Basics of Environmental Science

By Michael Allaby | Go to book overview

5

Biological Resources
When you have read this chapter you will have been introduced to:
• evolution
• evolutionary strategies and game theory
• adaptation
• dispersal mechanisms
• species and habitats
• biodiversity
• fisheries
• forests
• agriculture
• human populations and demographic change
• genetic engineering

46

Evolution

Evolution is the formation of new species from pre-existing species. That is all the word means to biologists and it implies nothing with regard to the steps that might be involved. The word is often linked to the name of Darwin, giving the impression that in some sense he invented the concept. This is quite untrue. The evolution of species from pre-existing species was widely (although not universally) accepted by the time Darwin began to think about it seriously and today it is not in the least controversial. The evolution of species is a fact, well documented and observed.

Darwin contributed to the concept the proposal of a mechanism by which the evolutionary process may occur. He called it ‘natural selection’, and after his death its merging with the growing body of knowledge about genetics led some people to rename ‘Darwinism’ ‘neo-Darwinism’ or ‘the modern synthesis’. Nevertheless, it remains fundamentally the explanation Darwin proposed.

Today the great majority of biologists accept Darwinism as a valid explanation for evolution in general. There is argument about details and particular instances, but these tend to strengthen the Darwinian proposition rather than weaken it. When scientists talk of the ‘theory of evolution’, it is the Darwinian theory, of evolution by means of natural selection, to which they refer and they give ‘theory’ its scientific meaning of an explanation for observed phenomena. Never do they seek to imply that evolution itself is no more than a vague, albeit attractive, idea. To misuse the word ‘theory’ in this way, and to conflate the Darwinian theory with the observed fact of evolution, betokens ignorance or intellectual dishonesty.

Evolution proceeds from natural selection and at the centre of this concept lies the idea of ‘adaptedness’. This is the degree to which a species is suited to the conditions under which it lives. Those conditions vary from place to place and time to time, and the degree of adaptedness varies from one individual to another. These variations provide the ‘raw material’ on which evolution

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Basics of Environmental Science
Table of contents

Table of contents

  • Title Page iii
  • Contents v
  • Figures vii
  • Tables xi
  • Preface to the Second Edition xiii
  • How to Use This Book xv
  • 1 - Introduction 1
  • 2 - Earth Sciences 19
  • 3 - Physical Resources 90
  • 4 - Biosphere 137
  • 5 - Biological Resources 200
  • References 258
  • 6 - Environmental Management 261
  • Further Reading 296
  • Glossary 300
  • Bibliography 307
  • Index 316
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