Question

Some pigeons have scaly feet while other pigeons have feathered feet called muffs. there is a genetic component to this phenotype. you decide to use breeding experiments to estimate the number of genes that contribute to the pigeon foot phenotype. you cross two true breeding pigeon strains and count the number of toe feathers of the f1 and f2 offspring. pigeon strain #1 (s1) has an average of 12 toe feathers while pigeon strain 2 (s2) has an average of 60 toe feathers. you cross your s1 and s2 parental birds and observe the f1. the f1 birds have an average of 36 feathers in their toes.

a. what 2 assumptions do you make when you use breeding experiments like the one describes in this problem to estimate the number of genes that contribute to a phenotype?

Answer 1

To estimate the number of genes contributing to a phenotype in breeding experiments, it is assumed that trait inheritance follows Mendelian principles, and that the phenotypic variation is due to the additive effects of multiple genes. These assumptions enable the use of methods like Punnett squares to analyze phenotypic data.

Step-by-step explanation:

When using breeding experiments like the one described to estimate the number of genes that contribute to a phenotype, such as pigeons with scaly feet versus muffs, two assumptions are typically made:

• The first assumption is that traits like the number of toe feathers in pigeons are determined by genetic factors and that these factors segregate and assort independently following Mendelian principles.
• The second assumption is that the phenotypic variation observed (e.g., the number of toe feathers) is a quantitative trait and is a result of the additive effect of multiple genes, which can be estimated using Mendelian ratios and statistical models like the Punnett square to predict offspring phenotypes from the observed data.

In this scenario, we may relate the phenotype distribution of toe feathers to the offspring's genotype by applying Mendelian genetics. Assuming each allele contributes equally and additively to the trait, the intermediate F1 phenotype suggests incomplete dominance or the cumulative effect of multiple genes. Further breeding to obtain the F2 generation and analyzing the distribution of toe feather numbers could reveal if the genes assort independently and adhere to the classical Mendelian ratios.