Oxyurini: Difference between revisions

''[[Oxyura]]''<br/>

''[[Nomonyx]]''<br/>

The '''OxyurinaeOxyurini''' isare a [[subfamily]]tribe of the [[duck]], [[goose]] and [[swan]] familysubfamily of [[bird]]s, ''the [[AnatidaeAnatinae]]''. It has been subject of considerable debate about its validity and circumscription. Some taxonomic authorities place the group in its own subfamily, the ''Oxyurinae''. Most of its members have long, stiff tail feathers which are erected when the bird is at rest, and relatively large, swollen bills. Though their relationships are still enigmatic, they appear to be closer to swans and true geese rather than to the typical ducks. The highest diversity is found in the warmer parts of the [[Americas]], but at least one species occurs in a major part of the world{{clarify|date=May 2023}}.

Their [[Morphology (biology)|habitus]] resembles a freshwater [[diving duck]], particularly when moving on dry land. Their legs are set far back, making them awkward walkers, so they rarely leave the water. When at rest, thetheir tails are a notable difference as per above, and in the water they often swim very deep-set. Their unusual courtship displays involve drumming noises from inflatable throat- sacs, head throwing, and erecting short [[Crest (feathers)|crests]]. Most display singly with a very elaborate and peculiar display, but [[Muskmusk Duckduck]]s congregate at [[Lek (mating arena)|lek]]s and have a more limited display.

There is oneOne mid-sized [[genus]] and two or three which are [[monotypic]] are described today:

The [[Blackblack-headed Duckduck]] of ''Heteronetta'' is indisputably quite [[basal (evolution)|basal]], looking more like a typical ducklikeduck-like [[Anatidae]] with a short tail and normal bill. The [[Maskedmasked Duckduck]] of ''[[Nomonyx]]'' has a more intermediate position; it probably diverged from the lineage leading to the main radiation some time after ''Heteronetta''.

The musk ducks (''[[Biziura]]''), sometimes included in this group, are noted for their bizarre [[Morphology (biology)|habitus]] and pronounced [[sexual dimorphism]]; they are of uncertain position and decidedly aberrant. Their [[anatomy]] is more similar to ''[[Oxyura]]'' than to the two less derived genera, but still unique in many respects. [[mtDNA]] [[cytochrome b|cytochrome ''b'']] [[DNA sequence|sequence]] data suggestssuggest a closer relationship with the pink-eared ducks (''[[Malacorhynchus]]'') which if correct would represent one of the most drastic cases of divergent [[adaptation]] in the whole [[Anseriformes]].<ref name=Livezey/><ref name=Sraml/>

Altogether, however, the only thing that seems clear is that the musk ducks probably are not part of the stiff-tailed ducks in the strict sense, but rather represent a not-too-distantly related lineage that is highly [[convergent evolution|convergent]] as regards their hindlimbhind limb [[anatomy]]. These two are probably part of a very ancient [[radiation (evolution)|radiation]] of [[Gondwana]]n (often [[Australia]]n) waterfowl, including such forms as the [[Cape Barren Goosegoose]] (''Cereopsis''), the [[Coscorobacoscoroba Swanswan]] (''Coscoroba''), the [[Freckledfreckled Duckduck]] (''Stictonetta'') which once was placed in the Oxyurinae, or the [[pygmy geese]] (''Nettapus'')., Butbut the exact relationships between these lineages remains unresolved. For example, the [[Africa]]nAfrican [[Whitewhite-backed Duckduck]] (''Thalassornis'') also shows some similarities to ''Oxyura'', but again, this may be yet another case of convergent evolution.<ref name=Livezey/><ref name=McCrackenSraml/><ref name=SramlMcCracken/>

There is oneOne [[fossil]] genus of OxyurinaeOxyurini, ''[[Tirarinetta]]'' from the Pliocene of Australia, and some prehistoric members of genera are still extant. Three enigmatic genera of waterfowl, ''[[Mionetta]]'' from the [[Late Oligocene]] to [[Middle Miocene]] of central Europe and ''[[Dunstanetta]]'' and ''[[Manuherikia Group(genus)|Manuherikia]]'' from the [[Saint Bathans Fauna|Bathans]] Early/Middle Miocene of Otago, New Zealand, show some similarities to oxyurine ducks and judging from [[biogeography]], the latter two may plausibly be related. On the other handHowever, ''Manuherikia'' and ''Mionetta'' are sometimes held to be [[Dendrocheninae]] adapted to diving, and thereforeso closer to [[whistling- duck]]s, a very ancient lineage of the Anatidae.

<ref name=Livezey>{{cite journal|author=Livezey, Bradley C. |year=1986|title= A phylogenetic analysis of recent anseriform genera using morphological characters|journal=[[Auk (journal)|Auk]]|volume=103|issue=4|pages= 737–754|url=http://sora.unm.edu/sites/default/files/journals/auk/v103n04/p0737-p0754.pdf|jstor=4087184}}</ref>

<ref name=McCracken> {{cite journal|authorauthor1=McCracken, Kevin G.; |author2=Harshman, John; |author3=McClellan, David A. & |author4=Afton, Alan D. |name-list-style=amp|year=1999|url=http://mercury.bio.uaf.edu/~kevin_mccracken/reprints/syst-biol-48-683.pdf |title=Data set incongruence and correlated character evolution: An example of functional convergence in the hind-limbs of stifftail diving ducks|journal=Systematic Biology|volume=48|pages= 683–714|doi=10.1080/106351599259979|issue=4|pmid=12066296|url-status=dead|archiveurl=https://web.archive.org/web/20110614142405/http://mercury.bio.uaf.edu/~kevin_mccracken/reprints/syst-biol-48-683.pdf|archivedate=2011-06-14|doi-access=free}}</ref>

<ref name=Sraml>{{cite journal|authorauthor1=Sraml, M.; |author2=Christidis, L.; |author3=Easteal, S.; |author4=Horn, P. & |author5=Collet, C. |name-list-style=amp |title= Molecular Relationships Within Australasian Waterfowl (Anseriformes)|doi=10.1071/ZO9960047|year=1996|journal=Australian Journal of Zoology|volume=44|pages=47}}</ref>

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[[Category:OxyurinaeOxyurini| ]]