Hi,

It depends on the type of organism you are interested in. The Genus and Species names for mammals, insects, shellfish, freshwater fish, ocean fish, bacteria, viruses, fungi, etc. are not all equally accurate. For many organisms, the genetic relationships do not match up well with other classification and nomenclature systems.

Phylogenetics can be very helpful in sorting out genetic relationships, but one must be careful to understand that "gene trees" or phylogenies based on one or a small number of genes do not always agree with "species" or populations trees based on larger data sets, due primarily to horizontal gene transfer. The rates of horizontal gene transfer vary greatly between types of organisms.