One strain of Drosophila melanogaster is homozygous for two recessive mutations, scruff and echinus . A male from the scruff echinus is crossed to a wild type female. An F1 hybrid female is test crossed to a scruff echinus male.
The numbers of four phenotypes in F2 offspring are: Wild type 2337 scruff 461 echinus 462 scruff ,echinus 2416 What is the distance between the scruff and echinus genes?