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EVOLUTION. VERY SIMPLY PUT- - Evolution is. change in a species over time. How long did it take to CHANGE?. 66 million years ago. 54 million years ago. 37 million years ago. 26 million years ago. Present Day. There are two models for HOW this change occurs. Gradualism. - PowerPoint PPT Presentation
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EVOLUTION
VERY SIMPLY PUT--Evolution is
change in a species over time.
How long did it take to CHANGE?
66 million
years ago
54 million
years ago
37 million
years ago
26 million
years ago
Present Day
There are two models for HOW this change occurs.
Gradualism gradual change over
a long period of time
Punctuated Equilibrium periods of rapid
change in species are separated by periods of little or no change.
We have learned about the origins of evolutionary thought.
1773-Boston Tea Party
1785-James Hutton
1831-Charles Darwin
1809-Jean-Baptiste Lamarck
1798-Thomas Malthus
1787-The U.S Constitution is signed
1861-U.S. Civil War Begins
1859-Darwin publishes The Origin of the Species
1858-Alfred Wallace
1833-Charles Lyell
1850-California Gold Rush
Share out some of the contributions of the scientists that led to today’s model of evolution.
Who was Charles Darwin?
How did Darwin come up with the theory of natural selection?
He collected evidence in the Galapagos Islands that pointed towards his theory of natural selection.
The Galapagos Tortoise
Geological Formation of the Islands
Darwin’s Finches Adapted to their Food Source
What is natural selection?In a nut shell…
Better traits
easier to survive
more likely to reproduce
Over time better traits dominate a population
What type of mouse is more likely to survive to produce offspring?
Biological Fitness Fitness—an organisms ability to reproduce
and pass their genes on to their next generation
Survival of the FittestThose who are more “Fit” will be more likely to survive.
More AttractiveSmarterStronger
More Likely To Survive and Reproduce
Which species is most fit for this exam? Why?
Quick QuestionOrganisms well suited to their environment
a. reproduce at a greater rate than those less suited to the same environment.b. are always larger than organisms less suited to that environment.
c. always live longer than organisms less suited to that environment.
d. need less food than organisms less suited to that environment.
What did Darwin call the
process?
Natural Selection
Natural Selection operates on 4 factors:
Genetic variation: all the genes that make up the population.
Overproduction of offspring: more is better. Struggle for existence: compete for food,
territory, and mate (survival of the fittest) Survival and reproduction: individuals that
are better able to cope or have advantages over another will leave more offspring
AdaptationA trait produced by natural selection that has become common in a population because it provides a selective advantage.
Successful reproduction of the fittest members of a population eventually leads to an adaptation within that population.
Organisms adapt to their environments in many ways…
Storage Adaptations
Conserves water – not stored in hump
Stored fat provides insulation
Reproductive Adaptations
Protection
Camouflage
Owl moth
Wasp moth
Fish
Adaptations to food
Parasite orchids
Carnivorous plants
Specialized beaks
Parasitic
Specialized teeth
Plant adaptations
Wind dispersalWater
dispersal
Animal dispersal
So how do adaptations occur?
Other Mechanisms of Evolution that lead to adaptions.
Mutations Gene flow (migration) Genetic drift
Mutations
They may produce a different phenotype that may be an advantage for a species.
A mutation could cause parents with genes for bright green coloration to have offspring with a gene for brown coloration. That would make the genes for brown beetles more frequent in the population.
A mutation is any change to the genetic material of a cell.
Gene Flow (Migration)
Some individuals from a population of brown beetles might have joined a population of green beetles. That would make the genes for brown beetles more frequent in the green beetle population.
Gene Flow (Migration) The amount of gene
flow within a population varies. Very mobile organisms
have a higher rate of gene flow than organisms that are immobile.
Which would have a higher rate of gene flow?
This is corn.
Effects of Gene Flow on Evolution
Within a population Across populations
When the brown beetle joins the green beetle population, the brown beetle genes enter the populations gene pool.
Can make distant populations genetically similar to one another.
Can introduce genes into a population increasing genetic variation
Genetic Drift
A random change in allele frequencies that occur in small populations. Usually brought on by natural disasters or catastrophic events such as ?
Several green beetles were killed when someone stepped on them and had no offspring. The next generation would have a few more brown beetles than the previous generation—but just by chance.
Genetic Drift
Bottleneck effect Population’s size is
reduced for at least one generation
Reduced variation may affect the ability to adapt to natural selection pressures- climate change, shift in resources.
Founder’s effect A new colony is started
by a few members of the original populations.
Colony will have reduced genetic variation.
Can decrease genetic variation, especially in small populations!
SPECIATIONHow do these changes lead to the
formation of new species? Eventually the gene pools of the populations
become too different. The populations can no longer interbreed.
This is called REPRODUCTIVE ISOLATION.
Why does evolution matter now?
If it happens as a long slow process, how does it affect me?
Tampering with Evolution
Artificial Selection –Humans breed organisms for specific traits
Interbreeding animals that would not normally interbreed in nature to create new species
Cockapoo
Artificial Selection is an example of evolution where humans choose which
plants/animals reproduce to make cuter pets or better crops. We like to call it “breeding”.
Wild tomatoes Tomato crop