Using Henk's punnett square gif generator...
* I'll use B^Sp (B
Sp) for spotty mutation (this not determined yet)
If the sex-linked spotty mutation is an allele of the B locus...
Het. ER/e+ B/BSp (barred/spotty cockerel) X e+/e+ wild-type hen
Offspring Phenotypes:
1/4 (25%) ER/e+ or e+/e+ B/b+ het. barred males
1/4 (25%) ER/e+ or e+/e+ B/b+ het. spotty males
1/4 (25%) ER/e+ or e+/e+ B/- barred females
1/4 (25%) ER/e+ or e+/e+ B^Sp/- spotty females
*So no b+/b+ or b+/- non-barred or non-spotty, nor any B/B^Sp barred/spotty should segregate (if spotty is an allele of the B locus).
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If the sex-linked spotty mutation is an allele of the B locus...
Het. ER/e+ B/BSp (barred/spotty cockerel) X e+/e+ B/- Crele (barred) hen
Offspring Phenotypes:
1/4 (25%) ER/e+ or e+/e+ B/B hom. barred males
1/4 (25%) ER/e+ or e+/e+ B/B^Sp het. barred/spotty males
1/4 (25%) ER/e+ or e+/e+ B/- barred females
1/4 (25%) ER/e+ or e+/e+ B^Sp/- spotty females
*So no B/b+ or B^Sp/b+ het. barred or het. spotty non-barred males, no b+/- non-barred or non-spotty & no B/B^Sp barred/spotty females (if spotty is an allele of the B locus).