Does Sexual Selection Influence Ornamentation of Hemipenes in Old World Snakes?

Abstract

In the present study, we investigated and documented the morphology of the male copulatory organs (hemipenes) in fifteen wide-ranging snake species. The species represent four families (Boidae, Colubridae, Lamprophiidae, and Viperidae) and ten genera. We applied the same preparation techniques for all species, successfully everting and expanding the organs completely. The detailed description of the general morphology of the male copulatory organs was based on 31 specimens. Our data were compared with published observations and we point out some incorrectly described details in previous investigations. We provide the first description of the hemipenial morphology for three ophidian species (Elaphe sauromates, Telescopus fallax, and Malpolon insignitus). In addition to the morphological characteristics of the hemipenes presented in the research, we propose the adoption of a standardized index describing the hemipenial proportions. The immense variation in hemipenial morphology presupposes its dynamic evolution, but we suggest that many of the significant structures observed here may have escaped previous researchers due to differing methodologies. Some of the highly ornamented morphologies that we describe are consistent with a locking mechanism during copulation. However, other morphologies may relate to the variety of mating behaviors observed. As a result, we propose that sexual selection is the major driver affecting the hemipenial ornamentation in snakes. Anat Rec, 300:1680-1694, 2017. © 2017 Wiley Periodicals, Inc.

A new, rare, small-ranged, and endangered mountain snake of the genus Elaphe from the Southern Levant

“…Hemipenis Proportion Index (maximal width of the hemipenis divided by total length): 0.36. A hemipenis with HPI > 0.5 is considered “stubby”; HPI between 0.5 and 0.25, “medium formed”; and HPI < 0.25, elongated 39 . In general aspects, the hemipenis of E. druzei sp.…”

“…We prepared the hemipenis of one specimen of Elaphe from the Israeli-controlled part of Mount Hermon (TAU-R 13149) following the protocols of [95][96][97] . Terminology for hemipenis description and comparisons with hemipenal morphology of E. quatuorlineata and E. sauromates were based on descriptions provided by 39 .…”

Are hemipenial traits under sexual selection in Tropidurus lizards? Hemipenial development, male and female genital morphology, allometry and coevolution in Tropidurus torquatus (Squamata: Tropiduridae)

“…A similar situation occurs in the gymnophthalmid lizard Calyptommatus sinebrachiatus , in which hemipenes show ornamental structures in late developmental stages, recognized even under stereoscopic analysis [42]. Once ornamental structures have been recognized as crucial for differentiation between cryptic species with hemipenial variation [5,6,43], late embryological studies may explain this variation and should be considered in studies of hemipenial evolution driven by processes such as natural and sexual selection [15,44].…”

Hemipenial morphology does not provide insight on mating barriers between the two main lineages of Hierophis viridiflavus (Lacépède, 1789)

“…Reptilian hemipenes show highly variable morphological traits, in terms of the gross shape of the organ itself (unilobed, bilobed) as well as of its external ornamentations, which can consist of rigid spines (spread across the organ or aggregated in a specific region, i.e., basal region or the apex; Fig. 1) or soft tissue folds, or otherwise can be completely absent (Zaher et al, 1999;Andonov et al, 2017).…”