Question

Evolutionary Biology/Quantitative Genetics problem... Please explain and show all work

Imagine that you are in charge of a Drosophila (fruit fly) colony for a laboratory. The laboratory prides itself for having true-breeding strains of fruit flies in which allele frequencies are fixed at certain loci. Suppose that the "saggy" locus is one such locus. You are responsible for maintaining a strain that is fixed for allele A at this locus. This strain is so valuable that it is kept in a sealed room so that no flies can escape, and no flies from outside can contaminate the colony. After you have been in charge of the colony for 10 generations, your boss surveys the colony and finds that it is no longer fixed for allele A at the "saggy " locus; now, there is another allele, "a" that is at a frequency of 1% in the colony. 1) What seems to have happened? Assuming that the rate of mutation from a,A is 0, what is the mutation rate from A a? Show your work. 2)

Answer 1

(a) Allele fixation is the process that occurs when only one variant exists for that gene in a population.
An allele can become "un-fixed" or lose it fixation, when another allele appears. This occurs either due to random mutations or through immigrations.

In this case, special care was taken to prevent flies from outside contaminating the colony. Thus, the presence of allele a is due to random mutation that would have occurred during meiosis.