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Terms in this set (21)
A group of interbreeding individuals of a species in a given area
Increase in variability through mutations and gene shuffling
any change in the DNA sequence. does not always affect an organisms phenotype
Genetic variability, cont.
Many mutations produce changes in the organisms phenotype affecting its fitness (ability to survive and reproduce) and eventually changes in the gene pool
Brings together a new combination of genes
How does natural selection act on traits ?
Acts on phenotype, does not directly on genes. It determines which alleles are passed on from one generation to the next
What are the three ways where natural selection can affect the distribution of phenotypes?
1) Stabilizing selection
2) directional selection
3) disruptive selection
What is stabilizing selection?
When individuals near the center of the curve have higher fitness than individuals at either end of the curb, causing the graph to Narrow.
What is directional selection?
When individuals at one end of the curve have higher fitness than individuals in the middle or at the end causing the graph to shift to one side
What is disruptive selection?
When individuals at the upper and lower end of the curve have higher fitness than individuals near the middle, causing a dip in the ground
What is a gene pool?
Common groups of gene shared by a population that contains two or more alleles (or forms) of a certain gene for each trait
What is Relative frequency?
The number of times that an allele occurs in a gene pool compared with the number of times other alleles occur
What is the Hardy-Weinberg principle?
Allele frequency's in a population will remain constant unless one or more factors cause those frequencies to change
What is genetic equilibrium
Allele frequency's in a population will remain constant from generation to generation
What are the five conditions required to maintain genetic equilibrium from generation to generation?
1) Random mating
2) large population
3) no movement into or out of the population
4) no mutations
5) no natural selection
What is the Hardy-Weinberg equation?
p^2 + 2pq + q^2 = 1
What does p equal in the Hardy Weinberg equation?
frequency of the dominant allele in the population (T)
What does Q equal in the Hardy Weinberg equation ?
frequency of the recessive allele in the population (t)
What does P^2 equal in the Hardy Weinberg equation ?
Percentage of the homozygous dominant individuals (TT)
What does Q^2 equal in the Hardy Weinberg equation ?
Percentage of the homozygous recessive individual (tt)
What does 2pq equal in the Hardy Weinberg equation ?
Percentage of the heterocycles individuals (Tt)
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