Relationships between male secondary sexual traits, physiological state and offspring viability in the three-spined stickleback

Background Sexual signals produced by males play a central role in sexual selection, but the relationship between these traits and the quality of the bearer are often ambiguous. Secondary sexual traits may represent genetic quality of the bearer, resulting in positive relationships with physiological state, or may be costly to produce, showing trade-off with physiological state. A number of studies have explored the relationships between secondary sexual traits and other functional traits, but few have studied their fitness consequences. We studied the link between diverse physiological traits and both morphological and behavioural sexual traits and examined how their interplay influences offspring viability in the three-spined stickleback. Results Male sticklebacks showing nest building and courtship behaviour were smaller than those not investing in reproductive activities. There was no evidence that the expression of red nuptial colouration and the quality of courtship behaviour of males are positively related to their metabolic rates, swim ability, oxidative damage and mtDNA copy number. However, individuals showing larger red nuptial colour areas had higher levels of oxidative DNA damage in their sperm. Male courtship behaviour and aggressiveness, but not red colour area, were good predictors of offspring hatching and survival. Conclusions Our results suggest that, in our study population at the southern edge of the species’ distribution, sexual colouration of male sticklebacks was not a good indicator of their body state, but both courtship quality and aggressiveness during the courtship are reliable cues of their gamete quality, influencing the viability of their offspring. Thus, females that choose mates based on their courtship behaviour will have high fitness. In the study population, which represents a fast pace-of-life with high reproductive rate and short lifespan, sexual ornaments of males may not honestly signal their physiological and physical state because they invest at maximum in a single reproductive season despite high costs.

Rare benign tumor in a prepubescent accessory breast: a case report

Background Polymastia or accessory breast is a congenital condition seen in 1% of the population at birth and in 2–6% of the female population. The most common presentation is in the pubertal age group when secondary sexual characters begin to develop or during pregnancy and lactation. Giant cell fibroblastoma is an exceedingly rare benign soft tissue neoplasm in the pediatric age group, usually seen over the back and thigh. We report a case of giant cell fibroblastoma in accessory breast tissue in a 4-year-old, female child. This case is rare in its presentation at the age of 4 years with an enlarging accessory breast without any secondary sexual characters. Giant cell fibroblastoma in the accessory breast tissue is unreported yet. Case presentation A 4-year-old female child presented with a progressively enlarging accessory breast. A wide local excision of the accessory breast with underlying growth was done. The histopathological examination revealed a giant cell fibroblastoma within the breast tissue. Conclusions Enlargement of an accessory or normal breast at a prepubescent age with the absence of secondary sexual characters should arouse suspicion of benign tumors in the breast tissue.

Intersexual and intrasexual selection for neck musculature in men: Attractiveness, dominance, and actual fighting success

Countless organisms are equipped with physiological armor that reduce damage from opponents. Because humans have sustained a long evolutionary history of hand-to-hand combat, selection would have been placed on morphological structures which reduce rotational acceleration to the head and increase the likelihood of victory. Grounded in over 60 years of sports performance theory and recent theoretical work in evolutionary biology, geometric morphometric analyses revealed that larger neck musculature in professional combatants (N = 715) was associated with greater real-world fighting success, after for adjusting for allometry (Study 1). Because sexual dimorphism emerges from selection on morphological structures that improve men’s fighting success, we then discovered that the human neck is the most sexually dimorphic feature of human anatomy when compared to 91 other anatomical features (N = 6,068; Study 2). This male-biased sexual dimorphism held after controlling for these 91 allometric measurements, and held across every world region (Africa, Asia, Europe, Oceania, and North, Central, and South America). Because human psychological systems consequently evolved to attend to men’s secondary sexual characteristics, we discovered that men (N = 564 stimuli) with larger neck musculature (Study 3: geometric morphometrics; Study 4: physiological neck strength; Study 5: photorealistic stimuli) are rated (N = 772 raters) as stronger, more masculine, and higher in fighting ability and short-term attractiveness, after accounting for allometry. Combined, our research introduced a new secondary sexual characteristic to the biological, anthropological, and psychological sciences: the human neck.

Polygenic sex determination produces modular sex polymorphism in an African cichlid fish

For many vertebrates, a single genetic locus initiates a cascade of developmental sex differences in the gonad and throughout the organism, resulting in adults with two, phenotypically distinct sexes. Species with polygenic sex determination (PSD) have multiple interacting sex determination alleles segregating within a single species, allowing for more than two genotypic sexes, and scenarios where sex genotype at a given locus can be decoupled from gonadal sex. Here we investigate the effects of PSD on secondary sexual characteristics in the cichlid fish Metriaclima mbenjii, where one female (W) and one male (Y) sex determination allele interact to produce siblings with four possible sex classes: ZZXX females, ZWXX females, ZWXY females, and ZZXY males. We find that PSD in M. mbenjii produces an interplay of sex-linkage and sex-limitation resulting in modular variation in morphological and behavioral traits. Further, the evolution or introgression of a novel sex determiner creates additional axes of phenotypic variation for varied traits, including genital morphology, craniofacial morphology, gastrointestinal morphology, and home tank behaviors. In contrast to single-locus sex determination, which broadly results in sexual dimorphism, polygenic sex determination can induce higher-order sexual polymorphism. The modularity of secondary sexual characteristics produced by PSD provides novel context for understanding the evolutionary causes and consequences of maintenance, gain, or loss of sex determination alleles in populations.

The Coexistence of Gonadal Dysgenesis With Mayer-rokitansky-küster-hauser Syndrome, and Dandy-Walker Variant

Background: Gonadal dysgenesis, the most common cause of primary amenorrhea, is characterized by absent or underdeveloped ovaries. Although the coexistence of gonadal dysgenesis and Mayer-Rokitansky-Küster-Hauser (MRKH) has been reported, it is still quite infrequent. To the extent that authors searched, just one study reported the association between Rokitansky sequence and Dandy-Walker malformation. Clinical Presentation and Intervention: We aimed to report a case with gonadal dysgenesis, MRKH, and the Dandy-Walker variant. In this care report, the authors reported a 15-year-old girl with primary amenorrhea and underdeveloped secondary sexual properties. Her karyotype was 46, XX. The abdominopelvic MRI without contrast demonstrated bilateral ovarian agenesis and no uterus or cervix. Vagina was normal in length. Brain MRI was consistent with the Dandy-Walker variant. Conclusion: Although some affected chromosomal regions have been identified, further genetic analyses should be performed to elucidate the probable association between these anomalies.

Ovarian inguinal hernia – a possibility in MURCS syndrome

Background Inguinal hernia containing ovary and fallopian tube can be found in paediatric population and is a rare finding in women of reproductive age group. Most of the cases are associated with congenital abnormalities of the female genital tract. Case presentation A 20 year old female presented with right reducible inguinal hernia, primary amenorrhea and normal secondary sexual characteristics. Clinical examination revealed scoliosis with convexity towards left side, prominence of left rib cage with Sprengel deformity and right sided heart sounds. Ultrasound of the inguinal swelling revealed right ovary within the hernial sac, Chest X-ray revealed right lung collapse and dextrocardia. Further Magnetic resonance imaging (MRI) of pelvis revealed inguinal hernia with right ovary as its content, normal left ovary and absent uterus. Computed tomography (CT) revealed complete collapse of right lung with compensatory left lung hyperinflation and absent right kidney. Karyotyping of the patient was normal, 46XX. A diagnosis of MURCS syndrome with right ovarian hernia was made. The hernia was surgically managed with repositioning of ovary and fallopian tube into the pelvis. Discussion Ovary in inguinal hernia is rare in women of reproductive age group. MRKH syndrome, a mullerian duct anomaly, is the congenital aplasia of uterus and upper two-thirds of vagina in a female with normal ovaries, fallopian tube, secondary sexual characteristics and 46XX karyotype. MURCS is a subtype of MRKH type 2 having mullerian duct agenesis with renal, cardiac, muscular & vertebral defects. General physical examination and primary investigations if yields abnormal findings; the patient must undergo an array of investigations to rule out MRKH/MURCS, or other congenital abnormality. Early diagnosis is essential to prevent its incarceration or torsion. The primary treatment of ovary in inguinal hernia is repositioning the ovary and fallopian tube back to pelvis to preserve fertility and repair of inguinal hernia. A multidisciplinary team is required to deal with various abnormalities present in a patient with MURCS.