Consider a simplistic
life cycle
where the genotypes (a single locus way of referring to
adults) produce
gametes
. These gametes
mate
to form new genotypes (=adults). See
5.1, pg. 93 and 5.3, pg. 99. The relationship between allele frequencies (sometimes
called "gene" frequencies) and genotype frequencies is determined by the
Hardy
Weinberg Theorem
which defines the probabilities by which gametes will join to
produce genotypes. Consider a coin toss: probability of a head = 0.5; of a tail = 0.5;
prob. of two heads = 0.5x0.5 = 0.25; prob. of one head and one tail = 0.5x0.5 = 0.25,
etc. Each coin is analogous to the type of allele you can get from one of your diploid
parents; the tossing of two coins is analogous to the mating of two individuals to
produce four possible genotypes (but heads,tails is the same as tails,heads). Now
consider a roll of the dice. The probability of each face is 1/6, and is actually
analogous to cases where more than two different alleles exist in the population at a
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 Fall '10
 JessicaDigirolamo
 Microbiology, Genetics, Evolution

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