(15 pts) (a) Asian rice ( Oryza sativa) is an important crop that can self-ferti
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Question
(15 pts) (a) Asian rice (Oryza sativa) is an important crop that can self-fertilize. At a particular locus, the three genotypes have the following frequencies:
AA = 0.36 AB = 0.48 BB = 0.16
What are the genotype frequencies after 2 generations of self-fertilization? What are the allele frequencies after 2 generations of self-fertilization?
(b) Other plants have a mixture of mating systems. This means they can self-fertilize or cross pollinate. Wild soybeans (Glycine soja) are an example of a plant having a mixed mating system. They self-fertilize approximately 87% of the time, but outcross 13% of the time.
Given the same initial genotype frequencies as stated above, what are the genotype frequencies after 2 generations of mating where 87% of the plants self-fertilize and 13% outcross? What are the allele frequencies after 2 generations of this mating?
Explanation / Answer
Self fertilization is very significant inbreeding process takes place commonly in plants like cearels.
In self fertilization the progeny of homozygous will be homozygous and progeny of hetrozygous is half homozygous and half hetrozygous.So by this we can conclude that frequency of heterozygous is halfed every generation.
In the present situation the rice have following frequency of genotype AA,AB,BB
AA AB BB
0.36 0.48 0.16
p2+2pq+q2=1
0.36+0.48+0.16=1
p+q=1
p=0.36+0.48/2=0.6)allele frequency of AA
q=0.16+0.48/2=0.4allele frequency of BB
0.6+0.4=1
in self fertilization the allele frequency doesn't change according to generation.
Genotype frequency
AA AB BB
F1 0,36 0.48 0.16
F2 0.6 0.24 0.4
AA''=2 GENERATION-0.36+0.48/4=0.6
AB''=2 GENERATION=0.48/2=0.24
BB''=2 GENERATION=0.16+0.48/4=0.4
During self fertilization the hetrozygous frequency decreases with generation and homozygous freuency increases.
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