Genetic Inheritance in Moths: Miniature and Spotting Alleles Distribution

[TECHXHEAD]

I am not sure about how to solve this one:

In a particular species of moths, the miniature gene is located on the Z chromosome; two alleles are known: the recessive allele m causes homozygotes to have a small wing phenotype, whereas the dominant allele M confers a normal wing size to the carrier. The spotting gene is also located on the Z chromosome, and maps 10 cM away from the miniature gene. The recessive allele sp causes a spotted wing coloration in homozygotes, wheras the dominant allele Sp results in uniformly coloured wings.

In the cross between a heterozygous male moth: M sp // m So and a female that has normal wings and uniform colouration (M, Sp) what phenotypes would you expected to see in the progeny and how would those phenotypes be distributed (in percentages of total)?

 

[nate808]

Based on the information provided, we can predict the phenotypes and their distribution in the progeny using a Punnett square. The male moth in the cross is heterozygous for both the miniature gene (Mm) and the spotting gene (sp), while the female is homozygous dominant for both genes (MM, SpSp).

The possible genotypes and corresponding phenotypes in the offspring are:

- MM, SpSp (homozygous dominant for both genes): normal wing size and uniform wing coloration
- Mm, SpSp (heterozygous for miniature gene, homozygous dominant for spotting gene): normal wing size and uniform wing coloration
- MM, Sp (homozygous dominant for miniature gene, heterozygous for spotting gene): normal wing size and spotted wing coloration
- Mm, Sp (heterozygous for both genes): normal wing size and spotted wing coloration

Therefore, we can expect to see a 50% chance of normal wing size and uniform wing coloration, a 25% chance of normal wing size and spotted wing coloration, and a 25% chance of small wing size and spotted wing coloration in the progeny. This distribution follows the principle of independent assortment, where the inheritance of one gene (miniature gene) does not affect the inheritance of another gene (spotting gene) on the same chromosome.

It is important to note that these predictions are based on Mendelian genetics and may not always be reflected in actual observations due to factors such as genetic linkage and environmental influences. Further studies and experiments may be needed to confirm these predictions and understand the underlying mechanisms of these genetic traits in moths.

 

[Blueshift5]

Based on the information provided, we can predict the phenotypes and their distribution in the progeny of the cross between a heterozygous male moth (M sp // m So) and a female with normal wings and uniform coloration (M, Sp).

Firstly, we can determine the possible genotypes of the offspring by using the principles of Mendelian genetics. The male moth has one dominant allele for normal wing size (M) and one dominant allele for uniform coloration (Sp), while the female moth has two dominant alleles for both traits (M, Sp). Therefore, the possible genotypes of the offspring are:

1. M Sp // M Sp (25%): These offspring will have normal wing size and uniform coloration, as they have two dominant alleles for both traits.

2. M Sp // m Sp (25%): These offspring will also have normal wing size and uniform coloration, as the dominant M allele will mask the recessive m allele for wing size. However, they will carry the recessive allele for spotting (sp) which may be expressed in future generations.

3. M sp // M So (25%): These offspring will have normal wing size, but will exhibit spotted coloration due to the presence of one dominant allele for spotting (Sp) and one recessive allele for wing size (m).

4. M sp // m So (25%): These offspring will have normal wing size, but may exhibit either uniform or spotted coloration depending on which allele (Sp or sp) is expressed.

Therefore, we can expect to see a 50% distribution of offspring with normal wing size and 50% with spotted coloration. However, the exact distribution of phenotypes may vary due to chance. This cross demonstrates the principles of genetic inheritance and the importance of understanding the location and nature of genes in determining an organism's traits.