scholarly journals The levels of selection and evolution of individuality

2019 ◽  
Vol 62 (1) ◽  
pp. 51-67
Author(s):  
Eva Kamerer
Keyword(s):  
Social Evolution ◽  
Multilevel Selection ◽  
Levels Of Selection ◽  
Selection Models ◽  
Evolutionary Transitions ◽  
Major Transitions ◽  
Evolutionary Transitions In Individuality ◽  
Major Transitions In Evolution

In this article I will analyze the transfer of fitness during the major transitions in evolution and its place in the multilevel selection models. The aim of the analysis is to show how social evolution can explain the evolutionary transitions in individuality.

scholarly journals Multilevel selection as Bayesian inference, major transitions in individuality as structure learning

2019 ◽  
Vol 6 (8) ◽  
pp. 190202 ◽  
Author(s):  
Dániel Czégel ◽  
István Zachar ◽  
Eörs Szathmáry
Keyword(s):  
Bayesian Inference ◽  
Learning Theory ◽  
Model Comparison ◽  
Replicator Dynamics ◽  
Life Forms ◽  
Multilevel Selection ◽  
Evolutionary Transitions ◽  
Major Transitions ◽  
Bayesian Model Comparison ◽  
Evolutionary Transitions In Individuality

Complexity of life forms on the Earth has increased tremendously, primarily driven by subsequent evolutionary transitions in individuality, a mechanism in which units formerly being capable of independent replication combine to form higher-level evolutionary units. Although this process has been likened to the recursive combination of pre-adapted sub-solutions in the framework of learning theory, no general mathematical formalization of this analogy has been provided yet. Here we show, building on former results connecting replicator dynamics and Bayesian update, that (i) evolution of a hierarchical population under multilevel selection is equivalent to Bayesian inference in hierarchical Bayesian models and (ii) evolutionary transitions in individuality, driven by synergistic fitness interactions, is equivalent to learning the structure of hierarchical models via Bayesian model comparison. These correspondences support a learning theory-oriented narrative of evolutionary complexification: the complexity and depth of the hierarchical structure of individuality mirror the amount and complexity of data that have been integrated about the environment through the course of evolutionary history.

4. Levels of selection

2019 ◽  
pp. 45-62
Author(s):  
Samir Okasha
Keyword(s):  
Kin Selection ◽  
Group Selection ◽  
Evolutionary Biology ◽  
Levels Of Selection ◽  
Major Transitions ◽  
Individual Level ◽  
Or Groups ◽  
The Subject ◽  
The Individual ◽  
Major Transitions In Evolution

‘Levels of selection’ examines the levels-of-selection question, which asks whether natural selection acts on individuals, genes, or groups. This question is one of the most fundamental in evolutionary biology, and the subject of much controversy. Traditionally, biologists have mostly been concerned with selection and adaptation at the individual level. But, in theory, there are other possibilities, including selection on sub-individual units such as genes and cells, and on supra-individual units such as groups and colonies. Group selection, altruistic behaviour, kin selection, the gene-centric view of evolution, and the major transitions in evolution are all discussed.

scholarly journals Nascent life cycles and the emergence of higher-level individuality

2017 ◽  
Vol 372 (1735) ◽  
pp. 20160420 ◽  
Author(s):  
William C. Ratcliff ◽  
Matthew Herron ◽  
Peter L. Conlin ◽  
Eric Libby
Keyword(s):  
Mathematical Modelling ◽  
Crucial Role ◽  
Early Life ◽  
Life Cycles ◽  
Levels Of Selection ◽  
Evolutionary Transition ◽  
Beneficial Mutations ◽  
Evolutionary Transitions ◽  
Key Innovation ◽  
Evolutionary Transitions In Individuality

Evolutionary transitions in individuality (ETIs) occur when formerly autonomous organisms evolve to become parts of a new, ‘higher-level’ organism. One of the first major hurdles that must be overcome during an ETI is the emergence of Darwinian evolvability in the higher-level entity (e.g. a multicellular group), and the loss of Darwinian autonomy in the lower-level units (e.g. individual cells). Here, we examine how simple higher-level life cycles are a key innovation during an ETI, allowing this transfer of fitness to occur ‘for free’. Specifically, we show how novel life cycles can arise and lead to the origin of higher-level individuals by (i) mitigating conflicts between levels of selection, (ii) engendering the expression of heritable higher-level traits and (iii) allowing selection to efficiently act on these emergent higher-level traits. Further, we compute how canonical early life cycles vary in their ability to fix beneficial mutations via mathematical modelling. Life cycles that lack a persistent lower-level stage and develop clonally are far more likely to fix ‘ratcheting’ mutations that limit evolutionary reversion to the pre-ETI state. By stabilizing the fragile first steps of an evolutionary transition in individuality, nascent higher-level life cycles may play a crucial role in the origin of complex life. This article is part of the themed issue ‘Process and pattern in innovations from cells to societies’.

scholarly journals Toward major evolutionary transitions theory 2.0

2015 ◽  
Vol 112 (33) ◽  
pp. 10104-10111 ◽  
Author(s):  
Eörs Szathmáry
Keyword(s):  
Genetic Code ◽  
Eukaryotic Cell ◽  
Multilevel Selection ◽  
High Fidelity ◽  
Evolutionary Transitions ◽  
Major Transitions ◽  
Transitions Theory ◽  
Explanatory Mechanism

The impressive body of work on the major evolutionary transitions in the last 20 y calls for a reconstruction of the theory although a 2D account (evolution of informational systems and transitions in individuality) remains. Significant advances include the concept of fraternal and egalitarian transitions (lower-level units like and unlike, respectively). Multilevel selection, first without, then with, the collectives in focus is an important explanatory mechanism. Transitions are decomposed into phases of origin, maintenance, and transformation (i.e., further evolution) of the higher level units, which helps reduce the number of transitions in the revised list by two so that it is less top-heavy. After the transition, units show strong cooperation and very limited realized conflict. The origins of cells, the emergence of the genetic code and translation, the evolution of the eukaryotic cell, multicellularity, and the origin of human groups with language are reconsidered in some detail in the light of new data and considerations. Arguments are given why sex is not in the revised list as a separate transition. Some of the transitions can be recursive (e.g., plastids, multicellularity) or limited (transitions that share the usual features of major transitions without a massive phylogenetic impact, such as the micro- and macronuclei in ciliates). During transitions, new units of reproduction emerge, and establishment of such units requires high fidelity of reproduction (as opposed to mere replication).

scholarly journals Spontaneous emergence of multicellular heritability

2021 ◽  
Author(s):  
Seyed Alireza Zamani-Dahaj ◽  
Anthony Burnetti ◽  
Thomas Day ◽  
william C Ratcliff ◽  
Peter J. Yunker ◽  
...  
Keyword(s):  
Genetic Regulation ◽  
Darwinian Evolution ◽  
Analytical Models ◽  
Biological Individuality ◽  
Cell Level ◽  
Evolutionary Transitions ◽  
Major Transitions ◽  
Additional Layer ◽  
Multicellular Organisms ◽  
Major Transitions In Evolution

The Major Transitions in evolution include events and processes that result in the emergence of new levels of biological individuality. For collectives to undergo Darwinian evolution, their traits must be heritable, but the emergence of higher-level heritability is poorly understood and has long been considered a stumbling block for nascent evolutionary transitions. A change in the means by which genetic information is utilized and transmitted has been presumed necessary. Using analytical models, synthetic biology, and biologically-informed simulations, we explored the emergence of trait heritability during the evolution of multicellularity. Contrary to existing theory, we show that no additional layer of genetic regulation is necessary for traits of nascent multicellular organisms to become heritable; rather, heritability and the capacity to respond to natural selection on multicellular-level traits can arise ''for free.'' In fact, we find that a key emergent multicellular trait, organism size at reproduction, is usually more heritable than the underlying cell-level trait upon which it is based, given reasonable assumptions.

scholarly journals Kin and group selection are both flawed but useful data analysis tools

2019 ◽  
Author(s):  
jeff smith ◽  
R. Fredrik Inglis
Keyword(s):  
Empirical Research ◽  
Social Evolution ◽  
Multilevel Selection ◽  
Selection Theory ◽  
Fitness Effects ◽  
Data Driven Approach ◽  
Biological Interpretation ◽  
Multilevel Selection Theory ◽  
Microbial Systems ◽  
Analytical Tools

AbstractFor understanding the evolution of social behavior in microbes, mathematical theory can aid empirical research but is often only used as a qualitative heuristic. How to properly formulate social evolution theory has also been contentious. Here we evaluate kin and multilevel selection theory as tools for analyzing microbial data. We reanalyze published datasets that share a common experimental design and evaluate these theories in terms of data visualization, statistical performance, biological interpretation, and quantitative comparison across systems. We find that the canonical formulations of both kin and multilevel selection are almost always poor analytical tools because they use statistical regressions that are poorly specified for the strong selection and nonadditive fitness effects common in microbial systems. Analyzing both individual and group fitness outcomes helps clarify the biology of selection. We also identify analytical practices in empirical research that suggest how theory might better handle the challenges of microbial data. A quantitative, data-driven approach thus shows how kin and multilevel selection theory both have substantial room for improvement as tools for understanding social evolution in all branches of life.

scholarly journals Evolution of simple multicellularity increases environmental complexity

2016 ◽  
Author(s):  
María Rebolleda-Gómez ◽  
William C. Ratcliff ◽  
Jonathon Fankhauser ◽  
Michael Travisano
Keyword(s):  
Fluid Dynamics ◽  
Saccharomyces Cerevisiae ◽  
Experimental Evolution ◽  
Single Cells ◽  
Environmental Complexity ◽  
Major Transitions ◽  
Rapid Diversification ◽  
Ecological Mechanisms ◽  
Major Transitions In Evolution ◽  
Maintenance Of Diversity

AbstractMulticellularity—the integration of previously autonomous cells into a new, more complex organism—is one of the major transitions in evolution. Multicellularity changed evolutionary possibilities and facilitated the evolution of increased complexity. Transitions to multicellularity are associated with rapid diversification and increased ecological opportunity but the potential mechanisms are not well understood. In this paper we explore the ecological mechanisms of multicellular diversification during experimental evolution of the brewer’s yeast, Saccharomyces cerevisiae. The evolution from single cells into multicellular clusters modifies the structure of the environment, changing the fluid dynamics and creating novel ecological opportunities. This study demonstrates that even in simple conditions, incipient multicellularity readily changes the environment, facilitating the origin and maintenance of diversity.

Units and levels of selection

2018 ◽  
Author(s):  
Samir Okasha
Keyword(s):  
Natural Selection ◽  
Kin Selection ◽  
Evolutionary Biology ◽  
Evolutionary Process ◽  
Levels Of Selection ◽  
Evolutionary Transitions ◽  
Individual Organism ◽  
Selection Processes ◽  
Hierarchical Levels ◽  
The Individual

In a standard Darwinian explanation, natural selection takes place at the level of the individual organism, i.e. some organisms enjoy a survival or reproduction advantage over others, which results in evolutionary change. In principle however, natural selection could operate at other hierarchical levels too, above and below that of the organism, for example the level of genes, cells, groups, colonies or even whole species. This possibility gives rise to the ‘levels of selection’ question in evolutionary biology. Group and colony-level selection have been proposed, originally by Darwin, as a means by which altruism can evolve. (In biology, ‘altruism’ refers to behaviour which entails a fitness cost to the individual so behaving, but benefits others.) Though this idea is still alive today, many theorists regard kin selection as a superior explanation for the existence of altruism. Kin selection arises from the fact that relatives share genes, so if an organism behaves altruistically towards its relatives, there is a greater than random chance that the beneficiary of the altruistic action will itself be an altruist. Kin selection is closely bound up with the ‘gene’s eye view’ of evolution, which holds that genes, not organisms, are the true beneficiaries of the evolutionary process. The gene’s eye approach to evolution, though heuristically valuable, does not in itself resolve the levels of selection question, because selection processes that occur at many hierarchical levels can all be seen from a gene’s eye viewpoint. In recent years, the levels of selection discussion has been re-invigorated, and subtly transformed, by the important new work on the ‘major evolutionary transitions’. These transitions occur when a number of free-living biological units, originally capable of surviving and reproducing alone, become integrated into a larger whole, giving rise to a new biological unit at a higher level of organization. Evolutionary transitions are intimately bound up with the levels of selection issue, because during a transition the potential exists for selection to operate simultaneously at two different hierarchical levels.

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