T-G-C-C-C-T-A-A-C-A-T-C-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’
(Means the same!)
Can you create a cladogram from the information above?
http://www.youtube.com/watch?v=faRlFsYmkeY
http://www.youtube.com/watch?v=faRlFsYmkeY