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What is an aquired characteristic?
A trait obtained during one's lifetime. An example is Arnold Schwartzenager's muscles
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What is a mutation?
8.7 Mutation—a direct change in the DNA of an individual—is the ultimate source of all genetic variation.
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What is genotype?
The genetic makeup of an organism
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What is natural selection?
The consequence of certain individual organisms in a population being born with characteristics that enable them to survive better and reproduce more than the offspring of other individuals in the population
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Who is Charles Darwin?
developed the idea that organisms change over time...
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What is evolution?
the change is allele frequency in a given population over time
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What can cause a mutation?
exposure to chemicals, radiation or an error during DNA replication.
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What is phenotype?
The physical makeup of an organism.
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What is artificial selection?
The “artificial selection” used by animal breeders and farmers is also natural selection because the three conditions are satisfied even though the differential reproductive success is being determined by humans and not nature.
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Why did Darwin, in 1859, after decades of mulling and procrastinating, published his thoughts on natural selection?
Alfred Russel Wallace
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What is genetic variation?
The varying alleles for a specific trait seen in any population. (ex: eye color)
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What is gene flow?
Migration- when a portion of an existing population migrates to a new population and change the allele frequency seen in the new population.
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What does the term "Fittest" mean?
individuals with the greatest reproductive success
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Define adaptation.
Adaptation—the process by which organisms become better matched to their environment and the specific features that make an organism more fit—occurs as a result of natural selection.
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What type of cells would a mutation have to occur in to lead to genetic variation? Why?
reproductive cells- because somatic cells do not pass information onto the offspring.
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What is a population?
A group of individuals of a particular species that can interbreed.
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What is a bottle-neck?
When the genetic variation found in the remaining members of a population changes after a catostrophic event.
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Explain directional selection. Give an example.
Favors indiviuals with phenotypes at the extreme end. An example would be cows that produce alot of milk.
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What is stabilizing selection? Give an example
When the mean (or average) traits are selected for. An example is birth weight.
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Why would the beak sizes of the galapagos finches fluctuate over time?
Because of the change in rain amounts, the seed size and shell hardness changed. This selected for a particular type of beak in order to consume the seeds
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What is the founder effect?
The genetic variation found in a newly established population is different from the original population from which they came.
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Explain the fruit fly experriment we see in the beginning of the chapter and what was the significance of the results.
Shows that genetic variation within the population exists and due to environmental changes, certain flies were selected for by nature. As a result, the individuals that survived and reproduced were able to pass the genes onto their offspring. Eventually the population changed over time to be more resistant to starvation.
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Explain distruptive selection. Give an example.
Favors organisms that have phenotypes at BOTH extremes. An example would be the large and small salmon succeed but the medium salmon do not.
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What are the four agents of evolutionary change?
1. Mutation 2. Genetic drift 3. Migration 4. Natural selection
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What are the 3 conditions that need to be present for evolution by natrual selection to occur
1. There must be variation for the particular trait within a population. 2. That variation must be inheritable. 3. Individuals with one version of the trait must produce more offspring than those with a different version of the trait.
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