Normally, hermaphrodites (XX) self-fertilize to only produce more hermaphrodites

Question

Normally, hermaphrodites (XX) self-fertilize to only produce more hermaphrodites. You have a mutant strain in C. elegans (m1/m1) that has in interesting mutant phenotype: XX hermaphrodites have a high incidence of males (30% in comparison to 0.3%). The gene maps to an autosome. m1 is recessive.

Let’s say you do a parental cross (m1/m1 X +/+) then an F1 self cross: m1/+ X m1/+. Since C. elegans hermaphrodites are self-fertile, you just need to place one m1/+ hermaphrodite (XX) on a plate and allow it to self-fertilize (just like with pea plants)! No males are necessary. What percentage of the offspring (F2 generation) will have the genotype m1/m1 (this is not a trick question)?

Surprisingly, nearly 100% of the offspring are hermaphrodites (few to no males) despite the presence of animals with the genotype m1/m1. Speculate why you do not see the percentage of males expected?

Explanation / Answer

The answer for the first part is the percentage of m1/m1 gneotype in the F2 generation is about 25%.

Since the m1 genotype is recessive, the occurence of males in the F2 generation is all the more lower which is almost negliglible.

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.