Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- PART I Evolution by natural selection
- PART II Simple population growth models and their simulation
- PART III Population genetics and evolution
- Chapter 6 Gene frequencies and the Hardy–Weinberg principle
- Chapter 7 Mutation and the genetic variation of populations
- Chapter 8 Small populations, genetic drift and inbreeding
- Chapter 9 Migration, gene flow and the differentiation of populations
- Chapter 10 Quantifying natural selection: haploid and zygotic selection models
- Chapter 11 Applying zygotic selection models to natural systems
- Chapter 12 Polygenic inheritance, quantitative genetics and heritability
- Chapter 13 Population genetics: summary and synthesis
- PART IV Demography
- PART V Interactions between species, and the behaviour of individuals
- Glossary
- Solutions to problems
- References
- Index
Chapter 7 - Mutation and the genetic variation of populations
- Frontmatter
- Contents
- Preface
- Acknowledgements
- PART I Evolution by natural selection
- PART II Simple population growth models and their simulation
- PART III Population genetics and evolution
- Chapter 6 Gene frequencies and the Hardy–Weinberg principle
- Chapter 7 Mutation and the genetic variation of populations
- Chapter 8 Small populations, genetic drift and inbreeding
- Chapter 9 Migration, gene flow and the differentiation of populations
- Chapter 10 Quantifying natural selection: haploid and zygotic selection models
- Chapter 11 Applying zygotic selection models to natural systems
- Chapter 12 Polygenic inheritance, quantitative genetics and heritability
- Chapter 13 Population genetics: summary and synthesis
- PART IV Demography
- PART V Interactions between species, and the behaviour of individuals
- Glossary
- Solutions to problems
- References
- Index
Summary
There must be genetic variation for evolution to occur. Mutation is the ultimate source of genetic variation, which is amplified by recombination during sexual reproduction. Mutations will only play a role in evolution if they are heritable. In most organisms this means that only the mutations occurring in the germ line leading to the production of gametes may have evolutionary consequences.
Gene mutations
The word mutation may refer to any change in the genetic material, ranging from a change to a single base pair in DNA, to changes in the structure and number of chromosomes. The discussion of mutation and genetic variation in this book will only consider mutations within a gene, and this gene mutation can be simply thought of as a change in the sequence of DNA. In principle the DNA must be sequenced to detect a mutation, but in practice most mutations are identified and named by their phenotypic effects.
The simplest kind of gene mutation is the substitution of one base pair by another. These point mutations, as they are called, may result in the replacement of one amino acid by another, but in many cases there is no change in the amino acid because of the redundancy of the genetic code (Fig. 7.1). In the example of isoleucine, two of the three substitutions in the third position do not result in a change of amino acid.
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- Introduction to Population Biology , pp. 100 - 115Publisher: Cambridge University PressPrint publication year: 2003