Safer sex with feeding females: sexual conflict in a cannibalistic spider

Mating strategies are to a large degree shaped by conflictsbetween the sexes, causing a rapid antagonistic coevolutionof traits involved in reproduction. The view that sexual cannibalismrepresents a form of sexual conflict leads to the predictionof male traits that facilitate escape from cannibalistic females.A variety of traits have been suggested to serve this functionin spiders, where sexual cannibalism is comparatively common.Empirical evidence, however, is virtually absent. Here we showexperimentally that opportunistic mating with feeding females,which has been reported from several species of orb-weavingspiders, greatly reduces the risk of cannibalism and injuryfor males in the spider Nephila fenestrata. This has directconsequences for a male's fertilization success because survivingmales can reduce the female's remating probability by guardingher against rivals. Although copulation with previously matedfemales sometimes appears to be mechanically impossible, secondmales that do copulate can expect to fertilize on average 64%of a female's eggs. Our results support the view that opportunisticmating may have evolved as a male tactic in a context of sexualconflict over sexual cannibalism.     

Biofeedback-assisted sexual arousal in females: a comparison of visual and auditory modalities

This study was undertaken to investigate the effects of instructional set and biofeedback modality upon the ability of 23 females to achieve control over sexual arousal. Two levels of instructional set (increase, decrease) were completely crossed with three feedback modalities (audio, visual, no feedback). Changes in vaginal blood volume (VBV) and vaginal pulse amplitude (VPA) were monitored by a vaginal plethysmograph and reduced on line by a microcomputer. During feedback trials, all subjects received audio- or visual feedback of the VBV response. Subjects participated in two sessions, each consisting of six 3-minute trials, one in each instruction/feedback combination. Order of trials was counterbalanced. Subjective levels of arousal, VBV, and VPA were significantly higher under increase instructions. Also, a significant feedback effect was noted in the subjective measure and the VBV measure, favoring visual feedback for overall control of sexual arousal. However, the feedback effect accounted for a small portion of the variance, and it was concluded that performance was not appreciably superior with or without feedback. Thus practical considerations may determine the feedback modality to be used for vaginal vasocongestion in future research. Higher positive correlations of subjective ratings with vaginal blood volume occurred during feedback trials, which suggests that biofeedback may be helpful in discrimination training to facilitate awareness of the feelings associated with different arousal levels and correct labeling of increased vasocongestion as sexual. Further research is necessary to see if sexually dysfunctional women can benefit from a biofeedback component in a comprehensive therapy program and to determine the effect of many training sessions on discrimination and self-control of arousal.     

Incidence of post-abortion psychosis: a prospective study.

Twenty-one cunsultant psychiatrists participated in a prospective study of post-abortion psychosis among a population of 1 333 000 people. During the 15-month study only a single case was reported, concerning a woman who had a history of two previous attacks of puerperal psychosis. The incidence of post-abortion psychosis was 0-3 per 1000 legal abortions. The incidence of puerperal psychosis, which was also studied as an index of validity, was 1-7 per 1000 deliveries. This conforms with currently accepted figures and indicates that the study population was representative. I suggest that physiological changes, which are probably more profound after childbirth than after abortion, may be responsible for the higher incidence of puerperal psychosis.     

A preference for a sexual signal keeps females safe

Predation is generally thought to constrain sexual selection by female choice and limit the evolution of conspicuous sexual signals. Under high predation risk, females usually become less choosy, because they reduce their exposure to their predators by reducing the extent of their mate searching. However, predation need not weaken sexual selection if, under high predation risk, females exhibit stronger preferences for males that use conspicuous signals that help females avoid their predators. We tested this prediction in the fiddler crab Uca terpsichores by increasing females' perceived predation risk from crab-eating birds and measuring the attractiveness of a courtship signal that females use to find mates. The sexual signal is an arching mound of sand that males build at the openings of their burrows to which they attract females for mating. We found that the greater the risk, the more attractive were males with those structures. The benefits of mate preferences for sexual signals are usually thought to be linked to males' reproductive contributions to females or their young. Our study provides the first evidence that a female preference for a sexual signal can yield direct survival benefits by keeping females safe as they search for mates.     

Patient-physician sexual involvement: a Canadian survey of obstetrician-gynecologists.

OBJECTIVE: To determine obstetrician-gynecologists'' (ob-gyns'') awareness of and experience with sexual abuse of patients and former patients and their opinions about appropriate consequences. DESIGN: Mailed survey. SETTING: Canada. PARTICIPANTS: All 792 members of the Society of Obstetricians and Gynaecologists of Canada (SOGC); 618 (78%) responded. Approximately half of all ob-gyns in Canada belong to the SOGC. MAIN OUTCOME MEASURES: Knowledge of sexual involvement by an ob-gyn colleague with a patient or former patient (as defined by the respondents and by the College of Physicians and Surgeons of Ontario [CPSO]), self-report of such involvement, attitudes toward physician sexual abuse, desirable length of time a physician should wait before seeing a former patient in a situation that could lead to a sexual encounter, suggested consequences of sexual abuse. RESULTS: Overall, 10% of the respondents indicated that they knew about another ob-gyn who at some time had been sexually involved with a patient. In all, 3% of the male respondents and 1% of the female respondents reported sexual involvement with a patient; the corresponding proportions of those who reported having been accused of sexual abuse by a patient were 4% and 2%. Significantly more of the female ob-gyns than of their male counterparts (37% v. 19%) reported awareness of a colleague''s sexual involvement with a patient that would meet the CPSO''s definition of sexual impropriety, transgression or violation. Most of the respondents felt that the consequence of proven sexual impropriety should be reprimand and fine (chosen by 33%) or rehabilitation without loss of licence (28%). Most of the physicians supported loss of licence for proven sexual transgression (57%) or proven sexual violation (74%), but fewer felt that loss of licence should be permanent for these types of abuse (4% and 24% respectively). The female ob-gyns supported stronger sanctions against sexual transgression and sexual violation than the male ob-gyns. A wide range of opinion was seen regarding the propriety of sexual relationships with former patients. CONCLUSIONS: Ob-gyns have varied opinions about how sexual abuse of patients should be defined and how it should be sanctioned. There is a discrepancy between proposed public policy and the beliefs of physicians to whom the policy is to be applied.     

Non-lactating versus lactating females: a comparison of sex steroids,sexual coloration,and sexual behavior in Japanese macaques

Female Japanese macaques are seasonal breeders distinguished by their red-colored hindquarters, face, and nipple skin areas. Intensity of coloration seems to be associated with sexual attractiveness, behavior, and fluctuating sex steroids. Our aim was to investigate whether the color intensity of these regions differed between lactating (LA) and non-lactating (NLA) females during sexually inactive (SI) and active (SA) phases. Coloration scores of 19 adult females were classified using color tables. Estrogen and progesterone metabolites were determined in fecal samples. Weekly comparison between both groups revealed significantly increased coloration of the hindquarters area from week 13 (SI) until the end of the observation period, and for the nipple skin throughout the SI and SA periods. Face coloration differed marginally. Hormonally, NLA females showed significantly increased excretion rates of sex steroids at the end of the SI phase and throughout the whole SA period. Logistic regression analyses between elevated fecal steroids and nipple coloration disclosed a significant relationship for NLA females during the SI period. This connection persisted and included hindquarter coloration during the SA period. NLA females showed increased intromission with ejaculation, but no difference was found for intromission without ejaculation. In conclusion, results demonstrate increased endocrine excretion rates for NLA females during the whole observation period, paralleled by an enhanced, fertility-signaling sexual attractiveness.     

Biofeedback-assisted sexual arousal in females a comparison of visual and auditory modalities

This study was undertaken to investigate the effects of instructional set and biofeedback modality upon the ability of 23 females to achieve control over sexual arousal. Two levels of instructional set (increase, decrease) were completely crossed with three feedback modalities (audio, visual, no feedback). Changes in vaginal blood volume (VBV) and vaginal pulse amplitude (VPA) were monitored by a vaginal plethysmograph and reduced on line by a microcomputer. During feedback trials, all subjects received audio- or visual feedback of the VBV response. Subjects participated in two sessions, each consisting of six 3-minute trials, one in each instruction/feedback combination. Order of trials was counterbalanced. Subjective levels of arousal, VBV, and VPA were significantly higher under increase instructions. Also, a significant feedback effect was noted in the subjective measure and the VBV measure, favoring visual feedback for overall control of sexual arousal. However, the feedback effect accounted for a small portion of the variance, and it was concluded that performance was not appreciably superior with or without feedback. Thus practical considerations may determine the feedback modality to be used for vaginal vasocongestion in future research. Higher positive correlations of subjective ratings with vaginal blood volume occurred during feedback trials, which suggests that biofeedback may be helpful in discrimination training to facilitate awareness of the feelings associated with different arousal levels and correct labeling of increased vasocongestion as sexual. Further research is necessary to see if sexually dysfunctional women can benefit from a biofeedback component in a comprehensive therapy program and to determine the effect of many training sessions on discrimination and self-control of arousal.     

Achieving high sexual size dimorphism in insects: females add instars

Abstract.  1. In arthropods, the evolution of sexual size dimorphism (SSD) may be constrained by a physiological limit on growth within each particular larval instar. A high SSD could, however, be attained if the larvae of the larger sex pass through a higher number of larval instars.
2. Based on a survey of published case studies, the present review shows that sex-related difference in the number of instars is a widespread phenomenon among insects. In the great majority of species with a sexually dimorphic instar number, females develop through a higher number of instars than males.
3. Female-biased sexual dimorphism in final sizes in species with sexually dimorphic instar number was found to considerably exceed a previously estimated median value of SSD for insects in general. This suggests a causal connection between high female-biased SSD, and additional instars in females. Adding an extra instar to larval development allows an insect to increase its adult size at the expense of prolonged larval development.
4. As in the case of additional instars, SSD is fully formed late in ontogeny, larval growth schedules and imaginal sizes can be optimised independently. No conflict between selective pressures operating in juvenile and adult stages is therefore expected.
5. In most species considered, the number of instars also varied within the sexes. Phenotypic plasticity in instar number may thus be a precondition for a sexual difference in instar number to evolve.     

雌性延迟发育的蚜虫的性别分配

某些物种的蚜虫中,雌性个体成熟较晚,可以认为是雄性个体的“侄女”。当冬季即将来临,剩余时间就不能满足发育需求时,发育延迟了,发育延迟应当也终止了雌性功能上的投资。然而,最近的证明表明,雌性功能的投资并不停止。这种未预料到的发现可能归因于一种进化限制因素,归因于雄性个体在不同年龄阶段对配偶的竞争,或归因于不能预测导致随机非遗传多型性的最后期限。本文讨论了这三种可能性,最后一种可能性由于暂时性地解释了雌性功能中的连续投资而是一种可取的解释。尽管延缓发育和开始繁殖的最后期限常见于那些生活在严寒地区的、雌性发育迟缓的蚜虫,本文的观点也适合于一个性别成熟较晚的、具有繁殖最后期限的任何一个蚜虫物种。     

Receptive females mitigate costs of sexual conflict

Males typically gain fitness from multiple mating, whereas females often lose fitness from numerous mating, potentially leading to sexual conflict over mating. This conflict is expected to favour the evolution of female resistance to mating. However, females may incur male harassment if they refuse to copulate; thus, greater female resistance may increase costs imposed by males. Here, I show that the evolution of resistance to mating raises fitness disadvantages of interacting with males when mating is harmful in female adzuki bean beetles, Callosobruchus chinensis. Females that were artificially selected for higher and lower remating propensity evolved to accept and resist remating, respectively. Compared with females that evolved to accept remating, females that evolved to resist it suffered higher fitness costs from continuous exposure to males. The costs of a single mating measured by the effect on longevity did not differ among selection line females. This study indicates that receptive rather than resistant females mitigate the fitness loss resulting from sexual conflict, suggesting that even though mating is harmful, females can evolve to accept additional mating.     

Conflicting preferences within females: sexual selection versus species recognition

Preferences for mates within and between species are often harmonious, as traits that females prefer are usually more developed in conspecifics than heterospecifics. This need not be the case, however. When it is not, conflict between these arenas of mate choice can be resolved if females attend to different cues for each task. But this raises the potential for correlations among preferences to limit the opportunity for these two processes to operate independently. Here, we show that, within individual female pygmy swordtails (Xiphophorus pygmaeus), directional preferences for conspicuous ornamentation are inversely associated with discrimination against a sympatric heterospecific, Xiphophorus cortezi. Thus, mate choice among and within species need not be separate, independent processes; instead, they can be mechanistically intertwined. As a consequence, different arenas of mate choice can constrain one another, even when females assess multiple cues.     

Women's sexual dysfunction: revised and expanded definitions

ACCEPTANCE OF AN EVIDENCE-BASED CONCEPTUALIZATION OF WOMEN''S SEXUAL RESPONSE combining interpersonal, contextual, personal psychological and biological factors has led to recently published recommendations for revision of definitions of women''s sexual disorders found in the American Psychiatric Association''s Diagnostic and Statistical Manual (DSM–IV-TR). DSM-IV definitions have focused on absence of sexual fantasies and sexual desire prior to sexual activity and arousal, even though the frequency of this type of desire is known to vary greatly among women without sexual complaints. DSM-IV definitions also focus on genital swelling and lubrication, entities known to correlate poorly with subjective sexual arousal and pleasure. The revised definitions consider the many reasons women agree to or instigate sexual activity, and reflect the importance of subjective sexual arousal. The underlying conceptualization of a circular sex-response cycle of overlapping phases in a variable order may facilitate not only the assessment but also the management of dysfunction, the principles of which are briefly recounted.Sexual difficulties are common among women, but whether a problem causing distress is a “dysfunction” as opposed to a normal or logical response to difficult circumstances (e.g., a problem with the relationship, sexual context or cultural factors) remains controversial. Surveys of patients in physicians'' offices suggest that each year, family practitioners will see several women or couples who present with sexual problems, and even more if the physician inquires about patients'' sexual health.¹Sexual difficulties are particularly prevalent among women seeking routine gynecological care.² In population surveys, some 30%–35% of women aged 18–70 have reported a lack of sexual desire during the previous 1–12 months.^3,4Research into women''s sexual function over the past 2 decades has brought into question previous views, definitions and diagnostic labels such as those still found in DSM–IV-TR.⁵ Previous definitions of women''s sexual dysfunction were based on the linear model of human sex response of Masters and Johnson,⁶ as revised by Kaplan.⁷ The model assumes a linear progression from an initial awareness of sexual desire to one of arousal with a focus on genital swelling and lubrication, to orgasmic release and resolution. The resulting diagnostic categories such as hypoactive sexual desire disorder, female sexual arousal disorder and female orgasmic disorder reflected this linear and rather genitally focused model of sexual function. Thus, relatively discrete, non-overlapping phases of sexual response were portrayed and discrete dysfunctions defined.The evidence to date shows that many facets of women''s sexual function are at variance with this model. This review is based on the recent report of an international committee convened by the American Foundation of Urological Disease to revise and expand definitions of women''s sexual dysfunction.⁸ The committee relied on empirical and clinical research as well as clinical experience. Literature searches provided the background to extensive collaboration from September 2002 to February 2003. Informal pilot testing of the committee''s conclusions in clinical practice, plus presentation to a large international audience, led to further revisions over the next 6 months, acceptance by the Second International Consensus of Sexual Medicine⁹ and subsequent publication.^9,10After a review of normal characteristics of women''s sexual motivation and interest, sexual arousability and response, this article presents recommended expanded and revised definitions of women''s sexual dysfunction, along with suggested approaches to diagnosis and treatment.     

Reversed sexual size dimorphism in microtines: Are females larger than males or are males smaller than females?

Summary We analysed sexual size dimorphism for 21 populations of microtine rodents. Female to male size ratio varied considerably among populations from females significantly larger than males (ratio=1.18) to males larger than females (ratio=0.78). In a multiple regression analysis female to male home range size ratio explained 94% of the total variation in body size dimorphism and was the only one of eight independent variables that was selected in a stepwise regression procedure. When females are the larger sex, males have home range sizes much larger than females. We suggest that the relationship between home range size ratio and body weight size dimorphism reflects different selection pressures on males and females in competition for resources and mates.     

Transgenerational effects of sexual interactions and sexual conflict: non-sires boost the fecundity of females in the following generation

The consequences of sexual interactions extend beyond the simple production of offspring. These interactions typically entail direct effects on female fitness, but may also impact the life histories of later generations. Evaluating the cross-generational effects of sexual interactions provides insights into the dynamics of sexual selection and conflict. Such studies can elucidate whether offspring fitness optima diverge across sexes upon heightened levels of sexual interaction among parents. Here, we found that, in Drosophila melanogaster, components of reproductive success in females, but not males, were contingent on the nature of sexual interactions experienced by their mothers. In particular, maternal sexual interactions with non-sires enhanced female fecundity in the following generation. This highlights the importance of non-sire influences of sexual interactions on the expression of offspring life histories.     

Testosterone and sexual behavior in oral contraceptive users and nonusers: a prospective study

The relationship between plasma testosterone (T) secretion and patterns of sexual behavior was examined in 18 women using oral contraceptives (OCs) and 13 nonusers matched for partner availability. Retrospective assessments of perimenstrual symptoms, sexual attitudes, and sexual experience were obtained and women completed daily ratings of the frequency of sexual activities and the level of well-being for 1 month. Plasma levels of sex hormone binding globulin (SHBG), progesterone, Total T, Free T, and non-SHBG bound T were determined by radioimmunoassay at four phases of the pill or menstrual cycle. Overall, women not using OCs had higher plasma levels of Total, Free, and non-SHBG bound T and lower plasma levels of SHBG than those of OC users. Further, only nonusers had perimenstrual decreases in plasma levels of Total and Free T. The two groups were comparable on most retrospective measures. However, OC users reported more satisfaction with their sexual partners than did nonusers and prospective monitoring revealed that they engaged in sexual interactions more frequently than did nonusers across the cycle. In contrast, both groups reported a similar frequency of autosexual activities across the cycle. There were no correlations between average levels of T and levels of sexual desire, sexual interactions, or autosexuality. Moreover, only nonusers reported a decrease in levels of sexual desire during the perimenstrual period that was associated with the changes in Free T over the menstrual cycle.