Male Pairs Research Articles

Prolonged partner separation erodes nucleus accumbens transcriptional signatures of pair bonding in male prairie voles.

The loss of a spouse is often cited as the most traumatic event in a person's life. However, for most people, the severity of grief and its maladaptive effects subside over time via an understudied adaptive process. Like humans, socially monogamous prairie voles (Microtus ochrogaster) form opposite-sex pair bonds, and upon partner separation, show stress phenotypes that diminish over time. We test the hypothesis that extended partner separation diminishes pair bond-associated behaviors and causes pair bond transcriptional signatures to erode. Pairs were cohoused for 2 weeks and then either remained paired or were separated for 48hrs or 4wks before collecting fresh nucleus accumbens tissue for RNAseq. In a separate cohort, we assessed partner-directed affiliation at these time points. We found that these behaviors persist despite prolonged separation in both same-sex and opposite-sex paired voles. Opposite-sex pair bonding led to changes in accumbal transcription that were stably maintained while animals remained paired but eroded following prolonged partner separation. Eroded genes are associated with gliogenesis and myelination, suggesting a previously undescribed role for glia in pair bonding and loss. Further, we pioneered neuron-specific translating ribosomal affinity purification in voles. Neuronally-enriched transcriptional changes revealed dopaminergic-, mitochondrial-, and steroid hormone signaling-associated gene clusters sensitive to acute pair bond disruption and loss adaptation. Our results suggest that partner separation erodes transcriptomic signatures of pair bonding despite core behavioral features of the bond remaining intact, revealing potential molecular processes priming a vole to be able to form a new bond.

A nonsensory odorant-binding protein plays an important role in the larval development and adult mating of Spodoptera frugiperda.

Odorant-binding proteins (OBPs) play key roles in the perception of semiochemicals in insects. Several OBPs in insect olfactory systems have been functionally characterized, and they provide excellent targets for pest control. The functions of some OBPs that are highly expressed in the nonsensory organs of insects remain unclear. Here, the physiological function of an OBP (OBP27) that was highly expressed in the nonsensory organs of Spodoptera frugiperda was studied. OBP27 was nested within the Plus-C cluster according to phylogenetic analysis. The transcription of OBP27 steadily increased throughout the development of S. frugiperda, and transcripts of this gene were abundant in the fat body and male reproductive organs. An OBP27 knockout strain with an early frameshift mutation was obtained using the clustered regularly interspaced palindromic repeats (CRISPR) / CRISPR-associated protein 9 (Cas9) system. The development time of OBP27-/- larvae was significantly longer than that of other larvae. Both male and female OBP27-/- pupae weighed significantly less than wild-type (WT) pupae. In crosses of OBP27-/- males or females, the mating rate was lower and the mating duration was longer for OBP27-/- male-WT female pairs than for WT-WT pairs. By contrast, the mating rate, hatching rate, and number of eggs of OBP27-/- female-WT male pairs and WT-WT pairs were similar. These findings indicate that OBP27 plays an important role in the larval development and mating process in male adults. Generally, our findings provide new insights into the physiological roles of nonsensory OBPs.

1-octadecene, A Female Produced Aggregation Pheromone of the Coffee White Stem Borer (Xylotrechus quadripes)

Coffee white stem borer, Xylotrechus quadripes is a serious insect pest of coffee across the world. Pheromone traps baited with male produced 2-hydroxy- 3-decanone (2H3D) attracted females, and also males. Interestingly, a pair of males and females in a cage attracted more beetles compared to 2H3D traps. We hypothesized volatiles emitted from females are perceived by males. Volatiles from females were collected through the air entrainment method and identified 1-octadecene by using gas chromatography coupled with mass spectrometry. Release of 1-octadecene was female specific, however, both male and female antennae elicited responses in chromatography-electroantennography. Electroantennogram responses were dose-dependent in both sexes and were higher in the antennae of females. Combination of male pheromone component 2H3D, and female produced 1-octadecene at 1:2 ratio increased both male (0.69 ± 0.13; mean ± SEM in -mV) and female (0.98 ± 0.20) antennal responses. Responses to constant doses of 2H3D and increasing doses of 1-octadecene (1:4, 1:6, 1:8, 1:10) were not different from male pheromone alone. Beetle captures to male pheromone alone at 3 different doses (75, 150 and 300 mg) were not significantly different from a pair of live beetle traps. A blend of 2H3D and 1-octadecene at 1:2 ratio trapped more beetles (3.50 ± 0.65; mean ± SEM) over 2H3D alone (2.00 ± 0.82), overall, our experiments suggest 1-octadecene is an aggregation pheromone. Our results support the hypothesis that males use 1-octadecene in mate finding, and potential to use it for monitoring and mass trapping.

Sibling Cannibalism in Group-Living Larvae of the Solitary Wasp, Isodontia harmandi (Hymenoptera: Sphecidae): Effects of Prey Availability and Size Discrepancy.

Sibling cannibalism has rarely been documented in the resource-based context of sibling rivalry. The solitary wasp Isodontia harmandi (Pérez) (Hymenoptera: Sphecidae) has an exceptional style of nursery 'communal brood cells', in which multiple larvae gregariously develop while relying on maternal prey provisioning. In this species there are several distinct features; e.g., cannibalism-driven brood reduction, single-sex broods, and mass provisioning. Rearing of the wasp larvae in artificial nest chambers provides the novel opportunity to study larval interactions under controlled conditions. To determine the factors that influence the occurrence of cannibalism and its timing, we conducted a rearing experiment using sib and non-sib pairs under two prey-availability treatments, and recorded the occurrence of cannibalism and the processes of larval growth and prey consumption over a 96-hr period. Cannibalism occurred more frequently in the low-prey treatment than in the high-prey treatment, and in female pairs than in male pairs. Cannibalism tended to occur earlier when the amount of prey remaining decreased rapidly. However, cannibalism did not occur only when all prey had been completely consumed, implying that it was not triggered directly by prey exhaustion. Cannibals were always larger than their victims, whose growth rates had often slowed before they were eaten. These results strongly imply that wasp larvae commit sibling cannibalism in the context of resource-based sibling rivalry, ensuring the double benefit of nutritional gains and reduced resource competition. We also investigated the possibility that wasp larvae monitor the size difference and/or body condition of brood-mates as an indicator of prey availability.

Description of the females of two species of the genus Lasaia (Lepidoptera: Riodinidae) and new records for Mexico

Females of two species of the genus Lasaia Bates, 1868, L. arsis Staudinger, [1887] and L. pseudomeris Clench, 1972 are described from specimens deposited in entomological collections. The identity of these species had been uncertain due to scarcity of data, causing misidentifications and confusion in pairing males and females of the same species. Distribution maps for both species, as well as new records of L. arsis for Mexico are provided.

Sex‐dependent habitat selection modulates risk management by meadow voles

AbstractForaging involves a trade‐off between food and safety. Most research into the trade‐off invokes safety from predation. But danger and its associated risk arise from multiple causes that cannot be assessed solely with reference to predators. A more complete assessment of risk management requires experimental designs that attempt to modify and measure risks, regardless of the source of danger. I aimed to do so by adding shelter (mulched straw) and time‐varying supplemental food (rabbit chow), while measuring foraging behavior and habitat use by a seminatural population of meadow voles. Voles foraged more intensely under safety, recognized least risk when given access to both food and shelter, but altered their risk management through time: management included a novel form of sex‐dependent habitat selection in which male–male pairs occupied risky areas without shelter while female–female pairs occupied habitats sheltered by straw. The pattern is consistent with a sex‐dependent evolutionary game in which female territoriality and tolerance of other females limit conflict with, and space use by, males. Voles' array of interacting strategies demonstrates that ecologists must be wary of ascribing risk only to predation, and particularly so if experiments are blind to other dangers and processes that alter foraging behavior and habitat selection.

Same-sex Pairs Retain Their Reproductive Capacity as a Potential Opportunity for Individual Reproductive Success in Termites

In eusocial termites, successful pairing is an essential element of dispersal and distribution after the departure of alates from natal colonies. Two situations could arise during the pairing process: mixed-sex pairs and same-sex pairs. However, most previous studies focused on mixed-sex pairs, overlooking groups formed by same-sex pairings, especially potential fecundity (the total number of oocytes or ovarioles), oogenesis and the development stage of oocytes of females in female-female pairs, and spermatogenesis and testis development of males in male-male pairs. In this study, through experimentation, we investigated the reproductive ability of virgin dealates based on various pairing types as mentioned above. We found that the life spans of virgin dealates can cover 1 yr or even more when they establish a nest with a partner, which is more than 10-fold longer than the life span of individuals establishing a colony alone. After 1 yr of pairing, the potential fecundity of virgin same sex dealates did not degenerate significantly compared with newly emerged dealates, including the number of ovarioles, size of testis, oogenesis, and the development stage of the oocytes. Moreover, when individuals of same-sex pairings experimentally changed into mixed-sex pairs after 1 yr, the eggs produced in the colony hatched into larvae. These findings suggest that dealates which through same-sex pairs retain fecundity after 1 yr have more reproductive potential than dealates that failed to pair with heterosexuals, shedding light on the ecological significance of homosexual behaviors in terms of the successful extension and fecundity of eusocial termites.

990. Sex-Specific Analysis of Clinical Features and Outcomes in Staphylococcal Periprosthetic Joint Infections Managed with Two-Stage Exchange Arthroplasty

Abstract Background There are anatomical, pharmacokinetic, and joint biomechanical differences between males and females. Whether these differences result in differing presentation, treatment tolerability and outcomes in periprosthetic joint infection (PJI) has not been widely evaluated. Methods We undertook a retrospective case matched study of patients with staphylococcal PJI managed with two-stage exchange arthroplasty. In order to control for differences other than sex which may influence outcome or presentation, males and females were case-matched for age, causative organism (Coagulase-negative staphylococci vs Staphylococcus aureus) and joint involved. The two matched groups were analyzed for differences in duration of symptoms, inflammatory markers, duration of hospital stay, antimicrobial side effects, post-operative complications and recurrence rate. Recurrence of infection was defined as per Musculoskeletal Infection Society criteria for PJI and included both relapse with original microorganism or with an additional organism. Results 78 pairs of males and females with staphylococcal PJI were successfully matched. There were no significant baseline differences by sex, except for greater use of chronic immunosuppression among females (16.7% vs. 4.1%; p=0.012). Clinical characteristics and outcomes of the patients are summarized in table 1. We did not detect a statistically significant between the outcomes of the two groups. Overall, 16 recurrent infections occurred during a median follow-up time of 2.9 (IQR: 1.5 - 5.3) years. The 3-year cumulative incidence of treatment failure depicted in figure 1 was 16.1% for females, compared with 8.8% for males (p=0.434). Conclusion Success rates for PJI treated with two-stage exchange arthroplasty are high consistent with previously reported literature. A larger cohort of patients may be required to detect differences in relapse rates. This study included only staphylococcal PJI and was thus unable to evaluate the differences in microbiology of PJI between males and females, which could also impact outcomes. This retrospective case-matched study did not detect any significant differences in outcomes between males and females with staphylococcal PJI who underwent two stage exchange arthroplasty. Disclosures Gina A. Suh, M.D., Adaptive Phage Therapeutics (APT): Grant/Research Support|Adaptive Phage Therapeutics (APT): Dr. Suh received grants and has an equity and royalty-bearing know-how agreement with Adaptive Phage Therapeutics but is unrelated to project Aaron J. Tande, M.D., Uptodate: Dr Tande has received an honorarium from Uptodate for medical writing unrelated to this project.

Kinship and similarity drive coordination of breeding-group choice in male spotted hyenas.

When and where animals reproduce influences the social, demographic and genetic properties of the groups and populations they live in. We examined the extent to which male spotted hyenas (Crocuta crocuta) coordinate their breeding-group choice. We tested whether their propensity to settle in the same group is shaped by passive processes driven by similarities in their socio-ecological background and genotype or by an adaptive process driven by kin selection. We compared the choices of 148 pairs of same-cohort males that varied in similarity and kinship. We found strong support for both processes. Coordination was highest (70% of pairs) for littermates, who share most cumulative similarity, lower (36%) among peers born in the same group to different mothers, and lowest (7%) among strangers originating from different groups and mothers. Consistent with the kin selection hypothesis, the propensity to choose the same group was density dependent for full siblings and close kin, but not distant kin. Coordination increased as the number of breeding females and male competitors in social groups increased, i.e. when costs of kin competition over mates decreased and benefits of kin cooperation increased. Our results contrast with the traditional view that breeding-group choice and dispersal are predominantly solitary processes.

Epigenome-wide association study of physical activity and physiological parameters in discordant monozygotic twins

An epigenome-wide association study (EWAS) was performed on buccal cells from monozygotic-twins (MZ) reared together as children, but who live apart as adults. Cohorts of twin pairs were used to investigate associations between neighborhood walkability and objectively measured physical activity (PA) levels. Due to dramatic cellular epigenetic sex differences, male and female MZ twin pairs were analyzed separately to identify differential DNA methylation regions (DMRs). A priori comparisons were made on MZ twin pairs discordant on body mass index (BMI), PA levels, and neighborhood walkability. In addition to direct comparative analysis to identify specific DMRs, a weighted genome coexpression network analysis (WGCNA) was performed to identify DNA methylation sites associated with the physiological traits of interest. The pairs discordant in PA levels had epigenetic alterations that correlated with reduced metabolic parameters (i.e., BMI and waist circumference). The DNA methylation sites are associated with over fifty genes previously found to be specific to vigorous PA, metabolic risk factors, and sex. Combined observations demonstrate that behavioral factors, such as physical activity, appear to promote systemic epigenetic alterations that impact metabolic risk factors. The epigenetic DNA methylation sites and associated genes identified provide insight into PA impacts on metabolic parameters and the etiology of obesity.

Habitat detection, habitat choice copying or mating benefits: What drives conspecific attraction in a nomadic songbird?

Conspecific attraction during habitat selection is common among animals, but the ultimate (i.e. fitness-related) reasons for this behaviour often remain enigmatic. We aimed to evaluate the following three hypotheses for conspecific attraction during the breeding season in male Wood Warblers (Phylloscopus sibilatrix): the habitat detection hypothesis, the habitat choice copying hypothesis and the female preference hypothesis. These hypotheses make different predictions with respect to the relative importance of social and nonsocial information during habitat assessment, and whether benefits accrue as a consequence of aggregation. We tested the above hypotheses using a combination of a 2-year playback experiment, spatial statistics and mate choice models. The habitat detection hypothesis was the most likely explanation for conspecific attraction and aggregation in male Wood Warblers, based on the following results: (1) males were attracted to conspecific song playbacks, but fine-scale habitat heterogeneity was the better predictor of spatial patterns in the density of settling males; (2) male pairing success did not increase, but instead slightly decreased, as connectivity with other males (i.e. the number and proximity of neighbouring males) increased. Our study highlights how consideration of the process by which animals detect and assess habitat, together with the potential fitness consequences of resulting aggregations, are important for understanding conspecific attraction and spatially clustered distributions.

Male aggressiveness during the female fertile phase in relation to extra-pair paternity, plumage ornaments and female traits

In many bird species, physical aggression between males become more frequent during the female’s fertile period, as female encounters with extra-pair males are more frequent and can entail paternity losses. Male aggressiveness during this stage has been proposed as crucial for ensuring male reproductive success. Thus, plumage ornaments could represent honest signals of individual quality that could reflect the aggressiveness of paired territorial males. Furthermore, male aggressiveness could be related to mate quality or defensive capacity. We quantified extra-pair paternity in the broods and investigated the association of male and female traits with the aggressive behaviour of territorial paired males in a Spanish population of Pied Flycatchers (Ficedula hypoleuca), where territorial intrusions were simulated during the female fertile period by placing a taxidermic male mount close to the nest. We predicted that (1) more aggressive males should better protect their mates from intruding males and thereby reduce their paternity losses, (2) males with larger white patches and higher UV reflectance of wing patches should respond more strongly to intrusions, and (3) that males should be more aggressive when mated with higher quality females. We found evidence that males that responded less intensely to a territorial intrusion suffered a higher paternity loss, which offers strong support to the basic tenet of the theory of territoriality as paternity defence. Moreover, both the level of male aggressiveness and control of the territory increased with male UV reflectance of wing patches. Finally, we found, contrary to our prediction, that males were less aggressive when mated with more ornamented females.

Sex-dependent growth regulation in monogamous pairs of a cichlid fish

Abstract In some social groups, non-breeding subordinates regulate their growth, relative to the size of their immediate dominants in ways that reduce conflict over dominance rank. We predicted that such strategic growth adjustment should also occur in breeding pairs, if this is beneficial for the more subordinate individual within a pair. Using the cichlid fish, Julidochromis transcriptus, held in a laboratory, we examined whether strategic growth regulation occurs in monogamous pairs. In female-largest pairs, smaller males grew slower than their partner when the initial size ratio of pairs (large/small) was small, but faster when the ratio was large, and the number of pairs with an intermediate size ratio increased over time. However, in male-largest pairs, smaller females had a low growth rate and the size ratio of these pairs increased over time. The most important factors for predicting the growth rate of fish were the initial size ratio of pairs for smaller males in female-largest pairs and the initial body size for larger individuals in both pair types, but no such predictors were found for smaller females in male-largest pairs. Neither feeding rate nor attacking rate of the two individuals in a pair predicted the growth rate of smaller fish in a pair. These results suggest that smaller males strategically adjust their own growth, relative to the size of their partner in female-largest pairs, wherein the growth of larger females unrestrained by social relationship with their partner can increase female fecundity, being beneficial for both sexes. The adaptive significance of a low growth rate of smaller females in male-largest pairs is also discussed.

Agonistic Behaviour and Sound Production during Male–Male Varunid Crabs (Cyrtograpsus angulatus, Dana 1851) Encounters

Crustacean sounds are the main contributor to shallow water soundscape biophonic components. Here, we investigate the sound production of Cyrtograpsus angulatus, one of the most important intertidal decapods of the Southwestern Atlantic Ocean. Underwater audio and video were recorded during encounters among male pairs. Two kinds of experimental settings were conducted involving same size (SS) and different-size (DS) male crabs. Behavioural states, behavioural events and sound emission were investigated. SS spent more time in contact and still behaviour and showing competitive interactions than did DS. Crabs presented body displays involving chelae, legs, and maxillae movements with the same frequency in both settings. Our results demonstrate the production of impulsive sounds in male C. angulatus with high rates during contact and still behaviour (specifically during agonistic interactions and body displays without contact between individuals). Furthermore, we were able to describe behaviour-related variability within impulsive sounds. These outcomes provide a better understanding of the role and behavioural context of these sounds in the natural soundscape.

Social regulation of immediate early gene induction in gonadotropin releasing-hormone 1 neurons and singing behavior in canaries (Serinus canaria)

Social cues modulate the neuroendocrine control of reproduction. However, the neural systems involved in the integration of social cues are not well described. Gonadotropin-releasing hormone 1 (GnRH1) cells in the preoptic area (POA) are the final common node that links the brain with peripheral reproductive physiology. These experiments investigated whether induction of the immediate early gene, EGR1, in anatomically localized GnRH1 cell populations in Border canaries is regulated by the social environment. First, we characterized behavioral modifications in singing behavior and found males paired with a female for 2 weeks significantly reduced many aspects of singing behavior. However, paired males had a significantly higher percentage of GnRH1 cells co-labeled with EGR1. The second experiment manipulated the social environment by pairing males and females in mixed sex dyads, same sex dyads or housed birds in isolation. Only when birds are paired in mixed sex dyads was there a significantly greater percentage of GnRH1 cells expressing EGR1 cells. Increased GnRH1-EGR1 co-expression was localized to the rostral POA. These data reveal that discrete GnRH1 cells are involved in the neural integration of specific social cues and support the hypothesis that the POA exhibits functional topography related to courtship and sexual behaviors.

Brazilian portuguese version of twin relationship questionnaire (TRQ-BR): Evidence of validity

Our aim was to adapt and validate a Brazilian Portuguese version of the Twin Relationship Questionnaire developed by Fortuna et al. (2010) and validated by H. Segal and Knafo-Noam (2019) in Israel. The respondents were 862 Brazilian mothers of twins ( N = 1724 twins) with mean age of 35 years (SD = 6.1). The majority of the sample lived in the Southeast (61.8%) or in the South (24.5%) of Brazil. We conducted a Multilevel Confirmatory Factor Analysis with the pair of twins as second level variable, and the five-factor structure (closeness, dependence, conflict, dominance, and rivalry) proposed by the original validation study of H. Segal and Knafo-Noam (2019) was confirmed. The final model retained 15 items out of 22 proposed in the original version of the questionnaire. Although the TRQ-BR has fewer items, the accuracy compared to the original questionnaire was maintained. Mixed Model Analysis (LMM) of TRQ scores were used to investigate twins’ relationships as a function of zygosity, age groups, and sex in order to provide evidence of convergent validity of the instrument. As expected, mothers perceived monozygotic twins (MZ) as more depedent than dizygotic twins (DZ). Furthermore, male twin pairs were considered more conflictive when compared to female twins. The present study showed that TRQ-BR is an adequate instrument for research purposes in the Brazilian population. It can also be useful for applied areas such as clinical and educational fields.

Gender and pair programming–Effects of the gender composition of pairs on collaboration in a robotics workshop

The goal of this video study was to investigate whether the gender composition of a pair influences collaboration during the pair programming process. Pair programming is an agile software development technique in which two people share a computer and jointly develop a program. One of the programmers, the driver, operates the keyboard and mouse; the other, the navigator, reviews the code and helps without touching the keyboard or mouse. These two roles are swapped at regular intervals. Video data were collected during a half-day robotics workshop for students in Grades 5–9 (10–14 years old) and gifted students in Grades 3–6 (8–11 years old) at the University of Teacher Education Lucerne. A total of 203 pairs with different gender compositions (homogeneous female, homogeneous male, heterogeneous) were filmed during the pair programming process. Without consideration of the grade level the research results showed that there were no significant differences between the pairs based on gender composition in terms of task-solving speed, number of assistance requests, role changes, or rule violations by the navigator. In heterogeneous pairs, male and female students in the navigator role intervened equally often. These results initially appear to be consistent with several previous studies, which also found no significant differences based on gender composition. However, when only students in Grades 7–9 (12–14 years old) were considered, there were two significant differences. First, the homogeneous male pairs violated the rule that the navigator does not touch the keyboard or mouse more often than the other pairs. This suggests that homogeneous male pairs are not ideal for students in Grades 7–9 (12–14 years old). Second, as previously shown in other studies, heterogeneous pairs showed the greatest variability in task-solving speed. This may indicate compatibility issues among some heterogeneous pairs in Grades 7–9. In this study, only quantitatively measurable indicators of collaboration were considered. Further research on gender and pair programming should therefore focus on the quality of collaboration.

Improving discrimination capacity through rapidly mutating Y-STRs in structured populations from the African continent

Y chromosome short tandem repeats (Y-STRs) typing is becoming increasingly popular in forensic casework mainly because it allows the recovery of male-specific genetic information from severely unbalanced male-female DNA mixtures. The relatively low discrimination power of conventional Y-STR multiplexes, due to linkage disequilibrium among polymorphic loci, has been partially overcome by the introduction of rapidly mutating Y microsatellites (RM Y-STRs) with mutation rates exceeding 1 × 10-2/generation. In previous works, we reported an unexpectedly high level of haplotype sharing among African males using the Yfiler Plus PCR Amplification kit, the most powerful commercially available system, including 19 conventional Y-STRs and 6 RM Y-STRs. In particular, analyzing 1370 males from northern, eastern and central Africa, 240 subjects were found to share 100 Y-STR haplotypes. We attributed the relatively low discrimination capacity to several factors including patrilocality, endogamy, sampling bias and degree of urbanization. In the present study, using a blind search analysis based on 16 autosomal STRs, we first investigated the kinship between pairs of African males previously found to share the Yfiler Plus haplotype; then, we evaluated the improvement in identification capacity allowed by a PCR multiplex assay (RM-YPlex) based on 13 “first generation” RM Y-STR, seven of which are not included in the Yfiler Plus multiplex. Among 228 pairs of males sharing a Yfiler Plus haplotype, we detected 134 related (cousins or closer) and 94 unrelated (or distantly related) pairs of subjects. By using the RM-YPlex, we observed a full genotype concordance for the six loci shared with the Yfiler Plus, while the additional seven RM Y-STRs allowed the discrimination among 58.2 % related pairs and 84.0 % unrelated pairs. The discrimination capacity increased from 0.898 to 0.958, while the proportion of males sharing a haplotype decreased from 17.5 % to 8.0 %. These findings further highlight the capability of RM Y-STRs to distinguish males even in close kinship scenarios and in sub-structured populations as African ones, but at the same time call for the discovery and testing of additional RM Y-STRs to fully differentiate male relatives.

Heritability of Psychotic Experiences in Adolescents and Interaction With Environmental Risk

Genetic risk factors are known to play a role in the etiology of psychotic experiences in the general population. Little is known about whether these risk factors interact with environmental risks for psychotic experiences. To assess etiological heterogeneity and exposure to environmental risks associated with psychotic experiences in adolescence using the twin design. This twin study, conducted from December 1, 2014, to August 31, 2020, included a UK-based sample of twin pairs aged 16 years. This investigation evaluated the extent to which the genetic variance underlying psychotic experiences and the magnitude of the heritability of psychotic experiences was moderated by exposure to 5 environmental risk factors (bullying, dependent life events, cannabis use, tobacco use, and low birth weight). Psychotic experiences were assessed by 5 self-reported measures and 1 parent-reported measure. Participants' exposure to environmental risks was assessed at birth and age 12 to 16 years. Structural equation models were used to assess differences in the variance in and heritability of psychotic experiences across these exposures, while controlling for gene-environment correlation effects. Analyses were repeated in an independent Swedish sample. Data analyses were performed from September 1, 2018, to August 31, 2020. Primary outcome measures were exposure to environmental factors, as measured by a composite score, and psychotic experiences. A total of 4855 twin pairs (1926 female same-sex pairs, 1397 male same-sex pairs, and 1532 opposite-sex pairs) were included from the Twins Early Development Study (TEDS), and 6435 twin pairs (2358 female same-sex pairs, 1861 male same-sex pairs, and 2216 opposite-sex pairs) were included from the Child and Adolescent Twin Study in Sweden (CATSS). Mean age of twins from TEDS was 16.5 years. Mean age of twins from CATSS was 18.6 years. More exposure to environmental risk factors was associated with having more psychotic experiences. The relative contribution of genetic influences to psychotic experiences was lower with increasing environmental exposure for paranoia (44%; 95% CI, 33%-53% to 38%; 95% CI, 14%-58%), cognitive disorganization (47%; 95% CI, 38%-51% to 32%; 95% CI, 11%-45%), grandiosity (41%; 95% CI, 29%-52% to 32%; 95% CI, 9%-48%), and anhedonia (49%; 95% CI, 42%-53% to 37%; 95% CI, 15%-54%). This pattern was replicated for the measure of psychotic experiences in the independent Swedish replication sample. The heritability of hallucinations and parent-rated negative symptoms remained relatively constant. Findings of this twin study suggest that environmental factors play a greater role in the etiology of psychotic experiences than genetic factors. The relative importance of environmental factors is even higher among individuals exposed to environmental risks for psychotic experiences, highlighting the importance of a diathesis-stress or bioecological framework for understanding adolescent psychotic experiences.

Rapid colonization of the post‐burn environment improves egg survival in pyrophilic ground beetles

AbstractMany insects are drawn to the heat, ash, and smoke produced by forest fires and arrive in large numbers at recent burns, often while the fire is still active. Some of these insects are pyrophilic and reproduce exclusively in the immediate aftermath of fire but are rarely, if ever, collected from unburnt habitats. Numerous observations made at active fires note an apparent preference among some pyrophilic insects to oviposit exclusively in the burnt portions of trees, raising broader questions about the adaptive benefits of reproduction in the post‐burn environment. Here, we tested whether the reproductive output of pyrophilic ground beetles (i.e., Sericoda spp.) increased in heat‐sterilized soils. In the first experiment, the eggs of Sericoda quadripunctata were reared in three types of soil collected from burnt forests: recently burnt soil (collected 1–2 weeks after the fire), soil collected 1 year after burn, and soil from an unburnt patch of forest adjacent to the fire. Daily monitoring through a dissecting microscope documented extensive predation of eggs by soil microarthropods (mites, springtails, and nematodes), especially in 1‐year‐old and unburnt soil treatments. This led to a second experiment that included the same three treatments and an additional fourth soil treatment: recently, burnt soil reheated to 100°C for 2 h (i.e., reheated soil). In this experiment, male and female pairs (n = 100) of Sericoda obsoleta were reared for 14 days in jars containing 90 g of soil corresponding to each of the four soil treatments. Reproductive output, measured as the number of larvae produced by each breeding pair, was significantly higher in the reheated soil, suggesting that heat sterilization and removal of soil‐dwelling predators improved egg survival. Our findings suggest that pyrophily in insects may have evolved as a means of increasing reproductive output in the post‐burn environment through access to heat‐sterilized ovipositing substrates. Furthermore, the abrupt disappearance of Sericoda and other pyrophilic insects following fire may be explained by suboptimal reproductive conditions as the burn is colonized by other organisms and by local emigration in favor of other recent burns on the landscape.