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Women ornament themselves for intrasexual competition near ovulation, but for intersexual attraction in luteal phase.

ABSTRACT: The present study examined women's attentional bias toward ornamental objects in relation to their menstrual phase as well as to motivations of intersexual courtship or intrasexual competition. In Experiment 1, 33 healthy heterosexual women were tested in a bias-assessment visual cuing task twice: once on a high-fertility day (during the ovulatory phase) and once on a low-fertility day (during the luteal phase). They paid greater attention to pictures of ornamental objects than to pictures of non-ornamental objects near ovulation, but not during the luteal phase, suggesting an ornamental bias during the high-fertility phase. In Experiment 2, before the visual cuing task, 40 participants viewed 10 same-sex or opposite-sex facial photographs with either high or low attractiveness as priming tasks to activate the intrasexual competition or intersexual courtship motives. Results showed that women's ornamental bias was dependent on the interaction of menstrual phase and mating motive. Specifically, the ornamental bias was observed on the high-fertility day when the subjects were primed with high-attractive same-sex images (intrasexual competition) and was observed on the low-fertility day when they were primed with high-attractive opposite-sex photographs (intersexual courtship). In conclusion, the present findings confirm the hypothesis that, during the high-fertility phase, women have an attentional bias toward ornamental objects and further support the hypothesis that the ornamental bias is driven by intrasexual competition motivation near ovulation, but driven by intersexual courtship motivation during the luteal phase.

SUBMITTER: Zhuang JY

PROVIDER: S-EPMC4152269 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Women ornament themselves for intrasexual competition near ovulation, but for intersexual attraction in luteal phase.

Zhuang Jin-Ying JY Wang Jia-Xi JX

PloS one 20140902 9

The present study examined women's attentional bias toward ornamental objects in relation to their menstrual phase as well as to motivations of intersexual courtship or intrasexual competition. In Experiment 1, 33 healthy heterosexual women were tested in a bias-assessment visual cuing task twice: once on a high-fertility day (during the ovulatory phase) and once on a low-fertility day (during the luteal phase). They paid greater attention to pictures of ornamental objects than to pictures of no ...[more]

PMID: 25180577

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Project description:Ovarian prostaglandins are critical in normal ovulation processes; thus, their inhibition may provide contraceptive benefits. This study was performed to determine the effect of the cyclooxygenase-2 (COX2) inhibitor celecoxib on ovulation and luteal events in women.The study had a randomized, double-blind, crossover design. Ovulatory, reproductive-aged women underwent ovarian ultrasound and serum hormone monitoring during four menstrual cycles (control cycle, treatment cycle 1, washout cycle, treatment cycle 2). Subjects received study drug (oral celecoxib 400 mg or placebo) either (a) once daily starting on cycle day 8 and continuing until follicle rupture or the onset of next menses if follicle rupture did not occur [pre-luteinizing hormone (LH) surge dosing] or (b) once daily beginning with the LH surge and continuing for 6 days (post-LH surge dosing). Subjects were randomly assigned to one of the above treatment schemes and received the other in the subsequent treatment cycle. The main outcomes were evidence of ovulatory and luteal dysfunction as determined by inhibited/delayed follicle rupture and reduced luteal progesterone synthesis or lifespan, respectively.A total of 20 women enrolled and completed the study (Group 1=10, Group 2=10), with similar demographics between groups. Nineteen subjects exhibited normal ovulation in the control cycle (one had a blunted LH peak). In comparison to control cycles, treatment cycles resulted in a significant increase in ovulatory dysfunction [pre-LH treatment: 30% (6/20), p=.04; post-LH treatment: 25% (5/20), p=.04]. Mean peak progesterone, estradiol, and LH levels and luteal phase length did not differ significantly between control and either treatment cycle.Although treatment with celecoxib before or after the LH surge increases the rate of ovulatory dysfunction, most women ovulate normally. Thus, this selective COX2 inhibitor appears to be of limited usefulness as a potential emergency contraceptive.

Project description:BackgroundIntense competition for access to females can lead to males exploiting different components of sexual selection, and result in the evolution of alternative mating strategies (AMSs). Males of Poecilia parae, a colour polymorphic fish, exhibit five distinct phenotypes: drab-coloured (immaculata), striped (parae), structural-coloured (blue) and carotenoid-based red and yellow morphs. Previous work indicates that immaculata males employ a sneaker strategy, whereas the red and yellow morphs exploit female preferences for carotenoid-based colours. Mating strategies favouring the maintenance of the other morphs remain to be determined. Here, we report the role of agonistic male-male interactions in influencing female mating preferences and male mating success, and in facilitating the evolution of AMSs.ResultsOur study reveals variation in aggressiveness among P. parae morphs during indirect and direct interactions with sexually receptive females. Two morphs, parae and yellow, use aggression to enhance their mating success (i.e., number of copulations) by 1) directly monopolizing access to females, and 2) modifying female preferences after winning agonistic encounters. Conversely, we found that the success of the drab-coloured immaculata morph, which specializes in a sneak copulation strategy, relies in its ability to circumvent both male aggression and female choice when facing all but yellow males.ConclusionsStrong directional selection is expected to deplete genetic variation, yet many species show striking genetically-based polymorphisms. Most studies evoke frequency dependent selection to explain the persistence of such variation. Consistent with a growing body of evidence, our findings suggest that a complex form of balancing selection may alternatively explain the evolution and maintenance of AMSs in a colour polymorphic fish. In particular, this study demonstrates that intrasexual competition results in phenotypically distinct males exhibiting clear differences in their levels of aggression to exclude potential sexual rivals. By being dominant, the more aggressive males are able to circumvent female mating preferences for attractive males, whereas another male type incorporates subordinate behaviours that allow them to circumvent male aggression and female mating preferences. Together, these and previous results indicate that exploiting different aspects of social interactions may allow males to evolve distinct mating strategies and thus the long term maintenance of polymorphisms within populations.

Project description:BackgroundEvidence of male-male courtship display is widespread across the animal kingdom. Yet, its function and evolutionary origin remain unclear. Here, we hypothesise that male-male courtship display evolved in response to selection pressure exerted by intrasexual competition during male-female courtship interactions. Intrasexual competition can be caused by bystander male pressure through eavesdropping and exploiting on displayer male's courtship interactions with females. This bystander pressure can lead to an audience effect by the displayer, who will change their courtship behaviour in the presence of bystanders and display directly towards them, even in the absence of females, as an intimidation strategy. In species where this selection pressure has taken place, we predict that the male courtship display will have a dual function: attract females and deter competitors. Therefore, we expected to find more evidence of bystander-related behaviours in species for which male-male courtship display is linked to intrasexual competition compared to species for which other explanatory hypotheses are more plausible (e.g., mistaken identity or courtship practice).MethodologyWe conducted two systematic reviews to test this hypothesis. First, we conducted a search for studies of species with courtship display between males and of the hypotheses provided to explain this behaviour. Our goal was to identify the species with male-male courtship display and evidence of intrasexual competition. Second, among the species with male-male courtship display, we searched for evidence of bystander-related behaviours, i.e., articles referring to eavesdropping, exploitation, and audience effect during male-female courtship interactions. Our goal was to test whether species with intrasexual competition are also more likely to show bystander-related behaviours.ResultsAlthough most studies reporting male courtship display towards other males do not suggest any explanatory hypothesis for this behaviour, the intrasexual competition hypothesis was largely mentioned and supported by some studies reviewed. Additionally, there is more evidence of eavesdropping and of all three bystander-related behaviours combined in species for which the intrasexual competition hypothesis was suggested.ConclusionsOverall, our review supports the hypothesis that intrasexual competition can play a key role in male courtship display evolution, namely that male-male courtship display may have evolved as a secondary function of male-female courtship interactions via bystander male pressure. However, our review also shows that despite the increasing interest in same-sex sexual behaviours, and male-male courtship display in particular, most studies were found to be merely descriptive, and the hypotheses they suggested to explain courtship display between males mostly speculative. This highlights an important gap in the literature. To clarify both the evolution and the function of male-male courtship display, this behaviour needs to be empirically studied more often. Our review can help advancing this research area, as it makes the 20 species with male-male courtship display for which the intrasexual competition hypothesis was suggested excellent candidates for empirical research.

Project description:Sexes often differ more obviously in secondary sexual characteristics than in traits that appear naturally selected, despite conceivable benefits to intersexual niche partitioning. Genetic constraints may play a role in limiting sex-specific niche evolution; however, it is not clear why this limit should apply to naturally selected traits more than those under sexual selection; the latter routinely produces dimorphism. We ask whether ecological factors and/or features of the mating system limit dimorphism in resource use, or conversely, what conditions are the most permissible ones for sexual niche differences. The scale of mating competition and spatial variation in resource availability can help predict sexually dimorphic niches or the lack thereof. We investigate why and when dimorphism might fail to evolve even if genetic covariation between the sexes posed no constraint. Our analytical model incorporates the first aspect of spatial interactions (scale of mating competition). It is followed by simulations that explore broader conditions, including multiple resources with habitat heterogeneity, genetic correlations and non-Gaussian resource-use efficiency functions. We recover earlier known conditions for favourable conditions for the evolution of niche partitioning between sexes, such as narrow individual niche and low degrees of genetic constraint. We also show spatial considerations to alter this picture. Sexual niche divergence occurs more readily when local mating groups are small and different resources occur reliably across habitats. Polygyny (medium-sized or large mating groups) can diminish the prospects for dimorphism even if no genetic constraints are present. Habitat heterogeneity typically also disfavours niche dimorphism but can also lead to polymorphism within a sex, if it is beneficial to specialize to be very competitive in one habitat, even at a cost to performance in the other. Sexual conflict is usually used to explain dimorphic traits or behaviours. Our models highlight that introducing conflict (achieved by switching from monogamy to polygamy) can also be responsible for sexual monomorphism. Under monogamy, males benefit from specializing to consume other resources than what feeds the female best. Polygyny makes males disregard this female benefit, and both sexes compete for the most profitable resource, leading to overlapping niches.

Project description:The major limitations associated with gonadotropin-releasing hormone agonist (GnRHa) triggering are inferior clinical outcomes in fresh embryo transfer cycles caused by luteal phase insufficiency following the GnRHa triggering. We included 153 high-risk patients in this study. In group I, the patients received gonadotropin-releasing hormone agonist (GnRHa) trigger + 1,500 IU human chorionic gonadotropin (hCG) support on the oocyte pick-up (OPU) day; in group II, the patients had a dual trigger (GnRHa + 1,500 IU hCG); and in group III (control), 10,000 IU hCG trigger was prescribed for the final oocyte maturation. The levels of LH, estradiol, and progesterone were evaluated in serum on the stimulation starting day, day 6 of stimulation, on the day of the trigger administration, OPU day, days 3 and 5 post-OPU, and day 14 post-ET, as well as in follicular fluid. Progesterone concentration was significantly lower in group I on OPU+5 compared to the hCG group (I vs. III, р = 0.0065). Progesterone levels were significantly lower in group II in serum on OPU+5 compared to groups I and III (I vs. II, р = 0.0068; II vs. III, р = 1.76 × 108). The progesterone levels were significantly higher in follicular fluid in group III compared to the study groups (I vs. III, р = 0.002; II vs. III, p = 0.009). However, no significant differences in clinical outcomes were found between the groups. Then, we divided all women into pregnant and non-pregnant groups and found that estradiol (p = 0.00009) and progesterone (p = 0.000036) on the day of the pregnancy test were significantly higher in the pregnant women group. Also, progesterone on OPU day was significantly higher in the non-pregnant group (p = 0.033). Two cases of moderate ovarian hyperstimulation syndrome (OHSS) late-onset occurred in group I (3.5%, 2/56), no case of moderate/severe OHSS late-onset in group II, and three cases of moderate late-onset in group III (5.7%, 3/53). The low-dose hCG supplementation improves the luteal phase insufficiency after GnRHa triggering, which is confirmed by the comparable pregnancy rates in fresh transfer cycles between the groups. However, low-dose hCG carries a similar risk of OHSS as the full dose of hCG in high-responder patients.

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Women ornament themselves for intrasexual competition near ovulation, but for intersexual attraction in luteal phase.

Publications

Women ornament themselves for intrasexual competition near ovulation, but for intersexual attraction in luteal phase.

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