Male-male Pairs Research Articles

Long-term video and genetic data yield insights into complex sociality of a solitary large carnivore

American black bears (Ursus americanus) may be more social than currently understood. We used long-term video and genetic data to evaluate social interactions among wild, independent-aged black bear on a conservation property in western Montana, USA. We used multinomial logistic regression to evaluate predictions about male-male interactions within the context of individual fitness, female-female interactions within the context of inclusive fitness, and male-female interactions within the context of female counterstrategies to infanticide. Overall, our findings challenged the assumption that independent-aged bears interact only during the mating season or when concentrated feeding sites are present. We documented 169 interaction events by at least 66 bear pairs, 92 (54%) of which occurred outside of the peak mating season and in the absence of concentrated feeding sites. The probability that male-male pairs engaged in play and other non-agonistic behaviours was higher than that for female-female pairs. Conversely, the probability that female-female pairs engaged in chase behaviour was higher than that for male-male and male-female pairs. We documented evidence of female mate choice, female resource defense, sexually selected infanticide (SSI), and female counterstrategies to avoid SSI. Our findings improve our understanding of ursid ethology and underscore the complexity of ursid sociality.

Abstract 13063: Gut Microbiota-Derived Metabolites and Cardiometabolic Traits: Findings From a Monozygotic Twin Study

Introduction: Microbial metabolites are small chemical compounds produced by gut microbiota when it breaks down food, chemicals, or other environmental exposures. These metabolites serve as signaling molecules between the host and gut microbiota and regulate numerous aspects of host physiology, immunity, and metabolism. Hypothesis: Gut dysbiosis is associated with cardiometabolic disorders via alterations in microbial metabolites. Aims: To identify gut-microbiota-derived metabolites associated with cardiometabolic traits. Methods: Using hydrophilic interaction liquid chromatography (HILIC), we measured the relative abundances of 62 food and gut-microbiota-derived metabolites in plasma sample of 46 complete monozygotic twin pairs (34 female-female pairs, 12 male-male pairs, mean age 36.2) enrolled in the Mood and Methylation Study (MMS), an observational study designed to identify biomarkers associated with depressive symptoms using a twin design. Information for cardiometabolic traits, including body mass index, waist circumference, blood glucose, HbA1c, insulin, triglycerides, total cholesterol, HDL and LDL, was collected using standard questionnaires or laboratory methods. The association of each metabolite with cardiometabolic trait was examined by a linear mixed-effects model, adjusting for age, sex, smoking, drinking, and depressive symptoms. The co-twin correlation was accounted for by including twin pair as a random effect in the model. Results: After correction for multiple testing by false discovery rate (FDR<0.05), 15 microbial metabolites were significantly associated with one or more cardiometabolic traits. Of these, 7 glycerophospholipids (e.g., PC(32:1), PC(34:4), PE(38:6)) and 2 sphingomyelins (i.e., SM(d36:1), SM(d36:2)) were positively, whereas betaine, creatinine, urea, pipecolic acid, N1, N12-diacetylspermine, and 3-chloro-L-tyrosine were negatively associated with LDL, triglycerides, total cholesterol, and HbA1c. Conclusions: Our results revealed novel microbial metabolites associated with cardiometabolic traits and support their potentially important role in mediating the interactions between gut microbiota and host pathophysiology.

A 10-Year Observational Study on Twin Pregnancy: Role of Fetal Sex Pairing on Obstetric Outcome.

Fetal sex contributes to the determination of obstetric outcome, as pregnancies carrying male babies seem to have an increased risk of maternal-fetal complications. Most studies have been conducted on singleton pregnancies, whereas less evidence is available for twins. A 10-year retrospective observational study was conducted on a cohort of 1180 women with twin pregnancy delivered at a single tertiary hospital. Clinical data on maternal characteristics, and obstetric and neonatal outcomes were collected, and the analysis was performed on monochorionic (MC) and dichorionic (DC) diamniotic twins separately. The group of DC twins included 837 cases, and those conceived by assisted reproductive technologies (ART) were more likely to have one or both female fetuses rather than males. The incidence of hypertensive disorders of pregnancy (HDP) was higher in same-sex pairs than in opposite-sex pairs. No differences were found regarding other obstetric and neonatal outcomes among the three sex-pairing groups. The MC twins group included 228 cases, and in female-carrying pregnancies a higher incidence of gestational diabetes (GDM) was observed compared to the male group. Furthermore, male pairs had significantly lower Apgar scores than females. Fetal sex seems to have a mild effect in twins compared to singleton pregnancies, suggesting a more complex set of factors contributing to pregnancy outcome in multiple pregnancies. However, we observed a higher incidence of HDP among same-sex DC pairs, a higher rate of GDM among MC female-female pairs, and a worse adaptation to extrauterine life among male-male pairs in MC twins.

Spatial-temporal clustering of an outbreak of SARS-CoV-2 Delta VOC in Guangzhou, China in 2021.

In May 2021, the SARS-CoV-2 Delta variant led to the first local outbreak in China in Guangzhou City. We explored the epidemiological characteristics and spatial-temporal clustering of this outbreak. Based on the 153 cases in the SARS-CoV-2 Delta variant outbreak, the Knox test was used to analyze the spatial-temporal clustering of the outbreak. We further explored the spatial-temporal clustering by gender and age groups, as well as compared the changes of clustering strength (S) value between the two outbreaks in Guangzhou. The result of the Knox analysis showed that the areas at short distances and brief periods presented a relatively high risk. The strength of clustering of male-male pairs was higher. Age groups showed that clustering was concentrated in cases aged ≤ 18 years matched to 18-59 years and cases aged 60+ years. The strength of clustering of the outbreak declined after the implementation of public health measures. The change of strength of clustering at time intervals of 1-5 days decreased greater in 2021 (S = 129.19, change rate 38.87%) than that in 2020 (S = 83.81, change rate 30.02%). The outbreak of SARS-CoV-2 Delta VOC in Guangzhou has obvious spatial-temporal clustering. The timely intervention measures are essential role to contain this outbreak of high transmission.

Community structure of the solitary giant pandas is maintained by indirect social connections

BackgroundIndirect interactions between individual solitary mammals, such as the giant panda, are often overlooked because of their nature, yet are important for maintaining the necessary sociality in solitary species.Methods and resultsHere, we determined the genetic identity of all giant panda individuals in a local population and matched these identities with their associations to determine social network of this solitary animal. Total thirty-five giant panda individuals were found in our field survey, and we constructed genetic and social networks for thirty-three individuals who successfully obtained genetic, age and sex information. The results showed that sex had great impact on both social network and genetic network, and age may have the potential to influence the social network of the giant pandas. Adult males, mostly in the central of the social network, which appeared significantly larger network connections than adult females. Due to the female-biased dispersal pattern of wild giant pandas, male-male pairs showed higher relatedness than female-female ones and multi-generational patrilinear assemblages are expected in the study area.ConclusionsThe relatedness of individuals has an influence on the formation of community social structure of giant pandas, and indirect interactions among solitary giant pandas potentially function to reduce competition for resources and inbreeding.

The myth of the male negotiator: Gender’s effect on negotiation strategies and outcomes

Conventional wisdom holds that women are worse negotiators than men. However, in an incentivized negotiation with explicit verbal communication, we find that women perform equally well compared to men, contrary to a control game without communication where men perform better. This is driven by men’s underperformance against male partners, and more specifically when they know their partner is male. Using chat transcripts to classify the negotiation approaches used, we show that men over-use aggressive negotiation strategies against known male partners, increasing mis-match and reducing their payoffs. Due to this, male-male pairs capture significantly less value than any other pair type. In contrast, female negotiators create joint gains without reducing their individual payoffs. Our findings suggest that verbal communication may trigger “toxic masculinity” that undoes men’s advantage in one-shot non-communication games.

Analysis of factors affecting the behaviour of both dogs during a Strange Situation Procedure (SSP) to assess intraspecific attachment

Previous studies on the dog intraspecific attachment carried out with the Strange Situation Procedure (SSP) have not been able to clarify the nature of this bond. Several factors may affect the behaviour of the dog dyads involved the procedure. In the current study, fifty-five dyads of adult dogs living in the same household participated in a SSP. The duration of fifteen behaviours was measured. Data were analysed using Generalised Linear Mixed Models considering single behaviours as dependent variables. The predictors were episodes (1, 4, and 7), type of relationship (mother-offspring pairs, non-related cohabitant pairs), sex (female-female, male-female, and male-male), and age difference. Bonferroni Holmes post hoc tests were performed to allow pairwise comparison. Dog dyads spent significantly more time trying to escape from the experimental room in episodes 1 (p = 0.008) and 4 (p = 0.029) than episode 7, in passive behaviours in episode 7 compared to episode 1 (p = 0.001), in environmental exploration in episode 1 compared to both episode 4 (p = 0.001) and 7 (p = 0.001), in proximity to each other in episode 4 and 7 compared to episode 1 (4 vs 1: p = 0.001, 7 vs 1: p = 0.001), and in locomotion in episode 1 than episodes 4 (p = 0.009) and 7 (p = 0.001), and in episode 4 compared to 7 (p = 0.007). Mother-offspring pairs spent more time in passive behaviours (p = 0.028) compared to unrelated cohabitant pairs. Male-male pairs spent more time oriented to the door/window compared to female-male (p = 0.030) and female-female pairs (p = 0.030). Finally, proximity to the conspecific decreased (p = 0.040), while locomotion increased (p = 0.027) with age difference. According to our findings, dogs involved in an intraspecific SSP seem to be primarily distressed by the initial separation from the owner. However, they may be able to use the conspecific as a buffer against stress as the test progresses. Other factors related to the subjects involved in the procedure, such as the type of relationship, sex and age difference may also affect their behaviour. Future studies should take these factors into account if they use the SSP to explore dog intraspecific attachment.

Gender differences in bargaining with asymmetric information

We conduct an experiment on gender differences in bargaining with asymmetric information. Based on Abreu and Gul (2000) , we introduce asymmetric information about commitments by inducing irrational types, who never back down from a fixed bargaining position. Bargaining behavior depends on whether gender is revealed or not. When gender is unknown, men are more likely to mimic irrational types than women, but this gender gap is eliminated when gender is known. Male-male pairs also experience longer delays than other pairs, but only when gender is revealed and only in pairs where one subject mimics the irrational type.

Molecular sexing in the formation of pairs of blue-and-yellow macaw (Ara ararauna) in reintroduction programs

Blue and yellow macaw is a species which does not show sexual dimorphism and is threatened by animal traffic. The identification of heterosexual pairs is important for reintroduction programs. The aim of this work was select parameters for sexing and use them to determine the frequency of heterosexual pairs in a population of blue-and-yellow macaws allocated in a Wild Animal Screening Center. Blood samples from 23 macaws were collected and genomic DNA extracted by Tris/SDS washes. Allele-specific molecular markers for sexing were amplified by PCR, and identified on 2% agarose gel. Three pairs of primers were tested: Pair 1 (P2/P8), Pair 2 (1237L/1272H) and Pair 3 (2550F/2718R). For the determination of animal pairs, all individuals had their social behavioral acts observed. The results showed that the low complexity DNA extraction protocol used was adequate. Pairs 2 and 3 of primers were effective for sexing and the Pair 3 was the most efficient. The study also showed that in the sample studied, the composition of males and females was similar (0.4 males n=10 and 0.6 females n=13); 70% (n=16) of the individuals formed pairs and 75% (n=12) of the pairs were heterosexual and the others male-male or female-female pairs. These results were used in the management of the animals in the reintroduction program.

Effects of dominance and female presence on secondary sexual characteristics in male tufted capuchin monkeys (Sapajus apella).

Alpha status may lead to physiological changes that enhance secondary sexual characteristics, which may serve as competitive signals to conspecific males, sexual signals to females, or possibly a combination of both. Here, we report measurements of secondary sexual characteristics in captive dominant and subordinate male tufted capuchin monkeys (Sapajus apella) with varying access to females. An adult male (who had previously been subordinate while housed with other males) was paired with an adult female. This male–female pair was introduced into a room that housed three other male–male pairs with stable hierarchy arrangements. We analyzed weight, body measurements, facial photographs, and hair cortisol before, during, and after introducing a female into the room. While there were no differences in weight or measurements between alphas and subordinates without physical access to the female prior to or during the female's presence, we found that direct access to the female resulted in dramatic changes in facial appearance, body size, and testicular volume in the male who was paired with her. Overall, we found little evidence to suggest that alpha males advertise their status within all‐male groups via sexual secondary characteristics. However, direct physical access to females appears to trigger the development of such characteristics in alpha males. It remains of continued interest to identify the endocrine mechanisms responsible for the development, and possible loss, of secondary sexual characteristics.

Neonatal outcomes of extremely preterm twins by sex pairing: an international cohort study

ObjectiveInfant boys have worse outcomes than girls. In twins, the ‘male disadvantage’ has been reported to extend to female co-twins via a ‘masculinising’ effect. We studied the association between sex...

Individual, but not population asymmetries, are modulated by social environment and genotype in Drosophila melanogaster

Theory predicts that social interactions can induce an alignment of behavioral asymmetries between individuals (i.e., population-level lateralization), but evidence for this effect is mixed. To understand how interaction with other individuals affects behavioral asymmetries, we systematically manipulated the social environment of Drosophila melanogaster, testing individual flies and dyads (female-male, female-female and male-male pairs). In these social contexts we measured individual and population asymmetries in individual behaviors (circling asymmetry, wing use) and dyadic behaviors (relative position and orientation between two flies) in five different genotypes. We reasoned that if coordination between individuals drives alignment of behavioral asymmetries, greater alignment at the population-level should be observed in social contexts compared to solitary individuals. We observed that the presence of other individuals influenced the behavior and position of flies but had unexpected effects on individual and population asymmetries: individual-level asymmetries were strong and modulated by the social context but population-level asymmetries were mild or absent. Moreover, the strength of individual-level asymmetries differed between strains, but this was not the case for population-level asymmetries. These findings suggest that the degree of social interaction found in Drosophila is insufficient to drive population-level behavioral asymmetries.

Size Does Not Matter: Same-Sex Sexual Behavior Occurred Regardless of Mandible Size in Male Stag Beetle Aegus chelifer chelifer (Coleoptera: Lucanidae)

Male Aegus chelifer chelifer stag beetles are normally equipped with long mandibles as a weapon to compete with rival males over females, where fighting or aggressive behavior is generally expected during the encounter between two male stag beetles. However, three main patterns were observed between 164 pairings of male stag beetles. Besides the predominant aggressive or fighting behavior (107 pairings), male stag beetles also exhibited disregarding behavior (29 pairings) and same-sex sexual behavior (28 pairings). For sexual interactions, active males exhibited courting and mating behavior as found in male-female interactions, but the insemination process was unsuccessful. Responses of passive males varied from totally passive to resisting and running away. Visual confusion of short-mandible males for females by active males was not likely to be responsible for the same-sex sexual behavior because the correlation between body size and the sexual behavior or sexual role between male-male pairs was not significant. Rather, sexual recognition via chemicals on the cuticle surface might be responsible for the same-sex sexual behavior.

Factors Associated With Human Immunodeficiency Virus Infections Linked in Genetic Clusters But Disconnected in Partner Tracing.

Successful partner notification can improve community-level outcomes by increasing the proportion of persons living with human immunodeficiency virus (HIV) who are linked to HIV care and virally suppressed, but it is resource intensive. Understanding where HIV transmission pathways may be undetected by routine partner notification may help improve case finding strategies. We combined partner notification interview and HIV sequence data for persons diagnosed with HIV in Wake County, NC in 2012 to 2013 to evaluate partner contact networks among persons with HIV pol gene sequences 2% or less pairwise genetic distance. We applied a set of multivariable generalized estimating equations to identify correlates of disparate membership in genetic versus partner contact networks. In the multivariable model, being in a male-male pair (adjusted odds ratio [AOR], 16.7; P = 0.01), chronic HIV infection status (AOR, 4.5; P < 0.01), and increasing percent genetic distance between each dyad member's HIV pol gene sequence (AOR, 8.3 per each 1% increase, P < 0.01) were all associated with persons with HIV clustering but not being identified in the partner notification network component. Having anonymous partners or other factors typically associated with risk behavior were not associated. Based on genetic networks, partnerships which may be stigmatized, may have occurred farther back in time or may have an intervening partner were more likely to be unobserved in the partner contact network. The HIV genetic cluster information contributes to public health understanding of HIV transmission networks in these settings where partner identifying information is not available.

Dietary Supplementation With the Ketogenic Diet Metabolite Beta-Hydroxybutyrate Ameliorates Post-TBI Aggression in Young-Adult Male Drosophila.

Traumatic brain injury (TBI), caused by repeated concussive head trauma can induce chronic traumatic encephalopathy (CTE), a neurodegenerative disease featuring behavioral symptoms ranging from cognitive deficits to elevated aggression. In a Drosophila model, we used a high-impact trauma device (Katzenberger et al., 2013, 2015) to induce TBI-like symptoms and to study post-TBI behavioral outcomes. Following TBI, aggression in banged male flies was significantly elevated as compared with that in unbanged flies. These increases in aggressive behavior were not the result of basal motility changes, as measured by a negative geotaxis assay. In addition, the increase in post-TBI aggression appeared to be specific to concussive trauma: neither cold exposure nor electric shock—two alternate types of trauma—significantly elevated aggressive behavior in male-male pairs. Various forms of dietary therapy, especially the high-fat, low-carbohydrate ketogenic diet (KD), have recently been explored for a wide variety of neuropathies. We thus hypothesized that putatively neuroprotective dietary interventions might be able to suppress post-traumatic elevations in aggressive behavior in animals subjected to head-trauma-inducing strikes, or “bangs”. We supplemented a normal high-carbohydrate Drosophila diet with the KD metabolite beta-hydroxybutyrate (β-HB)—a ketone body (KB). Banged flies raised on a KB-supplemented diet exhibited a marked reduction in aggression, whereas aggression in unbanged flies was equivalent whether dieted with KB supplements or not. Pharmacological blockade of the ATP-sensitive potassium (KATP) channel abrogated KB effects reducing post-TBI aggression while pharmacological activation mimicked them, suggesting a mechanism by which KBs act in this model. KBs did not significantly extend lifespan in banged flies, but markedly extended lifespan in unbanged flies. We have thus developed a functional model for the study of post-TBI elevations of aggression. Further, we conclude that dietary interventions may be a fruitful avenue for further exploration of treatments for TBI- and CTE-related cognitive-behavioral symptoms.

A Contagion Model for Within-Family Transmission of Drug Abuse.

The purpose of this study was to determine whether, controlling for genetic effects, drug abuse was transmitted within families as predicted by a contagion model. The authors examined 65,006 parent-offspring, sibling, and cousin pairs ascertained from Swedish population registries in which the primary case subject had a drug abuse registration. The rate of drug abuse registration among at-risk secondary case subjects ages 19-23 was studied. Utilizing matched control pairs, a difference-in-difference approach was used to infer causal effects. In offspring, risk for drug abuse registration in the 3 years after an index registration of a parent residing in the same household, neighborhood, or municipality increased 5.9%, 3.4%, and 1.8%, respectively. For siblings of sibling index case subjects, parallel results were 5.9%, 3.9%, and 1.2%. For cousins of cousin index case subjects, excess risk for those in the same neighborhood or municipality was 2.9% and 0.9%, respectively. In all sets of relatives, drug abuse transmission was strongest in male-male pairs and in pairs closest in age. In sibling pairs, stronger transmission was observed in older to younger siblings compared with younger to older siblings. Transmission was stronger within than across the two drug classes with sufficient data (opiates and cannabis). These results suggest that drug abuse can be transmitted within families by an environmentally mediated temporally defined model of contagion. The most important methodological limitation is that drug abuse registration is an inaccurate measure of the onset of drug abuse. Indeed, as predicted, drug abuse risk increased among potential secondary case subjects in the year before drug abuse registration of the index case subject.

Is there a relationship between fetal sex and placental pathological characteristics in twin gestations?

BackgroundPlacenta plays a central role in mediating growth and development of fetuses. Sex-specific placentas may complicate this role.MethodsThe study aimed at investigating the association between fetal sex and placental pathological findings in twin gestations using generalized estimating equation modeling. We used a large population-based clinical data born in British Columbia (BC) and linked the fetal-maternal data to hand-searched pathology reports of 1493 twin placentas from twins born in BC Women hospital. We analyzed the data using generalized estimating equations taking the cluster nature of twins into consideration.ResultsAbout 26.5% of twins were monochorionic and 73.5% were dizygotic. Most twins were male (51.3%). About 2/3 of twins were sex concordant (66.6%). Of the sex concordant twins, similar percentages were male-male (34.7%) and female-female (31.2%). Of the sex discordant twins, the male-female (33.3%) group constituted about 1/3 of the whole population.Adjusted for chorionicity, birth weight discordance ≥30% and gestational age, the odds of chorionitis (1.38, 95% CI = 1.04–1.84), anastomosis (1.63, 95% CI = 1.22–2.19), unequal sharing of placenta (1.72, 95% CI = 1.11–2.64), placental inflammation (1.30, 95% CI = 1.05–1.62) and lesions (1.83, 95% CI = 1.02–3.31) were higher in male twins compared with females. Twins of either sex from sex-discordant pairs were less likely to have placental anastomosis compared to the reference category. Males from male-male pairs had higher odds of unequal placental sharing (74% higher) and composite inflammation (52% higher) compared with the reference twins.ConclusionOur findings suggest a relationship between sex and placental pathological results.

Vocalizations of North American river otters (Lontra canadensis) in two human care populations

There is a dearth of information regarding the vocal repertoire of North American river otters (Lontra canadensis). This indicator species is cosmopolitan yet elusive, making recordings methodologically difficult in the wild. Therefore, this exploratory study uses video and audio recordings of two populations of North American river otters in human care to broaden the known vocal repertoire of river otters in various social contexts. The populations consist of a male-female and a male-male pair. This study is the first to examine the vocalizations produced in a male-male pair of river otters. Call types were acoustically distinguished based on their appearance on a spectrogram. Parameters including average duration, frequency (high, low, max, 1st quarter, center, and 3rd quarter), and power (max and average) were measured for each call. Because vocalizations are the focal point of this study, only behaviors co-occurring with vocalizations were included in the chi square analysis that showed a significant relationship between call type and behavior. Squeaks and whines were present during agonistic behaviors while chirps were produced during non-agonistic behaviors including investigating, stationary, and grooming. Results support that behavior likely plays a role in the type of calls produced by river otters in human care.

The bone collector: temporal patterns of bone-gnawing behaviour define osteophagia as a female prerogative in a large rodent

Calcium and phosphorous consumption is essential for bone development and maintenance throughout life, particularly to pregnant and lactating females. Bone consumption may provide mothers with the required supplemental amount of calcium and phosphorous. Osteophagia has been reported in a number of herbivore species as supplying such key mineral elements, although sound evidence is lacking for rodents. The diet of the crested porcupine is vegetarian and predominantly composed by roots and hypogeal storage organs. Gnawed bone residuals have often been observed in the surroundings of porcupine setts. This behaviour may have evolved to reduce the indefinite growth of incisor teeth, to increase calcium and phosphorous supply, or to fulfil both these functions. To clarify this issue, five setts were monitored for 3 years and bones in front of sett entries were counted and collected once a month. A total of 63 bones (mainly femurs and shins: 38.8%) was detected, mainly belonging to wild (46.03%) and domestic (28.57%) ungulates. The presence of gnawed bones in front of sett entries was recorded throughout the year, with a peak at the start of February. Camera-trapping data confirmed that areas surroundings house-farms, where most bones were probably collected, were only selected in the cold season. The peak of gnawed bone detection overlapped with the birth peak, suggesting that bones may be consumed by lactating females to increase the amount of minerals in their diet. This suggestion was further confirmed by the detection of no gnawed bones in front of the sett of the male-male pair. Porcupines are known to collect and gnaw bones in the surroundings of their setts, but ecological explanations and temporal patterns of this behaviour are unknown. We monitored five setts for 3 years, measuring and identifying gnawed bones in front of sett entries once a month. We then conducted an intensive camera-trapping session to monitor areas surrounding house-farms. Bone collection occurred throughout the year, with a peak in February, coinciding with the birth peak of this species. We therefore suggested that bone consumption could be a female prerogative, related to a supply of minerals in diet, as no gnawed bone was observed at the sett of a male-male pair.

Male-male pair bonding, nesting and egg incubation in a wild passerine

Examples of nesting behavior between pair-bonded males are exceedingly rare among songbirds. We observed a male same-sex pair bond that resulted in the partial development of one egg while monitoring the breeding activity of a population of wild Crimson Finches (Neochima phaeton) over four breeding seasons. This male–male pair built four nests and incubated two clutches, each with a single egg of unknown origin, with at least one developing partially before failing. This same-sex behavior is unusual among passerines and its origin and evolutionary significance remain poorly understood.