Genital Variation Research Articles

The function and evolution of male and female genitalia in Phyllophaga Harris scarab beetles (Coleoptera: Scarabaeidae).

Genitalia diversity in insects continues to fuel investigation of the function and evolution of these dynamic structures. Whereas most studies have focused on variation in male genitalia, an increasing number of studies on female genitalia have uncovered comparable diversity among females, but often at a much finer morphological scale. In this study, we analysed the function and evolution of male and female genitalia in Phyllophaga scarab beetles, a group in which both sexes exhibit genitalic diversity. To document the interaction between male and female structures during mating, we dissected flash-frozen mating pairs from three Phyllophaga species and investigated fine-scale morphology using SEM. We then reconstructed ancestral character states using a species tree inferred from mitochondrial and nuclear loci to elucidate and compare the evolutionary history of male and female genitalia. Our dissections revealed an interlocking mechanism of the female pubic process and male parameres that appears to improve the mechanical fit of the copulatory position. The comparative analyses, however, did not support coevolution of male and female structures and showed more erratic evolution of the female genitalia relative to males. By studying a group that exhibits obvious female genitalic diversity, we were able to demonstrate the relevance of female reproductive morphology in studies of male genital diversity.

Coevolution of female and male genital components to avoid genital size mismatches in sexually dimorphic spiders.

BackgroundIn most animal groups, it is unclear how body size variation relates to genital size differences between the sexes. While most morphological features tend to scale with total somatic size, this does not necessarily hold for genitalia because divergent evolution in somatic size between the sexes would cause genital size mismatches. Theory predicts that the interplay of female-biased sexual size dimorphism (SSD) and sexual genital size dimorphism (SGD) should adhere to the ‘positive genital divergence’, the ‘constant genital divergence’, or the ‘negative genital divergence’ model, but these models remain largely untested. We test their validity in the spider family Nephilidae known for the highest degrees of SSD among terrestrial animals.ResultsThrough comparative analyses of sex-specific somatic and genital sizes, we first demonstrate that 99 of the 351 pairs of traits are phylogenetically correlated. Through factor analyses we then group these traits for MCMCglmm analyses that test broader correlation patterns, and these reveal significant correlations in 10 out of the 36 pairwise comparisons. Both types of analyses agree that female somatic and internal genital sizes evolve independently. While sizes of non-intromittent male genital parts coevolve with male body size, the size of the intromittent male genital parts is independent of the male somatic size. Instead, male intromittent genital size coevolves with female (external and, in part, internal) genital size. All analyses also agree that SGD and SSD evolve independently.ConclusionsInternal dimensions of female genitalia evolve independently of female body size in nephilid spiders, and similarly, male intromittent genital size evolves independently of the male body size. The size of the male intromittent organ (the embolus) and the sizes of female internal and external genital components thus seem to respond to selection against genital size mismatches. In accord with these interpretations, we reject the validity of the existing theoretical models of genital and somatic size dimorphism in spiders.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0734-9) contains supplementary material, which is available to authorized users.

Studying Genital Coevolution to Understand Intromittent Organ Morphology.

Male intromittent organs are exceedingly diverse, yet we know comparatively little about female genital diversity. However, the most direct mechanical interaction between males and females occurs during copulation, and therefore, genital coevolution is expected to be widespread. This means that diversification of male structures must influence diversity of female genital features and vice versa. As we expand our understanding of coevolutionary interactions between the sexes, we need to expand our knowledge of three basic areas: First, we need quantitative data, on morphological variation of female genitalia. Second, we need to study the mechanics of copulatory interactions, and third, we need to use this understanding to determine which features of genital morphology are under selection, and how their variable morphology and function may affect fitness. Though studying coevolution is certainly difficult, this knowledge is crucial to our understanding of diversity in morphology of the male intromittent organ.

Toward more accountability: Modeling ternary genitive variation in Late Modern English

AbstractWhereas the alternation between thes-genitive (the New Year's message) and theof-genitive (the message of the New Year) is well documented, our study offers a more accountable analysis of genitive variation by including noun-noun (NN)-genitives (the New Year message). We consider four different variable contexts (sversusof, NN versusof, NN versuss, and NN versussversusof ), which we analyze using regression analysis. The dataset consists of 10,054 variable genitives drawn from theRepresentative Corpus of Historical English Registers. The material covers the period between 1650 and 2000, thus enabling us to track the evolution of variable genitive grammar in real time. We report that there is an overall drift toward the NN-genitive, which is preferred over other variants when constituent noun phrases are short, possessor constituents are inanimate, and possessum constituents are thematic. In addition to these substantive contributions, we showcase methods of dealing with a complex dataset covering nonbinary grammatical variation.

Genital Self-Image and Considerations of Elective Genital Surgery

The present study explores how genital self-image may be related to considerations of surgically altering one's genitals and documents the wanted genital changes among young adults. Evidence of a nontrivial proportion of respondents (98 of 1,110) had seriously considered elective genital surgery. Regression models indicate that, for both men and women, identifying as heterosexual and reporting lower composite genital self-image scores results in higher odds of considering genital surgery. Additionally for men, feeling unsatisfied with penis size increased the odds. Clinical and educational efforts to normalize and celebrate genital variation may influence considerations for genital modification in young adults.

THE (LIMITED) EFFECT OF PSYCHO-EDUCATION ON WOMEN'S ATTITUDES TO LABIAPLASTY

Event Abstract Back to Event THE (LIMITED) EFFECT OF PSYCHO-EDUCATION ON WOMEN'S ATTITUDES TO LABIAPLASTY Shauna Byrne1*, Desirée Kozlowski1 and Stephen Provost1 1 Southern Cross University, Psychology, School of Health and Human Sciences, Australia Aims: Despite a lack of data on the complications associated with labiaplasty, demand for the surgery has been increasing at least since 2005. However, between 2014 and 2015 there was a 28% decrease in labial surgeries funded by Australian Medicare. This drop has been attributed to guidelines recommending general practitioners provide education to women seeking surgery. Whether this decrease reflects the efficacy of education or is the result of clients instead undergoing labiaplasty within the private system, is unclear. This study investigated the effect of psycho-education about genital diversity and the possible complications of labiaplasty on women’s genital appearance satisfaction and their attitudes towards labiaplasty.Method: Female participants (N= 483; mean age = 30.78) were allocated to either the labiaplasty psycho-education (N= 237) or control condition (N= 246) of the online experiment. Participants completed the Genital Appearance Satisfaction Scale and the Acceptance of Cosmetic Surgery Scale – Labiaplasty. Participants in the experimental group were provided with psycho-education before completing the other measures; the control group received psycho-education afterwards. Results: Women’s genital appearance satisfaction was significantly related to their acceptance of labiaplasty r(483) = .58, p < .001. Labiaplasty psycho-education had no effect on women’s satisfaction with their genital appearance, t(481) = .33, p = .742. It was associated with a modest reduction in women’s conceptual acceptance of labiaplasty (CI: -0.37, -0.01), but not on the extent to which they would personally consider having the surgery. Conclusions: Despite receiving education on the possible negative outcomes of labiaplasty and the diversity in female genital appearance, women’s subjective dissatisfaction with their own genital appearance appears to be the main driver of their attitudes towards undergoing labiaplasty. The efficacy of education to deter women from undergoing unnecessary labial surgery is thus, and not for the first time, brought into question. Keywords: Education, media, body image, Labiaplasty, Labia, female genitals, Genital dissatisfaction, Labial Reduction Surgery Conference: Southern Cross University 13th Annual Honours Psychology Research Conference, Coffs Harbour, New South Wales, Australia, 7 Oct - 7 Oct, 2016. Presentation Type: Research Topic: Psychology Citation: Byrne S, Kozlowski D and Provost S (2016). THE (LIMITED) EFFECT OF PSYCHO-EDUCATION ON WOMEN'S ATTITUDES TO LABIAPLASTY. Front. Public Health. Conference Abstract: Southern Cross University 13th Annual Honours Psychology Research Conference. doi: 10.3389/conf.FPUBH.2016.02.00004 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 29 Sep 2016; Published Online: 30 Sep 2016. * Correspondence: Ms. Shauna Byrne, Southern Cross University, Psychology, School of Health and Human Sciences, Coffs Harbour, NSW, 2450, Australia, s.byrne.17@student.scu.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Shauna Byrne Desirée Kozlowski Stephen Provost Google Shauna Byrne Desirée Kozlowski Stephen Provost Google Scholar Shauna Byrne Desirée Kozlowski Stephen Provost PubMed Shauna Byrne Desirée Kozlowski Stephen Provost Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The contribution of online content to the promotion and normalisation of female genital cosmetic surgery: a systematic review of the literature.

BackgroundWomen considering female genital cosmetic surgery (FGCS) are likely to use the internet as a key source of information during the decision-making process. The aim of this systematic review was to determine what is known about the role of the internet in the promotion and normalisation of female genital cosmetic surgery and to identify areas for future research.MethodsEight social science, medical, and communication databases and Google Scholar were searched for peer-reviewed papers published in English. Results from all papers were analysed to identify recurring and unique themes.ResultsFive papers met inclusion criteria. Three of the papers reported investigations of website content of FGCS providers, a fourth compared motivations for labiaplasty publicised on provider websites with those disclosed by women in online communities, and the fifth analysed visual depictions of female genitalia in online pornography. Analysis yielded five significant and interrelated patterns of representation, each functioning to promote and normalise the practice of FGCS: pathologisation of genital diversity; female genital appearance as important to wellbeing; characteristics of women’s genitals are important for sex life; female body as degenerative and improvable through surgery; and FGCS as safe, easy, and effective. A significant gap was identified in the literature: the ways in which user-generated content might function to perpetuate, challenge, or subvert the normative discourses prevalent in online pornography and surgical websites.ConclusionsFurther research is needed to contribute to knowledge of the role played by the internet in the promotion and normalisation of female genital cosmetic surgery.

Male penile propulsion into spiraled spermathecal ducts of female chrysomelid beetles: A numerical simulation approach

Genital diversification in animals is an interesting evolutionary phenomenon. Sexual selection is the main driving force behind the diversification. However, evolutionary mechanisms that have established and maintained variations in genitalia shape parameters observed in related species are not well understood. Here, for the first time, we used numerical simulations to test the hypothesis that variations in female spermathecal duct shapes among related beetle species mechanically interfere with penile propulsion in varying ways. Our numerical simulations showed that high curvature of the spiraled spermathecal ducts of the female have effects with a threshold-based interaction on male penile insertion. The relative size of spirals observed in the beetle, Cassida rubiginosa, studied here is not small enough to interfere with penile propulsion. But the model revealed that propulsion is impeded by the presence of reverse turns in spermathecal ducts. This type of morphology leads to an increase in the velocity of the propulsion but also to an increase in the propulsion energy cost for males. Our results showed that quantitative differences in spermathecal duct shape can mediate qualitative differences in penile motion. This explains, in part, the mechanism behind origin and maintenance of genital divergence among closely related species in general.

Origins of female genital diversity: Predation risk and lock-and-key explain rapid divergence during an adaptive radiation.

The study of male genital diversity has long overshadowed evolutionary inquiry of female genitalia, despite its nontrivial diversity. Here, we identify four nonmutually exclusive mechanisms that could lead to genital divergence in females, and potentially generate patterns of correlated male-female genital evolution: (1) ecological variation alters the context of sexual selection ("ecology hypothesis"), (2) sexually antagonistic selection ("sexual-conflict hypothesis"), (3) female preferences for male genitalia mediated by female genital traits ("female-choice hypothesis"), and (4) selection against inter-population mating ("lock-and-key hypothesis"). We performed an empirical investigation of all four hypotheses using the model system of Bahamas mosquitofish inhabiting blue holes that vary in predation risk. We found unequivocal support for the ecology hypothesis, with females exhibiting a smaller genital opening in blue holes containing piscivorous fish. This is consistent with stronger postmating female choice/conflict when predators are present, but greater premating female choice in their absence. Our results additionally supported the lock-and-key hypothesis, uncovering a pattern of reproductive character displacement for genital shape. We found no support for the sexual conflict or female choice hypotheses. Our results demonstrate a strong role for ecology in generating female genital diversity, and suggest that lock-and-key may provide a viable cause of female genital diversification.

Genome-Wide Association Study on Male Genital Shape and Size in Drosophila melanogaster.

Male genital morphology of animals with internal fertilization and promiscuous mating systems have been one of the most diverse and rapidly evolving morphological traits. The male genital morphology in general is known to have low phenotypic and genetic variations, but the genetic basis of the male genital variation remains unclear. Drosophila melanogaster and its closely related species are morphologically very similar, but the shapes of the posterior lobe, a cuticular projection on the male genital arch are distinct from each other, representing a model system for studying the genetic basis of male genital morphology. In this study, we used highly inbred whole genome sequenced strains of D. melanogaster to perform genome wide association analysis on posterior lobe morphology. We quantified the outline shape of posterior lobes with Fourier coefficients obtained from elliptic Fourier analysis and performed principal component analysis, and posterior lobe size. The first and second principal components (PC1 and PC2) explained approximately 88% of the total variation of the posterior lobe shape. We then examined the association between the principal component scores and posterior lobe size and 1902142 single nucleotide polymorphisms (SNPs). As a result, we obtained 15, 14 and 15 SNPs for PC1, PC2 and posterior lobe size with P-values smaller than 10-5. Based on the location of the SNPs, 13, 13 and six protein coding genes were identified as potential candidates for PC1, PC2 and posterior lobe size, respectively. In addition to the previous findings showing that the intraspecific posterior shape variation are regulated by multiple QTL with strong effects, the present study suggests that the intraspecific variation may be under polygenic regulation with a number of loci with small effects. Further studies are required for investigating whether these candidate genes are responsible for the intraspecific posterior lobe shape variation.

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

Genital coevolution between the sexes is expected to be common because of the direct interaction between male and female genitalia during copulation. Here we review the diverse mechanisms of genital coevolution that include natural selection, female mate choice, male-male competition, and how their interactions generate sexual conflict that can lead to sexually antagonistic coevolution. Natural selection on genital morphology will result in size coevolution to allow for copulation to be mechanically possible, even as other features of genitalia may reflect the action of other mechanisms of selection. Genital coevolution is explicitly predicted by at least three mechanisms of genital evolution: lock and key to prevent hybridization, female choice, and sexual conflict. Although some good examples exist in support of each of these mechanisms, more data on quantitative female genital variation and studies of functional morphology during copulation are needed to understand more general patterns. A combination of different approaches is required to continue to advance our understanding of genital coevolution. Knowledge of the ecology and behavior of the studied species combined with functional morphology, quantitative morphological tools, experimental manipulation, and experimental evolution have been provided in the best-studied species, all of which are invertebrates. Therefore, attention to vertebrates in any of these areas is badly needed.

The Body in Revolt: The Impact and Legacy of Second Wave Corporeal Embodiment

Tensions between second and third wave understandings of the body and embodiment have led to disagreements about whether to situate the body as corporeal and concrete or theoretical, diverse, and complex. Drawing from key tactics of the second wave women's health movement, including cervical viewing, menstrual extraction, genital diversity work, orgasm training, and self‐defense classes, I first trace the political framing of the body in second wave feminism, followed by a consideration of third wave pedagogies transmitted through teaching the psychology of women. After analyzing the five most popular textbooks and ten syllabi for the psychology of women, I trace the stories about embodiment that have continued across waves and the stories that have shifted over time. I ultimately argue for a renewed consideration of how to merge the priorities of each wave into a new policy‐driven and activist‐centered understanding of corporeal embodiment both within and outside of the university.

Arabic and English genitive constructions

It is well documented that there is a one-to-many relationship between Arabic and English genitival constructions. However, it is unclear whether, given this syntactic variation, such constructions show equivalence in semantic function. For this purpose, a corpus-based contrastive analysis of these genitive constructions in a bilingual novel is carried out. As a prelude to a quantitative and qualitative inspection of the data, the (non)interchangeability of the alternative English genitives is determined by eliciting intuitive judgments from 10 linguistically naïve native speakers of British English. Quantitatively, the study shows that the Arabic genitive almost covers the semantic functions expressed by the various English genitives found in the corpus. Qualitatively, the study reveals that the flexibility derived from the English genitive variation, as opposed to the fixed word order of the Arabic genitive, allows the speaker to convey additional meaning. However, the Arabic genitive which employs various formal devices such as overt markers of case, gender, number, definiteness and person can express the same semantic functions. These features render Arabic functional with one genitive and require English to vary its genitive relative to certain phonological, syntactic, semantic and pragmatic conditions.

Comparative Transcriptomic Analysis of Two Closely Related Ground Beetle Species with Marked Genital Divergence Using Pyrosequencing

Ground beetles of the subgenus Ohomopterus (genus Carabus) show marked divergence in species-specific male and female genital morphologies, which contributes to reproductive isolation among species. Characterizing the genetic basis of species-specific genital morphology is essential for understanding their diversification, but genomic information on Ohomopterus is not yet available. We analyzed mRNA extracted from abdominal sections of the last instar larvae and pupae of two sister species, Carabus (Ohomopterus) iwawakianus and C. (O.) uenoi, which show marked differences in genital morphology, to compare transcriptomic profiles using Roche 454 pyrosequencing. We obtained 1,608,572 high-quality reads and assembled them into 176,278 unique sequences, of which 66,049 sequences were combined into 12,662 clusters. Differential expression analyses for sexed pupae suggested that four and five clusters were differentially expressed between species for males and females, respectively. We also identified orthologous sequences of genes involved in genital development in Drosophila, which potentially affect genital development and species-specific genital morphology in Ohomopterus. This study provides the first large transcriptomic data set for a morphologically diversified beetle group, which can facilitate future studies on the genetic basis of species-specific genitalia.

Introduction: new dimensions in genitive variation

This special issue concerns English genitive variation: the choice between the s-genitive and the of-genitive. It has grown out of the workshop ‘Genitive variation in English’, which was held at the conference of the International Society for the Linguistics of English at the University of Boston in June 2011. While previous research on genitive variation has already unearthed a wealth of factors predicting the variation, the aim of this volume is to add new dimensions to existing parameters.

Quirky quadratures: on rhythm and weight as constraints on genitive variation in an unconventional data set

This article explores measures, operationalisations and effects of rhythm and weight as two constraints on the variation between thes-genitive and theof-genitive. We base the analysis on interchangeable genitives in the news and letters sections of ARCHER (A Representative Corpus of Historical English Registers), which covers the period between 1650 and 1999. Thus, we are ultimately concerned with the applicability of two factors that have their roots in speech (rhythm: phonology; weight: online processing) to an ‘unconventional’, written data set with a historical dimension. As for weight, we focus on the comparison of simple single-constituent and more complex multi-constituent measurements. Our notion of rhythm centres on the ideally even distribution of stressed and unstressed syllables. We find that in our data set, both rhythm and weight show theoretically unexpected quadratic effects: rhythmically better-behaveds-genitives are not necessarily preferred overof-genitives, and short constituents exhibit odd weight effects. In conclusion, we argue that while rhythm is only a minor player in our data set, the quadratic quirks it exhibits should inspire further study. Weight, on the other hand, is a crucial factor which, however, likewise comes with measurement and modelling complications.

Genitive variation: the niche role of the oblique genitive

This article discusses the niche role that the oblique genitive of the type the friend of John’s occupies in the context of genitive variation. The article shows that the oblique genitive should be considered an independent construction which competes marginally in two syntactic contexts with the s-genitive (as in John's friend) and the of-genitive (as in the friend of John). The first context is one in which all three constructions function as the predicative complement of the clause (e.g. He is a friend of John's / John's friend / a friend of John). Note that in this context the definiteness effect of the s-genitive is downplayed, so that competition is possible with indefiniteness of the other two constructions. The second context is one where the oblique genitive and the of-genitive are introduced by the determiner the. Contrary to the claim that oblique genitive constructions introduced by the definite article must receive restrictive modification of the head (see e.g. Barker 1998; Lyons 1986), the quantitative data presented in this article reveal that oblique genitives introduced by the determiner the are not confined to pre- or postmodification of the head but can occur, albeit rarely, without any modification as in the example the executor of Sir Ralph’s.The article further compares the oblique genitive, s-genitive and of-genitive with respect to the following five features: noun-headed vs pronoun dependent; animacy of the dependent; length of the noun-headed dependent; determiner of the head; and the semantic relations that can hold between head (e.g. friend) and dependent (e.g. John). The most intriguing theoretical conclusion is that the semantic relations available to head and dependent in the oblique genitive are a subset of those found in the s-genitive, which, again constitute a subset of those that exist in the of-genitive. This means that variation between all three constructions is not only restricted to the two syntactic contexts outlined above but also to a shared set of semantic relations.

English genitive variation – the state of the art

This article is a survey of quantitative research on the choice between thes-genitive and theof-genitive in English. It provides a detailed and critical review of the methodological problems and advances as well as major findings and how these have been treated in theoretical frameworks. The article concludes with a discussion of objectives and challenges for future research. It is argued that research into English genitive variation not only enhances our knowledge of this specific case of syntactic variation but also helps us to further understand the mechanisms of syntactic alternations in general.

Genitive Variation in Old English Verse with Special Attention to Beowulf

Proper noun genitives and possessive pronouns occur more frequently in postnominal position than common noun genitives in Beowulf and in many Old English (OE) verse texts. This is the opposite of patterns seen in most OE prose texts; however, the word order variation in this text correlates with such linguistic factors as animacy and morphosyntactic weight. Postnominal position is most common for proper noun genitives and possessive pronouns when both the possessive element and the head noun are animate. With inanimate heads, prenominal proper noun genitives and possessive pronouns are preferred. These findings are consistent with predictions made by the animacy hierarchy that more animate nouns should precede less animate nouns, with more variation possible in the case that both nouns are animate. For noun phrases (NPs) with common noun genitives, both animate genitives and compound head nouns result in higher frequencies of postnominal genitive position. Metrical and alliterative considerations are further shown to have an impact on possessive position within NPs; however, these poetic factors alone do not account for all of the word order variation. Language change related to the role of animacy in adnominal genitive position is argued as a contributing factor in this variation, given the elevated levels of postnominal proper noun genitives and possessive pronouns relative to postnominal common noun genitives across OE verse, as well as higher levels of postnominal proper noun genitives in certain early OE prose texts, and finally similarities in adnominal genitive position in Beowulf and historical Germanic languages other than OE. As animacy of the possessor is widely held to correlate with prenominal genitive position from the OE period onward, these findings complicate that picture for the earliest OE.

Predation‐associated divergence of male genital morphology in a livebearing fish

Male genital morphology is remarkably diverse across internally fertilizing animals, a phenomenon largely attributed to sexual selection. Ecological differences across environments can alter the context of sexual selection, yet little research has addressed how this may influence the rapid, divergent evolution of male genitalia. Using the model system of Bahamas mosquitofish (Gambusia hubbsi) undergoing ecological speciation across blue holes, we used geometric morphometric methods to test (i) whether male genital shape (the small, approximately 1mm long, distal tip of the sperm-transfer organ, the gonopodium) has diverged between populations with and without predatory fish and (ii) whether any observed divergence has a genetic basis. We additionally examined the effects of genetic relatedness and employed model selection to investigate other environmental factors (i.e. interspecific competition, adult sex ratio and resource availability) that could potentially influence genital shape via changes in sexual selection. Predation regime comprised the most important factor associated with male genital divergence in this system, although sex ratio and some aspects of resource availability had suggestive effects. We found consistent, heritable differences in male genital morphology between predation regimes: Bahamas mosquitofish coexisting with predatory fish possessed more elongate genital tips with reduced soft tissue compared with counterparts inhabiting blue holes without predatory fish. We suggest this may reflect selection for greater efficiency of sperm transfer and fertilization during rapid and often forced copulations in high-predation populations or differences in sexual conflict between predation regimes. Our study highlights the potential importance of ecological variation, particularly predation risk, in indirectly generating genital diversity.