Fantastic Mr Fox

The Tibetan fox (Vulpes ferrilata), a distinctive fox species restricted to the Tibetan Plateau. Photo from the BBC via Lioncrusher's Domain.

Foxes are a widespread assemblage of canid predators, found through most of the Holarctic and drier Africa and also here in Australia, where the red fox Vulpes vulpes was introduced quite successfully. Too successfully, in fact - foxes are one of the most significant invasive species in Australia, and a dire threat to many native species. Of the slightly more than ten species in the fox genus Vulpes, the red fox is undoubtedly the most familiar, being both the most widespread species overall as well as the most abundant in developed countries. However, the familiarity of the red fox is a little misleading, as Vulpes vulpes is actually one of the more distinctive species in the genus, being considerably larger and arguably more dog-like than other foxes.

The morphological analysis of the Canidae by Tedford et al. (1995) supported a division of the living members of the family between two lineages, the Vulpini containing Vulpes, and the Canini including Canis (the genus including the domestic dog) and the South American canids. This early division is consistent with the early appearance of fossil species assigned to Vulpes, with V. stenognathus coming from the Late Miocene (Lyras & van der Geer, 2003). The majority of Vulpini were included in Vulpes except for the bat-eared fox (Otocyon megalotis) and the two species of grey foxes (Urocyon). Two species in the Vulpes clade, the fennec fox (Vulpes zerda or Fennecus zerda) and the Arctic fox (Alopex lagopus) have been regarded as separate genera, but it seems pretty well-established that doing so renders Vulpes paraphyletic (Zrzavý & Řičánková, 2004). More recent analyses using both molecular and morphological data have continued to support the Vulpes-Canini division (Zrzavý & Řičánková, 2004; Bardeleben et al., 2005), but results differ about the relationships of Vulpes to Urocyon and/or Otocyon, which may fall in a Vulpini clade or may be basal to the Vulpes + Canini split. Still, all recent authors seem to agree that, contrary to many older sources, the grey foxes should not be included in Vulpes.


The Indian fox (Vulpes bengalensis), the species nominated by Macdonald (1984) as the most representative of the genus. A nice atmospheric shot by Jon Hall.

Relationships within the Vulpes clade are fairly uncertain. Zrzavý & Řičánková (2004) tentatively suggested a division between two major groups that both may or may not be monophyletic, an 'Afro-Asiatic' clade and an 'Holarctic' clade. The 'Afro-Asiatic' group includes the fennec and pale fox (V. pallida) of northern Africa, the Cape fox (V. chama) of southern Africa, Blanford's fox (V. cana) of central Asia and probably the Indian fox (V. bengalensis), with the fennec and Blanford's foxes forming a clade. Within the 'Holarctic' group, Rüppell's fox (V. ruppelli) inhabits northern Africa, the red fox can be found across the entire Holarctic, and the corsac (V. corsac) and Tibetan foxes (V. ferrilata) are found in central Asia. The circumpolar Arctic fox forms a clade in the Holarctic group with the V. velox/V. macrotis complex, the swift and kit foxes, of North America. All fox species seem to inhabit temperate or dry climates - note particularly the wide geographical division between the Cape fox and all other species of the genus.

While foxes are generally characterised as solitary animals, and certainly do not form packs in the manner of Canis and closely related genera, individuals of at least some species may form small groups, usually a male and a number of vixens. Members of a group will still forage for food separately (Macdonald, 1984). All foxes use a characteristic high pounce in capturing prey, springing upwards and landing on their quarry from directly above it.



Of course, foxes are also famed for being one of the few animals able to transform their appearance at will. They share this ability with the tanuki (Nyctereutes procyonoides), a canid whose phylogenetic position relative to the Vulpes-Canini split remains uncertain. Nevertheless, the foxes would doubtless like to point out that they are not as prone to buffoonery as tanuki. Because of the uncertain position of the tanuki and a shocking shortage of studies of shape-changing abilities in fox species other than V. vulpes, we cannot presently comment whether the shape-changing ability is a plesiomorphy of crown canids that has been lost in the Canini, or has been acquired independently in foxes and tanuki.

REFERENCES

Bardeleben, C., R. L. Moore & R. K. Wayne. 2005. A molecular phylogeny of the Canidae based on six nuclear loci. Molecular Phylogenetics and Evolution 37 (3): 815-831.

Lyras, G. E., & A. A. E. van der Geer. 2003. External brain anatomy in relation to the phylogeny of Caninae (Carnivora: Canidae). Zoological Journal of the Linnean Society 138 (4): 505-522.

Macdonald, D. W. 1984. Foxes. In All the World’s Animals: Carnivores (D. Macdonald, ed.) pp. 60-67. Torstar Books Inc.: New York.

Tedford, R. H., B. E. Taylor & X. Wang. 1995. Phylogeny of the Caninae (Carnivora: Canidae): the living taxa. American Museum Novitates 3146: 1-37.

Zrzavý, J., & V. Řičánková. 2004. Phylogeny of Recent Canidae (Mammalia, Carnivora): relative reliability and utility of morphological and molecular datasets. Zoologica Scripta 33 (4): 311-333.