Anas

For other uses, see Anas (disambiguation).
Anas
Female mallard (Anas platyrhynchos) with brood of young
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Subfamily: Anatinae
Genus: Anas
Linnaeus, 1758
Type species
Anas platyrhynchos
Linnaeus, 1758
Species

40–50, see text

Anas is a genus of dabbling ducks. It includes mallards, wigeons, teals, pintails and shovelers in a number of subgenera. Some authorities prefer to elevate the subgenera to genus rank.[1] Indeed, as the moa-nalos are very close to this clade and may have 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. However, there are 42 species verified by ITIS,[2] and the IUCN recognizes 46 species.[3]

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 may have long played a major role in Anas evolution, with within-subgenus hybrids regularly and between-subgenus hybrids not infrequently being fully fertile.[1] The relationships between species are much obscured by this fact, and mtDNA sequence data is of dubious value in resolving their relationships;[4] 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.

For these reasons, the dabbling duck lineages more distantly related to mallard group (which includes the type species of Anas) than the wigeons should arguably 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 wigeons, which are very distinct in morphology[5] and behavior,[6] but much less so in mtDNA cytochrome b and NADH dehydrogenase subunit 2 sequences,[7] should also be considered a distinct genus Mareca (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.

Species

The following arrangement is based on current morphological,[5] molecular,[7][8] and behavioral[6] characters and presents apparent major evolutionary groupings compared to the subgenera the species were placed in at one time or another.

Baikal teal, Anas formosa

Probable genus Sibirionetta – Baikal teal

Probable genus Querquedula – Garganey (may include Punanetta)

Probable genus Punanetta

Red shoveler, Anas platalea

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

American wigeon, Anas americana

Possible genus Mareca – wigeons (may include Chaulelasmus and Eunetta)

Subgenus Chaulelasmus – gadwall

Subgenus Eunetta – falcated duck

Northern pintail, Anas acuta

Subgenus Dafila – pintails

Subgenus Nettion – teals (paraphyletic)

Green-winged teal, Anas carolinensis

Subgenus Melananas – African black duck

Yellow-billed duck, Anas undulata

Subgenus Anas – mallard and relatives (may include Melananas)

The last male Mariana mallard, ca. 1980
Spot-billed duck, Anas poecilorhyncha

Formerly placed in Anas:

Fossil record

Anas blanchardi fossil

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

Several prehistoric waterfowl supposedly part of the Anas assemblage are nowadays not placed in this genus anymore, at least not with certainty:

Highly problematic, albeit in a theoretical sense, is the placement of the moa-nalos. These are in may be derived from a common ancestor of the Pacific black duck, the Laysan duck, and the mallard, and an unknown amount of other lineages. Phylogenetically, they may even form a clade within the traditional genus Anas.[16] 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 phylogenetic taxonomy may be difficult to apply.

References

  1. 1 2 Carboneras, Carles (1992). "Family Anatidae (Ducks, Geese and Swans)". In del Hoyo, Josep; Elliott, Andrew; Sargatal, Jordi. Handbook of Birds of the World, Volume 1: Ostrich to Ducks. Barcelona: Lynx Edicions. pp. 536–629. ISBN 84-87334-10-5.
  2. ↑ "ITIS Standard Report Page: Genus Anas Linnaeus, 1758". Integrated Taxonomic Information System. Retrieved 20 December 2012.
  3. ↑ IUCN, (2012). IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 20 December 2012.
  4. ↑ Kulikova, Irina V.; Drovetski, Sergei V.; Gibson, Daniel D.; Harrigan, Ryan J.; Rohwer, Sievert; Sorenson, Michael D.; Winker, Kevin; Zhuravlev, Yuri N.; McCracken, Kevin G. (2005). "Phylogeography of the Mallard (Anas platyrhynchos): Hybridization, dispersal, and lineage sorting contribute to complex geographic structure". Auk 122 (3): 949–965. doi:10.1642/0004-8038(2005)122[0949:POTMAP]2.0.CO;2.
  5. 1 2 Livezey, B. C. (1991). "A phylogenetic analysis and classification of recent dabbling ducks (Tribe Anatini) based on comparative morphology" (PDF). Auk 108 (3): 471–507. doi:10.2307/4088089. JSTOR 4088089.
  6. 1 2 Johnson, Kevin P.; McKinney, Frank; Wilson, Robert; Sorenson, Michael D. (2000). "The evolution of postcopulatory displays in dabbling ducks (Anatini): a phylogenetic perspective" (PDF). Animal Behaviour 59 (5): 953–963. doi:10.1006/anbe.1999.1399. PMID 10860522.
  7. 1 2 Johnson, Kevin P.; Sorenson, Michael D. (1999). "Phylogeny and biogeography of dabbling ducks (genus Anas): a comparison of molecular and morphological evidence" (PDF). Auk 116 (3): 792–805. doi:10.2307/4089339. JSTOR 4089339.
  8. ↑ McCracken, Kevin G.; Johnson, William P.; Sheldon, Frederick H. (2001). "Molecular population genetics, phylogeography, and conservation biology of the mottled duck (Anas fulvigula)" (PDF). Conservation Genetics 2 (2): 87–102. doi:10.1023/A:1011858312115.
  9. ↑ Olson, Storrs L.; Jouventin, Pierre (1996). "A New Species of Small Flightless Duck From Amsterdam Island, Southern Indian Ocean (Anatidae: Anas)". Condor 98 (1): 1–9. doi:10.2307/1369501.
  10. ↑ Bernor, R.L.; Kordos, L.; Rook, L. "Recent Advances on Multidisciplinary Research at Rudabánya, Late Miocene (MN9), Hungary: A compendium" (PDF). Paleontographica Italiana 89: 3–36.
  11. ↑ Wilson, R. L. (1968). "Systematics and faunal analysis of a Lower Pliocene vertebrate assemblage from Trego County, Kansas". Contrib. Mus. Paleontol. Univ. Mich. 22 (7): 75–126.
  12. 1 2 Brodkorb, Pierce (1958). "Birds From the Middle Pliocene of Mckay, Oregon". Condor 60 (4): 252–255. doi:10.2307/1365194.
  13. ↑ Emslie, Steven D. "A New Species of Teal From the Pleistocene (Rancholabrean) of Wyoming". Auk 102: 201–205. doi:10.2307/4086849.
  14. 1 2 3 4 Worthy, T. H.; Tennyson, A. J. D.; Jones, C.; McNamara, J. A.; Douglas, B. J. (2007). "Miocene waterfowl and other birds from central Otago, New Zealand". J. Syst. Paleontol. 5 (1): 1–39. doi:10.1017/S1477201906001957.
  15. ↑ Brodkorb, Pierce (1962). "The Systematic Position of Two Oligocene Birds From Belgium". Auk 79 (4): 706–707. doi:10.2307/4082652.
  16. ↑ Sorenson, M. D.; Cooper, A.; Paxinos, E. E.; Quinn, T. W.; James, H. F.; Olson, S. L.; Fleischer, R. C. (1999). "Relationships of the extinct moa-nalos, flightless Hawaiian waterfowl, based on ancient DNA". Proceedings. Biological sciences / the Royal Society 266 (1434): 2187–93. doi:10.1098/rspb.1999.0907. PMC 1690346. PMID 10649633.

External links

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