Natural Selection and Random Genetic Drift in Phenotypic Evolution

Evolution ◽  
1976 ◽  
Vol 30 (2) ◽  
pp. 314 ◽  
Author(s):  
Russell Lande
Keyword(s):  
Natural Selection ◽  
Genetic Drift ◽  
Phenotypic Evolution ◽  
Random Genetic Drift

scholarly journals Evolution of gene regulatory networks by means of selection and random genetic drift

2018 ◽  
Author(s):  
Antonios Kioukis ◽  
Pavlos Pavlidis
Keyword(s):  
Natural Selection ◽  
Positive Selection ◽  
Genetic Drift ◽  
Regulatory Networks ◽  
Fitness Landscape ◽  
Random Genetic Drift ◽  
Maturation Period ◽  
Evolutionary Forces ◽  
Gene Regulatory

The evolution of a population by means of genetic drift and natural selection operating on a gene regulatory network (GRN) of an individual has not been scrutinized in depth. Thus, the relative importance of various evolutionary forces and processes on shaping genetic variability in GRNs is understudied. Furthermore, it is not known if existing tools that identify recent and strong positive selection from genomic sequences, in simple models of evolution, can detect recent positive selection when it operates on GRNs. Here, we propose a simulation framework, called EvoNET, that simulates forward-in-time the evolution of GRNs in a population. Since the population size is finite, random genetic drift is explicitly applied. The fitness of a mutation is not constant, but we evaluate the fitness of each individual by measuring its genetic distance from an optimal genotype. Mutations and recombination may take place from generation to generation, modifying the genotypic composition of the population. Each individual goes through a maturation period, where its GRN reaches equilibrium. At the next step, individuals compete to produce the next generation. As time progresses, the beneficial genotypes push the population higher in the fitness landscape. We examine properties of the GRN evolution such as robustness against the deleterious effect of mutations and the role of genetic drift. We confirm classical results from Andreas Wagner’s work that GRNs show robustness against mutations and we provide new results regarding the interplay between random genetic drift and natural selection.

Phenotypic evolution in a lineage of the Eocene ostracod Echinocythereis

Paleobiology ◽  
1985 ◽  
Vol 11 (2) ◽  
pp. 174-194 ◽  
Author(s):  
Richard A. Reyment
Keyword(s):  
New Species ◽  
Genetic Drift ◽  
Rapid Decrease ◽  
Weight Of Evidence ◽  
Evolutionary Status ◽  
Phenotypic Evolution ◽  
Random Genetic Drift ◽  
Sharp Rise ◽  
The Third ◽  
Long Period

Two speciation events occurred in the Eocene lineage beginning with Echinocythereis isabenana Oertli (Aragon, Spain). After a long period of stasis in ornament and shape/size, this species underwent a relatively rapid decrease in size, accompanied by ornamental changes. The transition required about 30,000 yr. The new species E. aragonensis Oertli is significantly smaller (20% decrease in size). The lateral papillation is denser and less regular, the papillae being significantly smaller than in the ancestral form. This ornament gradually yields to increasing frequencies of individuals with reduced papillae superimposed on a progressively better developed network of filaments. This change, which is regionally valid, is ultimately replaced by fully expressed reticulations, on which minute pustules may occur; this development typifies the third species, E. posterior Oertli. Some ornamental characteristics of E. aragonensis are anticipated in rare individuals of E. isabenana. Ornamental features of E. posterior appear in late larvae of E. isabenana. Generally, E. aragonensis and E. posterior do not differ significantly in size. A trend toward smaller carapaces in the upper samples of E. posterior could be related to ecophenotypic effects.All species are highly polymorphic for both shape and ornament; the morphs are not sharply bounded and are mostly of uncertain evolutionary status. The transition from isabenana to aragonensis is heralded by a sharp rise in the coefficient of variation for length measures of the carapace. There is a pronounced multivariate morphometric discontinuity between isabenana and the descendant forms, which are largely multivariately homogeneous. The isabenana-aragonensis transition could have occurred by selection or by random genetic drift. Both models can be accommodated by the data; however, the weight of evidence favors the former hypothesis. Evolution in the Echinocythereis lineage seems to have occurred by two different mechanisms. The first transition was rather rapid, with many disjunct features. The second was slow, the changes being more of degree than of kind.

scholarly journals Emergence of evolutionary driving forces in pattern-forming microbial populations

2018 ◽  
Vol 373 (1747) ◽  
pp. 20170106 ◽  
Author(s):  
Jona Kayser ◽  
Carl F. Schreck ◽  
QinQin Yu ◽  
Matti Gralka ◽  
Oskar Hallatschek
Keyword(s):  
Natural Selection ◽  
Pattern Formation ◽  
Genetic Drift ◽  
Cell Biology ◽  
Evolutionary Dynamics ◽  
Driving Forces ◽  
Population Level ◽  
Microbial Populations ◽  
Random Genetic Drift ◽  
Pattern Forming

Evolutionary dynamics are controlled by a number of driving forces, such as natural selection, random genetic drift and dispersal. In this perspective article, we aim to emphasize that these forces act at the population level, and that it is a challenge to understand how they emerge from the stochastic and deterministic behaviour of individual cells. Even the most basic steric interactions between neighbouring cells can couple evolutionary outcomes of otherwise unrelated individuals, thereby weakening natural selection and enhancing random genetic drift. Using microbial examples of varying degrees of complexity, we demonstrate how strongly cell–cell interactions influence evolutionary dynamics, especially in pattern-forming systems. As pattern formation itself is subject to evolution, we propose to study the feedback between pattern formation and evolutionary dynamics, which could be key to predicting and potentially steering evolutionary processes. Such an effort requires extending the systems biology approach from the cellular to the population scale. This article is part of the theme issue ‘Self-organization in cell biology’.

scholarly journals Testing Natural Selection vs. Genetic Drift in Phenotypic Evolution Using Quantitative Trait Locus Data

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 2099-2104 ◽  
Author(s):  
H Allen Orr
Keyword(s):  
Quantitative Trait Locus ◽  
Natural Selection ◽  
Genetic Drift ◽  
Quantitative Trait ◽  
Null Hypothesis ◽  
Sign Test ◽  
Phenotypic Evolution ◽  
Phenotypic Difference ◽  
Quantitative Trait Locus Data ◽  
Trait Locus

Abstract Evolutionary biologists have long sought a way to determine whether a phenotypic difference between two taxa was caused by natural selection or random genetic drift. Here I argue that data from quantitative trait locus (QTL) analyses can be used to test the null hypothesis of neutral phenotypic evolution. I propose a sign test that compares the observed number of plus and minus alleles in the “high line” with that expected under neutrality, conditioning on the known phenotypic difference between the taxa. Rejection of the null hypothesis implies a role for directional natural selection. This test is applicable to any character in any organism in which QTL analysis can be performed.

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