CHAPTER 4
Basic Biogeography: Estimating
Biodiversity and Mapping Nature
Brett R. Riddle
1
, Richard J. Ladle
2,3
, Sara A. Lourie
4 and Robert J. Whittaker
2
1 School of Life Sciences, University of Nevada, Las Vegas, USA
2 School of Geography and the Environment, University of Oxford, Oxford, UK
3 Department of Agricultural Engineering, Federal University of Vi ç osa, Brazil
4
Redpath Museum, McGill University, Montreal, Canada
4.1 INTRODUCTION
Are very closely allied species ever separated by a
wide interval of country? What physical features
determine the boundaries of species and of genera?
Do the isothermal lines ever accurately bound the
range of species, or are they altogether independent
of them? What are the circumstances which render
certain rivers and certain mountain ranges the
limits of numerous species, while others are not?
None of these questions can be satisfactorily
answered till we have the range of numerous species
accurately determined.
(Alfred Russel Wallace, 1852 , p. 110)
4.1.1 Our i ncomplete k nowledge of
b iodiversity
We may look at the natural world through many
different lenses. In Chapter 3 we divided these perspectives into two broad classes: compositionalist and
functionalist. These might also be respectively labelled
biogeographical versus ecological or ecosystem
approaches. When they are applied for conservation
purposes, both require the identifi cation of nature ’ s
units, which, as will already be clear from Chapter 3
represent human impositions.
In the present chapter we tackle both these themes,
beginning with the compositionalist/biogeographical
approaches – those concerned with describing biodiversity variation geographically. Here our prime focus
is typically with the species unit, but we can also be
concerned with higher or lower levels in the taxonomic
hierarchy. We give most attention to the terrestrial
realm, but go on to illustrate how compositionalist and
functionalist approaches are applied also in the marine
realm. The chapter embraces both foundational
approaches within biogeography, such as the endeavour of identifying the world ’ s major biogeographical
regions (a project that was well under way in the 19th
century), as well as some of the latest approaches to
analysing species interrelationships and present and
future distributions.
When we are contemplating conservation action,
we are often concerned with saving locally or globally
unique taxonomic elements, typically species which we
perceive to be threatened by anthropogenic extinction.
We may also be motivated by the notion of saving
valued ecosystem types, some of which may be
Conservation Biogeography
Edited by Richard J. Ladle and Robert J. Whittaker
© 2011 Blackwell Publishing Ltd. ISBN: 978-1-444-33503-3
Basic Biogeography: Estimating
Biodiversity and Mapping Nature
Brett R. Riddle
1
, Richard J. Ladle
2,3
, Sara A. Lourie
4 and Robert J. Whittaker
2
1 School of Life Sciences, University of Nevada, Las Vegas, USA
2 School of Geography and the Environment, University of Oxford, Oxford, UK
3 Department of Agricultural Engineering, Federal University of Vi ç osa, Brazil
4
Redpath Museum, McGill University, Montreal, Canada
4.1 INTRODUCTION
Are very closely allied species ever separated by a
wide interval of country? What physical features
determine the boundaries of species and of genera?
Do the isothermal lines ever accurately bound the
range of species, or are they altogether independent
of them? What are the circumstances which render
certain rivers and certain mountain ranges the
limits of numerous species, while others are not?
None of these questions can be satisfactorily
answered till we have the range of numerous species
accurately determined.
(Alfred Russel Wallace, 1852 , p. 110)
4.1.1 Our i ncomplete k nowledge of
b iodiversity
We may look at the natural world through many
different lenses. In Chapter 3 we divided these perspectives into two broad classes: compositionalist and
functionalist. These might also be respectively labelled
biogeographical versus ecological or ecosystem
approaches. When they are applied for conservation
purposes, both require the identifi cation of nature ’ s
units, which, as will already be clear from Chapter 3
represent human impositions.
In the present chapter we tackle both these themes,
beginning with the compositionalist/biogeographical
approaches – those concerned with describing biodiversity variation geographically. Here our prime focus
is typically with the species unit, but we can also be
concerned with higher or lower levels in the taxonomic
hierarchy. We give most attention to the terrestrial
realm, but go on to illustrate how compositionalist and
functionalist approaches are applied also in the marine
realm. The chapter embraces both foundational
approaches within biogeography, such as the endeavour of identifying the world ’ s major biogeographical
regions (a project that was well under way in the 19th
century), as well as some of the latest approaches to
analysing species interrelationships and present and
future distributions.
When we are contemplating conservation action,
we are often concerned with saving locally or globally
unique taxonomic elements, typically species which we
perceive to be threatened by anthropogenic extinction.
We may also be motivated by the notion of saving
valued ecosystem types, some of which may be
Conservation Biogeography
Edited by Richard J. Ladle and Robert J. Whittaker
© 2011 Blackwell Publishing Ltd. ISBN: 978-1-444-33503-3