Final answer:
The virulence of a pathogen can impact its phylogeny in different ways. High virulence may lead to a branching pattern that does not follow one host, while low virulence may result in a branching pattern that mirrors the host's phylogeny.
Step-by-step explanation:
The virulence of a pathogen can impact its phylogeny in various ways. Pathogens with high virulence may have a phylogeny with a branching pattern that does not follow one host (option d). This means that the pathogen can infect different host species and branch out in different directions. On the other hand, pathogens with low virulence may have a phylogeny with a branching pattern that mirrors that of its host (option c).
For example, consider a highly virulent pathogen like the influenza virus. It can infect humans, birds, and other mammals, leading to a phylogeny that branches out in different directions. In contrast, a less virulent pathogen like the common cold virus primarily infects humans, resulting in a phylogeny that closely mirrors the branching pattern of the human phylogeny.