Mallard - Taxonomy and Evolution

Taxonomy and Evolution

The Mallard was one of the many bird species originally described by Carl Linnaeus in his 18th-century work, Systema Naturae, and still bears its original binomial name.

"Mallard" is derived from the Old French malart or mallart "wild drake", although its ultimate derivation is unclear. It may be related to an Old High German masculine proper name Madelhart, clues lying in the alternate English forms "maudelard" or "mawdelard".

Mallards frequently interbreed with their closest relatives in the genus Anas, such as the American Black Duck, and also with species more distantly related, for example the Northern Pintail, leading to various hybrids that may be fully fertile. This is quite unusual among different species, and apparently is because the Mallard evolved very rapidly and recently, during the Late Pleistocene. The distinct lineages of this radiation are usually kept separate due to non-overlapping ranges and behavioural cues, but are still not fully genetically incompatible. Mallards and their domesticated conspecifics are, of course, also fully interfertile.

Mallards appear to be closer to their Indo-Pacific relatives than to their American ones judging from biogeography. Considering mtDNA D-loop sequence data, they may have evolved in the general area of Siberia; Mallard bones rather abruptly appear in food remains of ancient humans and other deposits of fossil bones in Europe, without a good candidate for a local predecessor species. The large ice age paleosubspecies which made up at least the European and west Asian populations during the Pleistocene has been named Anas platyrhynchos palaeoboschas.

Haplotypes typical of American Mallard relatives and Spotbills can be found in Mallards around the Bering Sea. The Aleutian Islands hold a population of Mallards that appear to be evolving towards a subspecies, as gene flow with other populations is very limited.

The size of the Mallard varies clinally, and birds from Greenland, although larger than birds further south, have smaller bills and are stockier. They are sometimes separated as subspecies, the Greenland Mallard (A. p. conboschas).