Biology subjects

Tung, S.

Publications and source records attributed to Tung, S..

14 recordsLinked to original sources

bioRxiv2026

Nutritional history affects stress-resistance architecture across ageing and sex

Diet can influence lifespan and age-dependent physiological function, but how nutrition during development and adulthood affects relationships among stress resistance traits across age remains unclear. Using an isocaloric full-factorial larval x adult diet design in outbred Drosophila melanogaster, we tested how protein- and carbohydrate-biased diets affected starvation, desiccation, cold, osmotic, and heat resistance across the adult life course and sex. We also measured whole-body triacylglyceride, protein, body weight, and water content, and compared responses with matched lifespan and reproductive-output data. Resistance declined across the adult life course, but the traits did not vary as a single phenotype: among the traits included in the covariance analysis, desiccation, osmotic, and heat resistance formed a tightly correlated core, whereas starvation resistance remained comparatively peripheral in both sexes. Developmental diet produced trait-specific effects, whereas protein-biased adult diet favoured heat and osmotic resistance, paralleling effects on lifespan and reproductive output, but had opposite effects on starvation and cold resistance in specific contexts. Thus, nutrition alters rather than uniformly improves stress resistance, and covariance among resistance traits does not necessarily predict how those traits respond to nutritional perturbation.

ecology↗

bioRxiv2024

Additive and context-dependent effects of developmental and adult diet on life-history traits and their associations in outbred Drosophila melanogaster population

Life-history traits such as body size, reproduction, survival, and stress resistance are fundamental to an organisms fitness and are highly influenced by nutritional environments across life stages. In this study, we employed a full factorial experimental design to investigate the effects of isocaloric diets (diets with equal caloric content but differing macronutrient composition) on key life-history traits in an outbred Drosophila melanogaster population. Our results demonstrated significant diet-induced plasticity, with male wing length (a proxy for body size) being influenced by the developmental diet; males reared on carbohydrate-rich developmental diets had larger wings as adults. Fertility increased with protein-rich diets at both developmental and adult stages, reaffirming the critical role of dietary protein in enhancing reproductive success. Lifespan exhibited sexually dimorphic responses to diet: carbohydrate-rich developmental diets extended male lifespan, while carbohydrate-rich adult diets reduced lifespan in both sexes. Stress resistance traits, including starvation and desiccation resistance, were unaffected by developmental diets but were influenced by adult diets, with carbohydrate-rich adult diets enhancing survival under both stress conditions in males and females. Importantly, while most traits exhibited additive effects of nutrition across life stages, a marginal interaction for male starvation resistance suggests that developmental and adult diets can interact in a trait- and sex-specific manner. Moreover, associations between dietary effects on life-history traits were context-dependent, driven primarily by adult diets and varying by sex. These findings emphasize the profound role of stage-specific nutritional environments in modulating life-history traits and their correlations, offering valuable insights into how organisms may adapt to changing ecological conditions and highlighting the importance of considering both developmental and adult dietary contexts in evolutionary studies.

evolutionary biology↗

bioRxiv2024

White matter connections of human ventral temporal cortex are organized by cytoarchitecture, eccentricity, and category-selectivity from birth

Category-selective regions in ventral temporal cortex (VTC) have a consistent anatomical organization, which is hypothesized to be scaffolded by white matter connections. However, it is unknown how white matter connections are organized from birth. Here, we scanned newborn to 6-month-old infants and adults to determine the organization of the white matter connections of VTC. We find that white matter connections are organized by cytoarchitecture, eccentricity, and category from birth. Connectivity profiles of functional regions in the same cytoarchitectonic area are similar from birth and develop in parallel, with decreases in endpoint connectivity to lateral occipital, and parietal, and somatosensory cortex, and increases to lateral prefrontal cortex. Additionally, connections between VTC and early visual cortex are organized topographically by eccentricity bands and predict eccentricity biases in VTC. These data show that there are both innate organizing principles of white matter connections of VTC, and the capacity for white matter connections to change over development.

neuroscience↗

bioRxiv2024

Effect of developmental and adult diet composition on reproductive aging in Drosophila melanogaster

Diet significantly affects reproductive outcomes across species, yet the precise effects of macronutrient compositions beyond caloric intake on reproductive aging are understudied. Existing literature presents conflicting views on the fertility impacts of nutrient-rich versus nutrient-poor developmental diets, underscoring a notable research gap. This study addresses these gaps by examining effects of isocaloric diets with varied protein-to-carbohydrate ratios during both developmental and adult stages on reproductive aging of a large, outbred Drosophila melanogaster population (n = [~]2100). Our results clearly demonstrate an age-dependent dietary impact on reproductive output, initially dominated by the developmental diet, then by a combination of developmental and adult diets in early to mid-life, and ultimately by the adult diet in later life. Importantly, we found that the effects of developmental and adult diets on reproductive output are independent, with no significant interaction. Further investigations into the mechanisms revealed that the effect of developmental diet on fecundity is regulated via ovarioles formation and vitellogenesis; while, the effect of adult diet on fecundity is mostly regulated only via vitellogenesis. These insights resolve disputes in the literature about dietary impacts on fertility and offer valuable perspectives for optimizing fertility strategies in improving public health and conservation efforts in this changing world. HighlightsO_LIEffect of developmental and adult diet composition on reproduction is age-dependent C_LIO_LIDevelopmental diet affects early-life; adult diet late-life; and both affect mid-life C_LIO_LIBut the effect of developmental and adult diets do not interact with each other C_LIO_LIDevelopmental diet regulates reproduction via ovarioles formation and vitellogenesis C_LIO_LIWhereas, adult diet regulates reproduction via differential vitellogenesis across age C_LI

ecology↗

bioRxiv2024

Comparison of six methods for stabilizing metapopulation dynamics and for their robustness against census noise

Natural populations face growing extinction risks due to mismatches between traits and ecological conditions, exacerbated by habitat degradation and climate change. While several population control methods have been proposed to protect vulnerable populations, their effectiveness in spatially structured populations (metapopulations) and resilience to census inaccuracies remain unexplored. This study uses simulations to evaluate six control methods, originally designed to stabilize isolated populations, in metapopulations. We compared these methods across twelve ecological conditions based on three stability metrices and implementation costs. Without interventions, the twelve metapopulation scenarios exhibited distinct dynamics and extinction susceptibilities. Comparing the control methods against these baseline dynamics, we found that Adaptive Limiter Control consistently reduced extinction probabilities, while Lower Limiter Control effectively minimized population fluctuations in most settings, followed by Adaptive and Both Limiter Controls. These performance rankings remained robust despite simulated census errors. Our findings provide actionable insights for conservation policies aimed at stabilizing vulnerable metapopulations and offer a general framework for studying metapopulation dynamics using external interventions.

ecology↗

bioRxiv2023

Diet-induced plasticity of life-history traits and gene expression in outbred Drosophila melanogaster population

Food is fundamental for the survival of organisms, governing growth, maintenance, and reproduction through the provision of essential macronutrients. However, access to food with optimum macronutrient composition, which will maximize the evolutionary fitness of an organism, is not always guaranteed. This leads to dietary mismatches with potential impacts on organismal performance. To understand the consequences of such dietary mismatches, we examined the effects of isocaloric diets varying in macronutrient composition on eight key organismal traits spanning across the lifespan of a large outbred Drosophila melanogaster population (n [~] 2500). Our findings reveal that carbohydrate-reduced isocaloric diets correlates to accelerated pre-adult development and boosts reproductive output without impacting pre-adult viability and body size. Conversely, an elevated dietary carbohydrate content correlated to reduced lifespan in flies, evidenced by accelerated functional senescence including compromised locomotor activity and deteriorating gut integrity. Furthermore, transcriptomic analysis indicated a substantial difference in gene regulatory landscapes between flies subject to high carbohydrate vs high protein diet, with elevated protein levels indicating transcriptomes primed for reduced synthesis of fatty acids. Taken together, our study helps advance our understanding of the effect of macronutrient composition on life history traits and their interrelations, offering critical insights into potential adaptive strategies that organisms might adopt against the continual dietary imbalances prevalent in the rapidly evolving environment.

evolutionary biology↗

bioRxiv2023

When Do Visual Category Representations Emerge in Infants' Brains?

Organizing the continuous stream of visual input into categories like places or faces is important for everyday function and social interactions. However, it is unknown when neural representations of these and other visual categories emerge. Here we used steady state evoked potential electroencephalography to measure cortical responses in infants at 3-4 months, 4-6 months, 6-8 months, and 12-15 months, when they viewed controlled, gray-level images of faces, limbs, corridors, characters, and cars. We found that distinct responses to these categories emerge at different ages. Reliable brain responses to faces emerge first, at 4-6 months, followed by limbs and places around 6-8 months. Between 6-15 months response patterns become more distinct, such that a classifier can decode what an infant is looking at from their brain responses. These findings have important implications for assessing typical and atypical cortical development as they not only suggest that category representations are learned, but also that representations of categories that may have innate substrates emerge at different times during infancy.

neuroscience↗

bioRxiv2022

Selection for greater dispersal in early life leads to increased rate of age-dependent decline in locomotor activity and shorter lifespan

Locomotor activity is one of the major traits that is affected by age. Greater locomotor activity is also known to evolve in the course of dispersal evolution. However, the impact of dispersal evolution on the functional senescence of locomotor activity is largely unknown. We addressed this knowledge gap using large outbred populations of Drosophila melanogaster selected for increased dispersal. We tracked locomotor activity of these flies at regular intervals until a late age. Longevity of these flies was also recorded. We found that locomotor activity declines with age in general. However interestingly, activity level of dispersal selected populations never drops below the ancestry-matched-controls, despite the rate of age-dependent decline in activity of the dispersal selected populations being greater than their respective controls. Dispersal selected population was also found to have shorter lifespan as compared to its control, a potential cost of elevated level of activity throughout their life. These results are crucial in the context of invasion biology as contemporary climate change, habitat degradation, and destruction provide congenial conditions for dispersal evolution. Such controlled and tractable studies investigating the ageing pattern of important functional traits are important in the field of biogerontology as well.

evolutionary biology↗

bioRxiv2021

Desiccation stress acts as cause as well as cost of dispersal in Drosophila melanogaster

O_LIEnvironmental stress is one of the important causes of biological dispersal. At the same time, the process of dispersal itself can incur and/or increase susceptibility to stress for the dispersing individuals. Therefore, in principle, stress can serve as both a cause and a cost of dispersal. C_LIO_LIDesiccation stress is an environmentally relevant stress faced by many organisms, known to shape their population dynamics and distribution. However, the potentially contrasting roles of desiccation stress as a cause and a cost of dispersal have not been investigated. Furthermore, while desiccation stress often affects organisms in a sex-biased manner, it is not known whether the desiccation-dispersal relationship varies between males and females. C_LIO_LIWe studied the role of desiccation stress as a cause and cost of dispersal in a series of experiments using D. melanogaster adults in two-patch dispersal setups. We were interested in knowing whether (a) dispersers are the individuals that are more susceptible to desiccation stress, (b) dispersers pay a cost in terms of reduced resistance to desiccation stress, (c) dispersal evolution alters the desiccation cost of dispersal, and (d) females pay a reproductive cost of dispersal. For this, we modulated the degree of desiccation stress faced by the flies as well as the provision of rest following a dispersal event. C_LIO_LIOur data showed that desiccation stress served as a significant cause of dispersal in both sexes. Further investigation revealed an increase in both male and female dispersal propensity with increasing desiccation duration. Next, we found a male-biased cost of dispersal in terms of reduced desiccation resistance. This trend was preserved in dispersal-selected and non-selected controls as well, where the desiccation cost of dispersal in females was very low compared to the males. Finally, we found that the females instead paid a significant reproductive cost of dispersal. C_LIO_LIOur results highlight the complex relationship between desiccation stress and dispersal, whereby desiccation resistance can show both a positive and a negative association with dispersal. Furthermore, the sex differences observed in these trait associations may translate into differences in movement patterns, thereby giving rise to sex-biased dispersal. C_LI

ecology↗

bioRxiv2021

The Genetic Basis of Differential Autodiploidization in Evolving Yeast Populations

Spontaneous whole-genome duplication, or autodiploidization, is a common route to adaptation in experimental evolution of haploid budding yeast populations. The rate at which autodiploids fix in these populations appears to vary across strain backgrounds, but the genetic basis of these differences remains poorly characterized. Here we show that the frequency of autodiploidization differs dramatically between two closely related laboratory strains of Saccharomyces cerevisiae, BY4741 and W303. To investigate the genetic basis of this difference, we crossed these strains to generate hundreds of unique F1 segregants and tested the tendency of each segregant to autodiplodize across hundreds of generations of laboratory evolution. We find that variants in the SSD1 gene are the primary genetic determinant of differences in autodiploidization. We then used multiple laboratory and wild strains of S. cerevisiae to show that clonal populations of strains with a functional copy of SSD1 autodiploidize more frequently in evolution experiments, while knocking out this gene or replacing it with the W303 allele reduces autodiploidization propensity across all genetic backgrounds tested. These results suggest a potential strategy for modifying rates of spontaneous whole-genome duplications in laboratory evolution experiments in haploid budding yeast. They may also have relevance to other settings in which eukaryotic genome stability plays an important role, such as biomanufacturing and the treatment of pathogenic fungal diseases and cancers.

evolutionary biology↗

bioRxiv2019

Mate-finding dispersal reduces local mate limitation and sex bias in dispersal

O_LISex-biased dispersal (SBD) often skews the local sex ratio in a population. This can result in a shortage of mates for individuals of the less-dispersive sex. Such mate limitation can lead to Allee effects in populations that are small or undergoing range expansion, consequently affecting their survival, growth, stability and invasion speed. C_LIO_LITheory predicts that mate shortage can lead to either an increase or a decrease in the dispersal of the less-dispersive sex. However, neither of these predictions have been empirically validated. C_LIO_LITo investigate how SBD-induced mate limitation affects dispersal of the less-dispersive sex, we used Drosophila melanogaster populations with varying dispersal propensities. To rule out any mate-independent density effects, we examined the behavioral plasticity of dispersal in presence of mates as well as same-sex individuals with differential dispersal capabilities. C_LIO_LIIn the presence of high-dispersive mates, the dispersal of both male and female individuals was significantly increased. However, the magnitude of this increase was much larger in males than in females, indicating that the former show greater mate-finding dispersal. Moreover, the dispersal of either sex did not change when dispersing alongside high- or low-dispersive individuals of the same sex. This suggested that the observed plasticity in dispersal was indeed due to mate-finding dispersal, and not mate-independent density effects. C_LIO_LIStrong mate-finding dispersal can diminish the magnitude of sex bias in dispersal. This can modulate the evolutionary processes that shape range expansions and invasions, depending on the population size. In small populations, mate-finding dispersal can ameliorate Allee effects. However, in large populations, it can dilute the effects of spatial sorting. C_LI

ecology↗

bioRxiv2017

Evolution of dispersal syndrome and its corresponding metabolomic changes

Dispersal is one of the strategies for organisms to deal with climate change and habitat degradation. Therefore, investigating the effects of dispersal evolution on natural populations is of considerable interest to ecologists and conservation biologists. Although it is known that dispersal itself can evolve due to selection, the behavioral, life-history and metabolic consequences of dispersal evolution are not well understood. Here we explore these issues by subjecting four outbred laboratory populations of Drosophila melanogaster to selection for increased dispersal. The dispersal-selected populations had similar values of body size, fecundity and longevity as the non-selected lines (controls), but evolved significantly greater locomotor activity, exploratory tendency, and aggression. Untargeted metabolomic fingerprinting through NMR spectroscopy suggested that the selected flies evolved elevated cellular respiration characterized by greater amounts of glucose, AMP and NAD. Concurrent evolution of higher level of Octopamine and other neurotransmitters indicate a possible mechanism for the behavioural changes in the selected lines. We discuss the generalizability of our findings in the context of observations from natural populations. To the best of our knowledge, this is the first report of the evolution of metabolome due to selection for dispersal and its connection to dispersal syndrome evolution.

evolutionary biology↗

bioRxiv2017

Pre-dispersal conditions and presence of opposite sex modulate density dependence and sex bias of dispersal

Density-dependent dispersal (DDD) has been demonstrated in many species and has several ecological and evolutionary consequences. Yet we know little about how robust DDD is to the various conditions experienced by individuals. In this study, we use three independent experiments on laboratory populations of Drosophila melanogaster to examine the effects of pre-dispersal adult density, sex of the dispersers and presence of mates on the robustness of DDD patterns. We show that DDD can be greatly affected by both pre-dispersal density and interaction between the sexes. Moreover, the direction of sex-biased dispersal can reverse completely due to an interaction between the pre-dispersal and dispersal densities. We also show that interaction between the sexes can lead to negative DDD at the population level, even if, by themselves, neither sex exhibits DDD. Finally, we discuss potential implications of our results for processes like evolutionary rescue from extinctions and genetic divergence of populations.

ecology↗

bioRxiv2017

Understanding The Dynamics Of Laboratory Populations Of Drosophila melanogaster: Long-Term Experiments Meet Individual-Based Modelling

The dynamics of stage-structured populations facing variability in resource availability and/or demographic factors like unequal sex-ratios, remains poorly understood. We addressed these issues using a stage-structured individual-based model that incorporates life-history parameters common to many holometabolous insects. The model was calibrated using time series data from a 49-generation experiment on laboratory populations of Drosophila melanogaster, subjected to four different combinations of larval and adult nutritional levels. The model was able to capture multiple qualitative and quantitative aspects of the empirical time series across three independent studies. We then simulated the model to explore the interaction of various life-history parameters and nutritional levels in determining population stability. In all nutritional regimes, stability of the populations was reduced upon increasing egg-hatchability, critical mass and proportion of body resource allocated to female fecundity. However, the stability-effects of increasing sensitivity of female-fecundity to adult density varied across nutrition regimes. The effects of unequal sex-ratio and sex-specific culling were greatly influenced by fecundity but not by levels of juvenile nutrition. Finally, we investigated the implications of some of these insights on the efficiency of the widely-used pest control method, Sterile Insect Technique (SIT). We show that increasing the amount of juvenile food had no effects on SIT efficiency when the density-independent fecundity is low, but reduces SIT efficiency when the density-independent fecundity is high.

ecology↗