scholarly journals Cost-free lifespan extension via optimization of gene expression in adulthood aligns with the developmental theory of ageing

2021 ◽  
Vol 288 (1944) ◽  
pp. 20201728
Author(s):  
Martin I. Lind ◽  
Hanne Carlsson ◽  
Elizabeth M. L. Duxbury ◽  
Edward Ivimey-Cook ◽  
Alexei A. Maklakov
Keyword(s):  
Gene Expression ◽  
Resource Allocation ◽  
Life Histories ◽  
Reproductive Period ◽  
Developmental Theory ◽  
Somatic Maintenance ◽  
Individual Fitness ◽  
Longevity Genes ◽  
Extended Lifespan ◽  
Reproduction Costs

Ageing evolves because the force of selection on traits declines with age but the proximate causes of ageing are incompletely understood. The ‘disposable soma’ theory of ageing (DST) upholds that competitive resource allocation between reproduction and somatic maintenance underpins the evolution of ageing and lifespan. In contrast, the developmental theory of ageing (DTA) suggests that organismal senescence is caused by suboptimal gene expression in adulthood. While the DST predicts the trade-off between reproduction and lifespan, the DTA predicts that age-specific optimization of gene expression can increase lifespan without reproduction costs. Here we investigated the consequences for lifespan, reproduction, egg size and individual fitness of early-life, adulthood and post-reproductive onset of RNAi knockdown of five ‘longevity’ genes involved in key biological processes in Caenorhabditis elegans . Downregulation of these genes in adulthood and/or during post-reproductive period increases lifespan, while we found limited evidence for a link between impaired reproduction and extended lifespan. Our findings demonstrate that suboptimal gene expression in adulthood often contributes to reduced lifespan directly rather than through competitive resource allocation between reproduction and somatic maintenance. Therefore, age-specific optimization of gene expression in evolutionarily conserved signalling pathways that regulate organismal life histories can increase lifespan without fitness costs.

scholarly journals Cost-free lifespan extension via optimisation of gene expression in adulthood supports the developmental theory of ageing

2019 ◽  
Author(s):  
Martin I. Lind ◽  
Hanne Carlsson ◽  
Edward Ivimey-Cook ◽  
Alexei A. Maklakov
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Reproductive Period ◽  
Developmental Theory ◽  
Nutrient Sensing ◽  
Selection Gradients ◽  
Trade Offs ◽  
Global Protein Synthesis ◽  
Longevity Genes ◽  
Energy Trade

SummaryClassic theory upholds that energy trade-offs between reproduction and somatic maintenance underpin the evolution of ageing and lifespan. In contrast, the developmental theory of ageing (DTA) suggests that organismal senescence is caused by dysregulated gene expression in adulthood due to decline in selection gradients with age. The DTA predicts that age-specific optimisation of gene expression can improve survival without fitness costs. Here we investigated consequences for survival, reproduction, egg size and fitness of early-life, adulthood and post-reproductive onset of RNAi knockdown of five well-described “longevity” genes involved in key biological processes in Caenorhabditis elegans nematodes: nutrient-sensing signalling via insulin/IGF-1 (age-1) and target-of-rapamycin (raga-1) pathways, global protein synthesis (ifg-1), global protein synthesis in somatic cells (ife-2) and mitochondrial respiration (nuo-6). Downregulation of these genes in adulthood and/or during post-reproductive period improves survival, while there was little evidence for a link between impaired reproduction and extended lifespan. Our findings demonstrate that hyper-function of diverse physiological processes after sexual maturation is detrimental for survival. Therefore, optimisation of gene expression in adult organisms can ameliorate ageing and increase fitness.

scholarly journals Protein Complexes Detection Based on Node Local Properties and Gene Expression On PPI Weighted Networks

2021 ◽  
Author(s):  
Yang Yu ◽  
Dezhou Kong
Keyword(s):  
Gene Expression ◽  
Resource Allocation ◽  
Protein Complex ◽  
Protein Complexes ◽  
Second Order ◽  
Topological Properties ◽  
Ppi Network ◽  
Weighted Networks ◽  
Gene Expression Information ◽  
Local Properties

Abstract Background Identifying protein complexes from protein–protein interaction (PPI) networks is a crucial task, and many related algorithms have been developed to solve this issue. These algorithms usually consider a node’s direct neighbors and ignore resource allocation and second-order neighbors. The effective use of such information is crucial to protein complex detection.Results To overcome this deficiency, this paper proposes a new protein complex identification method based on node-local topological properties and gene expression information on a new weighted PPI network, named NLPGE-WPN (joint node-local topological properties and gene expression information on weighted PPI network). First, based on the resource allocation of the PPI network and gene expression, a new weight metric is designed to describe the interaction between proteins. Second, our method constructs a series of dense complex cores based on density and network diameter constraints; the final complexes are recognized by expanding the second-order neighbor nodes of core complexes. Experimental results demonstrate that this algorithm has improved the performances of precision and f-measure, which is more valid in identifying protein complexes．Conclusions This identification method is simple and can accurately identify more complexes by integrating node-local properties and gene expression on PPI weighted networks.

scholarly journals Transcriptomic signatures of ageing vary in solitary and social forms of an orchid bee

2020 ◽  
Author(s):  
Alice C. Séguret ◽  
Eckart Stolle ◽  
Fernando A. Fleites-Ayil ◽  
José Javier G. Quezada-Euán ◽  
Klaus Hartfelder ◽  
...  
Keyword(s):  
Gene Expression ◽  
Juvenile Hormone ◽  
Candidate Genes ◽  
Gene Networks ◽  
Life Histories ◽  
Molecular Mechanisms ◽  
Trade Off ◽  
Eusocial Insects ◽  
Orchid Bee ◽  
Social Forms

AbstractEusocial insect queens are remarkable in their ability to maximise both fecundity and longevity, thus escaping the typical trade-off between these two traits. In species exhibiting complex eusocial behaviour, several mechanisms have been proposed to underlie the remoulding of the trade-off, such as reshaping of the juvenile hormone pathway, or caste-specific susceptibility to oxidative stress. However, it remains a challenge to disentangle the molecular mechanisms underlying the remoulding of the trade-off in eusocial insects from caste-specific physiological attributes that have subsequently arisen due to their different life histories. Socially plastic species such as the orchid bee Euglossa viridissima represent excellent models to address the role of sociality per se in longevity as they allow direct comparisons of solitary and social individuals within a common genetic background. We present data on gene expression and juvenile hormone levels from young and old bees, from both solitary and social nests. We found 940 genes to be differentially expressed with age in solitary females, versus only 14 genes in social dominant females, and seven genes in subordinate females. We performed a weighted gene co-expression network analysis to further highlight candidate genes related to ageing in this species. Primary “ageing gene” candidates were related to protein synthesis, gene expression, immunity and venom production. Remarkably, juvenile hormone titres did not vary with age or social status. These results represent an important step in understanding the proximate mechanisms underlying the remodeling of the fecundity/longevity trade-off that accompanies the evolutionary transition from solitary life to eusociality.Significance statementThe remarkably long lifespan of the queens of eusocial insects despite their high reproductive output suggests that they are not subject to the widespread trade-off between fecundity and longevity that governs solitary animal life histories, yet surprisingly little is known of the molecular mechanisms underpinning their longevity. Using a socially plastic bee in which some individuals of a population are social whilst others are solitary, we identified hundreds of candidate genes and related gene networks that are involved in the remoulding of the fecundity/longevity tradeoff. As well as identifying candidate ageing genes, our data suggest that even in incipient stages of sociality there is a marked reprogramming of ageing; long live the queen.

Evolution of Sociality and Nonlinear Population Dynamics

2020 ◽  
pp. 100-113
Author(s):  
Daniel Oro
Keyword(s):  
Population Dynamics ◽  
Cultural Transmission ◽  
Life Histories ◽  
Minimum Size ◽  
Stable States ◽  
Individual Fitness ◽  
Social Species ◽  
Strong Source ◽  
Adaptive Behaviours ◽  
Threshold Setting

Sociality appears in many life histories during evolution. Some eusocial bees show evolutionary reversions to solitary behaviour, and populations of the same species can be solitary or social, likely depending on local environmental features. Social species need a minimum size to perform adaptive behaviours, such as the search for resources, which is crucial especially under perturbations. This minimum size may become a threshold, setting a phase transition for separating two stable states, from disorganized and maladaptive to organized and adaptive, which also shows hysteresis. The chapter also explores evolution via facilitation or cooperation (e.g. social information) under the theoretical framework of multilevel selection, by which there is likely an effect of the social group’s genes on individual fitness. Perturbations appear as a strong source of evolutionary processes. In humans, warfare acts as a very powerful selective pressure for competition between groups and thus for cooperation. Sociality has also many costs, such as a higher risk for the spread of infectious disease, the appearance of traps by social haunting philopatry, stronger aggression and competition, and a higher risk of being attacked by predators. Finally, the evolution of cultures is explored; optimization of social learning, social copying, and cultural transmission may have nonlinear consequences for population dynamics.

scholarly journals Bet-hedging across generations can affect the evolution of variance-sensitive strategies within generations

2019 ◽  
Vol 286 (1916) ◽  
pp. 20192070 ◽  
Author(s):  
Thomas R. Haaland ◽  
Jonathan Wright ◽  
Irja I. Ratikainen
Keyword(s):  
Life Histories ◽  
Environmental Variability ◽  
Geometric Mean ◽  
Simulation Models ◽  
Arithmetic Mean ◽  
Bet Hedging ◽  
Individual Fitness ◽  
Mean Fitness ◽  
Selection For ◽  
Independent Decision

In order to understand how organisms cope with ongoing changes in environmental variability, it is necessary to consider multiple adaptations to environmental uncertainty on different time scales. Conservative bet-hedging (CBH) represents a long-term genotype-level strategy maximizing lineage geometric mean fitness in stochastic environments by decreasing individual fitness variance, despite also lowering arithmetic mean fitness. Meanwhile, variance-prone (aka risk-prone) strategies produce greater variance in short-term payoffs, because this increases expected arithmetic mean fitness if the relationship between payoffs and fitness is accelerating. Using evolutionary simulation models, we investigate whether selection for such variance-prone strategies is counteracted by selection for bet-hedging that works to adaptively reduce fitness variance. In our model, variance proneness evolves in fine-grained environments (lower correlations among individuals in energetic state and/or payoffs), and with larger numbers of independent decision events over which resources accumulate prior to selection. Conversely, multiplicative fitness accumulation, caused by coarser environmental grain and fewer decision events selection, favours CBH via greater variance aversion. We discuss examples of variance-sensitive strategies in optimal foraging, migration, life histories and cooperative breeding using this bet-hedging perspective. By linking disparate fields of research studying adaptations to variable environments, we should be better able to understand effects of human-induced rapid environmental change.

scholarly journals From stochastic environments to life histories and back

2009 ◽  
Vol 364 (1523) ◽  
pp. 1499-1509 ◽  
Author(s):  
Shripad Tuljapurkar ◽  
Jean-Michel Gaillard ◽  
Tim Coulson
Keyword(s):  
Life History ◽  
Growth Rates ◽  
Life Histories ◽  
Life History Evolution ◽  
Environmental Stochasticity ◽  
Vital Rates ◽  
Stochastic Growth ◽  
Individual Fitness ◽  
History Evolution ◽  
Average Individual

Environmental stochasticity is known to play an important role in life-history evolution, but most general theory assumes a constant environment. In this paper, we examine life-history evolution in a variable environment, by decomposing average individual fitness (measured by the long-run stochastic growth rate) into contributions from average vital rates and their temporal variation. We examine how generation time, demographic dispersion (measured by the dispersion of reproductive events across the lifespan), demographic resilience (measured by damping time), within-year variances in vital rates, within-year correlations between vital rates and between-year correlations in vital rates combine to determine average individual fitness of stylized life histories. In a fluctuating environment, we show that there is often a range of cohort generation times at which the fitness is at a maximum. Thus, we expect ‘optimal’ phenotypes in fluctuating environments to differ from optimal phenotypes in constant environments. We show that stochastic growth rates are strongly affected by demographic dispersion, even when deterministic growth rates are not, and that demographic dispersion also determines the response of life-history-specific average fitness to within- and between-year correlations. Serial correlations can have a strong effect on fitness, and, depending on the structure of the life history, may act to increase or decrease fitness. The approach we outline takes a useful first step in developing general life-history theory for non-constant environments.

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