Steamer duck

The steamer ducks are a genus (Tachyeres) of ducks in the family Anatidae. All of the four species occur at the southern cone of South America in Chile and Argentina, and all except the flying steamer duck are flightless; even this one species capable of flight rarely takes to the air.[2][3][4] The genus name Tachyeres, "having fast oars" or "fast rower", comes from Ancient Greek ταχυ- "fast" + ἐρέσσω "I row (as with oars)".[5] The common name "steamer ducks" arose because, when swimming fast, they flap their wings into the water as well as using their feet, creating an effect like a paddle steamer.[6] They can be aggressive and are capable of chasing off predators like petrels. Bloody battles of steamer ducks with each other over territory disputes are observed in nature. They even kill waterbirds that are several times their size.[7]

Steamer ducks
Falkland steamer duck, Tachyeres brachypterus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Subfamily: Tadorninae
Genus: Tachyeres
Owen, 1875
Species

Tachyeres patachonicus
Tachyeres pteneres
Tachyeres brachypterus
Tachyeres leucocephalus

Synonyms
  • Micropterus Lesson 1828 non Lacépède 1802
  • Microa Strand 1943[1]

Taxonomy

They are usually placed in the shelduck subfamily Tadorninae. However, mtDNA sequence analyses of the cytochrome b and NADH dehydrogenase subunit 2 genes indicate that Tachyeres rather belongs in a distinct clade of aberrant South American dabbling ducks, which also includes the Brazilian, the crested, and the bronze-winged ducks.[8]

Extant species

There are four species:[2][4]

ImageScientific nameCommon NameDistribution
Tachyeres patachonicusFlying steamer ducksouthern Chile and Argentina, Tierra del Fuego and the Falkland Islands.
Tachyeres pteneresFuegian steamer ducksouthern Chile and Chiloé to Tierra del Fuego
Tachyeres leucocephalusChubut steamer duckArgentina
Tachyeres brachypterusFalkland steamer duckthe Falkland Islands in the southern Atlantic Ocean.

The Chubut steamer duck was only described in 1981.[2]

Phylogeny

Based on the Taxonomy in Flux from John Boyd's website.[9]

Tachyeres
 

T. brachypterus (Latham 1790) (Falkland steamer duck)

 
 
 

T. pteneres (Forster 1844) (Fuegian steamer duck)

 
 
 

T. patachonicus (King 1831) (Flying steamer duck)

 
 

T. leucocephalus Humphrey & Thompson 1981 (Chubut steamer duck)

 
 
 
 

Evolution

Flightlessness

Flightless Tachyeres have a paraphyletic organization, as shown above. There are multiple possible explanations of these organizations. It is unlikely that flightlessness evolved once in all Tachyeres and then disappeared in T. patachonicus, because of there is no evidence for a reversal of evolution, and these reversals are extremely rare.[3] It is more likely that flightlessness evolved independently in each steamer duck species. However, a candidate gene for flightlessness in steamer ducks has been identified, and this combined with the range of flight capability means the evolutionary history of the group may not be so clear cut.

There is genomic evidence of recent speciation into four Tachyeres species. Flightless Tachyeres are thought to be undergoing a modern evolutionary transition to flightlessness, which explains the range of flight capability observed across the genus.[3] The largest males of the most volant species, the flying steamer duck, are completely incapable of flight, while other individuals rarely fly.[3] The flying steamer duck is the only species to reside in landlocked bodies of water.[10] Generally, island bound/isolated avian populations are more likely to experience evolution towards flightlessness, which may be the case for several Tachyeres populations in the coastal South American regions.[11]

References
  1. "Part 7- Vertebrates". Collection of genus-group names in a systematic arrangement. Retrieved 30 June 2016.
  2. Livezey, Bradley C.; Humphrey, Philip Strong (1992). Taxonomy and Identification of Steamer-Ducks (Anatidae: Tachyeres). Monograph of the Museum of Natural History, the University of Kansas. No. 8. Lawrence, Kansas: Museum of Natural History, University of Kansas. ISBN 0893380423.
  3. Campagna, Leonardo; McCracken, Kevin G.; Lovette, Irby J. (September 2019). "Gradual evolution towards flightlessness in steamer ducks*". Evolution. 73 (9): 1916–1926. doi:10.1111/evo.13758. ISSN 0014-3820. PMID 31106403.
  4. Livezey, Bradley (1986). "Flightlessness in steamer-ducks (Anatidae: tachyeres): its morphological bases and probable evolution". Evolution. 40 (3): 540–558. doi:10.1111/j.1558-5646.1986.tb00506.x. PMID 28556327.
  5. Kear, J., ed. (2005). Ducks, Geese and Swans. I. Oxford University Press. p. 378. ISBN 0198610084.
  6. Moynihan, M. (April 1958). "Notes on the Behavior of the Flying Steamer Duck" (PDF). The Auk. 75 (2): 183–202. doi:10.2307/4081889. JSTOR 4081889.
  7. "8 Birds That Can't Fly".
  8. 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.
  9. Boyd, John (2007). "Anatini" (PDF). Taxonomy in Flux. Retrieved 30 August 2016.
  10. "Flying steamer duck". Wikipedia.
  11. Wright, Natalie (2016). "Predictable evolution toward flightlessness in volant island birds" (PDF). Proceedings of the National Academy of Sciences.


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