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The role of microbial cooperation in the development of higher level organisation

István Zachar and Gergely Boza, researchers of the Institute of Evolution, ELKH Centre for Ecological Research (ÖK) investigated the role of cooperative interactions among microbial cells in the development of higher levels of organisation. They identified the selection forces that facilitate or inhibit microbial community formation, reproduction and the possible emergence of higher levels of selection and evolution. The study of their results has been published in the prestigious international journal Frontiers in Ecology and Evolution.

Microbial communities consist of unicellular organisms, often of species from different domains eukaryotes, bacteria or archaea. Examples are biofilms, the common lifeform of prokaryotes, that form on any surface, on rocks in riverbeds, on the roots of plants, on the skin of animals and humans, or on the inner surface of the digestive system. These communities are usually highly diverse but interactions are mostly limited to the immediate neighbourhood of cells.

One of the most common interactions among microbes and in microbial communities is metabolite-mediated cooperation, whereby cells leak various products into their environment, which can diffuse over small distances. These molecules may serve as food for others or antibiotics, enzymes or signal molecules, that may mediate higher-order interactions between cells, ultimately facilitating or inhibiting the partner’s reproduction.

Metabolic interactions based on mutual assistance and cooperation – such as syntrophy, or cross-feeding – are widespread among microbes and are crucial for the formation, functioning and maintenance of these communities, probably also responsible for the unculturabiolity of many prokaryotes. However, products are usually costly to produce and can easily be diluted or are subject to exploitation by free-riders.

The most effective form of metabolic cooperation between different species is symbiosis, in particular endosymbiosis, where one cell physically relocates into the other. While this is an obvious way of stabilising the mutually beneficial relationships so common among microbes, only one such (presumed) case is known so far. Mitochondria, a crucal eukaryotic acquisition, have evolved to cellular organelles via endosymbiosis, when a bacterium moved into an archaeal host, about 2 billion years ago. Some theories suggest that this highly successful relationship emerged from an already existing mutually beneficial metabolic syntrophy between partners. However, no syntrophic relationship approximating endosymbiosis is known at all among any two modern prokaryotes (unicells lacking a nucleus). The emergence of eukaryotes from prokaryotic ancestors was a major evolutionary transition, during which cells lost their autonomy and created a new evolutionary unit responsible for the macroscopic living world around us. Although syntrophy is extremely widespread in the prokaryotic world, we know of no demonstrable case leading to a major transition, syntrophic, endosymbiotic or other. Why is it that prokaryotes are seemingly not able to “level up”? Why do we not see more major transitions in the prokaryotic domain? Why do we not see a transiton in individuality in microbial biofilms, as it has happened multiple times independently in case of eukaryotic multicellularity?

In their studies, the researchers of ÖK have categorised selection forces according to which ones facilitate and which ones hinder the establishment, reproduction and possible higher organisation of microbial communities. They have taken into account the community characteristics: species composition, coupled metabolism, metabolic functions, community building and interaction patterns. Some of these can be stably maintained in by certain microbial communities, and may also reappear when new communities are formed. If communities can also transmit minor changes, it is capable of informational inheritanceing. If bacterial colonies have such an adaptive property, it may be stably maintained in the population, for example in new colonies that bud off from the parent colony. If this trait provides a selective advantage to the colony, it should be maintained through higher level, e.g. group selection. This would be the first step towards a prokaryotic major transition. However, due to the high variability of bacterial communities (and their composition), the chances of this happening are low, and we do not yet see convincing examples.

An alternative solution, the researchers suggest, is for the loose interaction network to lead to tight pairwise symbiosis through higher levels of selection. A textbook example of this is endosymbiosis, the engulfment of a cell by another cell, which is common in eukaryotes but unknown in the prokaryotic world except for the origin of the mitochondrion. Prokaryotes seem to have been given the opportunity to move to a higher level of organisation only once. It is this fruitful relationship that has led us to read these lines.

Publication:
Zachar, I. and Boza, G. (2022). The Evolution of Microbial Facilitation: Sociogenesis, Symbiogenesis, and Transition in Individuality. Front. Ecol. Evol. 10:798045. doi: 10.3389/fevo.2022.798045

Source: elkh.org

News

The Ecology of Spider Sociality: A Spatial Model

Zsóka Vásárhelyi and István Scheuring, researchers at the Institute of Evolution, Centre for Ecological Research, and Leticia Avilés, a researcher at the University of British Columbia, studied the geographical distribution of spiders with varying levels of sociality by modelling the Eastern slopes of the Andes in a computer simulation. They have shown that the ecological characteristics of a given habitat fundamentally determine whether social or subsocial species live in that habitat. The study presenting the results was published in the journal American Naturalist.

Spiders are typically known as solitary and aggressive animals, yet there exists a handful of spider species in the tropics where closely related individuals live in a common web. They maintain their dense, three-dimensional web together, they subdue and consume their prey together, and they care for the offspring together. These species are called social spiders. Their study may contribute, among others, to a deeper understanding of the evolutionary and ecological background of social behaviour.

It was empirically observed that with increasing altitude and latitude social spider species are being replaced by less cooperative, subsocial species, which, although characterised by long maternal care, do not show extensive social behaviour. The question naturally arises, what factors shape these geographical species distributions.

In the corresponding literature two separate hypotheses were offered to explain this pattern. According to the Prey Size Hypothesis, a common web (and a social lifestyle) is only worth maintaining where a sufficient amount of large prey are available. Although the surface-volume ratio of the web decreases with the size of the colony, the size of the prey items, available only for cooperating collectives, can compensate for this effect.

In contrast, the Disturbance Hypothesis suggests that where the environment is strongly disturbed (by wind, rain, or predators), solitary individuals cannot reproduce stably. This is because the dense three-dimensional web, characteristic of these species, is very expensive to maintain. If the mother is unable to care for her offspring long enough, for example, because of the energy loss due to web maintenance, the offspring will die before maturing. Thus, the two hypotheses suggest that the distribution of social species is limited by the size of the prey and that of the subsocial species by the degree of disturbance.

The researchers in their latest study modelled the Eastern slopes of the Andes with a computer simulation, incorporating the respective environmental gradients (changes in the maximum size of prey animals and the degree of disturbance). They then placed several social and subsocial “virtual colonies” into this modelled habitat, and observed which species survived in which environment, with what success.

The model illustrates well that together the prey size and the level of disturbance can indeed re-generate the naturally occurring distribution patterns. The researchers have shown that high disturbance is not only responsible for destroying small colonies, but can also have a potentially stabilising effect, especially in the largest colonies. The results suggest that the ecological characteristics of a given habitat may have a significant impact on the social behaviour of the species living there.

Image: A social spider colony and some of its members (top right). The images show one of the species that inspired the study (Anelosimus eximius). The photo was taken by L. Aviles in Equador.

Source: elkh.org

News

Spectral sensitivity transition in the compound eyes of a twilight-swarming mayfly and its visual ecological implications

Researchers of the ELKH Centre for Ecological Research, Institute of Aquatic Ecology and the Institute of Biology of Eötvös Loránd University (ELTE) studied the spectral sensitivity of mayflies during their larval and adult life stages. Using electroretinography, they showed that the visual system of the virgin mayfly (Ephoron virgo), a protected species in Hungary, adapts to changes in light conditions during development.
The study, which presents their results, was published in Proceedings of the Royal Society B.

Larvae of the virgin mayflies hatch from the eggs around April, they feed on organic material in the river bottom and develop until the swarming period, which takes place late summer. Swarming starts after sunset during twilight. The larvae float to the surface, where they emerge. The males undergo an additional moult, and after mating, the
fertilized females fly a few kilometres upstream above the river so that the eggs become laid into the water approximately at the same place where the previous generations developed.

The swarming of the virgin mayfly is restricted to a relatively short time frame during twilight, when the environment is almost completely dark for the human eye, but the scattered light of the sun still dominates the sky. At this time the content ratio of blue and ultraviolet photons compared to longer wavelength components is the
highest in the skylight.

In their most recent study, the researchers measured the spectral sensitivity of the compound eyes of larvae and adults of the virgin mayfly with electroretinography and found significant differences between these life stages. “The larval eyes were mostly sensitive to the green spectral range, while the eyes of the adults had a sensitivity
maximum in the ultraviolet” said Ádám Egri, research fellow at the Institute of Aquatic Ecology, the first author of the study.

The virgin mayfly develops underwater, where the short wavelength light is filtered out in the turbid water. This means that the green, yellow and red wavelengths are dominating this underwater world. Thus it is advantageous for the larvae to have eyes being primarily sensitive to the green spectral range.

Using webcams images, the researchers determined that the virgin mayfly typically swarms between solar elevations of 14 and 7 degrees below the horizon, when the content ratio of ultraviolet and green photons is the
highest in the skylight. Thus, the primarily ultraviolet-sensitive eyes of adults suggests adaptation to the light conditions of the twilight.

“We have previously shown that the virgin mayfly is mostly attracted to ultraviolet and blue light, which is in accordance with our new results” said György Kriska, associate professor at ELTE, who began to study the mass swarming and the streetlight-induced mass perishment of mayflies in 2012.

The mass perishment of the virgin mayfly at illuminated areas, e.g. bridges, is a well-known phenomenon, which can be reduced by the correct choice of the spectrum of outdoor lighting. Most short-wavelength light sources, such as the bluish cold-white LEDs, attract far more mayflies than the yellowish, warm-white LEDs which emit
light primarily in the longer-wavelength spectral range.

Thus, these results support the general agreement that long-wavelength artificial light cause the least ecological damage to the environment.

Photo: Imre Potyó

Source: elkh.org

News

Eurasian crane (Grus grus) as ecosystem engineer in grasslands

Ecosystem engineer organisms alter the local environmental conditions and resource distribution in a way that they create and maintain habitats or microhabitats for other organisms. The engineered patches are characterised by different structure and functioning compared to the surrounding habitats. Well-known ecosystem engineers include corals that create reef habitats or beavers that literally engineer whole landscapes. Among birds, woodpeckers are well-known engineers that create nesting places for many other birds. In grasslands, the ecosystem engineering effect of birds has been largely unknown. Members of the CER IEB ‘Lendület’ Seed Ecology Research Group studied this interesting phenomenon and published their results recently in the journal Land Degradation and Development.

They studied a large, iconic bird species, the Eurasian crane (Grus grus) which is a protected species across Europe. The global crane population – thanks to the conservation efforts, wetland restoration projects and to the ability of cranes to coexist with intensive agricultural practices –shows a growing trend. Because of this population increase, it is possible that the effects of cranes on natural ecosystems will also amplify, that is why it is timely and important to evaluate the effects of this large bird on the grassland ecosystems.
Hungary is an important stopover area during the migration of cranes. During autumn, 100,000 – 160,000 birds spend a few weeks in the lowland areas of East-Hungary. Cranes are usually foraging on maize stubbles on crop residue, but regularly visit grasslands where they forage on invertebrates. In grasslands they perform a special feeding habit called ‘crane-ploughing’: they heavily disturb the soil surface with their bill and remove the vegetation. The disturbed surface resembles to a ploughed area and their size range from a few square metres to a few hectares. These are characteristic landmarks in Hungarian alkaline grasslands, but until this recently published study, their ecological function was unknown.

The researchers compared the vegetation of crane-disturbed patches and undisturbed alkaline grasslands in the Hortobágy National Park. They found that the disturbed surfaces were characterised by different structure and function compared to the undisturbed patches. The pioneer vegetation on the disturbed patches sprouted earlier than in the undisturbed grasslands, and was characterised by short-lived plant species and forbs. The crane-ploughed patches harboured more species and a different species composition compared to the undisturbed grasslands.

There were important trade-offs between the positive and negative effects of the foraging activity of cranes on different structural and functional components of the ecosystems. The abundance and species richness of insect-pollinated plants increased on the disturbed patches which suggests that these areas offer important nectar sources for pollinators in the otherwise grass-dominated habitat. The early sprouting vegetation on the disturbed patches probably provides important forage source for the livestock early in the season, but in the dry summer period the forage quality value decreases considerably.

The study showed that foraging cranes have a fundamental effect on the structure and functioning of alkaline grassland ecosystems, by creating patches with altered vegetation composition and ecosystem functioning. This impressive ecosystem engineering is the result of a few-week long foraging, and even though the disturbance is temporal, its effect may last for many years.

Valkó, O., Borza, S., Godó, L., Végvári, Z., Deák, B. (2022) Eurasian crane (Grus grus) as ecosystem engineer in grasslands ‒ conservation values, ecosystem services and disservices related to a large iconic bird species. Land Degradation and Development https://doi.org/10.1002/ldr.4314

News

Science and pseudoscience, art and dilettantism – on pandemics

How does a good scientist and a good artist recognize that a new and significant value has been created in their field?
Why is it that this cannot always be immediately recognized in science and art? There is still an objective algorithm in science controlling quality: do we still believe it is objective? Are there paradigm shifts in modern science? What are the characteristic features of pseudoscience? Can we still trust in the wisdom of time that will separate art and pseudo-art, science and pseudoscience, the real and the false? What does success and popularity prove? Do critics, aesthetes, and other gatekeepers still guard any entrances? An art historian, literary critic, fine artist, and a research biologist look for answers and ask each other questions.

Brigitta Muladi, art historian
Ferenc László, literary critic
Tayler Patrick, artist
Gábor Földvári, research biologist

Concert: HIPERKARMA

Source: Garden on the cube

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Urbanization, anthropods and biological defense – natural control of insect pests is weaker in inhabited areas

At least half of the insect species on our planet feed on plants (i.e., herbivores). Insect pests among them pose one of the greatest threats to both cultivated and naturally occurring plants. Regulating their numbers is therefore essential for both the economy and plant health. Unfortunately, pest control in most ecosystems relies primarily on the use of synthetic chemicals, which cause significant damage to the environment and human health. To mitigate these adverse effects, environmentally friendly methods are needed, especially in cities where more than half of the world’s population lives.

The biological defense mechanism is one of the most important features provided by biodiversity, with an estimated economic value of more than $ 400 billion annually worldwide. Biological control of pest insects is provided by natural enemies, helping to keep the size of their populations below a threshold where they can no longer be considered pests. Natural enemies can be predators that kill and consume their prey, such as ladybugs feeding on aphids, or so-called parasitoids whose larvae parasitize and thus kill the host, such as ichneumon wasps that lay eggs on caterpillars.

The impact of cities on this feature of the ecosystem was examined in a global study by an international research team from the Centre for Ecological Research (Hungary), the Technical University of Munich (Germany) and the National Agricultural Research Institute (France). Their results were published in the international journal Science of the Total Environment.

The researchers used a statistical method called meta-analysis, which combines the results of several scientific papers on the same issue. Fifty-two studies were conducted in different cities around the world. Compared to more natural rural areas, urban areas have been found to have higher numbers of insect pests that feed on plant sap ( that is, insects that suck plant sap with their piercing-sucking oral organs, such as aphids and shield lice) while the number of their natural enemies of arthropods with poor propagation was lower. Researchers have also shown that the level of biological regulation provided by arthropods has weakened as the rate of urbanization has increased.

Their results show that natural regulation of plant-sap-feeding pest populations is not effective enough in cities. The first author of the study, Dr. Dávid Korányi, a researcher at the Centre for Ecological Research, said: “These insects are one of the most problematic plant pests in cities, as they can severely degrade plants and produce large amounts of honeydew from plants that result in sticky sidewalks and other surfaces. The results suggest that natural enemies, in particular predators with poorer transmission capacity (such as earwigs and some beetles), may play a significant role in the effective biological defense against pest insects.

The leader of the study, Dr. Péter Batáry, a scientific advisor at the Centre for Ecological Research, said: “We can help these beneficial arthropods with more cohesive and less intensively treated, more natural green spaces in cities. For example, diverse vegetation (including trees, shrubs, and taller herbs), less mowing, preserving moorlands and dead trees provide them with hiding places and a suitable environment, contributing to their continued presence in urban areas as well.

Accordingly, this study urges the development of nature-based solutions and the reduction of artificial surfaces in cities to restore ecological communities and their functioning, thereby reducing the ecological footprint of urbanization.

Source: Science of The Total Environment

News

New EASAC Report on European Regenerative Agriculture

The European Academies’ Science Advisory Council (EASAC), the Hungarian Academy of Sciences (HAS) and the Academia Europaea Budapest Knowledge Hub will present the EASAC’s latest report “Regenerative Agriculture in Europe” at a jointly organised public symposium on 6 April, in the main building of the HAS.

The concept of regenerative agriculture aims to create sustainable, resilient, healthy, equitable and climate-friendly food systems. It can be defined as a system of farming principles and practices that, while maintaining agricultural productivity, seeks to increase biodiversity, enrich soils, restore watersheds and improve ecosystem services, including increasing the carbon sequestration potential.
The European Academies’ Science Advisory Council (EASAC) prepared its report on this wide range of issues, which will published on 5 April 2022, and then presented at a public event in Budapest, on Wednesday 6 April at the Hungarian Academy of Sciences, and in Stockholm, on Thursday 7 April at the Royal Swedish Academy of Agricultural Sciences.

The report has been prepared by a dedicated expert working group within the EASAC Environment Steering Panel. The 26-member working group, whose members were nominated by EASAC member academies, worked on the issue for a year. Hungarian experts are regularly nominated to EASAC expert working groups by HAS as an EASAC member academy. In this way a Hungarian researcher, Orsolya Valkó (Centre for Ecological Research), was nominated to the working group on regenerative agriculture. Orsolya Valkó participated as co-chair of the working group, the other co-chair being Lars Walloe, Chair of the EASAC Environmental Steering Panel.

The public session, chaired by Széchenyi Prize winner HAS member Gábor Stépán, will be opened on behalf of the HAS by Ervin Balázs, Chairman of the Department of Agricultural Sciences, followed by a series of speeches by academics and researchers – Lars Walloe, Orsolya Valkó, Thomas Elmquist, Anders Wijkman, Diána Ürge-Vorsatz – who will not only present the report in a narrow sense, but also shed light on the policy implications and the wider links with climate policies. The academic event will be available live on the HAS’s YouTube channel.

Source: MTA

News

Inspiration and intuition in the light of music and evolution

30 April 2022 – Scholarly discussion, garden picnic and jazz concert during tulip blossom.
Is there a cultural evolution, namely are there similar processes operating behind the changes in fashions and habits as those that drive the living world?
Can inspiration be created by a machine or is it exclusively human?
What are the physical, biological and cultural influences that determine the concept of “musical beauty”?

Company on the cube

Evolutionary biologist András Szilágyi, music historian Ádám Bősze and journalist András Stumpf explore in their conversation the above questions: to some they know the answers already, some they suspect, and for some they can offer the thrill of asking the question.

Concert Binder Trio

Károly Binder, pianist, composer and head of department at the Liszt Ferenc Academy of Music
Tamás Hidász, drummer with a master’s degree, prize-winner of international jazz competitions
Tibor Fonay jazz bassist – Junior Príma award-winning musician, permanent member of several well-known Hungarian ensembles

Source: Kert a köbön

News

Drought is one of the greatest ecological threats of the coming decades

In a recent study published in the prestigious journal Nature Ecology & Evolution, researchers from the ELKH Centre for Ecological Research (CER) compared the results of field experiments on the consequences of droughts with data from actual drought observations in a global synthesis. The researchers found that although the experiments themselves predicted serious consequences, the data from observations far outweighed them.

The consequences of rapid climate change are relatively slow to emerge on a human scale, and the effects can often be masked by other processes, making it difficult to assess the ecological impacts of climate change. Researchers most often take one of two approaches: they observe natural phenomena and try to link changes in biota to changes in climate, for example, or they carry out field experiments to try to reproduce a particular component of climate change.

Both methods have their advantages and limitations. Experiments can be used to artificially accelerate the process of climate change, so that we do not have to wait 50-100 years to see the effects, as opposed to observing them continuously. An additional advantage of the experiments is that the effects of different elements of the climate can be investigated simultaneously under several scenarios and in isolation. The advantage of observations is that they show real changes, but we cannot be sure that the observed changes are caused by the changing climate.

In the current study, the CER researchers investigated the reliability of field experiments simulating the effects of drought, a method that has recently become more widespread, as one of the greatest threats to human life and wildlife in the coming decades will be the increasing frequency of droughts. They conclude that the experiments significantly underestimate the effects of droughts and may show a more positive vision of the future. This is probably due to the small size of the field experiments and the fact that the experiments only simulate a lack of precipitation, whereas in real droughts the weather is warmer, sunnier and drier. The researchers argue that the impact of natural droughts is a better indicator of the likely consequences of future droughts.

“The agricultural and ecological importance of drought is very high. If there is not enough rainfall in summer, yields are lower and the natural vegetation’s ability to store carbon is reduced. Total precipitation in Hungary is not expected to decrease, but summers will be drier and precipitation will be more unevenly distributed throughout the year. In other words, the same amount of precipitation will be seen in the form of less, but more intense rainfall,” said György Kröel-Dulay, head of the Experimental Vegetation Ecology Research Group at the CER Institute of Ecology and Botany, first author of the study. He added: “Southern Europe will become drier and northern Europe wetter. Since Hungary is on the border between the two regions, there is more uncertainty about the future of the climate here.”

“As we emphasise in our study, there is no suggestion that field experiments are bad overall and not worth looking at. I am also an experimental person, and I know that this method has many advantages,” said György Kröel-Dulay. “At the same time, it is very important to approach any problem using multiple methods in parallel and to evaluate the results of these methods together, rather than narrowing down our research to one approach that we think is better. Although the experiments show the same trends as the observations – for example, that already drier areas are more vulnerable to drought – it is clear that the experiments tend to underestimate the ecological consequences of the expected drought. However, to predict and manage change effectively, we need accurate data,” he noted.

Related link(s):

Nature.com

Source: ELKH

News

Bayes and Darwin: How replicator populations perform Bayesian calculations

Statistical inference is an essential component of both animal behavior and artificial intelligence algorithms. It focuses on two main tasks: combining information learned from the past and perceiving the present to try to predict the future (our teammate passes the ball to us, how to move to catch it, knowing our teammate and seeing the arc of the ball) while trying to make use of various past experiences for this prediction.

A new study by IE researchers shows that the population of the basic units of evolution, the self-reproducing replicators, are capable of performing exactly these calculations. The basis of this analogy is to view the competition of replicators as a competition for hypotheses about the future.

Bayesian learning theory and evolutionary theory both formalize adaptive competitive dynamics in a multidimensional, changing, and noisy environment. In this study, we discuss structural and dynamic analogies and their limitations, both at the computational and algorithmic-mechanical levels. We point out the mathematical equivalences between their basic dynamic equations, generalizing the isomorphism between Bayesian inference and replicator dynamics. We discuss how these mechanisms provide analogous responses to the challenge of adapting to a stochastically changing environment across multiple time scales. We shed light on the algorithmic equivalence between sampling approximation, particle filters, and the Wright-Fisher model of population genetics. These equivalences suggest that the frequency distribution of types in replicator populations optimally encodes the regularities of the stochastic environment to predict future environments, without reference to known mechanisms of multilevel selection and evolution. A unified approach to the theories of learning and evolution comes to the fore.

This theoretical link may lead to a better understanding of the diverse adaptations of biological evolution by showing a new adaptation goal emerging at the level of the population and not the individual. On the other hand, using this exact mathematical analogy, artificial evolutionary systems can become a more fundamental building block of intelligence.

Dániel Czégel, Giaffar Hamza, Josh Tenenbaum and Eörs Szathmáry
Bioessays. 2022 Feb 25: e2100255