Question

Summerize New X-chromosome data support the idea that mutations causing male lethality are X‑linked. Only about half of the F1 females produce the predicted deficit of male offspring, consistent with those females being heterozygous (one normal X and one mutant X), while surviving males carry only the normal X (males inherit their single X from their mothers, so a mutated maternal X can cause male lethality and skew the sex ratio). Classic experiments by Muller—inducing mutations on the male X with radiation and following them through crosses—further showed that the X chromosome can acquire and transmit such mutations. The authors note the hypothesis would be updated if unexpected data reveal additional mutations or patterns.

Answer 1

New X‑chromosome data support the idea that mutations causing male lethality are X‑linked. About half of F1 females show the predicted deficit of male offspring, consistent with those females being heterozygous (one normal X and one mutant X), while surviving males inherit only the normal maternal X. Classic experiments by Muller—inducing mutations on the male X with radiation and following them through crosses—further demonstrated that the X can acquire and transmit such mutations. The authors note the conclusion could change if future, unexpected data reveal additional mutations or patterns.