The steamer ducks are a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

(''Tachyeres'') of

duck Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form ...

s in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Anatidae The Anatidae are the biological family of water birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted for swimming, flo ...

. All of the four species occur at the southern cone of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...

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. 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.

Taxonomy

The genus ''Tachyeres'' was introduced in 1875 by the English zoologist

Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils. Ow ...

to accommodate the

Falkland steamer duck The Falkland steamer duck (''Tachyeres brachypterus'') is a species of flightless duck found on the Falkland Islands in the South Atlantic Ocean. The steamer ducks get their name from their unconventional swimming behaviour in which they flap the ...

. The genus name ''Tachyeres'', "having fast oars" or "fast rower", comes from

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...

ταχυ- "fast" + ἐρέσσω "I row (as with oars)". 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 A paddle steamer is a steamship or steamboat powered by a steam engine that drives paddle wheels to propel the craft through the water. In antiquity, paddle wheelers followed the development of poles, oars and sails, where the first uses wer ...

. They are usually placed in the

shelduck The shelducks, most species of which are found in the genus ''Tadorna'' (except for the Radjah shelduck, which is now found in its own monotypic genus ''Radjah''), are a group of large birds in the Tadorninae subfamily of the Anatidae, the biolog ...

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus Genus ( plural genera ) is a taxonomic rank used in the biological classifica ...

Tadorninae. However,

mtDNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial DNA ...

sequence In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is called ...

analyses of the cytochrome ''b'' and

NADH dehydrogenase NADH dehydrogenase is an enzyme that converts nicotinamide adenine dinucleotide (NAD) from its reduced form (NADH) to its oxidized form (NAD+). Members of the NADH dehydrogenase family and analogues are commonly systematically named using the for ...

subunit Subunit may refer to: * Subunit HIV vaccine, a class of HIV vaccine *Protein subunit, a protein molecule that assembles with other protein molecules *Monomer, a molecule that may bind chemically to other molecules to form a polymer * Sub-subunit, ...

genes In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

indicate that ''Tachyeres'' rather belongs in a distinct

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

of aberrant South American

dabbling duck The Anatinae are a subfamily of the family Anatidae (swans, geese and ducks). Its surviving members are the dabbling ducks, which feed mainly at the surface rather than by diving. The other members of the Anatinae are the extinct moa-nalo, a yo ...

s, which also includes the Brazilian, the crested, and the

bronze-winged duck The bronze-winged duck (''Speculanas specularis'') also known as the spectacled duck, is a dabbling duck and the sole member of its genus ''Speculanas''. It is often placed in ''Anas'' with most other dabbling ducks, but its closest relative is e ...

Extant species

There are four species: The Chubut steamer duck was only described in 1981.

Phylogeny

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

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 there is no evidence for a reversal of evolution, and these reversals are extremely rare. It is more likely that flightlessness evolved independently in each steamer duck species. The DYRK1A enzyme has been identified as a candidate gene for flightlessness in steamer ducks. This finding, 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. The largest males of the most volant species, the flying steamer duck, are completely incapable of flight, while other individuals rarely fly. The flying steamer duck is the only species to reside in landlocked bodies of water. 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.

References

External links

* * Ducks * {{duck-stub