You are studying the source of new virus that has recently
infected humans.

You suspect that the virus was transferred from other primates
(they exhibit a

similar infection), specifically chimpanzees, gorillas, or
orangutans. You sample

blood from several infected humans and sequence some viral
genes. You then

build a phylogenetic tree with the human sequences and all the
known strains

from each primate. Draw a hypothetical phylogenetic tree that
would suggest

that the virus came from gorillas, and this transfer occurred
twice

independently. Label chimp sequences (c), gorilla (g),
orangutans (o), and

humans (h).