Sexual Traits Research Articles

Size rather than complexity of sexual ornaments prolongs male metamorphosis and explains sexual size dimorphism in sepsid flies.

Male sexual ornaments often evolve rapidly and are thought to be costly, thus contributing to sexual size dimorphism. However, little is known about their developmental costs, and even less about costs associated with structural complexity. Here, we quantified the size and complexity of three morphologically elaborate sexually dimorphic male ornaments that starkly differ across sepsid fly species (Diptera: Sepsidae): (i) male forelegs range from being unmodified, like in most females, to being adorned with spines and large cuticular protrusions; (ii) the fourth abdominal sternites are either unmodified or are converted into complex de novo appendages; and (iii) male genital claspers range from small and simple to large and complex (e.g. bifurcated). We tracked the development of 18 sepsid species from egg to adult to determine larval feeding and pupal metamorphosis times of both sexes. We then statistically explored whether pupal and adult body size, ornament size and/or ornament complexity are correlated with sex-specific development times. Larval growth and foraging periods of male and female larvae did not differ, but the time spent in the pupal stage was ca 5% longer for sepsid males despite emerging 9% smaller than females on average. Surprisingly, we found no evidence that sexual trait complexity prolongs pupal development beyond some effects of trait size. Evolving more complex traits thus does not incur developmental costs at least in this system.

What are the consequences of clonal integration for floral traits and reproductive investment of a broadly distributed aquatic plant?

Reproductive plasticity allows plants to invest resources in distinct ways under different environmental conditions. Clonal reproduction has been considered a sink of resources that decreases sexual reproduction due to potential trade-offs between reproductive modes. However, clonal integration may allow plants to share resources such as water and nutrients among individual subunits, generating variability on key traits, as floral shape, and size. The objective of this work was to examine whether clonal integration affects floral traits on a widely distributed aquatic plant, and how this influence affect plants sexual reproductive traits. We found that clonal ramets exhibited larger and more robust flowers than isolated ones, but the number of flowers per inflorescence did not change in comparison to isolated plants. These changes are discussed as mechanisms of reproduction enhancement. We conclude that clonal integration changes Eichhornia crassipes resources investment on sexual reproduction and may be identified as a persistence strategy for aquatic plants.

Systematic metabolomic studies identified adult adiposity biomarkers with acetylglycine associated with fat loss in vivo.

Obesity is associated with various adverse health outcomes. Body fat (BF) distribution is recognized as an important factor of negative health consequences of obesity. Although metabolomics studies, mainly focused on body mass index (BMI) and waist circumference, have explored the biological mechanisms involved in the development of obesity, these proxy composite measures are not accurate and cannot reflect BF distribution, and thus may hinder accurate assessment of metabolic alterations and differential risk of metabolic disorders among individuals presenting adiposity differently throughout the body. Thus, the exact relations between metabolites and BF remain to be elucidated. Here, we aim to examine the associations of metabolites and metabolic pathways with BF traits which reflect BF distribution. We performed systematic untargeted serum metabolite profiling and dual-energy X-ray absorptiometry (DXA) whole body fat scan for 517 Chinese women. We jointly analyzed DXA-derived four BF phenotypes to detect cross-phenotype metabolite associations and to prioritize important metabolomic factors. Topology-based pathway analysis was used to identify important BF-related biological processes. Finally, we explored the relationships of the identified BF-related candidate metabolites with BF traits in different sex and ethnicity through two independent cohorts. Acetylglycine, the top distinguished finding, was validated for its obesity resistance effect through in vivo studies of various diet-induced obese (DIO) mice. Eighteen metabolites and fourteen pathways were discovered to be associated with BF phenotypes. Six of the metabolites were validated in varying sex and ethnicity. The obesity-resistant effects of acetylglycine were observed to be highly robust and generalizable in both human and DIO mice. These findings demonstrate the importance of metabolites associated with BF distribution patterns and several biological pathways that may contribute to obesity and obesity-related disease etiology, prevention, and intervention. Acetylglycine is highlighted as a potential therapeutic candidate for preventing excessive adiposity in future studies.

Men’s Self-Reported and Psychophysiological Affective Responses to Sexual Violence and Their Associations with Rape Myths, Personality, and Sexual Traits: A Preliminary Study

Objective: Despite alarming evidence on sexual violence against women, little is known about men’s emotional responses to rape and how these may be involved in sexual violence dynamics. Accordingly, our aim was to capture how rape scenarios are emotionally appraised. Methods: The current study evaluated men’s (N = 30) self-reported and psychophysiological emotional responses (facial EMG, electrodermal activity) to a rape scene, and contrasted it with their responses to stimuli depicting nonsexual violence and nonviolent male-female interactions. The associations between men’s emotional responses and their endorsement of rape myths, personality, and sexual traits were also examined. Results: Findings revealed that the rape scene resulted in higher negative affect, both subjectively and indexed by increased facial EMG (corrugator activity), than the other two stimuli. Additionally, personality traits of neuroticism, lower agreeableness, lower consciousness, psychopathic tendencies, as well as lower sexual inhibition proneness, were all associated with higher subjective sexual arousal toward rape. Conclusions: Findings add to the literature on the putative emotional processes underpinning the appraisal of sexual violence against women.

Quantitative genetics of breeding coloration in sand lizards; genic capture unlikely to maintain additive genetic variance

Sexual selection on fitness-determining traits should theoretically erode genetic variance and lead to low heritability. However, many sexually selected traits maintain significant phenotypic and additive genetic variance, with explanations for this “lek paradox” including genic capture due to condition-dependence, and breaks on directional selection due to environmental sources of variance including maternal effects. Here we investigate genetic and environmental sources of variance in the intrasexually selected green badge of the sand lizard (Lacerta agilis). The badge functions as a cue to male fighting ability in this species, and male–male interactions determine mate acquisition. Using animal models on a pedigree including three generations of males measured over an extensive 9-year field study, we partition phenotypic variance in both badge size and body condition into additive genetic, maternal, and permanent environmental effects experienced by an individual over its lifespan. Heritability of badge size was 0.33 with a significant estimate of underlying additive genetic variance. Body condition was strongly environmentally determined in this species and did not show either significant additive genetic variance or heritability. Neither badge size nor body condition was responsive to maternal effects. We propose that the lack of additive genetic variance and heritability of body condition makes it unlikely that genic capture mechanisms maintain additive genetic variance for badge size. That said, genic capture was originally proposed for male traits under female choice, not agonistic selection. If developmental pathways generating variance in body condition, and/or the covarying secondary sex trait, differ between inter- and intrasexual selection, or the rate at which their additive genetic variance or covariance is depleted, future work may show whether genic capture is largely restricted to intersexual selection processes.

Appealing but a cheat: choice of attractive but sick males reduces the fitness of females

Abstract One central tenet in sexual selection theory is that sexual traits are honest indicators of individual condition. This does not appear to be the case for Tenebrio molitor beetles whose males, when infected with the fungus Metarhizium robertsii, produce chemical signals (pheromones) that increase their attractiveness. Using this system, we have investigated the consequences of non-adaptive female choice with regard to: (a) survival of females in choosing fungus-infected males; and (b) whether the number and duration of copulations increases fungal infection in females. Females that mated with fungus-infected males lived half as long as females that mated with infection-free males. In addition, the greater the number and the longer the duration of copulation(s), the greater the fungal sporulation in females, suggesting that the fungus may be mainly transmitted during copulation. This study documents a conflict between the sexes: while the dishonesty of a sexual signal increases male fitness, it reduces female fitness.

A Semi-Automatic Method on a Small Italian Sample for Estimating Sex Based on the Shape of the Crown of the Maxillary Posterior Teeth

Teeth are known to be reliable substrates for human identification and are endowed with significant sexual dimorphism not only in the size but also in the shape of the crowns. In the preliminary phase of our study (already published in 2021), a novel sex estimation method based on dental morphometric geometric (GMA) analysis combined with the artificial neural network (ANN) was developed and validated on a single dental element (first upper premolar) with an accuracy rate of 80%. This study aims to experiment and validate the combination of GMA-ANN on the upper first and second left premolars and the upper left first molar to obtain a reliable classification model based on the sexual dimorphic traits of multiple maxillary teeth of Caucasian Italian adults (115 males and 115 females). A general procrustes superimposition (GPS) and principal component analysis (PCA) were performed to study the shape variance between the sexes and to reduce the data variations. The "set-aside" approach was used to validate the accuracy of the proposed ANN. As the main findings, the proposed method correctly classified 94% of females and 68% of males from the test sample and the overall accuracy gained was 82%, higher than the odontometric methods that similarly consider multiple teeth. The shape variation between male and female premolars represents the best dimorphic feature compared with the first upper molar. Future research could overcome some limitations by considering a larger sample of subjects and experimenting with the use of computer vision for automatic landmark positioning and should verify the present evidence in samples with different ancestry.

Genome-Wide Association Study of Growth and Sex Traits Provides Insight into Heritable Mechanisms Underlying Growth Development of Macrobrachium nipponense (Oriental River Prawn)

Male hybrid oriental river prawns grow significantly faster than hybrid females. In this study, the growth and sex traits of 181 individuals of Macrobrachium nipponense were recorded, and each individual genotype was evaluated using the 2b-RAD sequencing method. The genetic parameters for growth and sex traits were estimated. A genome-wide association analysis (GWAS) of these traits was performed. In total, 18 growth-related SNPs were detected from 12 chromosomes using a mixed linear model. The most significant loci of weight are located on the position of the SNP (102638935, chromosome 13), which can explain 11.87% of the phenotypic variation. A total of 11 significant SNPs were detected on four chromosomes associated with sex trait (three on chromosome 4, one on chromosome 7 and seven on chromosome 17). The heritability of this trait is 0.8998 and belongs to the range of ultra-high heritability. Genetic correlations were prevalent among the 11 traits examined, the genetic coefficient between sex and body weight reached a significant level of -0.23. This study is the first GWAS for sex of binary and growth traits in oriental river prawn. Our results provide a set of markers for the genetic selection of growth traits and help us to further understand the genetic mechanisms of growth in Macrobrachium nipponense.

A review : The Relationships Between Ovary Disease and Tumor Marker

The ovary is an organ found in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary found on each side of the body. The ovaries also secrete hormones that play a role in the menstrual cycle and fertility. The ovary progresses through many stages beginning in the prenatal period through menopause. It is also an endocrine gland because of the various hormones that it secrete. 
 The ovary starts secreting more and more hormones at puberty. The hormones trigger the development of secondary sex traits. Starting with adolescence, the ovary undergoes structural and functional changes. The ability of the ovaries to control hormones makes them crucial to fertility and conception. A number of feedback mechanisms are stimulated when egg cells, or oocytes, are expelled from the Fallopian tube, which changes the hormone levels in the body. 
 Ovaries release progesterone, estrogen, testosterone, and inhibin at sexual maturity. The adrenal glands and ovaries in women create 50% of the body's testosterone, which is then immediately delivered into the bloodstream. Estrogen is in charge of the maturation and maintenance of the reproductive organs in their mature functional state, as well as the appearance of secondary sex characteristics in females during puberty. The uterus and mammary glands are prepared for pregnancy and breastfeeding, respectively, by progesterone. Progesterone and estrogen work together to promote endometrial changes associated with the menstrual cycle.

Examining the potential for resource-dependent female reproductive fluid-sperm interactive effects in a livebearing fish.

Sexually selected traits can be costly to produce and maintain. The amount of resources available to an individual is therefore expected to influence investment in costly sexual traits. While resource-dependent expression of sexually selected traits has traditionally been examined in males, resource limitation can also influence how sexual selection operates in females. Female reproductive fluids are thought to be costly to produce and may play an important role in shaping the outcome of postcopulatory sexual selection by influencing sperm performance. However, we know surprisingly little about whether and how female reproductive fluids are influenced by resource limitation. Here, we examine if resource restriction influences female reproductive fluid-sperm interactive effects in the pygmy halfbeak (Dermogenys collettei), a small internally fertilizing freshwater fish where females store sperm. After experimentally altering female diets (high vs. restricted diets), we compared how female reproductive fluids influence two key metrics of sperm quality: sperm viability and velocity. While female reproductive fluids enhanced sperm viability and velocity, we found no evidence that female diet influenced the interactive effect between female reproductive fluids and sperm viability or velocity. Our findings build on the growing evidence that female reproductive fluids influence sperm performance and call for further attention to be devoted to understanding how resource quantity and quality influence how female reproductive fluids affect sperm performance.

Age-related changes in sperm traits and evidence for aging costs of sperm production in a sexually promiscuous passerine

In many animal species, organismal performance declines with age in a process known as aging or senescence. Senescence typically leads to a deterioration of physiological functionality and can impact the development of primary sexual phenotypes. Sperm production is a complex and costly process that is sensitive to changes in individual physiological state, yet remarkably little is known about age-related changes in sperm performance and aging costs of sperm production. Here we use a non-linear generalized additive mixed models (GAMM) modelling to evaluate age-related changes in postcopulatory sexual traits in the European barn swallow (Hirundo rustica rustica), a relatively short lived sexually promiscuous passerine species, where male extra-pair fertilization success has been shown to increase with age. We confirmed a positive relationship between sperm midpiece length and sperm velocity in this species. Within-male changes in sperm morphology and sperm velocity were in general absent, with only sperm length decreasing linearly with increasing age, although this change was negligible compared to the overall variation in sperm size among males. In contrast, the cloacal protuberance (CP) size changed nonlinearly with age, with an initial increase between the first and third year of life followed by a plateau. The results further indicate the existence of a trade-off between investments in sperm production and survival as males with large CP tended to have a reduced lifespan. This seems consistent with the idea of expensive sperm production and survival aging costs associated with investments in post-copulatory traits in this sexually promiscuous species.

A Comparison of Feathers and Oral Swab Samples as DNA Sources for Molecular Sexing in Companion Birds.

The early age determinism of the sex in case of monomorphic birds is very important, because most companion birds have no distinct sexual dimorphic traits. Molecular genetic sexing was proved to be one of the most accurate sex determinations in monomorphic birds. The aim of this study was to compare the results obtained by PCR performed on isolate genomic DNA from paired samples of feathers and oral swabs collected from the same individuals. Samples of oral swabs (n = 101) and feathers (n = 74) were collected from 101 companion birds from four different species (Columba livia domestica, Psittacula krameri, Neophema splendida and Agapornis spp.). The PCR was performed for the amplification of the CHD1W and CHD1Z genes in females and the CHD1Z gene in males. The overall PCR success rate of sex determination was significantly higher from oral swabs than from feathers. The PCR success rate from oral swabs was higher in juveniles and from feathers was significantly higher in adults. The similarity between the oral swab and feathers was obtained in 78.38% of the birds. Oral swabs proved to be a more reliable sample for genetic sex determination in the species tested in this study.

Lizard Dewlap Color and Malaria Infection: Testing the Hamilton-Zuk Hypothesis

The Hamilton-Zuk hypothesis indicates that parasites may have a negative effect on the appearance of sexual traits within an infected individual. Anolis sagrei, or brown anoles, are small invasive lizards common throughout Florida and many other areas where they have been introduced. The colorful dewlaps under the chins of males are used as a signal during territorial contests with other males and as an ornament to attract females. Anoles may be infected by the malaria parasite Plasmodium floridense. In this study, we investigated the relationship of malarial infection with dewlap color and spectral brightness of A. sagrei. We achieved this by capturing male brown anoles, taking blood samples to examine for malarial infection, and recording the color of their dewlaps. We found that the dewlaps of infected Anolis sagrei had duller coloration than the dewlaps of uninfected lizards. These results provide support for the Hamilton-Zuk hypothesis. Our results suggest that infection by P. floridense could potentially influence fitness of the lizards by reducing the expression of their color signals. Additional research on fitness effects of the malaria parasite on anoles is important for fully understanding this phenomenon.

Functional, genetic, and structural constraints on the exaggeration and diversification of male genital morphology inOhomopterusground beetles

AbstractThe evolution of exaggerated sexual traits may be possible by the relaxation of various constraints on exaggeration. Functional constraints refer to the reduced performance of exaggerated traitsper seor increased survival costs by holding the exaggerated traits. Genetic constraints, such as genetic correlations or pleiotropy, may hinder the independent evolution and exaggeration of traits. Structural constraints, such as competition for space and resources among traits, may require the coordination of the exaggerated trait with surrounding structures. The remarkable diversity of male genital morphology provides an ideal opportunity for examining constraints on sexual trait exaggeration. In this study, we addressed the constraints on the evolution of exaggerated male genital morphology based on a comparative analysis of phenotypic covariation between the genitalia and other body parts usingOhomopterusground beetles. We found that exaggerated male genitalia were related to a relaxation of functional constraint, as revealed by a steeper allometric slope in the species with exaggerated male genitalia. By contrast, genetic constraint based on a shared genetic basis for the male genitalia and other appendages may have little effect on diversification in male genitalia. Structural constraints were strongest in the species with the most exaggerated male genitalia, suggesting that the observed constraint was a result of exaggeration. These findings improve our understanding of sexual trait exaggeration and underlying constraints.

Analysis of the Differences in Muscle Nutrition among Individuals of Different Sexes in Redclaw Crayfish, Cherax quadricarinatus

Redclaw crayfish (Cherax quadricarinatus) was introduced to China many years ago. In recent years, a breeding boom for C. quadricarinatus has been set off in China due to a breakthrough in key technology of seedling breeding. The size and growth rate of C. quadricarinatus vary greatly between female and male individuals, usually the size and growth rate of male individuals are bigger than that of female individuals. There is usually a certain linkage relationship between the sex traits of crustaceans and their own nutrition. In order to explore the linkage relationship between the sex traits of C. quadricarinatus and its nutritional components, this study measured and analyzed the muscle nutritional components of female and male individuals. The results showed that the meat yield rate of male individuals was significantly higher than that of females (p < 0.05), and the crude fat content was significantly lower than that for females (p < 0.05). The ratios of essential amino acids to total amino acids for females and males were 39.61% and 38.49%, respectively. The ratios of essential amino acids to non-essential amino acids were 79.69% and 75.66%, respectively, which far exceed FAO/WHO standards and both belong to high-quality protein. The total amount of flavor amino acids of male individuals was significantly higher than that of female individuals (p < 0.05). The total amount of polyunsaturated fatty acids and the polyunsaturated fatty acid eicosapentaenoic acid of males are both significantly higher than that of females (p < 0.05). Studies have shown that there are certain differences in nutrition between male and female individuals. Compared with female individuals, the meat yield rate, crude protein content, and edible value of the muscles of male individuals is higher.

Descriptive versus causal morphology: gynandromorphism and intersexuality

In animal species with separate sexes, abnormal individuals with a mix of phenotypically male and phenotypically female body parts are generally indicated as gynandromorphs, whereas individuals with intermediate sexual phenotypic traits are generally indicated as intersexes. However, this distinction, clear as it may seem, is neither universally agreed upon, nor free of critical issues. In consideration of the role of sex anomalies in understanding normal development, we reassess these phenomena of abnormal sexual development, taking into consideration the more recent advances in the study of sex determination and sexual differentiation. We argue that a distinction between gynandromorphism and intersexuality, although useful for descriptive purposes, is not always possible or sensible. We discuss the conceptual and terminological intricacies of the literature on this subject and provide reasons for largely, although not strictly, preferring a terminology based on descriptive rather than causal morphology, that is, on the observed phenotypic patterns rather on the causal process behind them.

Integrative analysis reveals the divergence and speciation between sister Sooty Copper butterflies Lycaena bleusei and L. tityrus

The comparison of closely related taxa is cornerstone in biology, as understanding mechanisms leading up to differentiation in relation to extant shared characters are powerful tools in interpreting the evolutionary process. Hotspots of biodiversity such as the west-Mediterranean, where many lineages meet are ideal grounds to study these processes. We set to explore the interesting example of Sooty Copper butterflies: widespread Eurasian Lycaena tityrus (Poda, 1761) comes into contact in Iberia with closely related and local endemic, L. bleusei (Oberthür, 1884), which hasn’t always been considered a distinct species. An integrative analysis was designed, combining the use of extensive molecular data (five genes), geometric morphometrics analyses, verified and up-to-date distribution data, and environmental niche modelling, aimed at deciphering their true relationship, their placement within European Lycaena and trace their evolutionary history. We revealed several levels of differentiation: L. bleusei and L. tityrus appear to be reciprocally monophyletic independent gene-pools, distinct in all genes analysed, having mutually diverged 4.8 Ma ago. L. tityrus but not L. bleusei, further displays a genetic structure compatible with several glacial refugia, where populations assignable to infraspecific taxa surface. Conversely, L. bleusei shows a loss in mtDNA diversity in relation to nuDNA. Morphological analyses differentiate both species according to size and shape but also discriminate strong seasonal and sexual traits and a geographical phenotype segregation in L. tityrus. Finally, updated distribution and its modelling for current and glacial timeframes reveal both species respond differently to environmental variables, defining a mostly parapatric distribution and an overlapping belt where sympatry was recovered. During the last glacial maximum, a wider expansion in L. bleusei distribution explains current isolated populations. Our study highlights the importance of gathering several lines of evidence when deciphering the relationships between closely related populations in the fringe of cryptic species realm.

A broader theory of cooperation can better explain "purity".

Self-control provides one cooperative explanation for "purity." Other types of cooperation provide additional explanations. For example, individuals compete for status by displaying high-value social and sexual traits, which are moralised because they reduce the mutual costs of conflict. As this theory predicts, sexually unattractive traits are perceived as morally bad, aside from self-control. Moral psychology will advance more quickly by drawing on all theories of cooperation.

PROGNOSTIC VALUE OF PHYSIOLOGICAL PARAMETERS IN EQUINE COLIC PATIENTS

The article describes the results of a study of 46 heads of horses with colic syndrome at the veterinary clinic of the Lithuanian University of Medical Sciences in the period from 2016 to 2018. Upon arrival, anamnesis, condition of horses and duration of colic syndrome were recorded. During the clinical exami¬nation, 9 physiological parameters were recorded: temperature, heart rate, capillary filling time, mucosal color, respiratory rate, gastrointestinal noises, gastric reflux, digital pulse and volume of packed cells. All animals were divided into 2 groups: survivors and non-survivors. After that, the 9 physiological parameters described above were compared in two groups to determine their significant prognostic value for the survival of horses. Nine variables were used in the Cox proportional risk model. The odds ratio and the corresponding confidence interval were obtained. The paper shows the results of the survival rate of horses, taking into account the sexual trait. The causes of the appearance of colic syndrome are analyzed. The most important physiological parameters in relation to the appearance, course and completion of colic syndrome have been identified.

Divergence of a speciation trait through artificial selection: Insights into constraints, by-product effects and sexual isolation.

Speciation and sexual isolation often occur when divergent female mating preferences target male secondary sexual traits. Despite the importance of such male signals, little is known about their evolvability and genetic linkage to other traits during speciation. To answer these questions, we imposed divergent artificial selection for 10 non-overlapping generations on the Inter-Pulse-Interval (IPI) of male courtship songs; which has been previously shown to be a major species recognition trait for females in the Drosophila athabasca species complex. Focusing on one of the species, Drosophila mahican (previously known as EA race), we examined IPI's: (1) rate of divergence, (2) response to selection in different directions, (3) genetic architecture of divergence and (4) by-product effects on other traits that have diverged in the species complex. We found rapid and consistent response for higher IPI but less response to lower IPI; implying asymmetrical constraints. Genetic divergence in IPI differed from natural species in X versus autosome contribution and in dominance, suggesting that evolution may take different paths. Finally, selection on IPI did not alter other components of male songs, or other ecological traits, and did not cause divergence in female preferences, as evidenced by lack of sexual isolation. This suggests that divergence of male courtship song IPI is unconstrained by genetic linkage with other traits in this system. This lack of linkage between male signals and other traits implies that female preferences or ecological selection can co-opt and mould specific male signals for species recognition free of genetic constraints from other traits.