The lower reproductive tract of female mammals has several competing functions including mating, tract health maintenance, and parturition. Diverse vaginal anatomy suggests interactions between natural and sexual selection, yet despite its importance, female copulatory morphology remains under-studied. We undertook a comparative study across the species-rich mammalian order Chiroptera (bats) with a focus on the suborder Yangochiroptera (Vespertilioniformes) to examine how female vaginal features may have coevolved with male penis morphology to minimize mechanical damage to their tissues during copulation. The penis morphology is diverse, presenting great potential for post-copulatory sexual selection and coevolution with the female morphology, but vaginas have not been carefully examined. Here we test the hypotheses that vaginal thickness and collagen density have coevolved with features of the male penis, including the presence of spines and a baculum. We present histological data from females of 24 species from 7 families of bats, and corresponding data on male penis anatomy. We also examine the role of phylogenetic history in the morphological patterns we observe. We found evidence that female vaginal thickness has coevolved with the presence of penile spines, but not with baculum presence or width. Collagen density did not appear to covary with male penile features.more »
Harvestmen are a major arachnid order that has experienced a dramatic increase in biological knowledge in the 21st century. The publication of the book Harvestmen: The Biology of Opiliones in 2007 stimulated the development of many behavioral studies. Although the book is relatively recent, our understanding of the reproductive biology of harvestmen is already outdated due to the fast accumulation of new data. Our goal is to provide an updated review of the subject to serve as a benchmark for the following years. In the pre-copulatory phase, we explore the evolution of facultative parthenogenesis, the factors that may affect the types of mating system, and the role of nuptial gifts in courtship. Regarding the copulatory phase, harvestmen are unique arachnids because they have aflagellate spermatozoa and a penis with complex morphology. We discuss the implications of these two features for sperm competition and cryptic female choice. In the post-copulatory phase, we connect oviposition site selection and climate conditions to the widespread occurrence of resource defense polygyny, alternative reproductive tactics, and sexual dimorphism in several clades of tropical harvestmen. Finally, we present the different forms of parental care in the order, and discuss the benefits and costs of this behavior, more »
- Publication Date:
- NSF-PAR ID:
- 10403871
- Journal Name:
- Current Zoology
- ISSN:
- 1674-5507
- Publisher:
- Oxford University Press
- Sponsoring Org:
- National Science Foundation
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Abstract Quantification of genital variation in males and females can inform our understanding of likely copulatory interactions and evolution of genital diversity. However, no studies have quantified genital shape variation within a single snake species or examined the shape and size of both the vaginal pouch and hemipenes. Here, we examine the shape and size of the genitalia of female and male diamondback water snakes, Nerodia rhombifer, using a three-dimensional automated landmark geometric morphometric approach on models of the lumen of the vaginal pouch and inflated hemipenes, applying these techniques for the first time to the genital shape of vertebrates. Vaginal pouch shape is significantly associated with body size and reproductive status. As females grow larger and become reproductive, the vaginal pouch enlarges, widens and becomes more bifurcated. In reproductive males, the shape of the hemipenes is also significantly associated with body size. As males grow larger, the hemipenes enlarge and widen; their bifurcation becomes more defined and the spines at the base become more prominent. Vaginal pouch and hemipenial centroid size are isometric with respect to body length. The centroid sizes of the hemipenes and vaginal pouch are not significantly different from one another, hence the genitalia match inmore »
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