Trade-Offs Between Hepatic Host Defense and Metabolic Programs Underlie Sex-Biased Diseases

Current concepts in evolutionary medicine propose that trade-offs and mismatches with a shifting environment increase disease risk. While biological sex also impacts disease prevalence, contributions of environmental pressures to sex-biased diseases remain unexplored. Here, we show that sex-dependent hepatic programs confer a robust (~300%) survival advantage for male mice during lethal bacterial infection. The transcription factor BCL6, which masculinizes hepatic gene expression at puberty, is essential for this advantage. However, protection by BCL6 comes at a cost following dietary excess, resulting in overt fatty liver and glucose intolerance in males. Deleting hepatic BCL6 reverses these phenotypes but markedly lowers male fitness during infection, thus establishing a sex-dependent tradeoff between host defense and metabolic systems. We suggest that these tradeoffs, coupled with current environmental pressures, drive metabolic disease in males.

Fitness and mating consequences of variation in male allocation in a wind pollinated plant

In hermaphrodites, the allocation of resources to each sex function can influence fitness through reproductive success and mating success. In wind pollinated plants, sex allocation theory predicts that male fitness increases linearly with investment of resources into male function. However, there have been few empirical tests of this prediction. We experimentally manipulated allocation to male function in Ambrosia artemisiifolia (common ragweed) in a field experiment and measured mating success using genetic assays. We investigated the effects of various morphological traits and flowering phenology on male fitness, and on male and female mate diversity. Our results provide evidence for a linear relation between allocation to male function and fitness. We find earlier onset of male flowering time increases reproductive success, while later onset flowering time increases the probability of mating with diverse individuals. This research is among the first empirical studies testing the prediction of linear male fitness returns in wind pollinated plants. Our results provide insight into the large investment into male function by wind pollinated plants and temporal variation in sex allocation.

Repeated translocation of a supergene underlying rapid sex chromosome turnover in Takifugu fish

Recent studies have revealed a surprising diversity of sex chromosomes in vertebrates. However, the detailed mechanism of their turnover is still elusive. To understand this process, it is necessary to compare closely related species in terms of sex-determining genes and the chromosomes harboring them. Here, we explored the genus Takifugu, in which one strong candidate sex-determining gene, Amhr2, has been identified. To trace the processes involved in transitions in the sex determination system in this genus, we studied 12 species and found that while the Amhr2 locus likely determines sex in the majority of Takifugu species, three species have acquired sex-determining loci at different chromosomal locations. Nevertheless, the generation of genome assemblies for the three species revealed that they share a portion of the male-specific supergene that contains a candidate sex-determining gene, GsdfY, along with genes that potentially play a role in male fitness. The shared supergene span approximately 100 kb and are flanked by two duplicated regions characterized by CACTA transposable elements. These results suggest that the shared supergene has taken over the role of sex-determining locus from Amhr2 in lineages leading to the three species, and repeated translocations of the supergene underlie the turnover of sex chromosomes in these lineages. These findings highlight the underestimated role of a mobile supergene in the turnover of sex chromosomes in vertebrates.

No Correlation Between Pollen Fertility and Viability: Differential Measures of Male Gametophytic Fitness in Cannabis sativa L.

Pollen grains are male gametophytes, an ephemeral haploid generation of plants, commonly engaging in competition for a limited supply of ovules. Since differential male fertility may influence the direction and pace of population evolution, the relative fitness of pollen is regularly estimated as either pollen viability, the proportion of pollen containing intact cytoplasm's and regenerative nuclei, or pollen fertility, the frequency of pollen germinating under standardized conditions. Here, we estimated the relative fitness of pollen in a dioecious, wind-pollinated model system, Cannabis sativa, by characterizing pollen fertility and viability from multiple sires. Pollen fertility quickly declined within two weeks of anther dehiscence, and pollen stored under freezer conditions did not germinate regardless of storage time. In contrast, pollen viability declined slowly and persisted longer than the lifetime of a sporophyte plant under both room temperature and freezer conditions. Pollen samples that underwent both fertility and viability analysis displayed no significant correlation, implying researchers cannot predict pollen fertility from pollen viability, nor infer male gametophytic fitness from a single measure. Our work demonstrates two approaches to measure proxies of male fitness in C. sativa, and identifies new questions around what are valuable estimates of male fitness in plants.

Disordered eating symptoms in Austrian men of different ages in the context of fitness centers

Purpose To assess eating behavior and associated factors in male fitness-center attendees. Methods An anonymous questionnaire was administered to male fitness center members of Innsbruck (Austria), aged 18–80 years to assess socio-demographic features, weight history, sports activity, eating behavior including disordered eating based on the Eating Disorder Examination Questionnaire (EDE-Q) and DSM-5 key symptoms for eating disorders (anorexia nervosa, binge eating, bulimia nervosa, purging disorder) and body image. Three age groups (younger—middle-aged—older men) were compared regarding the variables described above. Results A total of 307 men included displayed high rates of disordered eating as described by EDE-Q cutoff scores (5–11%) as well as by DSM-5 eating disorder symptoms (10%). While EDE-Q cutoff scores did not differentiate between the groups, the prevalences of DSM-5 eating disorder symptoms yielded significant differences indicating a clear decrease with increasing age. Binge eating and bulimic symptoms with excessive exercising as the purging method were the most often reported symptoms. Conclusion Although described as typically female, disordered eating does occur in male fitness-gym attendees across all ages. The older the men, the less prevalent are the symptoms. Awareness of disordered eating and possible negative effects need to be addressed for attendees and trainers of the gym. Level of evidence V—descriptive survey study.

Welcome to “Planet Porno”

This article aims to explore the connections between bodybuilding, (hyper)masculinity, sexuality, and the construction of subcultural and sexual spaces among Swedish male fitness dopers. Analytically, the article employs the perspectives of hardcore masculinities—and the potential harms to relationships and health involved in the use of doping—as well as more legitimate and hegemonic masculinity configurations. The results show that there is a delicate balance between masculinity-connoted sexual and other bodily urges and desires, on the one hand, and the loss of control, on the other. Living in a pornographic imaginary can also result in a loss of reasonable contact with the world outside the subculture of bodybuilding. Upholding this lifestyle thus involves an ambivalent construction of masculinity found at the intersection between marginality and hegemony, which sometimes leads to loneliness and a lack of intimate relationships.

Migration Restores Hybrid Incompatibility Driven By Nuclear-Mitochondrial Sexual Conflict

In the mitochondrial genome, sexual asymmetry in transmission favors mutations that are advantageous in females even if they are deleterious in males. Called the “Mother’s Curse”, this phenomenon induces a selective pressure for nuclear variants that compensate for this reduction in male fitness. Previous work has demonstrated not only the existence of these interactions but also their potential for acting as Dobzhansky–Muller loci. However, it is not clear how readily they would give rise to and sustain hybrid incompatibilities. Here, we use computer simulations in SLiM 3 to expand analytical theory to investigate the consequences of sexually antagonistic mitochondrial-nuclear interactions in a subdivided population. We consider distinct migration schemes and vary the chromosomal location, and consequently the transmission pattern, of nuclear restorers. Disrupting these co-evolved interactions results in less-fit males skewing the sex ratio towards females. Restoration of male fitness depends on both the chromosomal location of nuclear restorers and the migration scheme. Our results show that these interactions may act as Dobzhansky–Muller incompatibilities, but their strength is not enough to drive population isolation. Combined, this model shows the varied ways in which populations respond to migration’s disruption of co-evolved mitochondrial-nuclear interactions.

Climbing up the ladder: male reproductive behaviour changes with age in a long-lived fish

High reproductive performance is the key attribute of male fitness, especially due to the high reproductive skew among the males of most animal species. Males of long-lived iteroparous species have opportunities to improve upon their previous reproductive attempts with increasing age. We collected individual-specific reproductive behaviour and age data on a cyprinid fish, the asp (Leuciscus aspius), from 2015 to 2019. We tested whether males changed their performance over time using a unique dataset where individual performance was recorded yearly with passive telemetry. Individual fish behaviour was tracked from one to five reproductive seasons at least a year after the tagging. Fish were scored by measures of quality (first arrival time, number of visits and time spent in the reproductive grounds, and encountered proportion of males to all adult fish). In general, fish improved in the first three metrics with age, suggesting a shift towards behaviours likely to enhance reproductive success as individuals aged. A larger size at tagging was predictive of earlier fish arrival on the spawning ground in subsequent years. Our study therefore demonstrates the importance of age as a factor when considering the potential reproductive success of long-lived fish species. Significance statement High reproductive performance is the key attribute of male fitness. Males of long-lived species reproducing multiple times in their life have opportunities to improve upon their previous reproductive performance with increasing age. In this 5-year study, we tracked a large cyprinid fish with telemetry systems during their reproduction. We investigated the age-related behavioural changes in males and demonstrated the improvement of male reproductive timing and length of stay with potential repercussions for male’s reproductive output. We emphasize the importance of old and experienced individuals among the fish population, which are often targeted and selectively removed from the human-managed waters.