Final answer:
Parents and Rr offspring display a red-spotted phenotype due to the dominance of the R allele, while RR offspring also show red spots as they are homozygous dominant. The rr offspring exhibit no spots, expressing the recessive phenotype.
Step-by-step explanation:
In salamanders, the phenotype of the parents with Rr genotypes would be red spots since R (red spots) is dominant over r (no spots). Phenotype refers to the observable characteristics of an organism as determined by its genotype.
The RR offspring would also display red spots, as both alleles contribute to the red pigment, resulting in a uniformly red phenotype. These offspring are homozygous for the dominant allele.
The Rr offspring would have a phenotype with red spots as well, since the presence of one R allele is sufficient to express the dominant trait. These offspring are heterozygous, carrying one dominant and one recessive allele.
Offspring with the rr genotype would not have red spots, displaying the recessive phenotype. In these cases, both alleles are for the recessive trait, meaning the organism is homozygous recessive.