Editing Muscovy duck (section)

==Biology==
The [[karyotype]] of the Muscovy duck is 2n=80, consisting of three pairs of [[macrochromosome]]s, 36 pairs of [[microchromosome]]s, and a pair of [[sex chromosome]]s. The two largest macrochromosome pairs are [[submetacentric]], while all other [[chromosomes]] are [[acrocentric]] or probably [[telocentric]] for the smallest microchromosomes. The submetacentric chromosomes and the [[Z chromosome|Z (female) chromosome]] show rather little [[constitutive heterochromatin]] (C bands), while the [[W chromosome]]s are at least two-thirds heterochromatin.{{sfn|Wójcik|Smalec|2008}}
 
Male Muscovy ducks have [[Helix|helical]] penises that become erect to {{convert|{{round|19.23|0}}|cm|in|abbr=on|0}} in {{Rnd|0.346|1}} [[Second|s]]. Females have vaginas that coil in the opposite direction that appear to have evolved to limit [[Sexual coercion among animals|forced copulation]] by males.<ref name="Brennan Clark Prum pp. 1309–1314">{{cite journal | last1=Brennan | first1=P. L. R. | last2=Clark | first2=C. J. | last3=Prum | first3=R. O. | title=Explosive eversion and functional morphology of the duck penis supports sexual conflict in waterfowl genitalia | journal=Proceedings of the Royal Society B: Biological Sciences | volume=277 | issue=1686 | date=2009-12-23 | issn=0962-8452 | doi=10.1098/rspb.2009.2139 | pmid=20031991 | pages=1309–1314| pmc=2871948 }}</ref><ref name=Sample2009/>