Radical Epistasis and the Genotype-Phenotype Relationship

1994 ◽  
Vol 2 (1) ◽  
pp. 117-128 ◽  
Author(s):  
David Sloan Wilson ◽  
Alexandra Wells
Keyword(s):  
Linkage Disequilibrium ◽  
Natural Selection ◽  
Assortative Mating ◽  
Evolutionary Process ◽  
Genetic System ◽  
Adaptive Landscape ◽  
Nk Model ◽  
Phenotypic Distribution ◽  
Adaptive Landscapes

Models of evolution often assume that the offspring of two genotypes, which are genetically intermediate by definition, are also phenotypically intermediate. The continuity between genotype and phenotype interferes with the process of evolution on multipeaked adaptive landscapes because the progeny of genotypes that lie on separate adaptive peaks fall into valleys of low fitness. This problem can be solved by epistasis, which disrupts the continuity between genotype and phenotype. In a five-locus sexual haploid model with maximum epistasis, natural selection in multipeak landscapes evolves a set of genotypes that a) occupy the adaptive peaks and b) give rise to each other by recombination. The epistatic genetic system therefore “molds” the phenotypic distribution to the adaptive landscape, without assortative mating or linkage disequilibrium. If the adaptive landscape is changed, a new set of genotypes quickly evolves that satisfies conditions a and b, above, for the new peaks. Our model may be relevant to a number of recalcitrant problems in biology and also stands in contrast to Kauffman's [3] NK model of evolution on rugged fitness surfaces, in which epistasis and recombination tend to constrain the evolutionary process.

scholarly journals Adaptive fitness landscape for replicator systems: to maximize or not to maximize

2018 ◽  
Vol 13 (3) ◽  
pp. 25 ◽  
Author(s):  
Alexander S. Bratus ◽  
Yuri S. Semenov ◽  
Artem S. Novozhilov
Keyword(s):  
Natural Selection ◽  
Fitness Landscape ◽  
Evolutionary Process ◽  
Hill Climbing ◽  
Adaptive Landscape ◽  
Basic Model ◽  
Mean Fitness ◽  
The Mean ◽  
The Hill ◽  
Fisher’S Fundamental Theorem

Sewall Wright’s adaptive landscape metaphor penetrates a significant part of evolutionary thinking. Supplemented with Fisher’s fundamental theorem of natural selection and Kimura’s maximum principle, it provides a unifying and intuitive representation of the evolutionary process under the influence of natural selection as the hill climbing on the surface of mean population fitness. On the other hand, it is also well known that for many more or less realistic mathematical models this picture is a severe misrepresentation of what actually occurs. Therefore, we are faced with two questions. First, it is important to identify the cases in which adaptive landscape metaphor actually holds exactly in the models, that is, to identify the conditions under which system’s dynamics coincides with the process of searching for a (local) fitness maximum. Second, even if the mean fitness is not maximized in the process of evolution, it is still important to understand the structure of the mean fitness manifold and see the implications of this structure on the system’s dynamics. Using as a basic model the classical replicator equation, in this note we attempt to answer these two questions and illustrate our results with simple well studied systems.

Contingency and determinism in evolution: Replaying life’s tape

Science ◽  
2018 ◽  
Vol 362 (6415) ◽  
pp. eaam5979 ◽  
Author(s):  
Zachary D. Blount ◽  
Richard E. Lenski ◽  
Jonathan B. Losos
Keyword(s):  
Natural Selection ◽  
Evolutionary Biology ◽  
Empirical Studies ◽  
Evolutionary Process ◽  
Random Mutation ◽  
Ongoing Research ◽  
Adaptive Landscapes ◽  
Historical Processes ◽  
History Of ◽  
Evolutionary Paths

Historical processes display some degree of “contingency,” meaning their outcomes are sensitive to seemingly inconsequential events that can fundamentally change the future. Contingency is what makes historical outcomes unpredictable. Unlike many other natural phenomena, evolution is a historical process. Evolutionary change is often driven by the deterministic force of natural selection, but natural selection works upon variation that arises unpredictably through time by random mutation, and even beneficial mutations can be lost by chance through genetic drift. Moreover, evolution has taken place within a planetary environment with a particular history of its own. This tension between determinism and contingency makes evolutionary biology a kind of hybrid between science and history. While philosophers of science examine the nuances of contingency, biologists have performed many empirical studies of evolutionary repeatability and contingency. Here, we review the experimental and comparative evidence from these studies. Replicate populations in evolutionary “replay” experiments often show parallel changes, especially in overall performance, although idiosyncratic outcomes show that the particulars of a lineage’s history can affect which of several evolutionary paths is taken. Comparative biologists have found many notable examples of convergent adaptation to similar conditions, but quantification of how frequently such convergence occurs is difficult. On balance, the evidence indicates that evolution tends to be surprisingly repeatable among closely related lineages, but disparate outcomes become more likely as the footprint of history grows deeper. Ongoing research on the structure of adaptive landscapes is providing additional insight into the interplay of fate and chance in the evolutionary process.

SHOULD INDIVIDUAL FITNESS INCREASE WITH HETEROZYGOSITY?

Genetics ◽  
1983 ◽  
Vol 104 (1) ◽  
pp. 191-209
Author(s):  
Michael Turelli ◽  
Lev R Ginzburg
Keyword(s):  
Linkage Disequilibrium ◽  
Natural Selection ◽  
Empirical Literature ◽  
Correlated Traits ◽  
Individual Fitness ◽  
Stable Product ◽  
Theoretical Results ◽  
Average Fitness

ABSTRACT Natural selection influences not only gamete frequencies in populations but also the multilocus fitness structures associated with segregating gametes. In particular, only certain patterns of multilocus fitnesses are consistent with the maintenance of stable multilocus polymorphisms. This paper offers support for the proposition that, at stable, viability-maintained, multilocus polymorphisms, the fitness of a genotype tends to increase with the number of heterozygous loci it contains. Average fitness always increases with heterozygosity at stable product equilibria (i.e., those without linkage disequilibrium) maintained by either additive or multiplicative fitness schemes. Simulations suggest that it "generally" increases for arbitrary fitness schemes. The empirical literature correlating allozyme heterozygosity with fitness-correlated traits is discussed in the light of these and other theoretical results.

scholarly journals Ecological Divergence and the Origins of Intrinsic Postmating Isolation with Gene Flow

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Aneil F. Agrawal ◽  
Jeffrey L. Feder ◽  
Patrik Nosil
Keyword(s):  
Linkage Disequilibrium ◽  
Gene Flow ◽  
Natural Selection ◽  
Theoretical Models ◽  
Ecological Speciation ◽  
Divergent Selection ◽  
Postmating Isolation ◽  
Divergent Natural Selection ◽  
Mathematical Exploration ◽  
Neutral Gene

The evolution of intrinsic postmating isolation has received much attention, both historically and in recent studies of speciation genes. Intrinsic isolation often stems from between-locus genetic incompatibilities, where alleles that function well within species are incompatible with one another when brought together in the genome of a hybrid. It can be difficult for such incompatibilities to originate when populations diverge with gene flow, because deleterious genotypic combinations will be created and then purged by selection. However, it has been argued that if genes underlying incompatibilities are themselves subject to divergent selection, then they might overcome gene flow to diverge between populations, resulting in the origin of incompatibilities. Nonetheless, there has been little explicit mathematical exploration of such scenarios for the origin of intrinsic incompatibilities during ecological speciation with gene flow. Here we explore theoretical models for the origin of intrinsic isolation where genes subject to divergent natural selection also affect intrinsic isolation, either directly or via linkage disequilibrium with other loci. Such genes indeed overcome gene flow, diverge between populations, and thus result in the evolution of intrinsic isolation. We also examine barriers to neutral gene flow. Surprisingly, we find that intrinsic isolation sometimes weakens this barrier, by impeding differentiation via ecologically based divergent selection.

scholarly journals The quantum mitochondrion and optimal health

2016 ◽  
Vol 44 (4) ◽  
pp. 1101-1110 ◽  
Author(s):  
Alistair V.W. Nunn ◽  
Geoffrey W. Guy ◽  
Jimmy D. Bell
Keyword(s):  
Natural Selection ◽  
Energy Production ◽  
Healthy Aging ◽  
Evolutionary Process ◽  
Emergent Behaviour ◽  
Whole Process ◽  
Optimal Health ◽  
Response To Stress ◽  
Will Self ◽  
Selection Of

A sufficiently complex set of molecules, if subject to perturbation, will self-organize and show emergent behaviour. If such a system can take on information it will become subject to natural selection. This could explain how self-replicating molecules evolved into life and how intelligence arose. A pivotal step in this evolutionary process was of course the emergence of the eukaryote and the advent of the mitochondrion, which both enhanced energy production per cell and increased the ability to process, store and utilize information. Recent research suggest that from its inception life embraced quantum effects such as ‘tunnelling’ and ‘coherence’ while competition and stressful conditions provided a constant driver for natural selection. We believe that the biphasic adaptive response to stress described by hormesis–a process that captures information to enable adaptability, is central to this whole process. Critically, hormesis could improve mitochondrial quantum efficiency, improving the ATP/ROS ratio, whereas inflammation, which is tightly associated with the aging process, might do the opposite. This all suggests that to achieve optimal health and healthy aging, one has to sufficiently stress the system to ensure peak mitochondrial function, which itself could reflect selection of optimum efficiency at the quantum level.

scholarly journals Who are We, and Who (or What) Do We Want to Become? An Evolutionary Perspective on Biotransformative Technologies

2021 ◽  
Author(s):  
James Lyons-Weiler
Keyword(s):  
Human Evolution ◽  
Adaptive Landscape ◽  
Endogenous Factors ◽  
Theoretical Contribution ◽  
Organic Evolution ◽  
Adaptive Landscapes ◽  
Augmented Cognition ◽  
Language Writing ◽  
Cognitive Plasticity ◽  
The Impact

AbstractHuman evolution sits at several important thresholds. In organic evolution, interplay between exogenous environmental and genetic factors rendered new phenotypes at rates limited by genetic variation. The interplay took place on adaptive fitness landscapes determined by correspondence of genetic and environmental relationships. Human evolution involved important emergences that altered the adaptive landscape: language, writing, organized societies, science, and the internet. These endogenous factors ushered in transformative periods leading to more rapidly evolving emergences. I explore the impact of development of emerging biotransformative technologies capable of being applied to effect self-genetic modification and artificial intelligence-augmented cognition on the evolutionary landscape of phenotypes important to cognitive plasticity. Interaction effects will yield unanticipated emergences resulting in hyperrealm adaptive landscapes with more rapid evolutionary processes that feed back upon more fundamental levels while vastly outpacing organic evolution. Emerging technologies exist that are likely to impact the evolution of cognitive plasticity in humans in ways and at rates that will lead to societal upheaval. I show that the theoretical contribution of organic evolution in future human evolution is expected to become comparatively insignificant relative to that made by endogenous environmental factors such as external cognition aids and manipulation of the human genome. The results support the conclusion of a strong recommendation of a moratorium on the adoption of any technology capable of completely altering the course of human evolution.

scholarly journals Agrowisata Berkelanjutan Berbasis Kopi di Satria Agrowisata Desa Manukaya, Kecamatana Tampak Siring, Kabupaten Gianyar, Bali (Studi Evolusi Pariwisata)

2020 ◽  
Vol 8 (2) ◽  
pp. 262
Author(s):  
Febrytha Nur Azizah ◽  
I Putu Anom
Keyword(s):  
Natural Selection ◽  
Evolutionary Process ◽  
Secondary Data ◽  
Primary Data ◽  
Tourist Attraction ◽  
Theory Of Evolution ◽  
Alternative Tourism ◽  
The World ◽  
Tourism Activity ◽  
Main Attraction

Agro-tourism is an alternative tourism activity that relies on plantations and agriculture as its main attraction. Along with the development of tourism, agro-tourism has now become an economic driving commodity for the surrounding community, so that agro-tourism is increasingly taken into account in the world of tourism. The development of an agro-tourism can not be separated from the evolutionary process that occurs through various stages of the beginning of the tourist attraction built until now. This study aims to determine the evolution of developments in Satria Agrowisata. The research method used is descriptive qualitative by conducting data collection techniques through online interview as primary data, and conducting online observations as secondary data. The results show that Satria Agrowisata can adapt well to the various changes that exist and continue to innovate in order to survive in the world of tourism until now. In Darwin's theory of evolution, he put forward two key words in his theory, natural selection and adaptation. Natural selection as a mechanism for evolutionary change, and adaptations that occur in its development over time.   Keyword: Evolution, Agrotourism, Satria Agrowisata, Bali.

scholarly journals Peak shifts and extinction under sex-specific selection

2021 ◽  
Author(s):  
Stephen P. De Lisle
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Peak Shift ◽  
Adaptive Landscape ◽  
Population Estimates ◽  
Sexual Antagonism ◽  
Adaptive Landscapes ◽  
Quantitative Genetic ◽  
Complex Adaptive ◽  
The Face

AbstractA well-known property of sexual selection combined with a cross sex genetic correlation (rmf), is that it can facilitate a peak shift on the adaptive landscape. How do these diversifying effects of sexual selection +rmf balance with the constraints imposed by such sexual antagonism, to affect macroevolution of sexual dimorphism? Here, I extend existing quantitative genetic models of evolution on complex adaptive landscapes. Beyond recovering classical predictions for the conditions promoting a peak shift, I show that when rmf is moderate to strong, relatively weak sexual selection is required to induce a peak shift in males only. Increasing the strength of sexual leads to a sexually-concordant peak shift, suggesting that macroevolutionary rates of sexual dimorphism may be largely decoupled from the strength of within-population sexual selection. Accounting explicitly for demography further reveals that sex-specific peak shifts may be more likely to be successful than concordant shifts in the face of extinction, especially when natural selection is strong. An overarching conclusion is that macroevolutionary patterns of sexual dimorphism are unlikely to be readily explained by within-population estimates of selection or constraint alone.

Getting Beyond the Apemen

2021 ◽  
pp. 1-18
Author(s):  
Lesley Newson ◽  
Peter J. Richerson
Keyword(s):  
At Risk ◽  
Natural Selection ◽  
Human Evolution ◽  
Evolutionary Process ◽  
Adult Males ◽  
Evolutionary Processes ◽  
Complex Information ◽  
History Of ◽  
Evolution By Natural Selection

This introductory chapter explains why a new story of human evolution is needed, and also lays the foundations of the story told in this book. One of the reasons we need a new story is that previous stories have concentrated on what our male ancestors were doing. Since survival is most at risk in the first years of life, it makes much more sense to concentrate on children and their mothers than on adult males. A brief account of the history of ideas in evolution by natural selection and human evolution provides readers with a background in evolutionary processes. Humans are a product of evolution, but we are not like other animals, because we are connected and readily share complex information. We are unique and our evolution was the result of a unique evolutionary process. To understand ourselves in evolutionary terms, it’s necessary to consider two intertwined evolutionary processes—genes and culture.

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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