The phylogenetic distribution and morphological variation of the ‘pouch’ in female snakes

Abstract

Siegel D.S., Miralles A, Trauth S.E. and Aldridge R.D. 2012. The phylogenetic distribution and morphological variation of the 'pouch' in female snakes. -Acta Zoologica (Stockholm) 93: 400-408.The urodaeum of female snakes is a chamber that receives the oviducts, urinary ducts, and intestine. Previous studies have indicated that a derived region of unknown function persists between the urodaeum and oviducts in some snakes of the Colubroides. This structure was recently termed the 'pouch'; however, it is also commonly referred to as the vaginal pouch. A broad sampling of female snakes revealed that the pouch evolved once on the branch leading to Colubroides. The presence of the pouch in Colubroides is not unambiguous, as this feature was lost in some members of the Atractaspididae and Lamprophiidae. Variation was also observed in pouch morphology between taxa of the Colubroides. Variation included the following: (1) whether the pouch was bifurcated and if so, were the arms of the pouch separated caudally, (2) whether separated pouch arms were split by a caudal bifurcation of the urodaeum or through medial septa of the pouch arms, and (3) the absence or presence of oviducal papillae invading the cranial ⁄ lateral extremity of the pouch. The variation in pouch morphology observed does not appear to be correlated with the evolutionary history of Colubroides and polymorphism within families is common.

Sperm storage and morphofunctional bases of the female reproductive tract of the snake Philodryas patagoniensis from southeastern Brazil

“…The shape of the vagina may be linked to the shape of the male hemipenis in snakes of some lineages (Boidae, Erycidae, Phytonidae, and Scolecophidae) (Cope 1898; Pope 1941). Nevertheless, a recent analysis showed the opposite (Siegel et al 2012). Moreover, the shape of the vagina is highly polymorphic within different species of a lineage (Siegel et al 2012).…”

“…Nevertheless, a recent analysis showed the opposite (Siegel et al 2012). Moreover, the shape of the vagina is highly polymorphic within different species of a lineage (Siegel et al 2012). The use of a correct nomenclature is based solely on the histological study of the whole oviduct aiming to differentiate its regions (Blackburn 1998).…”

Mechanisms and Evidence of Genital Coevolution: The Roles of Natural Selection, Mate Choice, and Sexual Conflict

“…4A) (PLR Brennan, K Zyscowski, and RO Prum, unpubl.). However, shape correspondence is apparently not universal in snakes (Siegel et al 2011). Similar to the dung beetles, there seems to be correspondence between how spiny the hemipenes are, and the thickness of the vaginal wall in two species of Asiatic pit vipers (Pope 1941).…”

“…Thus, the functional consequences to male and female genital morphology are hard to predict unless one knows how genitalia function during intromission. Despite these challenges, recent studies have examined variation of female genitalia and evidence is accumulating that features of female genitalia are variable enough to support coevolutionary processes (Polihronakis 2006;Puniamoorthy et al 2010;Siegel et al 2011;Showalter et al 2013; and see additional references in Ah- King et al 2014).…”

“…Female genitalia in snakes have been shown to vary at least among families (e.g., Siegel et al 2011). Eversion of one hemipenis takes place into the female cloaca and vaginal tract.…”