A sexually transmitted sugar orchestrates reproductive responses to nutritional stress.

Seminal fluid is rich in sugars, but their role beyond supporting sperm motility is unknown. In this study, we found Drosophila melanogaster males transfer a substantial amount of a phospho-galactoside to females during mating, but only half as much when undernourished. This seminal substance, which we named venerose, induces an increase in germline stem cells (GSCs) and promotes sperm storage in females, especially undernourished ones. Venerose enters the hemolymph and directly activates nutrient-sensing Dh44+ neurons in the brain. Food deprivation directs the nutrient-sensing neurons to secrete more of the neuropeptide Dh44 in response to infused venerose. The secreted Dh44 then enhances the local niche signal, stimulating GSC proliferation. It also extends the retention of ejaculate by females, resulting in greater venerose absorption and increased sperm storage. In this study, we uncovered the role of a sugar-like seminal substance produced by males that coordinates reproductive responses to nutritional challenges in females.

Male humpback whales switch to singing in the presence of seismic air guns.

Ocean noise produced by seismic exploration has been implicated in causing changes in baleen whale hearing, physiology, feeding, breeding, and migratory behaviours. Here, we observed changes in the mating tactics of humpback whales (Megaptera novaeangliae) during a one-hour exposure to nearby seismic air guns. Males employ a conditional mating strategy where they switch between singing and non-singing tactics. Singing is presumably an advertisement signal, while non-singing behaviours include seeking out and joining with females as well as forming competitive groups. During periods of active air guns, the number of male singing whales increased, and singers were more likely to be observed joining females. Conversely, non-singing males were less likely to engage in joining interactions suggesting that active air guns caused a switch in male breeding tactics. Though we cannot translate these effects into changes in breeding success, this indicates that seismic exploration has the potential to alter breeding behaviours in baleen whales.

Fruit resources shape sexual selection processes in a lek mating system.

The degree to which within-population variation in sexual trait expression relates to resource heterogeneity remains poorly explored. This is particularly true in lek-mating species, where genetic explanations for male phenotypic variance and mating success are dominant. Here, we demonstrate a link between fine-scale fruit resource availability and indices of male mating success in the white-bearded manakin (Manacus manacus), a lek-mating frugivorous bird that produces energetically costly courtship displays. We used motion-activated camera traps to monitor male display behaviour and female visitation at male courts while concurrently conducting twice-monthly fruit surveys around courts. We observed significant variability in ripe fruit biomass among display courts and leks, and mean fruit biomass at courts significantly predicted male display rates. In turn, male display rate was the strongest predictor of female visitation to courts. Causal modelling supported the hypothesis that hyper-local fruit availability indirectly affects female visitation via its direct effects on male display rate. The demonstration that resource availability at fine spatial scales predicts display rate in a lekking organism-for which resource-related variables are typically not considered to play important roles in shaping male reproductive variance-has implications for the expression, honesty and maintenance of sexually selected traits under fluctuating ecological conditions.

Mathematical Modeling of Mating Probability and Fertile Egg Production in Helminth Parasites.

In this work, we obtained a general formulation for the mating probability and fertile egg production in helminth parasites, focusing on the reproductive behavior of polygamous parasites and its implications for transmission dynamics. By exploring various reproductive variables in parasites with density-dependent fecundity, such as helminth parasites, we departed from the traditional assumptions of Poisson and negative binomial distributions to adopt an arbitrary distribution model. Our analysis considered critical factors such as mating probability, fertile egg production, and the distribution of female and male parasites among hosts, whether they are distributed together or separately. We show that the distribution of parasites within hosts significantly influences transmission dynamics, with implications for parasite persistence and, therefore, with implications in parasite control. Using statistical models and empirical data from Monte Carlo simulations, we provide insights into the complex interplay of reproductive variables in helminth parasites, enhancing our understanding of parasite dynamics and the transmission of parasitic diseases.

Paternity success for resident and non-resident males and their influences on paternal sibling cohorts in Japanese macaques (Macaca fuscata) on Shodoshima Island.

Reproductive success can be attributed to both resident and non-resident males in non-human primates. However, reproductive success of non-resident males has rarely been investigated at an individual level. As resident males achieve different degree of reproductive success with regard to various factors, such as male dominance relationships or female mate choice, the degree of reproductive success for non-resident males may vary between individuals. As male reproductive success is highly skewed towards specific individuals, the percentage of similar-aged paternal siblings within groups is expected to increase. However, the extent to which each male contributes to the production of cohorts of paternal siblings remains unclear. Here we examined the paternity of offspring born over five consecutive years in a free-ranging group of Japanese macaques Macaca fuscata on Shodoshima Island, Kagawa Prefecture. Genotypes of 87 individuals at 16 autosomal microsatellite loci were analyzed and paternity of 34 offspring was successfully assigned to a single candidate father. We quantitatively assessed paternity success for resident and a few non-resident males whose genetic samples were successfully collected. We quantitatively assessed the percentages of paternal siblings in the same age cohorts produced by those males. Non-resident males sired similar percentage of offspring compared to resident males. A large prime-aged non-resident male was the most successful sire among males in two of the five years. These results provide new insights that male reproductive success could be highly skewed toward a specific non-resident male. Subadult males had a lower percentage of paternity success, which may be because females may prefer physically mature males. Various males, including non-resident males, contributed to the creation of paternal sibling in the same age cohort. The overall results highlighted that not only resident but also non-resident males play an important role in shaping within-group kin structures.

Multimodal sexual signals are not precise indicators of fertility in female Kinda baboons.

Female fertility signals are found across taxa, and the precision of such signals may be influenced by the relative strength of different sexual selection mechanisms. Among primates, more precise signals may be found in species with stronger direct male-male competition and indirect female mate choice, and less precise signals in species with stronger indirect male-male competition (e.g. sperm competition) and direct female mate choice. We tested this hypothesis in a wild population of Kinda baboons in Zambia, combining data on female signals with reproductive hormones (estrogen and progesterone metabolites) and intra- and inter-cycle fertility. We predicted that Kinda baboons will exhibit less precise fertility signals than other baboon species, as they experience weaker direct and stronger indirect male-male competition. The frequency of copulation calls and proceptive behavior did not vary with hormones or intra- or inter-cycle fertility in almost all models. Sexual swelling size was predicted by the ratio of estrogen to progesterone metabolites, and was largest in the fertile phase, but differences in size across days were small. Additionally, there was variability in the timing of ovulation relative to the day of sexual swelling detumescence across cycles and swelling size did not vary with inter-cycle fertility. Our results suggest that female Kinda baboon sexual swellings are less precise indicators of fertility compared to other baboon species, while signals in other modalities do not reflect variation in intra- and inter-cycle fertility. Female Kinda baboon sexual signals may have evolved as a strategy to reduce male monopolizability, allowing for more female control over reproduction by direct mate choice.

Hot males: thermal biology of males and females during coercive mating in water striders Gerris lacustris.

Sexual conflict theory predicts that males that adopt coercive mating strategies impose costs to females during copulation. Nevertheless, conflicting mating strategies may also affect males, although such effects on males are often neglected in the literature. Here, we seek to understand whether male water striders (Gerris lacustris) experience higher body temperatures than females during coercive mating behavior. We we explored whether the water temperature affected male and female body temperature differently, considering that water contact by females might serve as a thermal regulator. We built generalized linear mixed models considering the male and female temperature as the dependent variables. Air temperature (as a proxy for solar radiation), water temperature, and sex were used as predictor variables. Our results suggest that males are warmer than females, and despite females coming into contact with water during skimming, this contact does not significantly contribute to lowering their body temperature or improving thermoregulation under the observed conditions. These findings provide novel insights into the thermal biology of water striders. Future studies should focus on addressing whether warmer temperatures confer some advantages to males, such as increased mobility and better ability to hold onto females or impose physiological constraints and fitness costs.

A roadmap for multiple paternity research with sea turtles.

There have been multiple paternity studies across many taxa, including birds, reptiles and insects, for many decades. Sea turtles are by far the most studied of any group of reptiles with up to ten fathers recorded for a clutch and multiple paternity in over 90% of clutches in some populations. Whether multiple paternity has any adaptive significance remains a key question in sea turtles, since the impact of environmental conditions often seems to swamp any impact of the incidence of multiple paternity. Climate warming and the resulting threat of feminisation of sea turtle populations is set to provide an intense new focus for studies. If male turtles become increasingly scarce as a result of warming incubation temperatures, then management intervention will be needed to promote male hatchling production. Multiple paternity studies may help inform when intervention is needed, with the expectation that the incidence of multiple paternity will decline as breeding males become scarce.

Reprint: A Review of Patterns of Multiple Paternity Across Sea Turtle Rookeries.

Why females would mate with multiple partners and have multiple fathers for clutches or litters is a long-standing enigma. There is a broad dichotomy in hypotheses ranging from polyandry having benefits to simply being an unavoidable consequence of a high incidence of male-female encounters. If females simply give in to mating when it is too costly to avoid being harassed by males (convenience polyandry), then there should be a higher rate of mating as density increases. However, if females actively seek males because they benefit from multiple mating, then mating frequency, and consequently the incidence of multiple paternity of clutches, should be high throughout. To explore these competing explanations, here we review the incidence of multiple paternity for sea turtles nesting around the World. Across 30 rookeries, including all 7 species of sea turtle, the incidence of multiple paternity was only weakly linked to rookery size (r2=0.14). However, using high resolution at-sea GPS tracking we show that the specifics of movement patterns play a key role in driving packing density and hence the likely rate of male-female encounters. When individuals use the same focal areas, packing density could be 100× greater than when assuming individuals move independently. Once the extent of adult movements in the breeding season was considered so that movements and abundance could be combined to produce a measure of density, then across rookeries we found a very tight relationship (r2=0.96) between packing density and the incidence of multiple paternity. These findings suggest that multiple paternity in sea turtles may have no benefit, but is simply a consequence of the incidence of male-female encounters.

External morphometric and microscopic analysis of the reproductive system in in- vitro reared stingless bee queens, Heterotrigona itama, and their mating frequency.

Stingless bees, prevalent in tropical and subtropical regions, are a tribe of eusocial bees that are crucial pollinators for economic crops and native plants and, produce honey and pollen. However, colony expansion is limited by a shortage of queens for new colonies. Therefore, mass artificial rearing of virgin queens could address this in commercially managed meliponiculture. Furthermore, the in vitro rearing of queen stingless bees can improve meliponiculture management and conservation efforts. Herein, we explored the efficacy of in vitro queen rearing for Heterotrigona itama, assessing the queen's body size, reproductive organ size (ovary and spermatheca), acceptance rate into new, small colonies, and mating frequency. H. itama larvae developed into queens when fed with 120 µL-150 µL of larval food, resulting in in vitro queens having body sizes similar to those of naturally produced queens. Microscopic analysis revealed well-developed ovaries and spermathecae in in vitro-reared queens, unlike the smaller ovaries and the absence of spermathecae in the naturally produced workers. Acceptance of in vitro-reared queens was independent of worker age, and mating frequency was low but not significantly different from naturally produced queens. These findings could enhance stingless beekeeping practices and conservation efforts for the native stingless bee species.

Male crickets in poor condition engage in less same-sex sexual behavior.

Same-sex sexual behavior (SSB) is widespread among animals and is often treated as an evolutionary anomaly or mistake. An alternative view is that SSB occurs because individuals have broader or more permissive "mating filters." A broader filter means directing courtship toward anything that resembles a potential mate, while a narrower filter means having stricter criteria about when to court. Broader filters help ensure animals do not miss out on mating opportunities. However, it may be advantageous for individuals to narrow their mating filters under some conditions, such as when the costs of courtship increase because courting individuals are in poor condition. We examined whether mating filters, and the expression of SSB, is condition dependent in the Pacific field cricket (Teleogryllus oceanicus). When males were in poor condition (because they were reared on a poor diet), they courted other males less. However, condition did not influence courtship toward females. This finding provides evidence that animals can decrease their expression of SSB by flexibly narrowing their mating filters when in poor condition. Our results demonstrate the benefits of a mating filters approach to studying SSB-rather than being a mistake or an anomaly in need of special explanation, SSB may be better viewed as a consequence of flexible, condition-dependent changes in mating behavior. Such an approach can be applied to other contexts where behavior is directed toward unintended targets. We emphasize that our results, like other studies of SSB in nonhuman animals, tell us nothing about sexual identities in humans.

Movement decisions driving metapopulation connectivity respond to social resources in a long-lived ungulate, bighorn sheep (Ovis canadensis).

The spatial availability of social resources is speculated to structure animal movement decisions, but the effects of social resources on animal movements are difficult to identify because social resources are rarely measured. Here, we assessed whether varying availability of a key social resource-access to receptive mates-produces predictable changes in movement decisions among bighorn sheep in Nevada, the United States. We compared the probability that males made long-distance 'foray' movements, a critical driver of connectivity, across three ecoregions with varying temporal duration of a socially mediated factor, breeding season. We used a hidden Markov model to identify foray events and then quantified the effects of social covariates on the probability of foray using a discrete choice model. We found that males engaged in forays at higher rates when the breeding season was short, suggesting that males were most responsive to the social resource when its existence was short lived. During the breeding season, males altered their response to social covariates, relative to the non-breeding season, though patterns varied, and age was associated with increased foray probability. Our results suggest that animals respond to the temporal availability of social resources when making the long-distance movements that drive connectivity. This article is part of the theme issue 'The spatial-social interface: a theoretical and empirical integration'.

No evidence for an up-regulation of female immune function in response to elevated risk of sexual conflict.

Sexual conflict is widespread among sexually reproducing organisms. Phenotypic plasticity in female resistance traits has the potential to moderate the harm imposed by males during mating, yet female plasticity has rarely been explored. In this experiment, we investigated whether female seed beetles invest more in immunocompetence, measured as phenoloxidase (PO) capacity, when exposed to cues signalling a greater risk of sexual conflict. Risk perception was manipulated by housing focal individuals alone or with a companion as developing larvae, followed by exposure to a mating-free male- or female-biased social environment when adults. We predicted that females exposed to cues of increased sexual conflict would have increased PO capacity. However, PO capacity did not differ between either larval or adult social treatments. Our results suggest that females may not perceive a risk to their fitness on the basis of increased male presence or are unable to adjust this aspect of their phenotype in response to that risk.

No evidence for population-level benefits of polyandry in sharks and rays.

Mating system variation refers to the spectrum between genetic monogamy and polyandry, and has important consequences for sexual conflict, sexual selection and individual fitness in animals. Theoretically this variation could also have substantial population-level effects, influencing population viability and extinction risk. Evidence for these effects is mixed, in part due to the fact that substantial environmental change is thought to be required for them to have visible demographic consequences. In this study we test for the presence of relationships between polyandry and population status in Elasmobranchii (sharks and rays). Elasmobranchii is a large vertebrate clade that exhibits substantial interspecific variation in both genetic mating system and population status, as well as being subject to intense anthropogenically-mediated environmental change. We also predict past macroevolutionary shifts in genetic mating system through elasmobranch phylogeny. Our results show that both genetic monogamy and polyandry have evolved multiple times independently within Elasmobranchii, and we suggest that both of these extremes represent alternative adaptive strategies that are favoured under discrete ecological and biological conditions. Nevertheless, there is no evidence of population-level consequences of mating system variation in elasmobranchs. These results are significant as they suggest that mating system variation in this clade is unlikely to be a major determinant of extinction vulnerability. Ultimately additional work will be required, however this study improves our understanding of the evolutionary dynamics underlying mating system variation in elasmobranchs, and the potential for resultant population-level consequences.

Poweromin X Ten, a polyherbal formulation improves male sexual function: In vivo and network pharmacology study.

Introduction: Poweromin X Ten (PXT) is a polyherbal formulation, traditionally used to enhance male sexual function. However, the safety and benefits of PXT have not been scientifically evaluated. Therefore, the present study investigated the toxicity and aphrodisiac potential of PXT in male rats and explored its principal mechanisms of action. Methods: Male Wistar rats were orally administered PXT (50 or 100 mg/kg) for 28 days, and sexual activity parameters, including latency and frequency of mounting and intromissions, were studied. The reproductive toxicity and spermatogenic potential were also examined. Furthermore, dopamine and serotonin levels in brain regions associated with sexual activity were assessed. Network analysis was used to identify the key bioactive compounds and their core targets involved in their beneficial actions. Results: Treatment with PXT improved sexual activity in male rats, as evidenced by reduced mounting and intromission latency and a significant increase in mount frequency. Moreover, PXT exhibited spermatogenic potential and did not induce reproductive toxicity. Notably, treatment with 50 mg/kg PXT elevated dopamine levels in median preoptic area and hypothalamus. Pathway analysis indicated that PXT primarily modulated the PI3K-Akt, calcium, and MAPK signalling pathways to enhance male sexual function. Network analysis identified macelignan, ß-estradiol, testosterone, and paniculatine as key bioactive components of PXT, which likely act through core targets, such as androgen receptor (AR), Mitogen-activated protein kinase 3 (MAPK3), epidermal growth factor receptor (EGFR), estrogen receptor 1 (ESR1), and vascular endothelial growth factor (VEGF) to facilitate the improvement of male sexual function. Conclusion: Study results suggest that PXT is a safer alternative with aphrodisiac and spermatogenic potential. These effects are partly attributed to the enhanced dopamine levels in the brain. Furthermore, this study provides insights into the specific signalling pathways and bioactive compounds that underlie the improvements in male sexual function associated with PXT.

Lifetime trajectories of male mating effort under reproductive conflict in a cooperatively breeding mammal.

The costs of reproductive conflict can shape the evolution of life-histories in animal societies. These costs may change as individuals age and grow, and with within-group competition. Social costs of reproductive conflict have been invoked to explain why females might gain from delaying maturity or ceasing reproduction midway through life, but not in males. Here, we analyse more than 20 years of data to understand how individual male banded mongooses adjust their reproductive activity in response to the costs of reproductive conflict. In banded mongoose groups, multiple female breeders enter oestrus synchronously that are each guarded by a single male that aggressively wards-off rivals. The heaviest males in the group gained the greatest share of paternity. Those lighter males that are reproductively active paid disproportionate survival costs, and by engaging in reproductive activity early had lower lifetime reproductive success. Our results suggest that reproductive inactivity early in life is adaptive, as males recoup any lost fitness by first growing before engaging in less costly and more profitable reproductive activity later in life. These results suggest that resource holding potential of males and the intensity of reproductive conflict interact to shape lifetime schedules of reproductive behaviour.

Male cuticular pheromones stimulate removal of the mating plug and promote re-mating through pC1 neurons in Drosophila females.

In birds and insects, the female uptakes sperm for a specific duration post-copulation known as the ejaculate holding period (EHP) before expelling unused sperm and the mating plug through sperm ejection. In this study, we found that Drosophila melanogaster females shortens the EHP when incubated with males or mated females shortly after the first mating. This phenomenon, which we termed male-induced EHP shortening (MIES), requires Or47b+ olfactory and ppk23+ gustatory neurons, activated by 2-methyltetracosane and 7-tricosene, respectively. These odorants raise cAMP levels in pC1 neurons, responsible for processing male courtship cues and regulating female mating receptivity. Elevated cAMP levels in pC1 neurons reduce EHP and reinstate their responsiveness to male courtship cues, promoting re-mating with faster sperm ejection. This study established MIES as a genetically tractable model of sexual plasticity with a conserved neural mechanism.

The function of juvenile-adult transition axis in female sexual receptivity of Drosophila melanogaster.

Female sexual receptivity is essential for reproduction of a species. Neuropeptides play the main role in regulating female receptivity. However, whether neuropeptides regulate female sexual receptivity during the neurodevelopment is unknown. Here, we found the peptide hormone prothoracicotropic hormone (PTTH), which belongs to the insect PG (prothoracic gland) axis, negatively regulated virgin female receptivity through ecdysone during neurodevelopment in Drosophila melanogaster. We identified PTTH neurons as doublesex-positive neurons, they regulated virgin female receptivity before the metamorphosis during the third-instar larval stage. PTTH deletion resulted in the increased EcR-A expression in the whole newly formed prepupae. Furthermore, the ecdysone receptor EcR-A in pC1 neurons positively regulated virgin female receptivity during metamorphosis. The decreased EcR-A in pC1 neurons induced abnormal morphological development of pC1 neurons without changing neural activity. Among all subtypes of pC1 neurons, the function of EcR-A in pC1b neurons was necessary for virgin female copulation rate. These suggested that the changes of synaptic connections between pC1b and other neurons decreased female copulation rate. Moreover, female receptivity significantly decreased when the expression of PTTH receptor Torso was reduced in pC1 neurons. This suggested that PTTH not only regulates female receptivity through ecdysone but also through affecting female receptivity associated neurons directly. The PG axis has similar functional strategy as the hypothalamic-pituitary-gonadal axis in mammals to trigger the juvenile-adult transition. Our work suggests a general mechanism underlying which the neurodevelopment during maturation regulates female sexual receptivity.

Experimental adaptation to pathogenic infection ameliorates negative effects of mating on host post-infection survival in Drosophila melanogaster.

Sexual activity (mating) negatively affects immune function in various insect species across both sexes. In Drosophila melanogaster females, mating increases susceptibility to pathogenic challenges and encourages within-host pathogen proliferation. This effect is pathogen and host genotype dependent. We tested if mating-induced increased susceptibility to infections is more, or less, severe in hosts experimentally adapted to pathogenic infection. We selected replicate D. melanogaster populations for increased post-infection survival following infection with a bacterial pathogen, Enterococcus faecalis. We found that females from the selected populations were better at surviving a pathogenic infection compared to the females from the control populations. This was true in the case of both the pathogen used for selection and other novel pathogens (i.e., pathogens the hosts have not encountered in recent history). Additionally, the negative effect of mating on post-infection survival was limited to only the females from control populations. Therefore, we have demonstrated that experimental selection for increased post-infection survival ameliorates negative effects of mating on host susceptibility to infections.

Expression of exploratory activity of rat offspring depends on the expression of exploratory activity of their parents at the moment of mating.

The aim of this work was to study the, so far, unexplored possibility that non-genetic inheritance of animal behavioral characteristics could depend on the state of the parents at the time of conception. In this study, we measured the levels of motor and exploratory activity in rats at the ages of 2 and 5 months. Male and female rats were mated at the age of 5 months. The following groups were used: male and female rats with high motor activity at ages of 2 and 5 months (ACT+); male and female rats with high activity at the age of 2 months, but low activity at the age of 5 months (ACT-); male and female rats with low activity at the ages of 2 and 5 months (PAS-); male and female rats with low activity at the age of 2 months, but high activity at the age of 5 months (PAS+). It was found that both males and females ACT+ had significantly higher motor activity, which was observed in the first 10 minutes, in the next 20-60 minutes, in the center of the cage and more rearings as compared with PAS- rats. Significant differences in the severity of exploratory activity were found between the male offspring of ACT+ and ACT- rats. Differences between the offspring of PAS+ and PAS- rats were observed in both the male and female rats. The motor activity of animals in the period from 20 minutes after the start of registration did not differ between groups. Thus, it can be considered that individual characteristics of general motor activity are due to genetically inherited factors, while differences in the level of exploratory activity, apparently, are formed due to non-genetic influences from parents during mating.