Persistence of functional microbiota composition across generations

Holobionts are defined as a host and its microbiota, however, only a fraction of the bacteria are inherited vertically and thus coevolve with the host. The “it’s the song, not the singer” theory proposes that functional traits, instead of taxonomical microbiota composition, could be preserved across generations if interspecies interaction patterns perpetuate themselves. We tested conservation of functional composition across generations using zooplankton, mosquito, and plant datasets. Then, we tested if there is a change of functional microbiota composition over time within a generation in human datasets. Finally, we simulated microbiota communities to investigate if (pairwise) interactions can lead to multiple stable community compositions. Our results suggest that the vertically transmitted microbiota starts a predictable change of functions performed by the microbiota over time, whose robustness depends on the arrival of diverse migrants. This succession culminates in a stable functional composition state. The results suggest that the host-microbiota interaction and higher order interactions in general have an important contribution to the robustness of the final community. If the proposed mechanism proves to be valid for a diverse array of host species, this would support the concept of holobionts being used as units of selection, including animal breeding, suggesting this has a wider applicability.

Beyond Fitness Decoupling: Tradeoff-breaking during Evolutionary Transitions in Individuality

Evolutionary transitions in individuality (ETIs) involve the formation of Darwinian collectives from Darwinian particles. The transition from cells to multicellular life is a prime example. During anETI, collectives become units of selection in their own right. However, the underlying processes are poorly understood. One observation used to identify the completion of an ETI is an increase in collective-level performance accompanied by a decrease in particle-level performance, for example, measured by growth rate. This seemingly counterintuitive dynamic has been referred to as “fitness decoupling” and has been used to interpret both models and experimental data. Using a mathematical approach we show this concept to be problematic in that the fitness of particles and collectives can never decouple: calculations of particle and collective fitness performed over appropriate and equivalent time intervals are necessarily the same. By way of solution, we draw attention to the value of mechanistic approaches that emphasise traits as opposed to fitness and tradeoffs among traits. This trait-based approach is sufficient to capture dynamics that underpin evolutionary transitions. In addition, drawing upon both experimental and theoretical studies, we show that while early stages of transitions might often involve tradeoffs among particle traits, later—and critical—stages are likely to involve rupture of such tradeoffs. Tradeoff-breaking thus stands as a useful marker for ETIs.

Group phenotypic composition in cancer

Although individual cancer cells are generally considered the Darwinian units of selection in malignant populations, they frequently act as members of groups where fitness of the group cannot be reduced to the average fitness of individual group members. A growing body of studies reveals limitations of reductionist approaches to explaining biological and clinical observations. For example, induction of angiogenesis, inhibition of the immune system, and niche engineering through environmental acidification and/or remodeling of extracellular matrix cannot be achieved by single tumor cells and require collective actions of groups of cells. Success or failure of such group activities depends on the phenotypic makeup of the individual group members. Conversely, these group activities affect the fitness of individual members of the group, ultimately affecting the composition of the group. This phenomenon, where phenotypic makeup of individual group members impacts the fitness of both members and groups, has been captured in the term ‘group phenotypic composition’ (GPC). We provide examples where considerations of GPC could help in understanding the evolution and clinical progression of cancers and argue that use of the GPC framework can facilitate new insights into cancer biology and assist with the development of new therapeutic strategies.

TENDENCIES OF FUNCTIONING FLASH MOBS IN RUSSIA: THE ROLE OF SOCIAL ONLINE ENVIRONMENT AND SELF-ISOLATION IN THE DEVELOPMENT OF NEW FORMS OF FLASH MOBS

This article focuses on analysis of flash mob as a form of social activity in contemporary society. The aim of this article is to define the main ways of representation of flash mobs in online environment of Russian society. The additional objectives of the article are as follows: finding out the last tendencies in development of flash mobs and their social functions; defining the main parameters of representation of flash mobs in media and Internet; assessment of the functioning of flash mobs in pandemic situation. Some characteristics of flash mobs are defined in the article, such as mass character, simultaneity, the use of modern technologies, and emotional involvement. Traditional flash mob originally was based on spontaneity, absurdity, and lack of specific subtext. Last years, traditional flash mob is increasingly loaded with meaning provided by different communities, leaders, and authorities. The “modernized” flash mobs with specific meaning and goals replaced their traditional forms and became powerful influence on social attitudes. It becomes a new form of presenting cultural, political, and other values, and actualizes social problems. For studying forms of Russian flash mobs, the publications in mass media, Internet, and social media for the period of 2018-2020 were analyzed. “VKontakte” communities dedicated to online flash mobs during the 2020 self-isolation period were also taken for analysis, in particular posts from the walls of the communities and their participants. The units of selection were the communities corresponding to the theme of self-isolation with the largest number of participants and characterized by the greatest activity. The results show the following tendencies in the development of flash mobs: the increasing role of social media in organization of flash mobs; decreasing proportion of classical flash mobs with entertaining goals; the development of art-mobs and prof-mobs, and patriotic flash mobs; compensatory and emotional functions of flash mobs in pandemic period.

The Origin of Niches and Species in the Bacterial World

Niches are spaces for the biological units of selection, from cells to complex communities. In a broad sense, “species” are biological units of individuation. Niches do not exist without individual organisms, and every organism has a niche. We use “niche” in the Hutchinsonian sense as an abstraction of a multidimensional environmental space characterized by a variety of conditions, both biotic and abiotic, whose quantitative ranges determine the positive or negative growth rates of the microbial individual, typically a species, but also parts of the communities of species contained in this space. Microbial organisms (“species”) constantly diversify, and such diversification (radiation) depends on the possibility of opening up unexploited or insufficiently exploited niches. Niche exploitation frequently implies “niche construction,” as the colonized niche evolves with time, giving rise to new potential subniches, thereby influencing the selection of a series of new variants in the progeny. The evolution of niches and organisms is the result of reciprocal interacting processes that form a single unified process. Centrifugal microbial diversification expands the limits of the species’ niches while a centripetal or cohesive process occurs simultaneously, mediated by horizontal gene transfers and recombinatorial events, condensing all of the information recovered during the diversifying specialization into “novel organisms” (possible future species), thereby creating a more complex niche, where the selfishness of the new organism(s) establishes a “homeostatic power” limiting the niche’s variation. Once the niche’s full carrying capacity has been reached, reproductive isolation occurs, as no foreign organisms can outcompete the established population/community, thereby facilitating speciation. In the case of individualization-speciation of the microbiota, its contribution to the animal’ gut structure is a type of “niche construction,” the result of crosstalk between the niche (host) and microorganism(s). Lastly, there is a parallelism between the hierarchy of niches and that of microbial individuals. The increasing anthropogenic effects on the biosphere (such as globalization) might reduce the diversity of niches and bacterial individuals, with the potential emergence of highly transmissible multispecialists (which are eventually deleterious) resulting from the homogenization of the microbiosphere, a possibility that should be explored and prevented.

Evolutionary Pathways and Trajectories in Antibiotic Resistance

Evolution is the hallmark of life. Descriptions of the evolution of microorganisms have provided a wealth of information, but knowledge regarding “what happened” has precluded a deeper understanding of “how” evolution has proceeded, as in the case of antimicrobial resistance. The difficulty in answering the “how” question lies in the multihierarchical dimensions of evolutionary processes, nested in complex networks, encompassing all units of selection, from genes to communities and ecosystems. At the simplest ontological level (as resistance genes), evolution proceeds by random (mutation and drift) and directional (natural selection) processes; however, sequential pathways of adaptive variation can occasionally be observed, and under fixed circumstances (particular fitness landscapes), evolution is predictable. At the highest level (such as that of plasmids, clones, species, microbiotas), the system’s degrees of freedom increase dramatically, related to the variable dispersal, fragmentation, relatedness or coalescence of bacterial populations, depending on heterogeneous and changing niches and selective gradients in complex environments. Evolutionary trajectories of antibiotic resistance find their way in these moving, frequently random landscapes and become highly entropic and therefore unpredictable. However, experimental, phylogenetic and ecogenetic analyses reveal preferential frequented paths (highways) where antibiotic resistance flows and propagates, allowing some understanding of evolutionary dynamics, modelling and designing interventions. Studies on antibiotic resistance have an applied aspect in improving individual health, one health and global health, as well as an academic value for understanding evolution. Most importantly, they have a heuristic significance as a model to reduce the negative influence of anthropogenic effects on the environment.

Exploring Traits of Engineered Coral Entities to be Employed in Reef Restoration

Aggregated settlement of coral larvae results in a complex array of compatible (chimerism) and incompatible (rejection) allogenic responses. Each chimeric assemblage is considered as a distinct biological entity, subjected to selection, however, the literature lacks the evolutionary and ecological functions assigned to these units of selection. Here, we examined the effects of creating chimera/rejecting partners in terms of growth and survival under prolonged field conditions. Bi/multichimeras, bi/multi-rejecting entities, and genetically homogenous colonies (GHC) of the coral Stylophora pistillata were monitored under prolonged field conditions in a mid-water floating nursery in the northern Red Sea. Results revealed an increased aerial size and aeroxial ecological volume for rejected and chimeric entities compared to GHCs. At age 18 months, there were no significant differences in these parameters among the entities and traits, and rejecting partners did not differ from GHC. However, survival probabilities were significantly higher for chimeras that further revealed disparate initiation of up-growing branches and high diversity of chimeric phenotypes. These results suggest enhanced fitness for chimerism, augmenting earlier alluded chimeric benefits that trail the increased size at crucial early life-stages. Adding chimerism to the tool-box of reef restoration may enhance coral fitness in mitigating anthropogenic/climate change impacts.

Persistence of Functional Microbiota Composition Across Generations

Background: Holobionts are defined as a host and its microbiota, and there is not a consensus about their status as a unit of selection. The “it’s the song, not the singer” theory proposes that functional traits, instead of taxonomical composition, could be preserved across generations if interspecies interaction patterns perpetuate themselves. We used a novel combination of community level analysis on the functional composition of microbiota-communities to test this theory by using empirical and simulated data. We tested the conservation of functional composition across generations using mosquito and plant datasets. Then, we tested if there is a change of functional composition over time within a generation in human datasets. Finally, we simulated microbiota communities with different amounts of pairwise interspecies interactions and initial configurations to investigate if the interactions can lead to multiple stable community compositions. Results: Our results suggest that the vertically transmitted microbiota starts a predictable change of functions performed by the microbiota over time (i.e. an ecological succession) whose robustness depends on the arrival of diverse migrants. This succession culminates in a stable functional composition state. The pairwise interactions between species of the community are not sufficient to explain the stability of the final community and the existence of alternative stable states, which suggests that the host-microbiota interaction and non-pairwise interactions in general have an important contribution to the robustness of the final community.Conclusions: If the proposed mechanism proves to be valid for a diverse array of host species, this would support the concept of holobionts being used as units of selection, suggesting this has a wider applicability, including animal breeding.

Why Did Memetics Fail? Comparative Case Study

Although the theory of memetics appeared highly promising at the beginning, it is no longer considered a scientific theory among contemporary evolutionary scholars. This study aims to compare the genealogy of memetics with the historically more successful gene-culture coevolution theory. This comparison is made in order to determine the constraints that emerged during the internal development of the memetics theory that could bias memeticists to work on the ontology of meme units as opposed to hypotheses testing, which was adopted by the gene-culture scholars. I trace this problem back to the diachronic development of memetics to its origin in the gene-centered anti-group-selectionist argument of George C. Williams and Richard Dawkins. The strict adoption of this argument predisposed memeticists with the a priori idea that there is no evolution without discrete units of selection, which in turn, made them dependent on the principal separation of biological and memetic fitness. This separation thus prevented memeticists from accepting an adaptationist view of culture which, on the contrary, allowed gene-culture theorists to attract more scientists to test the hypotheses, creating the historical success of the gene-culture coevolution theory.