Final answer:
Mendel's law of independent assortment doesn't apply to a butterfly species with antenna shape and color genes on the same chromosome because these linked genes are often inherited together. The closer these genes are on the chromosome, the less likely they will be separated by recombination during meiosis.
Step-by-step explanation:
In the case of a butterfly species with genes for antenna shape and color on the same chromosome, Mendel's law of independent assortment does not apply. This law states that the alleles of different genes assort independently of one another during gamete formation. However, when genes are linked, as they are on the same chromosome, they tend to be inherited together, leading to offspring ratios that violate Mendel's law.
This is because linked genes do not always separate into different gametes during meiosis. The degree to which they can assort independently depends on the likelihood of recombination events occurring between them. Genes that are far apart on the chromosome have a higher chance of being separated by recombination, and thus can still assort independently.