Finding the Fertile Phase

2018 ◽  
Vol 43 (3) ◽  
pp. 153-157 ◽  
Author(s):  
Mary Lee Barron ◽  
Kaitlin Vanderkolk ◽  
Kathleen Raviele
Keyword(s):  
Fertile Phase

Experimental increase in female mass during the fertile phase leads to enhanced extra-pair paternity in pied flycatchers Ficedula hypoleuca

2019 ◽  
Author(s):  
Mireia Plaza ◽  
Alejandro Cantarero ◽  
Juan Moreno
Keyword(s):  
Negative Relationship ◽  
Ficedula Hypoleuca ◽  
Egg Laying ◽  
Female Dominance ◽  
Laying Date ◽  
Control Group ◽  
Wing Loading ◽  
Potential Fecundity ◽  
Fertile Phase ◽  
Extra Pair Paternity

Female mass in most altricial birds reaches its maximum during breeding at egg-laying, which coincides temporally with the fertile phase when extra-pair paternity (EPP) is determined. Higher mass at laying may have two different effects on EPP intensity. On the one hand, it would lead to increased wing loading (body mass/wing area), which may impair flight efficiency and thereby reduce female’s capacity to resist unwanted extra-pair male approaches (sexual conflict hypothesis). On the other hand, it would enhance female condition, favouring her capacity to evade mate-guarding and to search for extra-pair mates (female choice hypothesis). In both cases, higher female mass at laying may lead to enhanced EPP. To test this prediction, we reduced nest building effort by adding a completely constructed nest in an experimental group of female pied flycatchers (Ficedula hypoleuca). Our treatment caused an increase in mass and thereby wing loading and this was translated into a significantly higher EPP in the manipulated group compared with the control group as expected. There was also a significant negative relationship between EPP and laying date and the extent of the white wing patch, an index of female dominance. More body reserves at laying mean not only a higher potential fecundity but a higher level of EPP as well. This interaction had not previously received due attention but should be considered in future studies of avian breeding strategies.

scholarly journals Female fertile phase synchrony, and male mating and reproductive skew, in the crested macaque

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
James P. Higham ◽  
Michael Heistermann ◽  
Muhammad Agil ◽  
Dyah Perwitasari-Farajallah ◽  
Anja Widdig ◽  
...  
Keyword(s):  
Group Living ◽  
Reproductive Skew ◽  
Male Dominance ◽  
Male Mating ◽  
Marked Variation ◽  
Phase Synchrony ◽  
Fertile Phase ◽  
Macaca Nigra ◽  
Primary Determinant ◽  
High Social Status

AbstractHigh social status is the primary determinant of reproductive success among group-living male mammals. Primates living in multimale–multifemale groups show the greatest variation in the strength of this link, with marked variation in reproductive skew by male dominance among species, dependent on the degree of female fertile phase synchrony, and the number of competing males. Here, we present data on two groups of wild crested macaques (Macaca nigra), living in the Tangkoko Reserve, Sulawesi, Indonesia. We investigated male monopolization of fertile females in 31 cycles of 19 females, and genetic paternity of 14 offspring conceived during the study period. We show that female fertile phase synchrony was low, that females had few mating partners in their fertile phase, and that dominant males monopolized a high proportion of consortships and matings, resulting in marked and steep mating and reproductive skew. We conclude that female cycle asynchrony provides the opportunity for strong direct male–male competition in crested macaques, resulting in monopolization of females by dominant males, consistent with their marked sexual dimorphism. Our study provides a test of the underlying factors that determine the relative occurrence and strength of different mechanisms of sexual selection, and the phenotypes that evolve as a result.

scholarly journals Faces of men with high serum testosterone are less attractive for women during the fertility phase of the menstrual cycle

2021 ◽  
Author(s):  
Jaroslaw Krejza ◽  
Rafal Sledziewski ◽  
Marek Tabedzki ◽  
Rong Chen ◽  
Ewa Krzystanek ◽  
...  
Keyword(s):  
Menstrual Cycle ◽  
Serum Testosterone ◽  
High Serum ◽  
Good Genes ◽  
Total Testosterone ◽  
High Concentration ◽  
Fertile Phase ◽  
Average Face ◽  
Women’S Preferences ◽  
Shift Hypothesis

The attractiveness of the human face plays an essential role in mating as it may signal the genetic suitability of a mate. The controversial 'ovulatory shift hypothesis' postulates that women in the fertile phase of the menstrual cycle would prefer faces of masculine men with high testosterone that signals 'good genes', whereas in the non-fertile phase they prefer traits signaling the willingness to provide parental care. To examine relationships between men's testosterone and women's preferences for men's faces on day 13 of the menstrual cycle, 19 young women rated the attractiveness of images of the natural faces of 77 young men. Using advanced Bayesian multilevel modeling we showed that the attractiveness of men's faces is significantly lower in men with a high concentration of serum total testosterone, even taking into account the concentration of serum estrogen in the raters. The average men's face composited from images of 39 faces rated above pool median attractiveness rate, was slightly narrower than the average face composited from 38 less attractive faces. Our results challenge the 'ovulatory shift hypothesis' as faces of males with high circulating testosterone were rated as less attractive than faces of males with lower testosterone by women on the fertile phase of the cycle.

scholarly journals Variability in the hormonally estimated fertile phase of the menstrual cycle

2008 ◽  
Vol 90 (4) ◽  
pp. 1232-1235 ◽  
Author(s):  
Richard J. Fehring ◽  
Mary Schneider
Keyword(s):  
Menstrual Cycle ◽  
Fertile Phase

scholarly journals Waist-to-Hip Ratio, but Not Body Mass Index, Is Associated with Testosterone and Estradiol Concentrations in Young Women

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Ricardo Mondragón-Ceballos ◽  
Mónica Dafne García Granados ◽  
Ana Lilia Cerda-Molina ◽  
Roberto Chavira-Ramírez ◽  
Leonor Estela Hernández-López
Keyword(s):  
Body Mass Index ◽  
Menstrual Cycle ◽  
Body Mass ◽  
Young Women ◽  
Luteal Phase ◽  
Significant Interaction ◽  
Saliva Sample ◽  
Follicular Phase ◽  
Waist To Hip Ratio ◽  
Fertile Phase

We studied if testosterone and estradiol concentrations are associated with specific female waist-to-hip ratios (WHRs) and body mass indices (BMIs). Participants were 187 young women from which waist, hips, weight, and height were measured. In addition, participants informed on which day of their menstrual cycle they were and provided a 6 mL saliva sample. Ninety-one of them were in the follicular phase and 96 in the luteal phase. Only in the fertile phase of the menstrual cycle we found a significant interaction between testosterone and estradiol affecting WHR (b±s.e.=-0.000003±0.000001; t94=-2.12, adjusted R2=-0.008, P=0.03). Women with the highest levels of both hormones had the lowest WHRs, while women with low estradiol and high testosterone showed the highest WHRs. BMI significantly increased as testosterone increased in female in their nonfertile days.

Does a Woman’s Skin Color Indicate Her Fertility Level?

2011 ◽  
Vol 70 (4) ◽  
pp. 199-202 ◽  
Author(s):  
Nadine Samson ◽  
Bernhard Fink ◽  
Paul Matts
Keyword(s):  
Menstrual Cycle ◽  
Skin Color ◽  
Facial Attractiveness ◽  
Fertility Level ◽  
Facial Skin ◽  
Fertile Phase ◽  
Skin Coloration ◽  
Caucasian Women ◽  
Two Phases ◽  
Midluteal Phase

Roberts et al. (2004 ) showed that perceived facial attractiveness of women is higher in the fertile phase of the menstrual cycle than in the luteal phase, suggesting the existence of visible cues of ovulation. However, the nature of such cues remains speculative. Here, in an initial pilot study, we test the hypothesis that changes in female facial skin coloration across the menstrual cycle could be one of the signals that men have adapted to in order to assess female fertility. Spectrophotometric measurements of the facial skin color of normally ovulating Caucasian women (aged 24–29 years) were collected in the late follicular and midluteal phase of their menstrual cycle. Facial images were also taken in both sessions and judged for attractiveness and health by a panel of German men (aged 16–37 years). In line with Roberts et al. (2004 ), our results show that men perceive women in the late follicular phase to be significantly more attractive and healthier than those in the midluteal phase. However, we did not detect any significant differences in objective measurements of skin color between the two phases. We conclude that the increase in male perception of female facial attractiveness and health in the fertile phase of the menstrual cycle is not caused by a change in overall skin color and/or lightness.

Risk taking and Women’s Menstrual Cycle: Near Ovulation, Women Avoid a Doubtful Man

2012 ◽  
Vol 3 (1) ◽  
pp. 1-3 ◽  
Author(s):  
Nicolas Guéguen
Keyword(s):  
Menstrual Cycle ◽  
Sexual Assault ◽  
Risk Taking ◽  
Waiting Room ◽  
Fertile Phase ◽  
Risk Taking Behaviors

Studies using surveys in which risk taking behaviors were measured show a decrease in risk taking during the ovulatory phase of the women’s menstrual cycle. In this study, the distance between a woman and a shady confederate was measured in a waiting room. Then, a LH test was done in order to measure the participant’s fertility risk. Results showed that near ovulation, participants sat further away from the confederate, revealing that women in their fertile phase displayed behavior to decrease the risk of sexual assault.

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