scholarly journals Eusociality and the evolution of aging in superorganisms

2021 ◽  
Author(s):  
Boris H. Kramer ◽  
Sander G van Doorn ◽  
Babak M. S. Arani ◽  
Ido Pen
Keyword(s):  
Natural Selection ◽  
Model Organisms ◽  
Evolutionary Divergence ◽  
Mortality Risks ◽  
Eusocial Insects ◽  
Aging Theory ◽  
Evolution Of Aging ◽  
Verbal Arguments ◽  
First Time ◽  
Sexual Offspring

Eusocial insects ants, bees, wasps and termites are being recognized as model organisms to unravel the evolutionary paradox of aging for two reasons: (1) queens (and kings, in termites) of social insects outlive similar sized solitary insects by up to several orders of magnitude; (2) all eusocial taxa show a divergence of long queen and shorter worker lifespans, despite their shared genomes and even under risk-free laboratory environments. Traditionally, these observations have been explained by invoking classical evolutionary aging theory: well-protected inside their nests, queens are much less exposed to external hazards than foraging workers, and this provides natural selection the opportunity to favor queens that perform well at advanced ages. Although quite plausible, these verbal arguments have not been backed up by mathematical analysis. Here, for the first time, we provide quantitative models for the evolution of caste specific aging patterns. We show that caste-specific mortality risks are in general neither sufficient nor necessary to explain the evolutionary divergence in lifespan between queens and workers and the extraordinary queen lifespans. Reproductive monopolization and the delayed production of sexual offspring in highly social colonies lead natural selection to inherently favor queens that live much longer than workers, even when exposed to the same external hazards. Factors that reduce a colony's reproductive skew, such as polygyny and worker reproduction, tend to reduce the evolutionary divergence in lifespan between queens and workers. Caste-specific extrinsic hazards also affect lifespan divergence but to a much smaller extent than reproductive monopolization.

scholarly journals Antifungals, arthropods and antifungal resistance prevention: lessons from ecological interactions

2021 ◽  
Vol 288 (1944) ◽  
pp. 20202716
Author(s):  
Steve Kett ◽  
Ayush Pathak ◽  
Stefano Turillazzi ◽  
Duccio Cavalieri ◽  
Massimiliano Marvasi
Keyword(s):  
Natural Selection ◽  
Conceptual Model ◽  
Antifungal Resistance ◽  
Antifungal Compound ◽  
Antifungal Compounds ◽  
Ecological Interactions ◽  
Eusocial Insects ◽  
Wide Range ◽  
Mutualistic Association

Arthropods can produce a wide range of antifungal compounds, including specialist proteins, cuticular products, venoms and haemolymphs. In spite of this, many arthropod taxa, particularly eusocial insects, make use of additional antifungal compounds derived from their mutualistic association with microbes. Because multiple taxa have evolved such mutualisms, it must be assumed that, under certain ecological circumstances, natural selection has favoured them over those relying upon endogenous antifungal compound production. Further, such associations have been shown to persist versus specific pathogenic fungal antagonists for more than 50 million years, suggesting that compounds employed have retained efficacy in spite of the pathogens' capacity to develop resistance. We provide a brief overview of antifungal compounds in the arthropods’ armoury, proposing a conceptual model to suggest why their use remains so successful. Fundamental concepts embedded within such a model may suggest strategies by which to reduce the rise of antifungal resistance within the clinical milieu.

Eusocial Insects as a Model for Understanding Altruism, Cooperation, and Levels of Selection

2020 ◽  
Author(s):  
Heikki Helanterä
Keyword(s):  
Natural Selection ◽  
Division Of Labor ◽  
Social Insect ◽  
Social Evolution ◽  
Inclusive Fitness ◽  
Family Structures ◽  
Major Transitions ◽  
Eusocial Insects ◽  
Insect Societies ◽  
Evolutionary Success

If the logic of natural selection is applied strictly at the level of individual production of offspring, sterile workers in insect societies are enigmatic. How can natural selection ever produce individuals that refrain from reproduction, and how are traits of such individuals that never produce offspring scrutinized and changed through natural selection? The solution to both questions is found in the family structures of insect societies. That is, the sterile helper individuals are evolutionary altruists that give up their own reproduction and instead are helping their kin reproduce and proliferate shared genes in the offspring of the fertile queen. Selection in such cases is not just a matter of individual’s direct reproduction, and instead of own offspring, the currency of the evolutionary success of sterile individuals is inclusive fitness. The concept of inclusive fitness and the process of kin selection are key to understanding the magnificent cooperation we see in insect societies, and reciprocally, insect societies are key case studies of inclusive fitness logic. In extreme cases, such as the highly advanced and sophisticated societies of ants, honeybees, and termites, the division of labor and interdependence of colony members is so complete, that it is justified to talk about a new level of evolutionary individuality. Such increases in the hierarchical complexity of life are called major transitions in evolution. We see adaptations of the colony, rather than individuals, in, e.g., their communication and group behaviors. The division of labor between morphologically differentiated queens and workers is analogous to germline-soma separation of a multicellular organism, justifying the term superorganism for the extreme cases of social lifestyle. Alongside these extreme cases, there is enormous diversity in the social lifestyles across social insect taxa, which provides a window into the balance of cooperation and conflict, and individual reproduction and helping others, in social evolution. Over the last decades, social insect research has been an area where the theoretical and empirical understanding have been developed hand in hand, together with examples of wonderful natural history, and has tremendously improved our understanding of evolution.

Time trends in incidence, comorbidity, and mortality of ischemic stroke in Denmark (1996–2016)

Neurology ◽  
2020 ◽  
Vol 95 (17) ◽  
pp. e2343-e2353
Author(s):  
Adelina Yafasova ◽  
Emil Loldrup Fosbøl ◽  
Mia Nielsen Christiansen ◽  
Naja Emborg Vinding ◽  
Charlotte Andersson ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Cox Regression ◽  
Initial Level ◽  
Age Groups ◽  
Incidence Rates ◽  
Lipid Lowering ◽  
Mortality Risks ◽  
Rate Ratios ◽  
New Treatments ◽  
First Time

ObjectiveTo examine whether the incidence, comorbidity, and mortality of first-time ischemic stroke changed in Denmark between 1996 and 2016 overall and according to age and sex using a nationwide cohort design.MethodsIn this cohort study, 224,617 individuals ≥18 years of age admitted with first-time ischemic stroke between 1996 and 2016 were identified through Danish nationwide registries. We calculated annual age-standardized incidence rates and absolute 30-day and 1-year mortality risks. Furthermore, we calculated annual incidence rate ratios using Poisson regression, odds ratios for 30-day mortality using logistic regression, and hazard ratios for 1-year mortality using Cox regression.ResultsThe overall age-standardized incidence rates of ischemic stroke per 1,000 person-years increased from 1996 (2.70 [95% confidence interval [CI] 2.65–2.76]) to 2002 (3.25 [95% CI 3.20–3.31]) and then gradually decreased to below the initial level until 2016 (1.99 [95% CI 1.95–2.02]). Men had higher incidence rates than women in all age groups except 18 to 34 and ≥85 years. Absolute mortality risk decreased between 1996 and 2016 (30-day mortality from 17.1% to 7.6% and 1-year mortality from 30.9% to 17.3%). Women between 55 and 64 and ≥85 years of age had higher mortality than men. Similar trends were observed for all analyses after multivariable adjustment. The prevalence of atrial fibrillation, hypertension, diabetes mellitus, and use of lipid-lowering medication increased during the study period.ConclusionsThe age-standardized incidence of first-time hospitalization for ischemic stroke increased from 1996 to 2002 and then gradually decreased to below the initial level until 2016. Absolute 30-day and 1-year mortality risks decreased between 1996 and 2016. These findings correspond to increased stroke prevention awareness and introduction of new treatments during the study period.

scholarly journals Transformation of internal head structures during the metamorphosis of Chrysopa pallens (Neuroptera: Chrysopidae)

2019 ◽  
Author(s):  
Chenjing Zhao ◽  
Yuchen Ang ◽  
Mengqing Wang ◽  
Caixia Gao ◽  
Kuiyan Zhang ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Pupal Stage ◽  
Model Organisms ◽  
Micro Computed Tomography ◽  
Muscular System ◽  
Dynamic Transformation ◽  
Morphological Differences ◽  
First Time ◽  
The Brain ◽  
Head Muscles

Abstract Background The metamorphosis is a complicated but very interesting process because of the highly dynamic transformation in sheath. Very few studies had coverage on the head muscles of larvae, pupae, and adults. Most of these studies were focusing on the model organisms about the rough changes of the external and internal tissues or the time of metamorphosis based on the traditional methods. In our study,the skeleto-muscular system of head, as well as the brain of Chrysopa pallens (Rambur, 1838) from larvae to adults are described in detail for the first time by the technology of micro computed tomography (µ-CT). The transformations of these systems during pupal stage are studied for the first time.Results The morphological differences and functional adaptations between the stages are assessed. Muscles are distinctly slender in larvae than in adults with a significantly larger quantity. A larger brain with improved sensory perception is suggested to be essential for dispersal, mating and flying for adults. For the pupae, the results show that the histolysis of the muscles happens in first third of the pupal period and their reconstruction happens in the following days. The brain exists all along.Conclusion We suggest the transformations of the skeleton occur earlier than the musculature. Most of the transformations are related to tasks they play in the developmental stages.

scholarly journals Visualizing Biological Membrane Organization and Dynamics

2019 ◽  
Author(s):  
Marc Baaden
Keyword(s):  
Nervous System ◽  
Natural Selection ◽  
Biological Membrane ◽  
Membrane Organization ◽  
Modern Biology ◽  
Biological Objects ◽  
First Time ◽  
Insect Eye ◽  
Camillo Golgi ◽  
Dioptric Apparatus

Biological membranes are fascinating. Santiago Ramón y Cajal, who received the Nobel prize in 1906 together with Camillo Golgi for their work on the nervous system, wrote “[..]in the study of this membrane[..] I felt more profoundly than in any other subject of study the shuddering sensation of the unfathomable mystery of life”[1]. The visualization and conceptualization of these biological objects have profoundly shaped many aspects of modern biology, drawing inspiration from experiments, computer simulations, as well as from the imagination of scientists and artists. The aim of this review is to provide a fresh look on current ideas of biological membrane organization and dynamics by discussing selected examples across fields [1] The full quotation is “I must not conceal the fact that in the study of this membrane I for the first time felt my faith in Darwinism (hypothesis of natural selection) weakened, being amazed and confounded by the supreme constructive ingenuity revealed not only in the retina and in the dioptric apparatus of the vertebrates but even in the meanest insect eye. There, in fine, I felt more profoundly than in any other subject of study the shuddering sensation of the unfathomable mystery of life.” from the autobiography Recollections of My Life.

scholarly journals Atypical chemoreceptor arrays accommodate high membrane curvature

2020 ◽  
Author(s):  
Alise R. Muok ◽  
Davi R. Ortega ◽  
Kurni Kurniyati ◽  
Wen Yang ◽  
Adam Sidi Mabrouk ◽  
...  
Keyword(s):  
Oxygen Sensor ◽  
Membrane Curvature ◽  
Model Organisms ◽  
Treponema Denticola ◽  
Signaling System ◽  
Dimerization Domain ◽  
Coupling Protein ◽  
Chemotaxis System ◽  
First Time

Abstract/SummaryThe prokaryotic chemotaxis system is arguably the best-understood signaling pathway in biology, but most insights have been obtained from only a few model organisms and many studies have relied on artificial systems that alter membrane curvature1–3. In all previously described species, chemoreceptors organize with the histidine kinase (CheA) and coupling protein (CheW) into a hexagonal (P6 symmetry) extended array that is considered universal among archaea and bacteria4,5. Here, for the first time, we report an alternative symmetry (P2) of the chemotaxis apparatus that emerges from a strict linear organization of CheA in Treponema denticola cells, which possesses arrays with the highest native curvature investigated thus far. Using cryo-ET, we reveal that the Td chemoreceptor arrays assume a truly unusual arrangement of the supra-molecular protein assembly that has likely evolved to accommodate the high membrane curvature. The arrays have several additional atypical features, such as an extended dimerization domain of CheA and a variant CheW-CheR-like fusion protein that is critical for maintaining an ordered chemosensory apparatus in an extremely curved cell. Furthermore, the previously characterized Td oxygen sensor ODP influences array integrity and its loss substantially orders CheA. These results suggest a greater diversity of the chemotaxis signaling system than previously thought and demonstrate the importance of examining transmembrane systems in vivo to retain native membrane curvature.

Evolution and Empire: Alfred Russel Wallace and Dutch Colonial Rule in Southeast Asia in the Mid-Nineteenth Century

2016 ◽  
Vol 9 (1) ◽  
pp. 55-75
Author(s):  
Mark Clement
Keyword(s):  
Natural Selection ◽  
Southeast Asia ◽  
Colonial Rule ◽  
Rapid Progress ◽  
Cultivation System ◽  
Cash Crops ◽  
Alfred Russel Wallace ◽  
Local Practices ◽  
Victorian Period ◽  
First Time

While Alfred Russel Wallace is sometimes remembered for his sympathy for ‘savages’, it has also been observed that he was closely associated with European colonial regimes during his long stint of fieldwork in Southeast Asia (1854–62). Moreover, it has been argued that as one of the first scientists to extend natural selection to humans following his return to Britain he acquiesced in the extinction of primitive peoples. This article examines in detail for the first time the development of Wallace's admiration for the Dutch Cultivation System, which combined paternalistic administration with a government monopoly over the production of cash crops. While travelling through the archipelago Wallace encountered numerous examples of Indo-Dutch creole culture and he himself made significant lifestyle adaptations to local practices. When he first observed the Cultivation System in the Minahasa region of northern Sulawesi Wallace experienced an epiphany as he witnessed the rapid progress towards ‘civilization’ made by former ‘savages’. This, he attributed to the Dutch system, which he believed to be well adapted to the principles of human mental and moral development. In advocating the Dutch model as a preferable alternative to British free trade and neglect of its civilising mission in India, Australia, and elsewhere, Wallace hoped not only to arrest the decline of primitive societies but also to promote the ultimate uniting of humankind in a single race. In the context of debates over human evolution, slavery, race, and imperial policy in Britain in the 1860s, this was an unusual and radical stance, which challenges simplistic representations of Wallace as a supporter of empire around mid-century who moved towards anti-imperialism in the late Victorian period.

The Island of Extremes: Giants and Dwarfs on a Small Remote Island

2021 ◽  
Vol 28 (4) ◽  
pp. 225-230
Author(s):  
Yuval Itescu ◽  
Johannes Foufopoulos ◽  
Rachel Schwarz ◽  
Petros Lymberakis ◽  
Alex Slavenko ◽  
...  
Keyword(s):  
Body Size ◽  
Natural Selection ◽  
Aegean Sea ◽  
Large Size ◽  
Size Evolution ◽  
Remote Island ◽  
Body Size Evolution ◽  
Remote Islands ◽  
First Time ◽  
Defensive Mechanism

Body size evolution on islands is widely studied and hotly debated. Gigantism and dwarfism are thought to evolve under strong natural selection, especially on small remote islands. We report a curious co-occurrence of both dwarf and giant lizards on the same small, remote island (Plakida): the largest Podarcis erhardii (Lacertidae) and smallest Mediodactylus kotschyi sensu lato; Gekkonidae — the two commonest insular reptiles in the Aegean Sea. The geckos of Plakida have a peculiar tail-waving behavior, documented here for the first time in this genus. We suspect that P. erhardii evolved large size to consume geckos and the geckos evolved a unique tail-waving behavior as a defensive mechanism.

scholarly journals What is Antagonistic Pleiotropy?

2018 ◽  
Author(s):  
Josh Mitteldorf
Keyword(s):  
Computer Simulation ◽  
Natural Selection ◽  
Environmental Conditions ◽  
Antagonistic Pleiotropy ◽  
High Fertility ◽  
Short Lifespan ◽  
Risk Of Extinction ◽  
Lower Fertility ◽  
Evolution Of Aging ◽  
Dominant Theory

AbstractAntagonistic Pleiotropy has been the dominant theory for evolution of aging since it was first proposed 60 years ago. Indeed, examples of pleiotropy have been observed, but there are also many examples of mutations that lead to longer lifespan without apparent cost. This poses a dilemma for the logic of the theory, which depends critically on the assumption that pleiotropy has imposed an inescapable precondition on evolution. Another interpretation is possible for the pleiotropy observed in nature. Natural selection may actually favor pleiotropy as an evolved adaptation. This is because the combination of high fertility and long lifespan is a temptation for individuals, but a danger for the health of populations. Predator populations that grow faster than their prey can recover are at risk of extinction. Once a sustainable mix of fertility and longevity has been established by multilevel natural selection, pleiotropy can help to assure that it is not lost. The population is free to shift from (high fertility/short lifespan) to (lower fertility/longer lifespan) as varying environmental conditions demand, without risking population overshoot and collapse. I describe herein experiments with an individual-based computer simulation in which pleiotropy evolves as a group-selected adaptation under a range of assumptions and in a broad swath of parameter space.

scholarly journals Inter-Molecular Electrostatic Interactions Stabilizing the Structure of the PD-1/PD-L1 Axis: A Structural Evolutionary Perspective

2020 ◽  
Author(s):  
Wei Li
Keyword(s):  
Natural Selection ◽  
Tumor Cell ◽  
Tumor Immunity ◽  
Electrostatic Interactions ◽  
Immune Escape ◽  
Complex Structure ◽  
Evolutionary Perspective ◽  
Binding Interface ◽  
First Time ◽  
Structural Hypothesis

PD-1/PD-L1 axis is one key therapeutic target against tumor cell immune escape. Structurally essential to the PD-1/PD-L1-linked immune escape is the binding interface of the PD-1/PD-L1 complex structure. Incorporating currently available PD-1/PD-L1-related experimental structures, this article unveils two sets of experimentally observed inter-molecular electrostatic interactions which stabilize the binding interface of the PD-1/PD-L1 complex structure. For the first time, this article proposes an evolutionary structural hypothesis that, as a result of natural selection, PD-1 is able to genetically mutate itself to structurally disrupt the PD-1/PD-L1 axis towards the restoration of T cell-mediated anti-tumor immunity.

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