The steamer ducks are a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

(''Tachyeres'') of

duck Duck is the common name for numerous species of waterfowl in the family (biology), family Anatidae. Ducks are generally smaller and shorter-necked than swans and goose, geese, which are members of the same family. Divided among several subfam ...

s in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

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

. 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 considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

in Chile and Argentina, and all except the flying steamer duck are

flightless Flightless birds are birds that cannot fly, as they have, through evolution, lost the ability to. There are over 60 extant species, including the well-known ratites ( ostriches, emus, cassowaries, rheas, and kiwis) and penguins. The smal ...

; 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 anatomy, comparative anatomist and paleontology, palaeontologist. Owen is generally considered to have been an outstanding naturalist with a remarkabl ...

to accommodate the Falkland steamer duck. 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 classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

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 driving paddle wheels to propel the craft through the water. In antiquity, paddle wheelers followed the development of poles, oars and sails, whereby the first uses were wh ...

. They are usually placed in the shelduck

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Tadorninae. However,

mtDNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the DNA contained in ...

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 cal ...

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 f ...

subunit 2

genes In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

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

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

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 y ...

s, which also includes the Brazilian, the crested, and the bronze-winged ducks.

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

* * {{Taxonbar, from=Q933654 Ducks *