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 F₁ 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 F₁ gold females and, separately, crosses the single-finned male to F₁ split-finned females. The results of the crosses are shown below.

   Black male x F₁ gold female:
        Gold                 32
        Black                34
   Single-finned male x F₁ split-finned female:
        Split fin              41
        Single fin           39

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

Key Concepts

Mendelian Inheritance

Mendelian inheritance refers to the principles of heredity established by Gregor Mendel, which include the concepts of dominant and recessive traits. In this context, the gold color in goldfish is likely a dominant trait, as all F₁ offspring from the black male and gold female are gold. Understanding these principles helps explain how traits are passed from parents to offspring.

Phenotypic Ratios

Phenotypic ratios are the relative frequencies of different phenotypes in the offspring resulting from a genetic cross. The results from the crosses show specific ratios of gold to black and split to single fins, indicating how traits segregate and assort independently. Analyzing these ratios can provide insights into the genetic basis of the traits observed.

Sex-Linked Traits

Sex-linked traits are characteristics that are associated with genes located on sex chromosomes. While the question does not explicitly mention sex-linked inheritance, understanding this concept is crucial for interpreting the inheritance patterns of traits like color and fin shape. If one trait were sex-linked, it could affect the expected ratios in the offspring, influencing the interpretation of the breeding results.