Chapter 2, Problem 14P

An experienced goldfish breeder receives two unusual male goldfish. One is black rather than gold, and the other has a single tail fin rather than a split tail fin. The breeder crosses the black male to a female that is gold. All the $F_1$ are gold. She also crosses the single-finned male to a female with a split tail fin. All the F1 have a split tail fin. She then crosses the black male to $F_1$ gold females and, separately, crosses the single-finned male to F1 split-finned females. The results of the crosses are shown below.

Black male $\times F_1$ gold female:

Gold 32

Black 34

Single-finned male $\times F_1$ split-finned female:

Split fin 41

Single fin 39

a. What do the results of these crosses suggest about the inheritance of color and tail fin shape in goldfish?

b. Is black color dominant or recessive? Explain. Is single tail dominant or recessive? Explain.

c. Use chi-square analysis to test your hereditary hypothesis for each trait.