The statement that would best support the relationships shown on the graph of different types of vertebrates is:
"Amphibians and mammals have similar traits that are not seen in reptiles and birds."
This statement suggests a close evolutionary relationship between amphibians and mammals, which would align with a graph indicating their proximity on a phylogenetic tree or similar representation of vertebrate evolution. The other statements either incorrectly suggest a lack of relationship or imply unexpected genetic similarities that would not support the shown relationships on the graph.