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bioRxiv2018

Admixture mapping in interspecific Populus hybrids identifies classes of genomic architectures for phytochemical, morphological and growth traits

The genomic architecture of functionally important traits is key to understanding the maintenance of reproductive barriers and trait differences when divergent populations or species hybridize. We conducted a Genome-Wide Association Study (GWAS) to study trait architecture in natural hybrids of two ecologically divergent Populus species. We genotyped 472 seedlings from a natural hybrid zone of Populus alba and P. tremula for genome-wide markers from reduced representation sequencing, phenotyped the plants in common gardens for 46 phytochemical (phenylpropanoid), morphological, and growth traits, and used a Bayesian polygenic model for mapping. We detected three classes of genomic architectures: (1) traits with finite, detectable associations of genetic loci with phenotypic variation in addition to highly polygenic heritability, (2) traits with indications for polygenic heritability only, (3) traits with no detectable heritability. For class (1), we identified genome regions with plausible candidate genes for phenylpropanoid biosynthesis or its regulation, including MYB transcription factors and glycosyl transferases. GWAS in natural, recombinant hybrids represents a promising step towards resolving the genomic architecture of phenotypic traits in long-lived species. This facilitates the fine-mapping and subsequent functional characterization of genes and networks causing differences in hybrid performance and fitness.

evolutionary biology↗

bioRxiv2018

Parallel genomic evolution of parasite tolerance in wild honey bee populations

Sudden biotic pressures, such as those from novel diseases and pathogens, require populations to respond rapidly or face potential extinction. How this response process takes place remains poorly understood, particularly in natural environments. In this study we take advantage of unique decade-long data sets of two wild honey bee (Apis mellifera) populations in the United States to reconstruct the evolution of tolerance to a novel parasite, the ectoparasitic mite Varroa destructor. Upon the arrival of Varroa, the two geographically isolated populations simultaneously suffered massive Varroa-induced mortality, but stabilized within two years. Here we sequenced and phased genomes of 465 bees sampled from both populations annually over the decade that spanned Varroas arrival. Remarkably, we found that genetic changes were strongly correlated between the populations, suggesting parallel selective responses to Varroa parasitization. The arrival of Varroa was also correlated with an influx of genes of African origin into both populations, though surprisingly it did not substantially contribute to the overall similarity of the evolutionary response between them. Genes involved in metabolic, protein processing and developmental pathways were under particularly strong selection. It is possible that interactions among highly connected gene groups in these pathways may help channelize selective responses to novel parasites, causing completely unrelated populations to exhibit parallel evolutionary trajectories when faced with the same biotic pressure. Our analyses illustrate that ecologically relevant traits emerge from highly polygenic selection involving thousands of genes contributing to complex patterns of evolutionary change.

evolutionary biology↗

bioRxiv2018

Rapid evolution of an overt metabolic defect restores balanced growth

In eukaryotes, conserved mechanisms ensure that cell growth is coordinated with nutrient availability. Overactive growth during nutrient limitation ("nutrient-growth dysregulation") can lead to rapid cell death. Here, we demonstrate that cells can adapt to nutrient-growth dysregulation by evolving major metabolic defects. Specifically, when yeast lysine auxotrophic mutant lys- encountered lysine limitation, an evolutionarily novel stress, cells suffered nutrient-growth dysregulation. A sub-population repeatedly evolved to lose the ability to synthesize organosulfurs (lys-orgS-). Organosulfurs, mainly glutathione and glutathione conjugates, were released by lys- cells during lysine limitation when growth was dysregulated, but not during glucose limitation when growth was regulated. Limiting organosulfurs conferred a frequency-dependent fitness advantage to lys-orgS- by eliciting a proper slow growth program including autophagy. Thus, nutrient-growth dysregulation is associated with rapid organosulfur release, which enables the selection of organosulfur auxotrophy to better tune cell growth to the metabolic environment. We speculate that evolutionarily novel stresses can trigger atypical release of certain metabolites, setting the stage for the evolution of new ecological interactions.

evolutionary biology↗

bioRxiv2018

Host evolutionary history predicts virus prevalence across bumblebee species

Why a pathogen associates with one host but not another is one of the most important questions in disease ecology. Here we use transcriptome sequencing of wild-caught bumblebees from 13 species to describe their natural viruses, and to quantify the impact of evolutionary history on the realised associations between viruses and their pollinator hosts. We present 37 novel virus sequences representing at least 30 different viruses associated with bumblebees. We verified 17 of them by PCR and estimate their prevalence across species in the wild. Through small RNA sequencing, we demonstrate that at least 10 of these viruses form active infections in wild individuals. Using a phylogenetic mixed model approach, we show that the evolutionary history of the host shapes the current distribution of virus/bumblebee associations. Specifically, we find that related hosts share viral assemblages, viruses differ in their prevalence averaged across hosts and the prevalence of infection in individual virus-host pairings depends on precise characteristics of that pairing. Authors SummaryDespite the importance of disease in the regulation of animal populations, our understanding of the distribution of pathogen burden across wild communities remains in its infancy. In this study, we investigated the distribution of viruses across natural populations of 13 different bumblebee species in Scotland. We first searched for viruses using a metatranscriptomic approach, finding at least 30 new viruses of bumblebees, and assayed a subset of them for their presence and absence in different host species. Then, in the first application of these methods to an animal-virus system, we used co-phylogenetic mixed models to investigate the factors that lead to species being having different prevalences for a subset of these viruses. While much of the variation in the prevalence of the viruses can be explained by the idiosyncrasies of individual bumblebee-virus pairings, there is a phylogenetic signal with related bumblebee species being infected at similar frequencies by the same sets of viruses. Consistent with previous work, our study indicates that, while in general the interaction between a host and a virus may be unpredictable, closely related species are more likely to exhibit similar patterns of infection.

evolutionary biology↗

bioRxiv2018

Effect of riverscape and exotic introgression on the genetic structure and local adaptation of the endangered Mexican golden trout (Oncorhynchus chrysogaster)

How environmental and anthropogenic factors influence genetic variation and local adaptation is a central issue in evolutionary biology. The Mexican golden trout (Oncorhynchus chrysogaster), one of the southernmost native salmonid species in the world, is susceptible to climate change, habitat perturbations and the competition and hybridization with exotic rainbow trout (O. mykiss). The present study aimed for the first time to use genotyping-by-sequencing to explore the effect of genetic hybridization with O. mykiss and of riverscape and climatic variables on the genetic variation among O. chrysogaster populations. Genotyping-by-sequencing (GBS) was applied to generate 9767 single nucleotide polymorphisms (SNPs), genotyping 272 O. chrysogaster and O. mykiss. Population genomics analyses were combined with landscape ecology approaches into a riverine context (riverscape genetics). The clustering analyses detected seven different genetic groups (six for O. chrysogater and one for aquaculture O. mykiss) and a small amount of admixture between aquaculture and native trout with only two native genetic clusters showing exotic introgression. Latitude and precipitation of the driest month had a significant negative effect on genetic diversity and evidence of isolation by river resistance was detected, suggesting that the landscape heterogeneity was preventing trout dispersal, both for native and exotic individuals. Moreover, several outlier SNPs were identified as potentially implicated in local adaptation to local hydroclimatic variables. Overall, this study suggests that O. chrysogater may require conservation planning given i) exotic introgression from O. mykiss locally threatening O. chrysogater genetic integrity, and ii) putative local adaptation but low genetic diversity and hence probably reduced evolutionary potential especially in a climate change context.

evolutionary biology↗

bioRxiv2018

A simple egg marking method for polygynous fishes

Fitness is the ultimate measure of organismal function; however, technical challenges can limit researchers ability to quantify fitness. We developed a simple and inexpensive method of marking eggs inside of the ovary of a nesting fish, the bluebanded goby (Lythrypnus dalli), in order to quantify female reproductive success. Multiple females in a harem of L. dalli can lay eggs inside of the males nest within a short period of time, making the timing of egg laying or developmental stage of the eggs insufficient to identify which female laid which clutch of eggs. After injecting small volumes of food coloring into the ovaries, each females eggs can be identified throughout development by the color of the yolk. We make preliminary observations about the efficacy of different colors (red, yellow, green, blue) for use in L. dalli, including effects on female survival, social behavior, and the enzyme immunoassays used to quantify hormones. While rigorous validations should be conducted for each species and experimental context, this method of marking eggs has the potential to be broadly useful for directly estimating fitness in species with external fertilization, as well as research in reproductive biology, development, behavioral ecology, and evolution.

physiology↗

bioRxiv2018

Phototrophic lactate utilization by Rhodopseudomonas palustris is stimulated by co-utilization with additional substrates

The phototrophic purple nonsulfur bacterium Rhodopseudomonas palustris is known for its metabolic versatility and is of interest for various industrial and environmental applications. Despite decades of research on R. palustris growth under diverse conditions, patterns of R. palustris growth and carbon utilization with mixtures of carbon substrates remain largely unknown. R. palustris readily utilizes most short chain organic acids but cannot readily use lactate as a sole carbon source. Here we investigated the influence of mixed-substrate utilization on phototrophic lactate consumption by R. palustris. We found that lactate was simultaneously utilized with a variety of other organic acids and glycerol in time frames that were insufficient for R. palustris growth on lactate alone. Thus, lactate utilization by R. palustris was expedited by its co-utilization with additional substrates. Separately, experiments using carbon pairs that did not contain lactate revealed acetate-mediated inhibition of glycerol utilization in R. palustris. This inhibition was specific to the acetate-glycerol pair, as R. palustris simultaneously utilized acetate or glycerol when either was paired with succinate or lactate. Overall, our results demonstrate that (i) R. palustris commonly employs simultaneous mixed-substrate utilization, (ii) mixed-substrate utilization expands the spectrum of readily utilized organic acids in this species, and (iii) R. palustris has the capacity to exert carbon catabolite control in a substrate-specific manner.\n\nIMPORTANCEBacterial carbon source utilization is frequently assessed using cultures provided single carbon sources. However, the utilization of carbon mixtures by bacteria (i.e., mixed-substrate utilization) is of both fundamental and practical importance; it is central to bacterial physiology and ecology, and it influences the utility of bacteria as biotechnology. Here we investigated mixed-substrate utilization by the model organism Rhodopseudomonas palustris. Using mixtures of organic acids and glycerol, we show that R. palustris exhibits an expanded range of usable carbon substrates when provided in mixtures. Specifically, co-utilization enabled the prompt consumption of lactate, a substrate that is otherwise not readily used by R. palustris. Additionally, we found that R. palustris utilizes acetate and glycerol sequentially, revealing that this species has the capacity to use some substrates in a preferential order. These results provide insights into R. palustris physiology that will aid the use of R. palustris for industrial and commercial applications.

microbiology↗

bioRxiv2018

Evolution of metabolic novelty: a trichome-expressed invertase creates specialized metabolic diversity in wild tomato

Plants produce myriad taxonomically restricted specialized metabolites. This diversity - and our ability to correlate genotype with phenotype - makes the evolution of these ecologically and medicinally important compounds interesting and experimentally tractable. Trichomes of tomato and other nightshade family plants produce structurally diverse protective compounds termed acylsugars. While cultivated tomato (Solanum lycopersicum) accumulates strictly acylsucroses, the South American wild relative Solanum pennellii produces copious amounts of acylglucoses. Genetic, transgenic and biochemical dissection of the S. pennellii acylglucose biosynthetic pathway identified a trichome gland cell expressed invertase-like enzyme that hydrolyzes acylsucroses (Sopen03g040490). This enzyme acts on the pyranose ring-acylated acylsucroses found in the wild tomato but not the furanose ring-decorated acylsucroses of cultivated tomato. These results show that modification of the core acylsucrose biosynthetic pathway leading to loss of furanose ring acylation set the stage for co-option of a general metabolic enzyme to produce a new class of protective compounds.

plant biology↗

bioRxiv2018

The whole genome sequence and mRNA transcriptome of the tropical cyclopoid copepod Apocyclops royi

Copepoda is one of the most ecologically important animal groups on Earth, yet very few genetic resources are available for this Subclass. Here, we present the first whole genome sequence (WGS, acc. UYDY01) and the first mRNA transcriptome assembly (TSA, Acc. GHAJ01) for the tropical cyclopoid copepod species Apocyclops royi. Until now, only the 18S small subunit of ribosomal RNA gene and the COI gene has been available from A. royi, and only one other cyclopoid copepod had WGS resources available. Overall, the provided resources are the 7th copepod species to have WGS available and the 19th copepod species with TSA information available. We analyze the length and GC content of the provided WGS scaffolds as well as the coverage and gene content of both the WGS and the TSA assembly. Finally, we place the resources within the copepod order Cyclopoida as a member of the Apocyclops genus. We estimate the total genome size of A. royi to 450 Mb, with 181 Mb assembled nonrepetitive, 76 Mb assembled repeats and 193Mb unassembled sequence. The TSA assembly consists of 29,737 genes and an additional 45,756 isoforms. In the WGS and TSA assemblies, >80% and >95% of core genes can be found, though many in fragmented versions. The provided resources will allow researchers to conduct physiological experiments on A. royi, and also increase the possibilities for copepod gene set analysis, as it adds substantially to the copepod datasets available.

genomics↗

bioRxiv2018

Population genomics perspectives on convergent adaptation

Convergent adaptation is the independent evolution of similar traits conferring a fitness advantage in two or more lineages. Cases of convergent adaptation inform our ideas about the ecological and molecular basis of adaptation. In judging the degree to which putative cases of convergent adaptation provide independent replication of the process of adaptation, it is necessary to establish the degree to which the evolutionary change is unexpected under null models and to show that selection has repeatedly, independently driven these changes. Here, we discuss the issues that arise from these questions particularly for closely-related populations, where gene flow and standing variation add additional layers of complexity. We outline a conceptual framework to guide intuition as to the extent to which evolutionary change represents the independent gain of information due to selection and show that this is a measure of how surprised we should be by convergence. Additionally, we summarize the ways population and quantitative genetics and genomics may help us address questions related to convergent adaptation, as well as open new questions and avenues of research.

evolutionary biology↗

bioRxiv2018

Opsin gene evolution in amphibious and terrestrial combtooth blennies (Blenniidae)

Evolutionary adaptations to life on land include changes to the physiology, morphology and behaviour of an animal in response to physical differences between water and air. The visual systems of amphibious species show pronounced morphological adaptations; yet, whether molecular changes also occur remains largely unknown. Here, we investigated the molecular evolution of visual pigment genes (opsins) in amphibious and terrestrial fishes belonging to the Salariini division of blennies (Blenniidae). We hypothesized that when conquering land, blenny opsins adapt - in terms of sequence variation and/or gene expression - to match both higher light intensities as well as the broader light spectrum. Using retinal transcriptomes in six species ranging from fully aquatic to fully terrestrial, we found very little variation in opsin gene sequences or gene expression between species. All blennies expressed a single rod opsin gene as well as two cone opsin genes sensitive to longer-wavelengths of light: RH2A-1 (green-sensitive) and LWS (red-sensitive). They also expressed one or two short-wavelength-sensitive cone opsin genes (SWS2A, SWS2A{beta}; blue-sensitive) in a phylogenetically inert manner. However, based on amino acid predictions, both SWS2A proteins confer similar peak spectral sensitivities and differential expression is therefore unlikely to be ecologically significant. Red-sensitivity is likely beneficial for feeding on algae and detritus, the main food source of Salariini blennies, and could be co-adapted to perceive visual displays in terrestrial species, which often use red dorsal fins to signal during aggressive disputes and courtship. Our data suggests that on the molecular level, the visual systems that evolved in aquatic blennies have been retained in species that have transitioned onto land.

evolutionary biology↗

bioRxiv2018

Viral metagenomic analysis of the cheese surface: a comparative study of rapid procedures for extracting virus-like particles

The structure and functioning of microbial communities from fermented foods, including cheese, have been extensively studied during the past decade. However, there is still a lack of information about both the occurrence and the role of viruses in modulating the function of this type of spatially structured and solid ecosystems. Viral metagenomics was recently applied to a wide variety of environmental samples and standardized procedures for recovering virus-like particles from different type of materials has emerged. In this study, we adapted a procedure originally developed to extract viruses from fecal samples, in order to enable efficient virome analysis of cheese surface. We tested and validated the positive impact of both addition of a filtration step prior to virus concentration and substitution of purification by density gradient ultracentrifugation by a simple chloroform treatment to eliminate membrane vesicles. Viral DNA extracted from the several procedures, as well as a vesicle sample, were sequenced using Illumina paired-end MiSeq technology and the subsequent clusters assembled from the virome were analyzed to assess those belonging to putative phages, plasmid-derived DNA, or even from bacterial chromosomal DNA. The best procedure was then chosen, and used to describe the Epoisses cheese virome. This study provides the basis of future investigations regarding the ecological importance of viruses in cheese microbial ecosystems.\n\nIMPORTANCEWhether bacterial viruses (phages) are necessary or not to maintain food ecosystem function is not clear. They could play a negative role by killing cornerstone species that are necessary for fermentation. But they might also be positive players, by preventing the overgrowth of unwanted species (e.g. food spoilers). To assess phages contribution to food ecosystem functioning, it is essential to set up efficient procedures for extracting viral particles in solid food matrix, then selectively sequence their DNA without being contaminated by bacterial DNA, and finally to find strategies to assemble their genome out of metagenomic sequences. This study, using cheese rind surface as a model, describes a comparative analysis of procedures for selectively extracting viral DNA from cheese and to efficiently characterize the genome of dominant phages with cross-sample assembly.

microbiology↗

bioRxiv2018

Reproduction associated gene expression under predation risk in Daphnia - a comparative transcriptomic approach

Phenotypic plastic responses allow organisms to rapidly adjust when facing environmental challenges - these responses comprise morphological, behavioral but also life-history changes. Alteration of life-history traits when exposed to predation risk have been reported often in the ecological and genomic model organism Daphnia. However, the molecular basis of this response is not well understood, especially in the context of fish predation. Here, we characterized the transcriptional profiles of two Daphnia galeata clonal lines with opposed life histories when exposed to fish kairomones. First, we conducted a differential gene expression, identifying a total of 125 candidate transcripts involved in the predator-induced response, uncovering substantial intra-specific variation. Second, we applied a gene co-expression network analysis to find clusters of tightly linked transcripts revealing the functional relations of transcripts underlying the predator-induced response. Our results showed that transcripts involved in remodeling of the cuticle, growth and digestion correlated with the response to environmental change in D. galeata. Furthermore, we used an orthology-based approach to gain functional information for transcripts lacking gene ontology (GO) information, as well as insights into the evolutionary conservation of transcripts. We could show that our candidate transcripts have orthologs in other Daphnia species but almost none in other arthropods. The unique combination of methods allowed us to identify candidate transcripts, their putative functions and evolutionary history associated with predator-induced responses in Daphnia. Our study opens up to the question as to whether the same molecular signature is associated fish kairomones-mediated life-history changes in other Daphnia species.

zoology↗

bioRxiv2018

A Mathematical Modeling Approach to The Cort-Fitness Hypothesis

The Cort-Fitness hypothesis has generated much interest from investigators integrating field endocrinology with evolutionary biology, ecology, and conservation. The hypothesis was developed on the assumption that if glucocorticoid levels increase with environmental challenges and fitness decreases with environmental challenges, then there should be a negative relationship between glucocorticoid levels and fitness. However, studies across diverse taxa have found that the relationship between glucocorticoid levels and fitness is not consistent: some studies show a positive relationship, others negative, and some show no correlation. Hence, support for the hypothesis is not consistent and thus a deeper understanding of the mechanisms underlying the relationship between glucocorticoid levels, environmental pressures, and fitness is needed. We propose a mathematical model representing the links between glucocorticoid levels, environmental challenges, and fitness. Our model explores how variation in the predictability and intensity of environmental challenges, reproductive strategies, and fitness metrics can all contribute to the variability observed in empirical tests of the Cort-Fitness hypothesis. We provide qualitative results showing the Cort-Fitness relationship for different environmental scenarios and discuss how the model can be used to inform future Cort-Fitness studies.

animal behavior and cognition↗

bioRxiv2019

Turning mechanics of the bipedal hopping Desert kangaroo rat (Dipodomys deserti).

A fundamental aspect of animal ecology is the ability to avoid getting eaten. Catching prey and avoiding depredation involves a dynamic interplay between forward and lateral acceleration. Success at these tasks depends on achieving sufficient performance. In turn, performance is determined by biomechanics. After observing several kangaroo rats utilize turns under the duress of simulated predation in the field, we designed and conducted an experiment in the lab to measure turning mechanics of desert kangaroo rats. The average turning speed in our study was 1.2 ms-1. While field performances are rarely replicable in the lab, we found that kangaroo rats utilize braking impulses (~0.4 N), followed by lateral impulses, and orientated their body early in the turn to match trajectory change. to execute a turn. Coordinating turn in this ways likely prioritizes safety.

physiology↗

bioRxiv2019

Birth-and-death evolution of the fatty acyl-CoA reductase (FAR) gene family and diversification of cuticular hydrocarbon synthesis in Drosophila

The birth-and-death evolutionary model proposes that some members of a multigene family are phylogenetically stable and persist as a single copy over time whereas other members are phylogenetically unstable and undergo frequent duplication and loss. Functional studies suggest that stable genes are likely to encode essential functions, while rapidly evolving genes reflect phenotypic differences in traits that diverge rapidly among species. One such class of rapidly diverging traits are insect cuticular hydrocarbons (CHCs), which play dual roles in chemical communications as short-range recognition pheromones as well as protecting the insect from desiccation. Insect CHCs diverge rapidly between related species leading to ecological adaptation and/or reproductive isolation. Because the CHC and essential fatty acid biosynthetic pathways share common genes, we hypothesized that genes involved in the synthesis of CHCs would be evolutionary unstable, while those involved in fatty acid-associated essential functions would be evolutionary stable. To test this hypothesis, we investigated the evolutionary history of the fatty acyl-CoA reductases (FARs) gene family that encodes enzymes in CHC synthesis. We compiled a unique dataset of 200 FAR proteins across 12 Drosophila species. We uncovered a broad diversity in FAR content which is generated by gene duplications, subsequent gene losses, and alternative splicing. We also show that FARs expressed in oenocytes and presumably involved in CHC synthesis are more unstable than FARs from other tissues. We suggest that a comparative approach investigating the birth-and-death evolution of gene families can identify candidate genes involved in rapidly diverging traits between species.

evolutionary biology↗

bioRxiv2019

Antagonistic coevolution between multiple quantitative traits: matching interactions can be subsets of difference interactions

AO_SCPLOWBSTRACTC_SCPLOWCoevolution is one of the major drivers of complex dynamics in population ecology. Historically, antagonistic coevolution in victim-exploiter systems has been a topic of special interest, and involves traits with various genetic architectures (e.g., the number of genes involved) and effects on interactions. For example, exploiters may need to have traits that \"match\" those of victims for successful exploitation (i.e., a matching interaction), or traits that exceed those of victims (i.e., a difference interaction). Different models exist which are appropriate for different types of traits, including Mendelian (discrete) and quantitative (continuous) traits. For models with multiple Mendelian traits, recent studies have shown that antagonistic coevolutionary patterns that appear as matching interactions can arise due to multiple difference interactions with costs of having large trait values. Here we generalize their findings to quantitative traits and show, analogously, that the multidimensional difference interactions with costs sometimes behave qualitatively the same as matching interactions. While previous studies in quantitative genetics have used the dichotomy between matching and difference frameworks to explore coevolutionary dynamics, we suggest that exploring multidimensional trait space is important to examine the generality of results obtained from one-dimensional traits.

evolutionary biology↗

bioRxiv2019

Factors Associated with Suicidal Ideation and Suicidal Attempts among Adolescent Students in Nepal: Findings from Global School Based Students Health Survey

IntroductionSuicide has been recognized as a public health problem with high burden in low and middle income countries. Suicide has long lasting psychological trauma on friends and relatives in addition to loss of economic productivity. Although the need of high quality evidence is acknowledged for designing suicide prevention program, Nepal lacks evidence from reliable and nationally representative data. In this context, this study aimed to estimate the prevalence of suicidal ideation and attempt and identify the factors associated with them.\n\nMaterials and MethodsTotal of 6,531 students of grade 7 to 11 from 74 schools representing all three ecological belts and five development regions participated in this cross sectional study. To select the representative sample from study population, we used the two stage cluster sampling method. The respondents filled the self-administed standardized questionnaire. We carried out a Complex survey analysis for adjusting the selection probability of each research participants.\n\nResultsNearly 14% had considered suicide while 10.33% had attempted suicide. Factors associated with suicidal ideation were the food insecurity (OR=2.31, CI=1.64-3.27), anxiety (OR=2.53, CI=1.48-4.30), loneliness (OR=2.50, CI=1.41-4.44) and gender (OR=1.38, CI=1.03, 1.88) as risk factors of suicidal ideation and anxiety (OR=2.99, CI=1.18-7.64), loneliness (OR=2.19, CI=1.28-3.74) truancy(OR= 1.99, CI=1.39-2.87), cigarette use(OR=3.06, CI=1.32-7.09) and gender (OR=1.60, CI=1.07-2.39) as risk factors of suicidal attempt. Having 3 or more close friends was found to have protective effect (OR=0.35, CI=0.16-0.74) against suicidal attempt.\n\nConclusionsStudy reveals the relatively high prevalence of suicidal ideation and suicidal attempt among school-going adolescents in Nepal. Appropriate coping strategies for factors like anxiety, loneliness seem could be useful for preventing both suicidal ideation and attempt.

epidemiology↗