Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- List of abbreviations
- 1 Introduction
- 2 Studying change
- 3 Key concepts in plant evolution
- 4 The origin and extent of human-influenced ecosystems
- 5 Consequences of human influences on the biosphere
- 6 Categories
- 7 Investigating microevolution in plants in anthropogenic ecosystems
- 8 Plant microevolution in managed grassland ecosystems
- 9 Harvesting crops: arable and forestry
- 10 Pollution and microevolutionary change
- 11 Introduced plants
- 12 Endangered species: investigating the extinction process at the population level
- 13 Hybridisation and speciation in anthropogenically influenced ecosystems
- 14 Ex situ conservation
- 15 In situ conservation: within and outside reserves
- 16 Creative conservation through restoration and reintroduction
- 17 Reserves in the landscape
- 18 Climate change
- 19 Microevolution and climate change
- 20 The implications of climate change for the theory and practice of conservation
- 21 Overview
- References
- Index
6 - Categories
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- Acknowledgements
- List of abbreviations
- 1 Introduction
- 2 Studying change
- 3 Key concepts in plant evolution
- 4 The origin and extent of human-influenced ecosystems
- 5 Consequences of human influences on the biosphere
- 6 Categories
- 7 Investigating microevolution in plants in anthropogenic ecosystems
- 8 Plant microevolution in managed grassland ecosystems
- 9 Harvesting crops: arable and forestry
- 10 Pollution and microevolutionary change
- 11 Introduced plants
- 12 Endangered species: investigating the extinction process at the population level
- 13 Hybridisation and speciation in anthropogenically influenced ecosystems
- 14 Ex situ conservation
- 15 In situ conservation: within and outside reserves
- 16 Creative conservation through restoration and reintroduction
- 17 Reserves in the landscape
- 18 Climate change
- 19 Microevolution and climate change
- 20 The implications of climate change for the theory and practice of conservation
- 21 Overview
- References
- Index
Summary
The world has been transformed by human activities, and mankind is centre stage in the evolutionary drama now being played out in the world's ecosystems. In this chapter, different groups of plant species in the evolutionary play are introduced – native, wild, crop, weedy, introduced, invasive, feral and endangered species. On the face of it there would appear to be little difficulty in assigning plants to species, and deciding into which category particular species fall. But as we shall see, in confronting the following major questions, there are many complications. How are species to be defined? How many species of plants are there in the world? How are native and introduced species distinguished? What do conservationists mean by wildlife? How many species are cultivated, weeds or invasive? In response to different kinds of environmental change and disturbance, how many species are presently at risk of extinction, and are current extinction rates greater than those of the past? Is there any agreement on the numbers of species that are endangered? Is there any evidence that conservationists might have exaggerated the situation?
Species
The concept of the species is at the heart of any consideration of evolution, and both the theory and the practice of conservation are to a large extent based on these concerns. Different groups of plants – wild, cultivated etc. – are widely discussed in terms of the numbers of species they contain. In considering these estimates, however, a major concern must be faced.
- Type
- Chapter
- Information
- Publisher: Cambridge University PressPrint publication year: 2009