The gene for fur color in rabbits is an incompletely dominant situation: BB rabbits are brown, Bb rabbits are grey, and bb rabbits are white. The gene for fur color distribution is however co-dominant. This gene, S, has two alleles, S1 and S2; S1S1 animals have stripes only; S2S2 animals have spots only; and S1S2 animals have both stripes and spots. The S gene cannot be expressed in white rabbits.

a) If one grey (striped and spotted) rabbit with a white rabbit (that is a carrier for spots only are bred), what are the genotypes and phenotypes expected?
b) If one the grey, striped and spotted parent is crossed with a brown spotted rabbit, predict the offsprings' genotypes and phenotypes.

To determine the genotypes and phenotypes expected in each scenario, we need to understand the basic principles of inheritance and the possibilities of genetic combinations.

a) If one grey (striped and spotted) rabbit and one white (carrier for spots only) rabbit are bred:

First, let's establish the possible genotypes of each parent:

- Grey rabbit (striped and spotted): S1S2

- White rabbit (carrier for spots only): S2s (where s represents the absence of the S1 allele)

To determine the genotypes and phenotypes of the offspring, we need to do a Punnett square analysis.

1) Cross the genotypes:
S1S2 x S2s

2) Set up the Punnett square:

| S1 | S2 |
--------------------------------
S2s | S1S2 | S2s |
S2s | S1S2 | S2s |

3) Determine the genotypes and phenotypes:

- Genotypes:
- 50% S1S2 (striped and spotted)
- 50% S2s (spots only)

- Phenotypes:
- 50% Striped and spotted rabbits
- 50% Spotted rabbits

Therefore, the expected genotypes are 50% S1S2 and 50% S2s, and the expected phenotypes are 50% striped and spotted rabbits and 50% spotted rabbits.

b) If one grey (striped and spotted) parent is crossed with a brown spotted rabbit:

Again, let's determine the possible genotypes of each parent:

- Grey rabbit (striped and spotted): S1S2

- Brown spotted rabbit: BB

1) Cross the genotypes:
S1S2 x BB

2) Set up the Punnett square:

| B | B |
--------------------------------
S1S2 | S1B | S1B |
S1S2 | S1B | S1B |

3) Determine the genotypes and phenotypes:

- Genotypes:
- 50% S1B (striped and brown spotted)
- 50% S1B (striped and brown spotted)

- Phenotypes:
- 100% Striped and brown spotted rabbits

Therefore, the expected genotypes are 50% S1B and 50% S1B, and the expected phenotype is 100% striped and brown spotted rabbits.