Genital morphology associated with mating strategy in the polymorphic lizard, Uta stansburiana

Abstract

Sexual selection can lead to rapid evolution of sexual traits and striking morphological diversity across taxa. In populations where competition for mates is intense, males sometimes evolve distinct behavioral strategies along with morphological differences that help them secure mating opportunities. Strong postcopulatory selection and differential resource allocation across male strategy type can result in strategy-specific differences in sexual traits, such as sperm morphology, ejaculate components, and testis size. Some polymorphic species also have strategyspecific genital morphology. Thus far, among vertebrates, this has only been observed in fish.Here, we present the first morphological description of the intromittant copulatory organ, the hemipenis, of the three mating types of the side-blotched lizard, Uta stansburiana, from a population that exhibits alternative mating strategies. We found that the isometrically scaling hemipenis was shortest in the nonterritorial (yellow) morph that sneaks copulations with other males' mates. Although the hemipenes were generally the same shape across morphs, the usurping territorial (orange) morph had a significantly wider apical horn than the nonterritorial sneaker morph. Sneaker males also had smaller relative body masses than both the mate-guarding (blue) morph and the usurper morph, and shorter tibia than the usurper morph. This study using a small sample of males suggests that strong sexual selection may drive genital trait differentiation across morphs within populations of terrestrial vertebrates. K E Y W O R D Salternative reproductive tactic, androgen, postcopulatory, sexual selection, sneaker

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

“…Considering that allometric results of genital traits are a predictor of sexual selection [10,23,36,46,47], the allometric pattern found among Tropidurus hemipenial lobes could be explained by directional selection over this trait, caused as an action of two non-exclusive mechanisms: female cryptic choice and genital coevolution, as following discussed.…”

“…Firstly, the major stimulatory capability of the urodeal glands and, secondly by the amount of secretion produced by these glands which can cause a mechanical and/or biochemical difficulty for semen from future copulations. Evidence of female mate choice and sperm competition among lizards has been demonstrated in some case studies [10,58–60]. In the polymorphic phrynosomatid lizard U .…”

“…In the polymorphic phrynosomatid lizard U . stansburiana , it was is demonstrated that genital morphology is particularly associated with mating strategy, whereby “usurper male morphs” evolve a wider apical horn in contrast to other morphs [10]. To date, it has been demonstrated that for T .…”

“…It is common that closely related species tend to differ in hemipenial morphology, leading to the use of hemipenis as a key taxonomic and phylogenetic character [5–8]. In addition, the size of hemipenial traits has a higher evolutionary rate than other morphological traits [9,10]. Few studies investigating the ontogenetic development of hemipenial morphology exist, the majority of which focus on the first stages of development [11–13].…”

Hierarchies and Dominance Behaviors in European Pond Turtle (Emys orbicularis galloitalica) Hatchlings in a Controlled Environment

“…In these species, a significant relationship between the individual rank and the number of successful copulations was found [ 4 , 5 ]. Studies on the lizard Uta stansburiana , a highly social species showing complex breeding strategies, with three male phenotypes, each one correlated with a different mating strategy, disproved the traditional view of reptiles as animals not suited for complex social interactions [ 6 , 7 ]. According to Gardner et al [ 2 ], the definition of sociality in reptiles cannot be separated from issues of seasonal and spatial stability.…”