DOCSLIB.ORG

On the Feasibility of Saltational Evolution

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
On the Feasibility of Saltational Evolution On the feasibility of saltational evolution Mikhail I. Katsnelsona,1, Yuri I. Wolfb, and Eugene V. Kooninb,1 aInstitute for Molecules and Materials, Radboud University, 6525AJ Nijmegen, The Netherlands; and bNational Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894 Contributed by Eugene V. Koonin, August 28, 2019 (sent for review May 28, 2019; reviewed by Christoph Adami and Claus O. Wilke) Is evolution always gradual or can it make leaps? We examine a in the landscape, for example to the slope of a different, mathematical model of an evolutionary process on a fitness land- higher peak, via simultaneous fixation of multiple mutations scape and obtain analytic solutions for the probability of multimutation (Fig. 1). leaps, that is, several mutations occurring simultaneously, within a We sought to obtain analytically, within the population single generation in 1 genome, and being fixed all together in the genetics framework, the conditions under which multimuta- evolving population. The results indicate that, for typical, empir- tional leaps might be feasible. The results suggest that, under ically observed combinations of the parameters of the evolution- most typical parameters of the evolutionary process, leaps ary process, namely, effective population size, mutation rate, and distribution of selection coefficients of mutations, the probabil- cannot be fixed. However, taking sign epistasis into account, we ity of a multimutation leap is low, and accordingly the contribu- show that saltational evolution could become relevant under tion of such leaps is minor at best. However, we show that, conditions of elevated mutation rate under stress so that stress- taking sign epistasis into account, leaps could become an induced mutagenesis could be considered an evolvable adaptation important factor of evolution in cases of substantially elevated strategy. mutation rates, such as stress-induced mutagenesis in microbes. We hypothesize that stress-induced mutagenesis is an evolvable Results adaptive strategy. Multimutation Leaps in the Equilibrium Regime. Let us assume (binary) genomes of length L (in the context of this analysis, L fitness landscape | stress-induced mutagenesis | epistasis | should be construed as the number of evolutionarily relevant EVOLUTION purifying selection | positive selection sites, such as codons in protein-coding genes, rather than the total number of sites), the probability of single mutation μ << venerable principle of natural philosophy, most consistently 1 per site per round of replication (generation), and constant Apropounded by Leibnitz (1) and later embraced by prom- effective population size Ne >> 1. Then, the transition inent biologists, in particular Linnaeus (2), is “natura non facit i j saltus” “ ” probability from sequence to sequence is (equation 3.11 in ( nature does not make leaps ). This principle then be- ref. 15) came one of the key tenets of Darwin’s theory that was inherited by the modern synthesis of evolutionary biology. In evolutionary hij L−hij qij = μ ð1 − μÞ , [1] biology, the rejection of saltation takes the form of gradualism, that is, the notion that evolution proceeds gradually, via accu- where hij is the Hamming distance (number of different sites mulation of “infinitesimally small” heritable changes (3, 4). between the 2 sequences). The number of sequences separated However, some of the most consequential evolutionary changes, by the distance h is equal to the number of ways h sites can be such as, for example, the emergence of major taxa, seem to selected from L, that is, occur abruptly rather than gradually, prompting hypotheses on the importance of saltational evolution, for example by Goldschmidt (“hopeful monsters”) and Simpson (“quantum Significance evolution”). Subsequently, these ideas have received a more systematic, even if qualitative, treatment in the concepts of In evolutionary biology, it is generally assumed that evolution punctuated equilibrium (5, 6) and evolutionary transitions occurs in the weak mutation limit, that is, the frequency of (7, 8). multiple mutations simultaneously occurring in the same genome Within the framework of modern evolutionary biology, and the same generation is negligible. We employ mathematical gradualism corresponds to the weak-mutation limit, that is, modeling to show that, although under the typical parameter an evolutionary regime in which mutations occur one by one, values of the evolutionary process the probability of multi- consecutively, such that the first mutation is assessed by se- mutational leaps is indeed low, they might become substantially lection and either fixed or purged from the population, be- more likely under stress, when the mutation rate is dramatically fore the second mutation occurs (9). A radically different, elevated. We hypothesize that stress-induced mutagenesis in saltational mode of evolution (10, 11) is conceivable under microbes is an evolvable adaptive strategy. Multimutational the strong-mutation limit (9) whereby multiple mutations leaps might matter also in other cases of substantially increased occurring within a single generation and in the same genome mutation rate, such as growing tumors or evolution of primordial potentially could be fixed all together. Under the fitness replicators. landscape concept (12, 13), gradual or more abrupt evolu- Author contributions: M.I.K. and E.V.K. designed research; M.I.K. and Y.I.W. performed tionary processes can be depicted as distinct types of trajec- research; M.I.K., Y.I.W., and E.V.K. analyzed data; and M.I.K. and E.V.K. wrote tories on fitness landscapes (Fig. 1). The typical evolutionary the paper. paths on such landscapes are thought to be 1 step at a time, Reviewers: C.A., Michigan State University; and C.O.W., The University of Texas at Austin. uphill mutational walks (12). In small populations, where The authors declare no competing interest. genetic drift becomes an important evolutionary factor, the This open access article is distributed under Creative Commons Attribution-NonCommercial- likelihood of downhill movements becomes nonnegligible NoDerivatives License 4.0 (CC BY-NC-ND). (14). In principle, however, a different type of moves on 1To whom correspondence may be addressed. Email: [email protected] or fitness landscapes could occur, namely, leaps (or “flights”) [email protected]. across valleys when a population can move to a different area www.pnas.org/cgi/doi/10.1073/pnas.1909031116 PNAS Latest Articles | 1of8 Downloaded by guest on September 24, 2021 AB CD Fig. 1. Walks and leaps on different types of fitness landscapes. Dots show genome states; blue (shirt straight) arrows indicate consecutive moves via fixation of single mutations; red (long curved) arrows indicate multimutation leaps. (A) Nearly neutral landscape. (B) Landscape dominated by slightly deleterious mutations. (C)Kimura’s model landscape (a fraction of mutations is neutral; the rest are lethal). (D) Landscape combining beneficial and deleterious mutations. L! Lh epistasis, that is, with additive fitness effects of individual N = ≈ [2] mutations: h ðL − hÞ!h! h! , ΔðhÞ = y1 + y2 + ... + yh, [6] where the last, approximate expression is valid under the assump- L >> L >> h h tion that 1and ( can be of the order of 1). where yi are independent random variables with the distribution func- μ << Assuming also 1, we obtain a typical combinatorial prob- tions GjðyjÞ. Then, the distribution function of the fitness difference is h ability of leaps over the distance : ! Y Z X h −Lμ ðLμÞ e ρ ðΔÞ = dyjGj yj δ yj − Δ QðhÞ ∼ N qðhÞ = P ðLμÞ ≡ [3] h h h h! , j j Z∞ Z [7] dk Y which is a Poisson distribution with the expectation Lμ. = e−ikΔ dy eikyj G y π j j j , i 2 j In steady state, the probability of fixation of the state is −∞ proportional to expð−νxiÞ where which is obtained by using the standard Fourier transformation ν = N − ð Þ [4] e 1 Moran process of the delta function. Now, let us specify the distribution of the fitness effects of ν = 2ðNe − 1Þ ðhaploid Wright-Fisher processÞ mutations GiðyiÞ, assuming an exponential dependency of the probability of a mutation on its fitness effect, separately for ν = 2Ne − 1 ðdiploid Wright-Fisher processÞ beneficial and deleterious mutations: x = − f f i x D e−eiyi y > and i ln i where i is the fitness of the genotype [ i is P ðy Þ = i , i 0 [8] i i eiyi , analogous to energy in the Boltzmann distribution within the Dirie , yi < 0 analogy between population genetics and statistical physics (16)]. For other demographic structures and assumptions on the mu- where Di is the normalization factor, ri is the ratio of the probabil- tation process, the relationship between fixation probability can ities of beneficial and deleterious mutations, and ei is the inverse of quantitatively differ while retaining the same form. In particular, the characteristic fitness difference for a single mutation (discussed for a population that produces offspring by binary division (fis- below). For simplicity, we assume here the same decay rates for the sion), ν ≈ 4Ne (17, 18). probability density of the fitness effects of beneficial and deleterious mutations. Empirical data on the distributions of fitness effects of Then, the rate of the occurrence and fixation of the transition r i → j is (15) mutations (19, 20) clearly indicate that i 1. From the normali- zation condition, À Á ν x − x W = q  À i jÁà [5] ei ij ij ν x − x − . Di = ≈ ei. [9] exp i j 1 1 + ri The distribution function of the fitness differential Δij = xi − xj Note that the mean of the fitness difference (selection co- has to be specified (hereafter, we refer to x as fitness, omit- efficient) when the distribution of the fitness effects is given ting logarithm for brevity). We analyze first the case without by 8 is 2of8 | www.pnas.org/cgi/doi/10.1073/pnas.1909031116 Katsnelson et al. Downloaded by guest on September 24, 2021 Z 1 A10 B jsij = dyiGiðyiÞyi ≈ .
Load more

Recommended publications
  • Transformations of Lamarckism Vienna Series in Theoretical Biology Gerd B
    Transformations of Lamarckism Vienna Series in Theoretical Biology Gerd B. M ü ller, G ü nter P. Wagner, and Werner Callebaut, editors The Evolution of Cognition , edited by Cecilia Heyes and Ludwig Huber, 2000 Origination of Organismal Form: Beyond the Gene in Development and Evolutionary Biology , edited by Gerd B. M ü ller and Stuart A. Newman, 2003 Environment, Development, and Evolution: Toward a Synthesis , edited by Brian K. Hall, Roy D. Pearson, and Gerd B. M ü ller, 2004 Evolution of Communication Systems: A Comparative Approach , edited by D. Kimbrough Oller and Ulrike Griebel, 2004 Modularity: Understanding the Development and Evolution of Natural Complex Systems , edited by Werner Callebaut and Diego Rasskin-Gutman, 2005 Compositional Evolution: The Impact of Sex, Symbiosis, and Modularity on the Gradualist Framework of Evolution , by Richard A. Watson, 2006 Biological Emergences: Evolution by Natural Experiment , by Robert G. B. Reid, 2007 Modeling Biology: Structure, Behaviors, Evolution , edited by Manfred D. Laubichler and Gerd B. M ü ller, 2007 Evolution of Communicative Flexibility: Complexity, Creativity, and Adaptability in Human and Animal Communication , edited by Kimbrough D. Oller and Ulrike Griebel, 2008 Functions in Biological and Artifi cial Worlds: Comparative Philosophical Perspectives , edited by Ulrich Krohs and Peter Kroes, 2009 Cognitive Biology: Evolutionary and Developmental Perspectives on Mind, Brain, and Behavior , edited by Luca Tommasi, Mary A. Peterson, and Lynn Nadel, 2009 Innovation in Cultural Systems: Contributions from Evolutionary Anthropology , edited by Michael J. O ’ Brien and Stephen J. Shennan, 2010 The Major Transitions in Evolution Revisited , edited by Brett Calcott and Kim Sterelny, 2011 Transformations of Lamarckism: From Subtle Fluids to Molecular Biology , edited by Snait B.
    [Show full text]
  • Natural Necessity Natural Selection
    NATURAL SELECTION NATURAL NECESSITY See Laws of Nature NATURAL SELECTION In modern evolutionary biology, a set of objects is Adaptationism said to experience a selection process precisely when At the close of his introduction to those objects vary in/itness (see Fitness). For exam­ On the Origin oj' ple, if zebras that run fast are fitter than zehras that Species, Darwin [1859] 1964, 6 says that natural selection is "the main but not the exclusive" cause run slow (perhaps because faster zebras are better ofevolution. In reaction to misinterpretations ofhis able to avoid lion predation), a selection process is theory, Darwin felt compelled to reemphasize, in the set in motion. If the trait that exhibits variation hook's last edition, that there was more to evolution in fit~ess is heritable-meaning, in our example, that faster parents tend to have faster offspring than natural selection. It remains a matter of con­ troversy in evolutionary biology how important and slower parents tend to have slower offspring­ then the selection process is apt to chancre trait natural selection has been in the history of life. frequencies in the population, leading fitte';. traits This is the poinl of biological substance that pres­ to increase in frequency and less fit traits to decline ently divides adaptationists and anti-adaptationists. The debate over adaptationism also has a separate (Lewontin 1970). This change is the one that selec­ tion is "apt" to engender, rather than the one that methodological dimension, with critics insisting that adaptive hypotheses be tested more rigorously must occur, because evolutionary theory describes <Gould and Lewontin 1979; Sober 1993).
    [Show full text]
  • Writings of Charles De Koninck, Volume
    D E K O N I N The Writings C K of ልሎ CHARLES C H DE KONINCK A R T L h E e S W D r i E t i n K g O s o N f I N C K ልሎ Edited and Translated by Ralph McInerny The Writings of CHARLES DE KONINCK Charles De Koninck, University of Laval, Quebec. The Writings of CHARLES DE KONINCK volume one Edited and Translated by Ralph McInerny with a biography by Thomas De Koninck andልሎ an introduction by Leslie Armour University of Notre Dame Press Notre Dame, Indiana DeKoninck-000.FM 4/15/08 1:17 PM Page iv Copyright © by University of Notre Dame Notre Dame, Indiana www.undpress.nd.edu All Rights Reserved Manufactured in the United States of America Designed by Wendy McMillen Set in ./. Minion by Four Star Books Printed on # Nature’s Recycle paper by Sheridan Books, Inc. Library of Congress Cataloging-in-Publication Data Koninck, Charles de, d. [Works. English. ] The writings of Charles De Koninck / edited and translated by Ralph McInerny ; with a biography by Thomas De Koninck ; and an introduction by Leslie Armour. p. cm. Includes bibliographical references and index. -: ---- (cloth : alk. paper) -: --- (cloth : alk. paper) . Koninck, Charles de, d. Science—Philosophy. I. McInerny, Ralph M. II. Title. '.—dc This book is printed on recycled paper. Contents Preface vii The Philosophy of Charles De Koninck 1 Leslie Armour Charles De Koninck: A Biographical Sketch 69 Thomas De Koninck ልሎ Works by Charles De Koninck The Philosophy of Sir Arthur Eddington (1934) 99 The Cosmos (1936) 235 The Problem of Indeterminism (1935) 355 Reflections on the Problem of Indeterminism (1937) 401 Are the Experimental Sciences Distinct from the Philosophy of Nature? (1941) 443 Index 457 Preface A few years ago, David Quackenbush, a tutor at Thomas Aquinas College in California, conceived the idea of photocopying the Charles De Koninck ar- chives at the University of Laval.
    [Show full text]
  • Mimicry, Saltational Evolution, and the Crossing of Fitness Valleys
    CHAPTER 16 Mimicry, Saltational Evolution, and the Crossing of Fitness Valleys Olof Leimar, Birgitta S. Tullberg, and James Mallet 16.1 Introduction saltationism. In terms of Adaptive Landscapes, if the mimic-to-be resides on one adaptive peak and The relative contribution of gradual and saltational the model on another, mimicry evolves in a single change to evolution has been debated ever since mutational leap, and the issue of natural selection Darwin (1859) emphasized gradualism in his the- only enters through the constraint that the peak ory of evolution by natural selection. The phe- jumped to should be higher than the starting peak. nomenon of mimicry was an important example This would apply both to Müllerian mimicry, where in this debate. In mimicry evolution, members of the starting point is an aposematic species, and to a population or species become similar in appear- Batesian mimicry, where the starting adaptive peak ance to an aposematic model species and thereby of the palatable mimic-to-be is determined by func- gain increased protection from predation. The num- tions other than aposematism, for instance crypsis ber of steps in the approach to mimicry could be or other protective coloration, like flash coloration few or many and their sizes either large or small. (Cott 1940; Ruxton et al. 2004), or partner choice. In 1915, Punnett published an influential book on In response to claims like those by Punnett (1915), mimicry in butterflies, in which he summed up and as part of his efforts to unify gradualism and his strong opposition to gradualistic accounts of Mendelian genetics, Fisher (1927, 1930) presented mimicry evolution.
    [Show full text]
  • The Origin of Historical Kinds in Biology and Culture Günter P. Wagne
    Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 24 April 2019 doi:10.20944/preprints201904.0266.v1 Extending the Explanatory Scope of Evolutionary Theory: The Origin of Historical Kinds in Biology and Culture Günter P. Wagner and Gary Tomlinson Yale University Abstract Since its inception, evolutionary theory has experienced a number of extensions. The most important of these took the forms of the Modern Evolutionary Synthesis (MES), embracing genetics and population biology in the early 20th century, and the Extended Evolutionary Synthesis (EES) of the last thirty years, embracing, among other factors, non-genetic forms of inheritance. While we appreciate the motivation for this recent extension, we argue that it does not go far enough, since it restricts itself to widening explanations of adaptation by adding mechanisms of inheritance and variation. A more thoroughgoing extension is needed, one that widens the explanatory scope of evolutionary theory. In addition to adaptation and its various mechanisms, evolutionary theory must recognize as a distinct intellectual challenge the origin of what we call “historical kinds.” Under historical kinds we include any process that acquires a quasi-independent and traceable lineage-history in biological and cultural evolution. We develop the notion of a historical kind in a series of paradigmatic exemplars, from genes and homologues to rituals and music, and we propose a preliminary characterization. Keywords: historical individuals, extended evolutionary synthesis, evolutionary innovation, culture 1. Introduction For the last several decades, a set of concerns has exerted increasing pressure on the modern evolutionary synthesis (MES) of the mid-twentieth century, with the goal of widening the explanatory powers of evolutionary theory.
    [Show full text]
  • Soft Inheritance: Challenging the Modern Synthesis
    Genetics and Molecular Biology, 31, 2, 389-395 (2008) Copyright © 2008, Sociedade Brasileira de Genética. Printed in Brazil www.sbg.org.br Review Article Soft inheritance: Challenging the Modern Synthesis Eva Jablonka1 and Marion J. Lamb2 1The Cohn Institute for the History and Philosophy of Science and Ideas, Tel-Aviv University, Tel-Aviv, Israel. 211 Fernwood, Clarence Road, London, United Kingdom. Abstract This paper presents some of the recent challenges to the Modern Synthesis of evolutionary theory, which has domi- nated evolutionary thinking for the last sixty years. The focus of the paper is the challenge of soft inheritance - the idea that variations that arise during development can be inherited. There is ample evidence showing that phenotypic variations that are independent of variations in DNA sequence, and targeted DNA changes that are guided by epigenetic control systems, are important sources of hereditary variation, and hence can contribute to evolutionary changes. Furthermore, under certain conditions, the mechanisms underlying epigenetic inheritance can also lead to saltational changes that reorganize the epigenome. These discoveries are clearly incompatible with the tenets of the Modern Synthesis, which denied any significant role for Lamarckian and saltational processes. In view of the data that support soft inheritance, as well as other challenges to the Modern Synthesis, it is concluded that that synthesis no longer offers a satisfactory theoretical framework for evolutionary biology. Key words: epigenetic inheritance, hereditary variation, Lamarckism, macroevolution, microevolution. Received: March 18, 2008; Accepted: March 19, 2008. Introduction 1. Heredity occurs through the transmission of germ- There are winds of change in evolutionary biology, line genes.
    [Show full text]
  • From Logos to Bios: Hellenic Philosophy and Evolutionary Biology
    From Logos to Bios: Hellenic Philosophy and Evolutionary Biology by Wynand Albertus de Beer submitted in accordance with the requirements for the degree of D Litt et Phil in the subject Religious Studies at the University of South Africa Supervisor: Prof Danie Goosen February 2015 Dedicated with grateful acknowledgements to my supervisor, Professor Danie Goosen, for his wise and patient guidance and encouragement throughout my doctoral research, and to the examiners of my thesis for their helpful comments and suggestions. From Logos to Bios: Hellenic Philosophy and Evolutionary Biology by W.A. de Beer Degree: D Litt et Phil Subject: Religious Studies Supervisor: Prof Danie Goosen Summary: This thesis deals with the relation of Hellenic philosophy to evolutionary biology. The first part entails an explication of Hellenic cosmology and metaphysics in its traditional understanding, as the Western component of classical Indo-European philosophy. It includes an overview of the relevant contributions by the Presocratics, Plato, Aristotle, and the Neoplatonists, focussing on the structure and origin of both the intelligible and sensible worlds. Salient aspects thereof are the movement from the transcendent Principle into the realm of Manifestation by means of the interaction between Essence and Substance; the role of the Logos, being the equivalent of Plato’s Demiurge and Aristotle’s Prime Mover, in the cosmogonic process; the interaction between Intellect and Necessity in the formation of the cosmos; the various kinds of causality contributing to the establishment of physical reality; and the priority of being over becoming, which in the case of living organisms entails the primacy of soul over body.
    [Show full text]
  • Calculus of Variations and Optimal Control for Gf 3
    CALCULUS OF VARIATIONS AND OPTIMAL CONTROL FOR GENERALIZED FUNCTIONS GAST¨I¿ŒO S.F. FREDERICO, PAOLO GIORDANO, ALEXANDR A. BRYZGALOV, AND MATHEUS J. LAZO Abstract. We present an extension of some results of higher order calculus of variations and optimal control to generalized functions. The framework is the category of generalized smooth functions, which includes Schwartz distributions, while sharing many nonlinear prop- erties with ordinary smooth functions. We prove the higher order Euler-Lagrange equations, the D'Alembert principle in differential form, the du Bois-Reymond optimality condition and the Noether's theorem. We start the theory of optimal control proving a weak form of the Pontryagin maximum principle and the Noether's theorem for optimal control. We close with a study of a singularly variable length pendulum, oscillations damped by two media and the Pais{Uhlenbeck oscillator with singular frequencies. Contents 1. Introduction: singular Lagrangian mechanics1 2. Basic notions 3 2.1. Open, closed and bounded sets generated by nets5 2.2. Generalized smooth functions and their calculus5 2.3. Embedding of Sobolev-Schwartz distributions and Colombeau generalized functions8 2.4. Functionally compact sets and multidimensional integration 10 3. Higher-order calculus of variations for generalized functions 13 3.1. Higher-order Euler{Lagrange equation, D'Alembert principle and du Bois{Reymond optimality condition 15 3.2. Higher-order Noether's theorem 19 4. Optimal control problems 22 4.1. Weak Pontryagin Maximum Principle 24 4.2. Noether's Principle for optimal control 29 5. Examples and applications 31 5.1. Modeling singular dynamical systems 31 5.2. How to use numerical solutions 31 5.3.
    [Show full text]
  • The Conceptual Structure of Evolutionary Biology: a Framework from Phenotypic Plasticity
    EUROPEAN JOURNAL OF ECOLOGY EJE 2018, 4(2): 111-123, doi: 10.2478/eje-2018-0018 The conceptual structure of evolutionary biology: A framework from phenotypic plasticity Universidade Federal Rogério Parentoni Martins* do Ceará, Programa de Pós-Graduação em, Ecologia e Recursos Naturais, Departamento ABSTRACT de Biologia, Centro de In this review, I approach the role of phenotypic plasticity as a key aspect of the conceptual framework of Ciências, Brazil Corresponding author, evolutionary biology. The concept of phenotypic plasticity is related to other relevant concepts of contemporary E-mail: rpmartins917@ research in evolutionary biology, such as assimilation, genetic accommodation and canalization, evolutionary gmail.com robustness, evolvability, evolutionary capacitance and niche construction. Although not always adaptive, pheno- typic plasticity can promote the integration of these concepts to represent some of the dynamics of evolution, which can be visualized through the use of a conceptual map. Although the use of conceptual maps is common in areas of knowledge such as psychology and education, their application in evolutionary biology can lead to a better understanding of the processes and conceptual interactions of the complex dynamics of evolution. The conceptual map I present here includes environmental variability and variation, phenotypic plasticity and natural selection as key concepts in evolutionary biology. The evolution of phenotypic plasticity is important to ecology at all levels of organization, from morphological, physiological and behavioral adaptations that influence the distribution and abundance of populations to the structuring of assemblages and communities and the flow of energy through trophic levels. Consequently, phenotypic plasticity is important for maintaining ecological pro- cesses and interactions that influence the complexity of biological diversity.
    [Show full text]
  • The Physics of Wind-Blown Sand and Dust
    The physics of wind-blown sand and dust Jasper F. Kok1, Eric J. R. Parteli2,3, Timothy I. Michaels4, and Diana Bou Karam5 1Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA 2Departamento de Física, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil 3Institute for Multiscale Simulation, Universität Erlangen-Nürnberg, Erlangen, Germany 4Southwest Research Institute, Boulder, CO USA 5LATMOS, IPSL, Université Pierre et Marie Curie, CNRS, Paris, France Email: [email protected] Abstract. The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This article presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small- scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan. PACS: 47.55.Kf, 92.60.Mt, 92.40.Gc, 45.70.Qj, 45.70.Mg, 45.70.-n, 96.30.Gc, 96.30.Ea, 96.30.nd Journal Reference: Kok J F, Parteli E J R, Michaels T I and Bou Karam D 2012 The physics of wind- blown sand and dust Rep. Prog. Phys. 75 106901. 1 Table of Contents 1. Introduction .......................................................................................................................................................... 4 1.1 Modes of wind-blown particle transport ...................................................................................................... 4 1.2 Importance of wind-blown sand and dust to the Earth and planetary sciences ...........................................
    [Show full text]
  • The Case for Saltational Events in Human Evolution
    The Case for Saltational Events in Human Evolution IAN TATTERSALL Summary. Evolutionary saltation is a rather ill-defined Victorian concept that may contrast in various ways with gradual (linear) evolution. In comparing evolutionary modes it is thus more pro- ductive to bear in mind the difference between ‘transformational’ and ‘taxic’ mindsets, each of which sharply influences the way in which the evolutionary record is interpreted. It is also important to recognise the fact that, even under traditional notions of natural selection, we cannot think of the evolutionary process as one of fine-tuning the myriad systems that make up each individual and each taxon. Both individuals and species thrive or fail reproduc- tively as the sums of their parts, not as the bearers of multiple fea- tures that can somehow be tracked independently of each other over vast spans of time. In this review I look at the human morpho- logical and behavioural records in an attempt to discern pattern in human evolution, and particularly in the emergence of our own species, Homo sapiens, as narrowly defined. Homo sapiens is a vari- able species, although not notably more so than Homo nean- derthalensis, which can itself be understood only in the context of its membership in a diverse clade of endemic European species. The record clearly indicates that both modern human morphology and modern human cognitive processes appeared rather suddenly, even saltationally, although not at the same time. INTRODUCTION I HAVE BEEN ASKED TO SPEAK at this Symposium about saltation and the evidence for it in the human evolutionary record.
    [Show full text]
  • Generating and Filtering Major Phenotypic Novelties: Neogoldschmidtian Saltation Revisited
    Chapter 7 Generating and filtering major phenotypic novelties: neoGoldschmidtian saltation revisited Richard N\. Bateman and William A. D/M/che/e ABSTRACT Further developing a controversial neoGoldschmidtian paradigm that we first pub- lished in 1994, we here narrowly define saltational evolution as a genetic modifica- tion that is expressed as a profound phenotypic change across a single generation and results in a potentially independent evolutionary lineage termed a prospecies (the 'hopeful monster' of Richard Goldschmidt). Of several saltational and parasaltational mechanisms previously discussed by us, the most directly relevant to evolutionary-developmental genetics is dichotomous saltation, which is driven by mutation within a single ancestral Uneage. It can result not only in instantaneous speciation but also in the simultaneous origin of a profound phenotypic novelty more likely to be treated as a new supraspecific taxon. Saltational events form unusually long branches on morphological phylogenies, which follow a punctuated equilibrium pattern, but at the time of origin they typically form zero length branches on the contrastingly gradualistic molecular phylogenies. Our chosen case- studies of heterotopy (including homeosis) and heterochrony in fossil seed-ferns and extant orchids indicate that vast numbers of prospecies are continuously generated by mutation of key developmental genes that control morphogenesis. First principles suggest that, although higher plant mutants are more likely to become established than higher animals, the fitness of even plant prospecies is in at least most cases too low to survive competition-mediated selection. The establishment of prospecies is most Hkely under temporary release from selection in environments of low biotic competition for resources, followed by honing to competitive fitness by gradual rein- troduction to neoDarwinian selection.
    [Show full text]