Question

The amino acid sequences encoded by the red and green visual pigment genes found in humans are 96% identical (Nathans et al. 1986). These two genes are found close together on the X chromosome, while the gene for the blue pigment is located on chromosome 7. Among pri- mates, only Old World monkeys, the great apes, and hu- mans have a third pigment gene—New World monkeys have only one X-linked pigment gene. Comment on the following three hypotheses:

• One of the two visual pigment loci on the X chromo- some originated in a gene duplication event.
• The gene duplication event occurred after New World and Old World monkeys had diverged from a common ancestor, which had two visual pigment genes.
• Human males with a mutated form of the red or green pigment gene experience the same color vision of our male primate ancestors.

Answer 1

This question asks for comments on three hypotheses regarding the origin of the visual pigment genes found in humans and primates.

Step-by-step explanation:

The subject of this question is Biology. This question asks for comments on three hypotheses regarding the origin of the visual pigment genes found in humans and primates. The first hypothesis suggests that one of the visual pigment loci on the X chromosome originated from a gene duplication event. The second hypothesis proposes that the gene duplication event occurred after the divergence of New World and Old World monkeys from a common ancestor. The third hypothesis suggests that human males with a mutated form of the red or green pigment gene experience the same color vision as male primate ancestors.