Andreas Wagner
- Published in print:
- 2011
- Published Online:
- December 2013
- ISBN:
- 9780199692590
- eISBN:
- 9780191774829
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199692590.003.0206
- Subject:
- Biology, Evolutionary Biology / Genetics
An evolutionary constraint is a bias or limitation in genotypic or phenotypic variation that a biological system produces. Striking phenotypic examples include the absence of photosynthesis in higher ...
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An evolutionary constraint is a bias or limitation in genotypic or phenotypic variation that a biological system produces. Striking phenotypic examples include the absence of photosynthesis in higher animals, and the general lack of teeth in the lower jaw of frogs. Constraints can influence the spectrum of evolutionary adaptations and innovations that are accessible to living things. Based on the cause of constrained phenotypic variation, one can distinguish physicochemical, selective, genetic, and developmental constraints. The latter class of constraints emerges from the processes that produce phenotypes from genotypes. This chapter examines these four causes for molecules, regulatory circuits, and metabolic networks in the genotype space framework. This framework shows that processes of phenotype formation cause the three other classes of constraints. It can help us appreciate why causes of constrained variation are often entangled and not clearly separable. The chapter also shows that the kind of evolutionary stasis that occurs during punctuated and episodic evolution is a consequence of genetic constraints, whose origins the genotype space framework can readily explain.Less
An evolutionary constraint is a bias or limitation in genotypic or phenotypic variation that a biological system produces. Striking phenotypic examples include the absence of photosynthesis in higher animals, and the general lack of teeth in the lower jaw of frogs. Constraints can influence the spectrum of evolutionary adaptations and innovations that are accessible to living things. Based on the cause of constrained phenotypic variation, one can distinguish physicochemical, selective, genetic, and developmental constraints. The latter class of constraints emerges from the processes that produce phenotypes from genotypes. This chapter examines these four causes for molecules, regulatory circuits, and metabolic networks in the genotype space framework. This framework shows that processes of phenotype formation cause the three other classes of constraints. It can help us appreciate why causes of constrained variation are often entangled and not clearly separable. The chapter also shows that the kind of evolutionary stasis that occurs during punctuated and episodic evolution is a consequence of genetic constraints, whose origins the genotype space framework can readily explain.
George R. McGhee
- Published in print:
- 2011
- Published Online:
- August 2013
- ISBN:
- 9780262016421
- eISBN:
- 9780262298872
- Item type:
- chapter
- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262016421.003.0007
- Subject:
- Biology, Evolutionary Biology / Genetics
This chapter deals with the theoretical analysis of evolutionary constraint in producing convergent evolution. It investigates the implications of theoretically possible, but nevertheless ...
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This chapter deals with the theoretical analysis of evolutionary constraint in producing convergent evolution. It investigates the implications of theoretically possible, but nevertheless nonexistent, ecological roles on Earth for the concept of convergent evolution, and also analyzes the phenomenon of convergent evolution with respect to the spectrum of existent, nonexistent, and impossible biological forms. The chapter shows that the evolution of development on Earth may have been a two-stage process, and also suggests that possible, but nonexistent, biological forms can be visualized using the techniques of theoretical morphology.Less
This chapter deals with the theoretical analysis of evolutionary constraint in producing convergent evolution. It investigates the implications of theoretically possible, but nevertheless nonexistent, ecological roles on Earth for the concept of convergent evolution, and also analyzes the phenomenon of convergent evolution with respect to the spectrum of existent, nonexistent, and impossible biological forms. The chapter shows that the evolution of development on Earth may have been a two-stage process, and also suggests that possible, but nonexistent, biological forms can be visualized using the techniques of theoretical morphology.
George McGhee
- Published in print:
- 2011
- Published Online:
- August 2013
- ISBN:
- 9780262016421
- eISBN:
- 9780262298872
- Item type:
- book
- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262016421.001.0001
- Subject:
- Biology, Evolutionary Biology / Genetics
Charles Darwin famously concluded On the Origin of Species with a vision of “endless forms most beautiful” continually evolving. More than 150 years later, many evolutionary biologists see not ...
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Charles Darwin famously concluded On the Origin of Species with a vision of “endless forms most beautiful” continually evolving. More than 150 years later, many evolutionary biologists see not endless forms but the same, or very similar, forms evolving repeatedly in many independent species lineages. A porpoise’s fishlike fins, for example, are not inherited from fish ancestors but are independently derived convergent traits. This book describes the ubiquity of the phenomenon of convergent evolution and connects it directly to the concept of evolutionary constraint—the idea that the number of evolutionary pathways available to life are not endless, but quite limited. Convergent evolution occurs on all levels, from tiny organic molecules to entire ecosystems of species. The author demonstrates its ubiquity in animals, both herbivore and carnivore; in plants; in ecosystems; in molecules, including DNA, proteins, and enzymes; and even in minds, describing problem-solving behavior and group behavior as the products of convergence. For each species example, he provides an abbreviated list of the major nodes in its phylogenetic classification, allowing the reader to see the evolutionary relationship of a group of species that have independently evolved a similar trait by convergent evolution. The author analyzes the role of functional and developmental constraints in producing convergent evolution, and considers the scientific and philosophical implications of convergent evolution for the predictability of the evolutionary process.Less
Charles Darwin famously concluded On the Origin of Species with a vision of “endless forms most beautiful” continually evolving. More than 150 years later, many evolutionary biologists see not endless forms but the same, or very similar, forms evolving repeatedly in many independent species lineages. A porpoise’s fishlike fins, for example, are not inherited from fish ancestors but are independently derived convergent traits. This book describes the ubiquity of the phenomenon of convergent evolution and connects it directly to the concept of evolutionary constraint—the idea that the number of evolutionary pathways available to life are not endless, but quite limited. Convergent evolution occurs on all levels, from tiny organic molecules to entire ecosystems of species. The author demonstrates its ubiquity in animals, both herbivore and carnivore; in plants; in ecosystems; in molecules, including DNA, proteins, and enzymes; and even in minds, describing problem-solving behavior and group behavior as the products of convergence. For each species example, he provides an abbreviated list of the major nodes in its phylogenetic classification, allowing the reader to see the evolutionary relationship of a group of species that have independently evolved a similar trait by convergent evolution. The author analyzes the role of functional and developmental constraints in producing convergent evolution, and considers the scientific and philosophical implications of convergent evolution for the predictability of the evolutionary process.
Glenn-Peter Sætre and Mark Ravinet
- Published in print:
- 2019
- Published Online:
- July 2019
- ISBN:
- 9780198830917
- eISBN:
- 9780191868993
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198830917.003.0005
- Subject:
- Biology, Evolutionary Biology / Genetics, Biomathematics / Statistics and Data Analysis / Complexity Studies
Adaptations are the products of natural selection—traits that evolved because they proved useful at some level. Often adaptations evolved because they enhanced the survival or reproductive output of ...
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Adaptations are the products of natural selection—traits that evolved because they proved useful at some level. Often adaptations evolved because they enhanced the survival or reproductive output of individuals, but selection can also operate at other levels—genes, individuals, populations, and species. Sometimes a genetic change has positive effects on all levels. A mutation that increases the survival of its carrier would increase in frequency; populations that become fixed for that allele may be less prone to extinction, which in turn may increase the longevity of that species. Other times there can be conflicting fitness effects at the different levels. This chapter explores the power of natural selection in shaping the living world by investigating the complexities of multilevel selection, biological solutions to heterogeneity and unpredictability in the environment, and how interactions between species can shape evolution. However, the chapter starts by investigating factors that may constrain adaptive evolution.Less
Adaptations are the products of natural selection—traits that evolved because they proved useful at some level. Often adaptations evolved because they enhanced the survival or reproductive output of individuals, but selection can also operate at other levels—genes, individuals, populations, and species. Sometimes a genetic change has positive effects on all levels. A mutation that increases the survival of its carrier would increase in frequency; populations that become fixed for that allele may be less prone to extinction, which in turn may increase the longevity of that species. Other times there can be conflicting fitness effects at the different levels. This chapter explores the power of natural selection in shaping the living world by investigating the complexities of multilevel selection, biological solutions to heterogeneity and unpredictability in the environment, and how interactions between species can shape evolution. However, the chapter starts by investigating factors that may constrain adaptive evolution.
