scholarly journals General Models of Multilocus Evolution

Genetics ◽  
2002 ◽  
Vol 161 (4) ◽  
pp. 1727-1750 ◽  
Author(s):  
Mark Kirkpatrick ◽  
Toby Johnson ◽  
Nick Barton
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Evolutionary Dynamics ◽  
Linkage Equilibrium ◽  
Sex Linkage ◽  
Genetic Composition ◽  
Evolutionary Forces ◽  
And Migration ◽  
The Web ◽  
Quasi Linkage Equilibrium

Abstract In 1991, Barton and Turelli developed recursions to describe the evolution of multilocus systems under arbitrary forms of selection. This article generalizes their approach to allow for arbitrary modes of inheritance, including diploidy, polyploidy, sex linkage, cytoplasmic inheritance, and genomic imprinting. The framework is also extended to allow for other deterministic evolutionary forces, including migration and mutation. Exact recursions that fully describe the state of the population are presented; these are implemented in a computer algebra package (available on the Web at http://helios.bto.ed.ac.uk/evolgen). Despite the generality of our framework, it can describe evolutionary dynamics exactly by just two equations. These recursions can be further simplified using a “quasi-linkage equilibrium” (QLE) approximation. We illustrate the methods by finding the effect of natural selection, sexual selection, mutation, and migration on the genetic composition of a population.

scholarly journals Evolution of correlated complexity in the radically different courtship signals of birds-of-paradise

2018 ◽  
Author(s):  
Russell A. Ligon ◽  
Christopher D. Diaz ◽  
Janelle L. Morano ◽  
Jolyon Troscianko ◽  
Martin Stevens ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Evolutionary Biology ◽  
Evolutionary Dynamics ◽  
Functional Integration ◽  
Empirical Support ◽  
Evolutionary Patterns ◽  
Evolutionary Innovation ◽  
Birds Of Paradise ◽  
Analytical Approaches

Ornaments used in courtship often vary wildly among species, reflecting the evolutionary interplay between mate preference functions and the constraints imposed by natural selection. Consequently, understanding the evolutionary dynamics responsible for ornament diversification has been a longstanding challenge in evolutionary biology. However, comparing radically different ornaments across species, as well as different classes of ornaments within species, is a profound challenge to understanding diversification of sexual signals. Using novel methods and a unique natural history dataset, we explore evolutionary patterns of ornament evolution in a group - the birds-of-paradise - exhibiting dramatic phenotypic diversification widely assumed to be driven by sexual selection. Rather than the tradeoff between ornament types originally envisioned by Darwin and Wallace, we found positive correlations among cross-modal (visual/acoustic) signals indicating functional integration of ornamental traits into a composite unit - the courtship phenotype. Furthermore, given the broad theoretical and empirical support for the idea that systemic robustness - functional overlap and interdependency - promotes evolutionary innovation, we posit that birds-of-paradise have radiated extensively through ornamental phenotype space as a consequence of the robustness in the courtship phenotype that we document at a phylogenetic scale. We suggest that the degree of robustness in courtship phenotypes among taxa can provide new insights into the relative influence of sexual and natural selection on phenotypic radiations.Author SummaryAnimals frequently vary widely in ornamentation, even among closely related species. Understanding the patterns that underlie this variation is a significant challenge, requiring comparisons among drastically different traits - like comparing apples to oranges. Here, we use novel analytical approaches to quantify variation in ornamental diversity and richness across the wildly divergent birds-of-paradise, a textbook example of how sexual selection can profoundly shape organismal phenotypes. We find that color and acoustic complexity, along with behavior and acoustic complexity, are positively correlated across evolutionary time-scales. Positive covariation among ornament classes suggests that selection is acting on correlated suites of traits - a composite courtship phenotype - and that this integration may be partially responsible for the extreme variation we see in birds-of-paradise.

scholarly journals REMARKS ON THE EVOLUTIONARY EFFECT OF NATURAL SELECTION

Genetics ◽  
1976 ◽  
Vol 83 (3) ◽  
pp. 601-607
Author(s):  
W J Ewens
Keyword(s):  
Natural Selection ◽  
Present Note ◽  
Great Majority ◽  
Linkage Equilibrium ◽  
Evolutionary Effect ◽  
Mathematical Theorem ◽  
Fitness Parameters ◽  
Mean Fitness ◽  
The Mean ◽  
Quasi Linkage Equilibrium

ABSTRACT The so-called "Fundamental Theorem of Natural Selection", that the mean fitness of a population increases with time under natural selection, is known not to be true, as a mathematical theorem, when fitnesses depend on more than one locus. Although this observation may not have particular biological relevance, (so that mean fitness may well increase in the great majority of interesting situations), it does suggest that it is of interest to find an evolutionary result which is correct as a mathematical theorem, no matter how many loci are involved. The aim of the present note is to prove an evolutionary theorem relating to the variance in fitness, rather than the mean: this theorem is true for an arbitrary number of loci, as well as for arbitrary (fixed) fitness parameters and arbitrary linkage between loci. Connections are briefly discussed between this theorem and the principle of quasi-linkage equilibrium.

scholarly journals Stronger net selection on males across animals

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Lennart Winkler ◽  
Maria Moiron ◽  
Edward H Morrow ◽  
Tim Janicke
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Natural Selection ◽  
Environmental Change ◽  
Evolutionary Dynamics ◽  
Comparative Approach ◽  
Sex Bias ◽  
Adaptive Potential ◽  
Stressful Environment ◽  
Preliminary Support

Sexual selection is considered the major driver for the evolution of sex differences. However, the eco-evolutionary dynamics of sexual selection and their role for a population’s adaptive potential to respond to environmental change have only recently been explored. Theory predicts that sexual selection promotes adaptation at a low demographic cost only if sexual selection is aligned with natural selection and if net selection is stronger on males compared to females. We used a comparative approach to show that net selection is indeed stronger in males and provide preliminary support that this sex bias is associated with sexual selection. Given that both sexes share the vast majority of their genes, our findings corroborate the notion that the genome is often confronted with a more stressful environment when expressed in males. Collectively, our study supports one of the long-standing key assumptions required for sexual selection to bolster adaptation, and sexual selection may therefore enable some species to track environmental change more efficiently.

scholarly journals Sexual selection and the evolutionary dynamics of the major histocompatibility complex

2014 ◽  
Vol 281 (1796) ◽  
pp. 20141662 ◽  
Author(s):  
Maciej Jan Ejsmond ◽  
Jacek Radwan ◽  
Anthony B. Wilson
Keyword(s):  
Sexual Selection ◽  
Major Histocompatibility Complex ◽  
Natural Selection ◽  
Evolutionary Dynamics ◽  
Allelic Variation ◽  
Allelic Diversity ◽  
Major Histocompatibility ◽  
Disassortative Mating ◽  
Functional Variants ◽  
Histocompatibility Complex

The genes of the major histocompatibility complex (MHC) are a key component of the adaptive immune system and among the most variable loci in the vertebrate genome. Pathogen-mediated natural selection and MHC-based disassortative mating are both thought to structure MHC polymorphism, but their effects have proven difficult to discriminate in natural systems. Using the first model of MHC dynamics incorporating both survival and reproduction, we demonstrate that natural and sexual selection produce distinctive signatures of MHC allelic diversity with critical implications for understanding host–pathogen dynamics. While natural selection produces the Red Queen dynamics characteristic of host–parasite interactions, disassortative mating stabilizes allele frequencies, damping major fluctuations in dominant alleles and protecting functional variants against drift. This subtle difference generates a complex interaction between MHC allelic diversity and population size. In small populations, the stabilizing effects of sexual selection moderate the effects of drift, whereas pathogen-mediated selection accelerates the loss of functionally important genetic diversity. Natural selection enhances MHC allelic variation in larger populations, with the highest levels of diversity generated by the combined action of pathogen-mediated selection and disassortative mating. MHC-based sexual selection may help to explain how functionally important genetic variation can be maintained in populations of conservation concern.

scholarly journals The evolution of genetic diversity in changing environments

2014 ◽  
Author(s):  
Oana Carja ◽  
Uri Liberman ◽  
Marcus W. Feldman
Keyword(s):  
Phenotypic Variation ◽  
Evolutionary Dynamics ◽  
Phenotypic Diversity ◽  
Theoretical Models ◽  
Fluctuating Selection ◽  
Evolutionary Forces ◽  
And Migration ◽  
Compare And Contrast ◽  
Insight Into

The production and maintenance of genetic and phenotypic diversity under temporally fluctuating selection and the signatures of environmental and selective volatility in the patterns of genetic and phenotypic variation have been important areas of focus in population genetics. On one hand, stretches of constant selection pull the genetic makeup of populations towards local fitness optima. On the other, in order to cope with changes in the selection regime, populations may evolve mechanisms that create a diversity of genotypes. By tuning the rates at which variability is produced, such as the rates of recombination, mutation or migration, populations may increase their long-term adaptability. Here we use theoretical models to gain insight into how the rates of these three evolutionary forces are shaped by fluctuating selection. We compare and contrast the evolution of recombination, mutation and migration under similar patterns of environmental change and show that these three sources of phenotypic variation are surprisingly similar in their response to changing selection. We show that knowing the shape, size, variance and asymmetry of environmental runs is essential for accurate prediction of genetic evolutionary dynamics.

Clines induced by variable selection and migration

1981 ◽  
Vol 214 (1194) ◽  
pp. 99-123 ◽  
Keyword(s):  
Natural Selection ◽  
Diffusion Equation ◽  
Carrying Capacity ◽  
Nonlinear Diffusion ◽  
Nonlinear Diffusion Equation ◽  
Spatial Distributions ◽  
Genetic Composition ◽  
Technical Sense ◽  
Stable Solutions ◽  
And Migration

Clines (non-uniform spatial distributions in the genetic composition of a population in equilibrium) are often modelled by non-constant solutions u(x) ∈ [0,1] of [ D(x) u ']' + h(x, u) = 0, – ∞ < x < ∞, where h satisfies h ( x , 0) = h ( x , 1) = 0, and D is often taken to be identically one. The functions D and h have interpretations in terms of mobility, carrying capacity and natural selection. We define clines as stable solutions satisfying u ( – ∞ ) = 0, u (∞) = 1. All past analyses of clines have considered the case when (say) 0 is the favoured state for large negative x , and 1 for large positive x (i. e. ∫ 0 1 h(x, u) d u changes sign from negative to positive as x increases from – ∞ to ∞). In this paper, however, we assume that the state 0 is favoured for all x , although both 0 and 1 are stable as uniform states. Conditions are given that ensure the existence of stable clines, or their analogues for bounded habitats. Conditions are also given that ensure the non-existence of clines. The concept of stability is to be understood with reference to the corresponding nonlinear diffusion equation, and is used in a special technical sense.

scholarly journals Understanding evolutionary dynamics of phosphorylation with fungal species as model system

2017 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Natural Selection ◽  
Protein Phosphorylation ◽  
Conformational Changes ◽  
Protein Function ◽  
Evolutionary Dynamics ◽  
Fungal Species ◽  
Cellular Level ◽  
Evolutionary Forces ◽  
Selection Factors ◽  
Selection Of

Movement in proteins requires energy. To this end, natural selection has selected phosphate as the principal energy currency in cells. On the other hand, depicting the state of transcription could come in the form of epigenetic markers, which are modifications on nucleotide residues. But, what are the deeper evolutionary forces that underpin the selection of phosphorylation as a key process for translating molecular information of cellular state into specific phenotype in movement and metabolism at the cellular level? From another perspective, what are the factors that guide the selection of particular phosphosites as principal phosphorylation sites? Seeking answers to the latter question, Villen and coworkers (“Evolution of protein phosphorylation across 18 fungal species”, Science, Link ) used mass spectrometry to profile the phosphoproteome of 18 fungal species and employed discovery science approaches to elucidate specific phosphosite highly conserved for particular functions such as transcription and translation. Using histone protein (H2) and transcription initiator factor (eIF4E) as model proteins for gaining a deeper understanding of the evolutionary forces that shape the annotation of specific phosphosite (from a large library of possible phosphosites) as key molecular effectors of cellular processes such as conformational changes in enzymes and ion channels. Results obtained suggests possible selection forces that define particular phosphosite for function, which are corroborated through assessing kinase motif usage and biochemical assays for the binding affinity between peptide libraries and cell lysates. Looking at a broader landscape of protein phosphorylation, the paper, however, does not yield sufficient insights to answer questions such as how protein phosphorylation first emerged as a defining mechanism for translating stored cellular energy in phosphate groups into movement necessary for protein function and, by extension, that of the cell. Understanding the evolutionary processes that first potentiated protein phosphorylation as well as the specific natural selection factors that resulted in the definition of specific phosphosite for particular function are fundamental questions important to understanding how biology utilizes chemical and physical principles for powering life.

scholarly journals Understanding evolutionary dynamics of phosphorylation with fungal species as model system

2017 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Natural Selection ◽  
Protein Phosphorylation ◽  
Conformational Changes ◽  
Protein Function ◽  
Evolutionary Dynamics ◽  
Fungal Species ◽  
Cellular Level ◽  
Evolutionary Forces ◽  
Selection Factors ◽  
Selection Of

Movement in proteins requires energy. To this end, natural selection has selected phosphate as the principal energy currency in cells. On the other hand, depicting the state of transcription could come in the form of epigenetic markers, which are modifications on nucleotide residues. But, what are the deeper evolutionary forces that underpin the selection of phosphorylation as a key process for translating molecular information of cellular state into specific phenotype in movement and metabolism at the cellular level? From another perspective, what are the factors that guide the selection of particular phosphosites as principal phosphorylation sites? Seeking answers to the latter question, Villen and coworkers (“Evolution of protein phosphorylation across 18 fungal species”, Science, Link ) used mass spectrometry to profile the phosphoproteome of 18 fungal species and employed discovery science approaches to elucidate specific phosphosite highly conserved for particular functions such as transcription and translation. Using histone protein (H2) and transcription initiator factor (eIF4E) as model proteins for gaining a deeper understanding of the evolutionary forces that shape the annotation of specific phosphosite (from a large library of possible phosphosites) as key molecular effectors of cellular processes such as conformational changes in enzymes and ion channels. Results obtained suggests possible selection forces that define particular phosphosite for function, which are corroborated through assessing kinase motif usage and biochemical assays for the binding affinity between peptide libraries and cell lysates. Looking at a broader landscape of protein phosphorylation, the paper, however, does not yield sufficient insights to answer questions such as how protein phosphorylation first emerged as a defining mechanism for translating stored cellular energy in phosphate groups into movement necessary for protein function and, by extension, that of the cell. Understanding the evolutionary processes that first potentiated protein phosphorylation as well as the specific natural selection factors that resulted in the definition of specific phosphosite for particular function are fundamental questions important to understanding how biology utilizes chemical and physical principles for powering life.

Darwinian Evolutionary Theory

2018 ◽  
Author(s):  
Michael Ruse
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Middle Class ◽  
Evolutionary Theory ◽  
Scientific Community ◽  
Homo Sapiens ◽  
Origin Of Species ◽  
Theory Of Evolution ◽  
Descent Of Man

Charles Robert Darwin, the English naturalist, published On the Origin of Species in 1859 and the follow-up work The Descent of Man in 1871. In these works, he argued for his theory of evolution through natural selection, applying it to all organisms, living and dead, including our own species, Homo sapiens. Although controversial from the start, Darwin’s thinking was deeply embedded in the culture of his day, that of a middle-class Englishman. Evolution as such was an immediate success in scientific circles, but although the mechanism of selection had supporters in the scientific community (especially among those working with fast-breeding organisms), its real success was in the popular domain. Natural selection, and particularly the side mechanism of sexual selection, were known to all and popular themes in fiction and elsewhere.

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