A Central Concept in Biology

Edited by

  • Benedikt Hallgrímsson, University of Calgary, Alberta, Canada
  • Brian Hall, Dalhousie University, Halifax, Nova Scotia, Canada

Darwin's theory of evolution by natural selection was based on the observation that there is variation between individuals within the same species. This fundamental observation is a central concept in evolutionary biology. However, variation is only rarely treated directly. It has remained peripheral to the study of mechanisms of evolutionary change. The explosion of knowledge in genetics, developmental biology, and the ongoing synthesis of evolutionary and developmental biology has made it possible for us to study the factors that limit, enhance, or structure variation at the level of an animals' physical appearance and behavior. Knowledge of the significance of variability is crucial to this emerging synthesis. This volume situates the role of variability within this broad framework, bringing variation back to the center of the evolutionary stage.
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Intended for scholars, advanced undergraduate students, and graduates in evolutionary biology, biological anthropology, paleontology, morphology, developmental biology, genomics and other related disciplines.


Book information

  • Published: June 2005
  • ISBN: 978-0-12-088777-4


"...Variation: A Central Concept in Biology, is sure to spark the interest of nearly all ecologists and evolutionary biologists...How does this variation arise? How do new variants evolve? What contrains variation? The answers are incomplete. However, the chapters of this book provide a glimpse at our current understanding of phenotypic variation." - James A. Fordyce, University of Tenessee, Department of Ecology and Evolutionary Biology, in ECOLOGY "Variation is certainly a topic of central interest in evolutionary biology and this new book offers an unusually inclusive array of perspectives on the topic. I especially enjoyed the breadth of coverage. Novel features are found that one might not have expected in a book of this nature, such as structural, functional and developmental variation, as contrasted with the expected emphases on genetic variation, canalization and phenotypic plasticity, and their relation to life history evolution. Palmer’s stimulating chapter on antisymmetry is particularly noteworthy for its originality. Another unusual treatment is Badyaev’s focus on the role of stress in evolution, which is examined from a different perspective by Hoffmann and McKenzie. On the whole this is an assemblage of excellent chapters by many of the central figures in the fields covered and will be a welcome addition to my library." - David B. Wake, University of California, Berkeley, U.S.A. "This comprehensive, diverse and stimulating volume is a must-read for anyone interested in development and evolution. Never has the critical subject of variation been so well treated in terms of how to analyze variation, how developmental processes induce and constrain its properties, and the complex relationships between genotypic, environmental and phenotypic variation. This is a tour-de-force treatment of a critical subject." - Daniel E. Lieberman, Harvard University, U.S.A. "Where do genetic and phenotypic diversity come from and how are they are maintained? Do the same processes link the differences within species to the stable differences between species? These are the big questions about the diversity of life on Earth and Hallgrimsson and Hall’s book provides the latest views from leading scientists of diversity and form." - Mark Pagel, University of Reading, England "“Variation is the basic material of evolution. At last we have a book that takes a modern approach to variation in all its forms—populational, developmental, genetic, morphological—and links it to the processes that generate the variation itself. This is not a collection of bland reviews, but a vital compendium of novel perspectives that begin to meld the new data of evo-devo with the accepted body of Modern Synthesis work. A must for any evolutionist’s library.” - Kevin Padian, University of California, Berkeley, U.S.A. Listed in NEW TITLES in BIOSCIENCE (April 2006) "...chapters are authoritative and well written, and graduate students and scientists will find much here that is thought-provoking." - Carl D. Schlichting, Professor, Department of Ecology and Evolutionary Biology, University of Connecticut, in BIOSCIENCE

Table of Contents

Foreword - Ernst MayrCHAPTER 1. Variation and Viability: Central Concepts in Biology- Benedikt Hallgrímsson & Brian K. HallCHAPTER 2. Variation from Darwin to the Modern Synthesis, by Peter J. BowlerIntroductionI. Variation before DarwinII. Darwin and VariationIII. Alternative Theories of Variation and EvolutionIV. Neo-DarwinismV. The Evolutionary SynthesisVI. ConclusionsCHAPTER 3. The Statistics of Variation, by Leigh Van ValenAbstractIntroductionI. Absolute Variation: Univariate CaseII. Absolute Variation: Multivariate CaseIII. Relative Variation: Univariate CaseIV. Relative Variation: Multivariate CaseV. Dimensionality of VariationVI. TightnessVII. Measurement Error and Single SpecimensCHAPTER 4. Landmark Morphometrics and the Analysis of Variation, by Joan T. Richtsmeier, Subhash R. Lele and Theodore M. Cole, IIIIntroductionI. Coordinate Data and the Coordinate SystemII. The General Perturbation Model for Landmark VariationIII. Proper Elimination of Nuisance Parameters using a Coordinate System Invariant Method of EstimationIV. Adding Assumptions to the Perturbation ModelV. ConclusionsCHAPTER 5. Variation in Ontogeny, by D.C. Jones and R.Z. GermanIntroductionI. Measuring Variation A. Data B. Levels of Variation in Data on Growth and Protein Malnutrition C. Measuring within Individual Variation D. Among Individual Variation E. Variation Between Treatment GroupsII. Results A. Factor Differences for Within Individual Variation B. Factor Differences for Among Individual VariationIII. Discussion A. Within Individual Variation B. Between or among Individual Variation C. Variation across hierarchial levelsIV. ConclusionsCHAPTER 6. Constraints on Variation from Genotype through Phenotype to Fitness, by Lauren Ancel MeyersIntroductionI. RNA Evolutionary ModelII. Evolving Constraints on Variation in RNAIII. Mechanistic Constraints A. The spectrum of mutational constraints B. The Evolution of Mutational ConstraintsIV. Epistatic Constraints A. The spectrum of epistatic constraints B. The evolution of epistatic constraintsV. Viability ConstraintsVI. Modularity: A Way out of the ConstraintsCHAPTER 7. Developmental Origins of Variation, by Ellen W. LarsenIntroductionI. Does Intrinsic Developmental Variation Exist?II. Intrinsic Variation in Different EnvironmentsIII. Potential Origins of Intrinsic Developmental Variation A. NoiseIV. An Example of Noise in Eukaryotic TranscriptionV. Noisy Bicoid Gene Expression in Fruit FliesVI. Noise in Asymmetry ProductionVII. Noisy Implication for EvolutionVIII. NetworksIX. Morphogenetic Fields a Potential Source of VariationX. ImplicationsXI. SummaryCHAPTER 8. Canalization, Cryptic Variation and Developmental Buffering: A Critical Examination and Analytical Perspective, by Ian DworkinIntroductionI. A Review of the ReviewsII. Empirical Concerns for the Study of Canalization A. The amount of genetic variation must be controlled between lines/populations B. The need for multiple, independent samples C. Genetic background must be controlled for comparisons between treatmentsIII. Definitions of CanalizationIV. Reaction Norm of the Mean (RXNM) Definition of CanalizationV. The Variation Approach to CanalizationVI. Partitioning Sources of VariationVII. Inferring Canalization: When is a trait Canalized?VIII. What are the appropriate tests for making statistical inferences about Canalization?IX. In the Interim…X. Analysis for the RXNM ApproachXI. The Analysis of Cryptic Genetic VariationXII. Mapping Cryptic Genetic VariantsXIII. Is the Genetic Architecture of Cryptic Genetic Variation different from that of other Genetic Variation involved with Trait Expression?XIV. Now that I have all of this Cryptic Genetic Variation, what do I do with it?XV. The future for studies of CanalizationCHAPTER 9. Mutation and Phenotypic Variation: Where is the connection Capacitators, Stressors, Phenotypic Variability and Evolutionary Change, by Ary A. Hoffmann and John A. McKenzieAbstractIntroduction: Variability and LimitsI. Mutators, Recombinators, Stressors and Genetic VariabilityII. RecombinationIII. The Impact of New Mutants and Recombinants – Canalization and CapacitatorsIV. In Search of Capacitators: Genes that influence Developmental Stability and CanalizationV. Capacitators, Stressors, and Quantitative VariationVI. Do we need Cariability Generators?VII. Concluding Remarks: Experimental Programs for Defining the Role of Variability GeneratorsCHAPTER 10. Within Individual Variation: Developmental Noise versus Developmental Stability, by Katherine E. Willmore and Benedikt HallgrímssonIntroductionI. Causes of Developmental Noise A. Causes of Developmental Noise at the Molecular Level B. Causes of Developmental Noise at the Developmental Systems Level C. Causes of Developmental Noise at the Organismal LevelII. Mechanisms of Developmental Stability A. Mechanisms of Developmental Stability at the Molecular Level B. Mechanisms of Developmental Stability at the Developmental Systems Level C. Mechanisms of Developmental Stability at the Organismal LevelIII. Implications CHAPTER 11. Developmental Constraints, Modules and Evolvability, by Christian Peter KlingenbergAbstractIntroductionI. Evolvability and ConstraintsII. Integration and ModularityIII. Developmental Origins of Covariation among TraitsIV. Developmental Interactions and PleiotropyV. Evolution of Pleiotropy and Developmental InteractionsVI. Modularity of Pleiotropic Effects: Inherent in Developmental Systems or Evolved Property?VII. From Pleiotropic Gene Effects to G MatricesVIII. G Matrices, Constraints, and Evolutionary DynamicsIX. Perspective: Developmental Processes and Evolutionary ConstraintsCHAPTER 12. Developmental Regulation of Variability, by Miriam ZelditchIntroductionI. Empirical PatternsII. The Ontogeny of Variation in Male Norway Rat Cranial ShapeIII. Biological Patterns Versus Artifacts A. Morphological Sampling B. Life-History/Developmental RateIV. Mechanisms Generating and Regulating Craniofacial Shape VarianceV. Targeted GrowthVI. Organismal Developmental TimingVII. Variation in Relative Developmental Timing of ModulesVIII. Neural Regulation of Musculoskeletal InteractionsIX. Canalized Shape as an EpiphenomenonCHAPTER 13. Role of Stress in Evolution: From Individual Adaptability to Evolutionary Adaptation, by Alexander BadyaevIntroductionI. Evolution of Response to Stress A. Detection and AvoidanceII. Evolutionary Consequences of Stress A. Stress-induced VariationIII. Buffering, Accommodating, and Directing Stress-Induced VariationIV. InheritanceV. Evolutionary AdaptationVI. ConclusionsCHAPTER 14. Environmentally Contingent Variation: Phenotypic Plasticity and Norms of Reaction, by Sonia Sultan and Steve StearnsIntroductionI. Plasticity ConceptsII. Specific Types of PlasticityIII. Reaction NormsIV. Parental Effect Reaction Norms (Cross-Generational Plasticity)V. Imprinted Reaction NormsVI. Iterated Reaction NormsVII. Dynamic Reaction NormsVIII. Photomorphogenetic Plasticity in PlantsIX. Adaptive Plasticity for Timing of Amphibian MetamorphosisX. Mediation of Phenotypic ExpressionXI. Genetic Variation and the Evolution of Plasticity A. How Plasticity interacts with conserved developmental patternsXII. Genetic Causation and the Butterfly Wing: A More complicated pictureXIII. The Same Networks may give rise to both Plasticity and Constraint A. What effects does plasticity have on populations and communities? B. Research AgendaCHAPTER 15. Variation and Life History Evolution, by Derek A. RoffIntroductionI. Phenotypic Variation in a Constant Environment A. Heterozygous advantage B. Antagonistic pleiotropy C. Frequency-dependent selectionII. Phenotypic Variation in a Stochastic Environment A. Temporal variation B. Spatial variation C. Spatial and temporal variationIII. Predictable Environments A. Temporal variation B. Spatial variationIV. Concluding CommentsCHAPTER 16. Antisymmetry, by A. Richard PalmerIntroductionI. Asymmetry Terminology A. Terms for Subtle Asymmetries B. Terms for Conspicuous Asymmetry in an Individual C. Terms for the Orientation of Bilateral or Spiral Asymmetries D. Terms for Conspicuous Asymmetries in a Population or SpeciesII. The History of AntisymmetryIII. Taxomonic Distribution and Functional Significance of Antisymmetry A. Plants B. Cnidaria C. Mollusca D. Annelida E. Arthropoda-Chelicerata F. Arthropoda-Crustacea G. Arthropoda-Insecta H. Brachiopods I. Bryozoa J. Echinodermata K. ChordataIV. Development and Regeneration of Asymmetry in Antisymmetric Species A. OntogenyV. Regeneration of Missing AntimeresVI. Inheritance of Direction in Antisymmetric SpeciesVII. Inheritance of Direction in Directionally Asymmetric SpeciesVIII. Evolutionary Significance of AntisymmetryIX. What Next?CHAPTER 17. Variation in Structure and its Relationship to Function: Correlation, Explanation and Extrapolation, by Anthony P. Russell and Adam M. BauerAbstractIntroductionI. BackgroundII. Approaches to the Study of Structural VariationIII. Variation as an Observable Phenomenon A. Variation and Taxonomic Utility B. Variation Associated with Developmental Plasticity C. Geographically-based VariationIV. In Situ Correlational Studies of the Relationship between Structural Variation and Functional Attributes A. Trophic Polymorphism and Environmental Fluctuation B. Clinical Variation C. Microgeographic VariationV. Ex Situ Studies of the Relationship between Structural Variation and Performance A. Variation in Trophic Performance B. Locomotor Performance C. Fluctuating Asymmetry and Variation in Performance D. Selection Experiments and the Investigation of the Limits of Variability E. Other Measures of Structural and Functional Variation V. Concluding RemarksCHAPTER 18. A Universal Generative Tendency Toward Increased Organismal Complexity, by D. McSheaIntroductionI. Internal Variance as ComplexityII. Three Simple ModelsIII. The Effect of Increased DimensionalityIV. Apparent DifficultiesV. Is there an Upward Bias in Real Lineages?VI. If so, the Principle is SupportedVII. If not, Why not?VIII. Testing the PrincipleIX. A Reversal of IntuitionCHAPTER 19. Variation and Versatility in Macroevolution, by V. Louise RothI. Principles A. To Vary is Easy B. Evolvability and VersatilityII. Examples A. Elephantid Teeth B. Disparity and Versatility in SciurdaeIII. Overview and ConclusionCHAPTER 20. Variation and Developmental Biology: Prospects for the Future, by David M. ParichyIntroductionI. Model Organisms: Expanding the FoldII. Ecologically Significant Differences in Form Between SpeciesIII. How many ways to make a Phenotype: Developmental Variation and Morphological SimilarityIV. Intraspecific Developmental Variation: Canalization, and Developmental PlasticityV. ConclusionsCHAPTER 21. Phenogenetics: Genotypes, Phenotypes, and Variation, by Samuel Sholtis and Kenneth WeissIntroductionI. Mechanism versus VariationII. From Genotype to Phenotype: Mechanism A. A quick digression concerning DNA sequence: arbitrary and saturated B. Pre-transcriptional mechanisms C. Post-transcriptional mechanismsIII. From Genotype to Phenotype: Variation A. A lexicographer’s nightmare: Canalization, Robustness, Plasticity, Polyphenism… B. Developmental process: patterning repeated traits C. Gene regulation and the evolution of phenotypes D. Phenogenetic drift: the role of chance in the evolution of genotype-phenotype relationshipsIV. SummaryCHAPTER 22. The Study of Phenotypic Variability, by Benedikt Hallgrímsson and Brian K. HallIntroductionI. Variability and the Biological HierarchyII. Components of VariabilityIII. Current Approaches to Understanding the Development-Genetic Architecture of Variability A. Pattern Based Approaches B. Perturbation Based Approaches C. Model Driven ApproachesIV. A Developmental Systems Approach to Phenotypic Variability A. The Regulation of Form in the Mouse Mandible B. The Regulation of Outgrowth of the Maxillary ProcessV. ConclusionIndex