Two different purebred lines of squash have mean fruit sizes of 3 kg and 1 kg respectively. A cross between these two plants will produce an F1 hybrid that has a mean fruit size of 2 kg. Progeny from a self of the F1 hybrid grown in strictly controlled environmental conditions will lead to F2 progeny with fruit sizes that range from 1 to 3 kg. From 4000 F2 progeny only four are found to weigh about 1 kg and only three are found to weigh about 3 kg.
a) Estimate the number of genes that are involved for controlling this trait in the two varieties. Show your calculations.
b) Estimate how much weight does a single additive allele of these genes contribute to the phenotypes observed.
c) How can two squash plants from the F2 progeny, both with fruit of moderate weight, produce progeny with fruit that are much larger than either of them when crossed? (Assume there is a negligible difference in the environment for this part of the question)
Two different purebred lines of squash have mean fruit sizes of 3 kg and 1 kg respectively. A cross between these two plants will produce an F1 hybrid that has a mean fruit size of 2 kg. Progeny from a self of the F1 hybrid grown in strictly controlled environmental conditions will lead to F2 progeny with fruit sizes that range from 1 to 3 kg. From 4000 F2 progeny only four are found to weigh about 1 kg and only three are found to weigh about 3 kg.
a) Estimate the number of genes that are involved for controlling this trait in the two varieties. Show your calculations.
b) Estimate how much weight does a single additive allele of these genes contribute to the phenotypes observed.
c) How can two squash plants from the F2 progeny, both with fruit of moderate weight, produce progeny with fruit that are much larger than either of them when crossed? (Assume there is a negligible difference in the environment for this part of the question)
