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Miller and Levine Biology Chapter 17

Terms in this set (34)

Gene Pool
Consists of all genes, including all the different alleles for each gene, that are present in a population.
Allele Frequency
The number of times an allele occurs in a gene pool, compared to the total number of alleles in that pool for the same gene.
Single-gene Trait
A trait controlled by only one gene.
Polygenic Traits
Many traits are controlled by two or more genes; each gene usually has two or more alleles.
Directional Selection
When individuals at one end of the curve have higher fitness than individuals in the middle or at the other end.
Stabilizing Selection
When individuals near the center of the curve have higher fitness than individuals at either end.
Disruptive Selection
When individuals at the outer ends of the curve have higher fitness than individuals near the middle of the curve.
Genetic Drift
Random change in allele frequency caused by a series of chance occurrences that cause an allele to become more or less common in a population.
Bottleneck Effect
A change in allele frequency following a dramatic reduction in size of a population.
Founder Effect
Allele frequencies change as a result of the migration of a small subgroup of a population.
Genetic Equilibrium
If a population is not evolving, allele frequencies in its gene pool do not change.
Sexual Selection
Individuals select mates based on heritable traits, such as size, strength, or coloration.
Species
A population or group of populations whose members can interbreed and produce fertile offspring.
Speciation
The formation of a new species.
Molecular Clock
Uses mutation rates in DNA to estimate the time that two species have been evolving independently.
50%
If an allele make up ½ of all the population allele what is its frequency?
Phenotypes
What does natural selection work on?
The population evolves
If the allele frequency in a population changes from 20 to 30 percent, what can you tell about the population?
Mutation
What do we call a change in the genetic material of an organism?
Mutations, lateral gene transfer, sexual reproduction
What are the three sources of genetic variation?
Genetic recombination during sexual reproduction
Organisms that reproduce sexually, most variation is due to what?
No because during the sexual reproduction the allele frequency stays the same
Does sexual reproduction change the allele frequency in a gene pool?
2
How many phenotypes do single gene traits have?
How many genes control the trait
The number of phenotypes produced for a given trait depends on what?
Bell curve
How do we illustrate the frequency of phenotypes for polygenic traits?
Natural selection and the environment
If in a population there is a new skin color, what might determine whether this skin color will increase in the population?
Chance
why does the allele frequency change? - genetic drift
Small
does genetic drift happen more in small or large populations?
They are able to mate and produce offspring
What is a species?
temporal selection
If we have flowers in a population and some open at mid day and some open in the evening, what will happen?
the ancestors came over from ecuador (the founds migrated over)
What happened first on the galapagos island?
speciation
What do we call the process when a new species is created?
because the availability of food
Why was there natural selection on beak size?
species with similar genes
Which species are closely related : species who have similar genes or species who have very different genes?
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