-
Female ducks fight back against ‘raping’ males – life – 01 May 2007 – New Scientist
They call this arms race: the more rapacious the male of a species is, the more devious the controls that the female develops. In ducks and goose, some vaginas have spirals channels that impede sex; in other there are pouches that capture unwelcome sperm- all these impediments are developed only in the species renowned for forced sex.
-
Males of some species, such as mallard, have a notorious habit of “raping” females. They and other wildfowl are among the 3% of bird species whose males have phalluses big enough to insert into the vaginas of females, whether or not the female consents.
-
Tim Birkhead at the University of Sheffield in the UK and colleagues examined vaginas and the corresponding phalluses from 16 wildfowl species. They discovered that the longer and more elaborate the male member, the longer and more elaborate its female recipient was.
Some vaginas had spiral channels that would impede sex by twisting in the opposite direction to that of the male phallus. Others had as many as eight cul-de-sac pouches en route, that could prevent fertilisation by capturing unwelcome sperm. Moreover, these features were only found in species renowned for forced sex. All other species had simple male and female genitalia.
-
Posted from Diigo.
