scholarly journals Cancer and the Levels of Selection

2021 ◽  
Author(s):  
Samir Okasha
Keyword(s):  
Levels Of Selection

Emergent group traits, reproduction, and levels of selection

2014 ◽  
Vol 37 (3) ◽  
pp. 268-269 ◽  
Author(s):  
Samir Okasha
Keyword(s):  
Levels Of Selection ◽  
Individual Traits

AbstractAll group traits, “emergent” or otherwise, are ultimately dependent on the traits and behaviours of the individuals that constitute the group. Unless a process of “group reproduction” is envisaged, this means that the evolution of group traits can in principle be studied in an individualistic way, by studying the dynamics of the underlying individual traits on which they depend.

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.

Adaptation and Natural Selection

2021 ◽  
pp. 125-154
Author(s):  
Áki J. Láruson ◽  
Floyd A. Reed
Keyword(s):  
Natural Selection ◽  
Allele Frequency ◽  
Levels Of Selection ◽  
Frequency Data ◽  
Selection Coefficient ◽  
Frequency Distributions ◽  
Single Allele ◽  
Selection Strength ◽  
The Difference ◽  
Over Time

Here non-random shifts in allele frequencies over time are introduced, as well as how to incorporate varying levels of selection into a model of a single population through time. This chapter highlights the difference between weak and strong selection, the dynamics of single allele versus genotype-level selection, and how selection strength and population size affect allele frequency distributions over time. Finally the inference of the selection coefficient from allele frequency data is discussed, alongside the concepts of overdominance and underdominance.

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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