Knowing taxonomic relationships can be important for better knowing
shared diseases.  For example, studies of wild animals populations
looking for ADV have found it in raccoons as well as skunks and minks.
That is important to know for ferret health especially since the
branching that led to mustelids, procyonids, etc.  is as recent as it
is compared to many other lineages.
 
For those who are interested in seeing possible future taxonomy changes
for ferrets and some of their relatives (by the way, notice that the
mongoose is NOT closely related, but instead developed from the feline
branch as has been long known):
 
Syst Biol. 2005 Apr;54(2):317-37; Molecular phylogeny of the carnivora
(mammalia): assessing the impact of increased sampling on resolving
enigmatic relationships; Flynn JJ, Finarelli JA, Zehr S, Hsu J, Nedbal
MA.
 
>We recovered all of the higher level carnivoran clades that had been
>robustly supported in previous analyses (by analyses of morphological
>and molecular data), including the monophyly of Caniformia,
>Feliformia, Arctoidea, Pinnipedia, Musteloidea, Procyonidae +
>Mustelidae sensu stricto, and a clade of (Hyaenidae + (Herpestidae +
>Malagasy carnivorans)).  All of the traditional "families," with the
>exception of Viverridae and Mustelidae, were robustly supported as
>monophyletic groups.
 
and
 
>We further have determined the relative positions of the major
>lineages within the Caniformia, which previous studies could not
>resolve, including the first robust support for the phylogenetic
>position of marine carnivorans (Pinnipedia) within the Arctoidea
>(as the sister-group to musteloids [sensu lato], with ursids as
>their sister group).
 
and
 
>In addition, we recovered a monophyletic clade of skunks and stink
>badgers (Mephitidae) and resolved the topology of musteloid
>interrelationships as: Ailurus (Mephitidae (Procyonidae, Mustelidae
>[sensu stricto])).  This pattern of interrelationships of living
>caniforms suggests a novel inference that large body size may have
>been the primitive condition for Arctoidea, with secondary size
>reduction evolving later in some musteloids.  Within Mustelidae,
>Bayesian analyses are unambiguous in supporting otter monophyly
>(Lutrinae), and in both MP and Bayesian analyses Martes is
>paraphyletic with respect to Gulo and Eira, as has been observed in
>some previous molecular studies.
 
Mol Phylogenet Evol. 2006 May 26; Molecular phylogeny of the
Arctoidea (Carnivora): Effect of missing data on supertree and
supermatrix analyses of multiple gene data sets; Fulton TL, Strobeck C.
>We recovered the three major arctoid lineages, Ursidae, Pinnipedia,
>and Musteloidea, as monophyletic, with Ursidae (bears) strongly
>supported as the basal arctoid lineage.
 
and
 
>All family designations within Musteloidea were strongly supported:
>Mephitidae (skunks), Ailuridae (monotypic red panda), Mustelidae
>(weasels, badgers, otters), and Procyonidae (raccoons). A novel
>hypothesis for the position of the red panda was recovered, placing
>it as branching after Mephitidae and before Mustelidae+Procyonidae.
>Within Mustelidae, subfamily taxonomic changes are considered.  This
>study represents the most comprehensive sampling to date of the
>Caniformia in a molecular study and contains the most complete
>molecular phylogeny for the Procyonidae.
 
Zoolog Sci. 2006 Feb;23(2):125-46; Evidence from nuclear DNA
sequences sheds light on the phylogenetic relationships of pinnipedia:
single origin with affinity to musteloidea; Sato JJ, Wolsan M, Suzuki
H, Hosoda T, Yamaguchi Y, Hiyama K, Kobayashi M, Minami S.
 
>Until most recently, the two major competing hypotheses were that
>the pinnipeds have a single (monophyletic) origin from a bear-like
>ancestor, or that they have a dual (diphyletic) origin, with sea
>lions (Otariidae) derived from a bear-like ancestor, and seals
>(Phocidae) derived from an otter-, mustelid-, or musteloid-like
>ancestor.  We examined phylogenetic relationships among 29 species of
>arctoid carnivorans
 
and
 
>Evidence from nuclear DNA evolution presented here contradicts the
>two major hypotheses of pinniped relationships and strongly suggests
>a single origin of the pinnipeds from an arctoid ancestor shared with
>Musteloidea to the exclusion of Ursidae.
 
Some others:
Zoolog Sci. 2004 Jan;21(1):111-8; Molecular phylogeny of arctoids
(Mammalia: Carnivora) with emphasis on phylogenetic and taxonomic
positions of the ferret-badgers and skunks; Sato JJ, Hosoda T, Wolsan
M, Suzuki H.
 
Zoolog Sci. 2003 Feb;20(2):243-64; Erratum in:  Zoolog Sci. 2003 Apr;
20(4):515; Phylogenetic relationships and divergence times among
mustelids (Mammalia: Carnivora) based on nucleotide sequences of the
nuclear interphotoreceptor retinoid binding protein and mitochondrial
cytochrome b genes; Sato JJ, Hosoda T, Wolsan M, Tsuchiya K, Yamamoto
M, Suzuki H.
 
>Strong support was found for a close affinity of Enhydra with
>Mustela to the exclusion of Martes and Gulo (causing Mustelinae to be
>paraphyletic); the most-basal position of Mustela vison within Mustela,
>followed by Mustela erminea; an association of Mustela lutreola, Mustela
>itatsi, Mustela sibirica, and the subgenus Putorius (including Mustela
>putorius and Mustela eversmanii), to the exclusion of Mustela nivalis
>and Mustela altaica; and a basal position of Mustela itatsi to a clade
>containing Mustela sibirica and Putorius.  Whereas cytochrome b strongly
>supported Mustela lutreola as the sister species to Putorius, IRBP
>strongly supported its basal placement to the Mustela itatsi-Mustela
>sibirica-Putorius clade.  The low level of sequence divergence in
>cytochrome b between Mustela lutreola and Putorius is therefore a result
>of interspecific mitochondrial introgression between these taxa, rather
>than a recent origin of Mustela lutreola in a close relationship to
>Putorius.  Time estimates inferred from IRBP and cytochrome b for
>mustelid divergence events are mostly in agreement with the fossil
>record.
[Posted in FML issue 5309]