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Anas

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Anas ibn Malik was an early follower of Islam who is credited with assistance in spreading the Hadith. Due to this, "Anas" is a common surname among Muslims.
iAnas
Image:Female mallard with ducklings.jpg
The Mallard (Anas platyrhynchos), a typical member of this genus.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Genus: Anas
Linnaeus, 1758
Species

Some 40-50; see text.

Anas is a genus of dabbling ducks. It includes mallards, wigeons, teals, pintails and shovelers. Some authorities prefer to the subgenera to genus rank (Carboneras, 1992). Indeed, as the moa-nalos evolved later than some of these lineages, it is rather the absence of a thorough review than lack of necessity that this genus is rather over-lumped.

[edit] Systematics

The phylogeny of this genus is one of the most confounded ones of all living birds. Research is hampered by the fact the radiation of the two major groups of Anas - the teals and mallard groups - took place in a very short time and fairly recently, roughly in the mid-late Pleistocene. Furthermore, hybridization probably has long played a major role in Anas evolution, with within-subgenus hybrids regularly and between-subgenus hybrids not infrequently being fully fertile (Carboneras, 1992; see also Mariana Mallard). The relationships between species are much obscured by this fact, and mtDNA sequence data is of dubious value in resolving their relationships; on the other hand, nuclear DNA sequences evolve too slowly to resolve the phylogeny of the subgenus Anas for example.

Some major clades can be discerned. For example, that the traditional subgenus Anas, the mallard group, forms a monophyletic (in the loose sense, i.e. non-holophyletic) group has never been seriously questioned by modern science and is as good as confirmed (but see below). On the other hand, the phylogeny of the teals is very confusing.

It is fairly clear by now that the dabbling duck lineages more distantly related to mallard group (which includes the type species of Anas) than the widgeons are should be separated in their own genera. These would include the Baikal Teal, the Garganey, the spotted black-capped Punanetta group, and the shovelers and other blue-winged species. Whether the widgeons, which are very distinct in morphology (Livezey, 1991) and behavior (Johnson et al., 2000), but much less so in mtDNA cytochrome b and NADH dehydrogenase subunit 2 sequences (Johnson & Sorenson, 1999), should also be considered a distinct genus (including the Gadwall and Falcated Duck) is essentially the one remaining point of dispute as regards the question which taxa should remain in this genus and which ones should not.

The following arrangement is based on morphological (Livezey, 1991), molecular (Johnson & Sorenson, 1999) and behavioral (Johnson et al., 2000) characters and presents apparent major evolutionary groupings compared to the subgenera the species were placed in at one time or another.

Probable genus N.N.

Probable genus Querquedula - Garganey (may include Punanetta)

Probable genus Punanetta

Probable genus Spatula - blue-winged ducks/shovelers and allies (polyphyletic?)

Probable genus Mareca - widgeons (may include Chaulelasmus and Eunetta)

Subgenus Chaulelasmus - Gadwall

Subgenus Eunetta - Falcated Duck

Subgenus Dafila - pintails

Subgenus Nettion - teals (paraphyletic)

  • Green-winged/Red-and-green head clade

Subgenus Melananas - African Black Duck

Subgenus Anas - mallard and relatives (may include Melananas')

Formerly placed in Anas:

A number of fossil species of Anas have been described. Their relationships are often undetermined:

  • Anas isarensis (Late Miocene of Aumeister, Germany)
  • Anas greeni (Ash Hollow Late Miocene?/Early Pliocene of South Dakota, USA) - Nettion red-and-green head clade (doubtful)?
  • Anas ogallalae (Ogalalla Late Miocene?/Early Pliocene of Kansas, USA) - Nettion red-and-green head clade (doubtful)?
  • Anas pullulans (Juntura Late Miocene?/Early Pliocene of Juntura, USA) - Punanetta?
  • Anas eppelsheimensis (Early Pliocene of Eppelsheim, Germany) - Nettion red-and-green head clade?
  • Anas bunkeri (Early -? Middle Pliocene - Early Pleistocene of WC USA) - Nettion red-and-green head clade?
  • Anas pachyscelus (Shore Hills Late Pleistocene of Bermuda, W Atlantic)
  • Anas schneideri (Late Pleistocene of Little Box Elder Cave, USA)

Highly problematic, albeit in a theoretical sense, ist the placement of the moa-nalos. These are in all probability derived from a common ancestor of the Pacific Black Duck, the Laysan Duck, and the Mallard, and would have to be placed in the genus Anas[citation needed]. However, as opposed to these species - which are well representative of dabbling ducks in general - the moa-nalos are the most radical departure from the anseriform bauplan known to science. This illustrates that in a truly evolutionary sense, a strictly parsimonious taxonomy may not always be desirable.

[edit] References

  • Carboneras, Carles (1992): Family Anatidae (Ducks, Geese and Swans). In: del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (editors): Handbook of Birds of the World, Volume 1: Ostrich to Ducks: 536-629. Lynx Edicions, Barcelona. ISBN 84-87334-10-5
  • Johnson, Kevin P. & Sorenson, Michael D. (1999): Phylogeny and biogeography of dabbling ducks (genus Anas): a comparison of molecular and morphological evidence. Auk 116(3): 792–805. PDF fulltext
  • Johnson, Kevin P. McKinney, Frank; Wilson, Robert & Sorenson, Michael D. (2000): The evolution of postcopulatory displays in dabbling ducks (Anatini): a phylogenetic perspective. Animal Behaviour 59(5): 953–963 PDF fulltext
  • Livezey, B. C. (1991): A phylogenetic analysis and classification of recent dabbling ducks (Tribe Anatini) based on comparative morphology. Auk 108(3): 471–507. PDF fulltextbg:Патици

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