Final answer:
To determine if the virulence genes in bordetella pertussis were acquired via horizontal gene transfer, compare their presence in less pathogenic species and unique presence in bordetella pertussis.
Step-by-step explanation:
In order to determine if the virulence genes in bordetella pertussis were acquired via horizontal gene transfer, you would compare certain characteristics. One characteristic to consider is the presence of the same virulence genes in other less pathogenic species, such as b. bronchiseptica.
If these genes are found in both species, it suggests they may be evolutionarily related. On the other hand, if the virulence genes are unique to bordetella pertussis and not present in other species, it suggests they were acquired via horizontal gene transfer.