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4 Boyer, T. and Polasky, S. (2004) Valuing urban wetlands: a review of
non-market valuation studies. Wetlands 24, 744–755
5 Ricketts, T.H. et al. (2004) Economic value of tropical forest to coffee
production. Proc. Natl. Acad. Sci. U. S. A. 101, 12579–12582
6 Naidoo, R. and Ricketts, T.H. (2006) Mapping the economic costs and
benefits of conservation. PLoS Biol. 4, e360 DOI: 10.1371/journal.
pbio.0040360
7 Polasky, S. et al. (2005) Conserving species in a working landscape: land
use with biological and economic objectives. Ecol. Appl. 15, 1387–1401
8 Boardman, A.E. et al. (2005) Cost Benefit Analysis: Concepts and
Practice, Prentice Hall
9 Hanley, N. et al. (2003) Aggregating the benefits of environmental
improvements: distance–decay functions for use and non-use values.
J. Environ. Manage. 68, 297–304
10 Brown, T.C. and Gregory, R. (1999) Why the WTA–WTP disparity
matters. Ecol. Econ. 28, 323–335
11 Turner, R.K. et al. (2003) Valuing nature: lessons learned and future
research directions. Ecol. Econ. 46, 493–510
12 Goulder, L.H. and Kennedy, D. (1997) Valuing ecosystem services:
philosophical bases and empirical methods. In Nature’ Services:
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a host of value judgments: whose benefits should be
estimated [9]? How should disparities in wealth be dealt
with? Which are the appropriate measures of welfare
changes [10]? Which of the multitude of ecosystem services
should be considered in an analysis [11]? All of these
require judgments on the part of researchers that are no
less value laden than those associated with biodiversity
measures. In addition, some aspects of nature’s worth are
simply not amenable to economic valuation and will never
be captured in a cost–benefit analysis [12].
For these reasons, it seems sensible to increase research
on the economic benefits of conservation, while recognizing
that improved measurements of biodiversity will (and should)
continue to have a central role in conservation planning.
References
1 Hockley, N.J. et al. (2007) Maximizing the efficiency of conservation.
Trends Ecol. Evol. 22, 287
2 Naidoo, R. et al. (2006) Integrating economic costs into conservation
planning. Trends Ecol. Evol. 21, 681–687
3 Balmford, A. et al. (2002) Economic reasons for conserving wild nature.
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doi:10.1016/j.tree.2007.02.016
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Book Review
Does an Earth system perspective provide
fundamental insights into ecology?
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Fundamental Processes in Ecology: An Earth Systems Approach by David M. Wilkinson, Oxford University Press, 2006.
£45.00, hbk (200 pages) ISBN 978 0198568469
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Julia Allen Jones
Department of Geosciences, 104 Wilkinson Hall, Oregon State University, Corvallis, OR 97331, USA
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Earth systems science focuses on exciting
and integrative concepts that have
emerged in the past few decades, catalyzing synthetic research among a variety of
disciplines and examining processes that
link the atmosphere, hydrosphere, geosphere and biosphere. Ecology is a key
component of Earth system science, but
an Earth systems perspective has yet to
emerge strongly in ecological journals. In
Fundamental Processes in Ecology: An Earth Systems
Approach, Wilkinson argues that an Earth systems
perspective leads to the question, ‘what are the fundamental processes in ecology?’ and thereby provides a novel and
thought-provoking organizational framework for ecology.
From the perspective of ecologists, arguably the most
intriguing aspect of Earth system science is the Gaia hypothesis, which characterizes the relationships among the
biosphere and the other ‘spheres’ on Earth: atmosphere,
hydrosphere and (less euphoniously named) geosphere. The
Gaia hypothesis asserts that life alters and stabilizes
the environment and that these changes contribute to the
persistence of life. Wilkinson focuses the chapters of his book
Corresponding author: Jones, J.A. ([email protected]).
Available online 23 March 2007.
www.sciencedirect.com
on six ‘fundamental processes’ in ecology through which life
interacts with the environment to produce conditions that
are favorable to life: (i) energy flow; (ii) the formation of
multiple guilds; (iii) the development of biological diversity;
(iv) ecophysiology; (v) photosynthesis; and (vi) carbon
sequestration. For each of these processes, he pursues several questions (which he calls ‘thought experiments’), many
of which are inspired by the Gaia hypothesis. For example,
in the chapter on biodiversity, Wilkinson discusses whether
the existence of tradeoffs (i.e. adaptations that favor survival of a species under one set of conditions but not under
others) would be expected to favor speciation; he then
considers whether speciation would tend to make a diversity
of species more stable.
The Gaia hypothesis, specifically the concept that life
involves processes whose feedbacks are positive or negative for life, provides an intriguing point of departure and
unifying theme for the book. Within each chapter, Wilkinson pursues this general question using observations
from present and past ecosystems to explore several
specific questions. In places, he adopts metaphors from
sports or finance to illustrate his arguments and much of
his reasoning involves simple mathematical models.
Although all the fundamental ecological processes
addressed by Wilkinson can be observed today, their origins
and (according to the Gaia hypothesis) initial positive
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TRENDS in Ecology and Evolution
feedback for life, occurred early during the history of the
Earth. The central fact that ecosystems might have developed only once in the universe, and that we lack replicates
or alternative ecosystems other than Earth, motivates the
thought experiment approach in the book. However, Wilkinson’s writing in places departs from the published literature consensus on Earth system processes and becomes an
idiosyncratic exploration of unverifiable hypothetical past
events. His use of ecological examples from Britain
and its former colonies is interesting, but it could also
limit the appeal of the book for non-UK-based students of
ecology.
The events involved in thought experiments in
Fundamental Processes in Ecology are outside of human
observation and require some knowledge of the basic
chronology of Earth system history, especially the origins
of life, the rise of oxygen in the atmosphere, mass extinction events and the creation of fossil fuel deposits. The
author also assumes that readers are familiar with basic
stoichiometric equations and biogeochemical pathways,
and can understand simple systems of equations.
Fundamental Processes in Ecology is an intriguing but
iconoclastic introduction to ecology for a reader lacking a
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background in the subject. Wilkinson derides the teaching
of ecology as a collection of things, rather than a set of
processes, a critique that makes sense to an Earth scientist. It is fascinating to consider ecology as a collection of
processes that are potentially unique in the universe, and
the author achieves the objective of modifying the reader’s
perspective and definition of the discipline of ecology. By
contrast, because it requires so much ancillary knowledge,
Fundamental Processes in Ecology does not provide a
convincing example of an alternative, process-focused
approach to teaching ecology at the introductory level.
Fundamental Processes in Ecology will be challenging
for a reader lacking a background in Earth system science.
It provides only a selective introduction to the subject and
many facets of Earth systems science that are most compelling, such as interactions among tectonic processes,
climate and geochemical cycling, are not mentioned. The
book could be a stimulating text for a graduate seminar in
ecology, but, if used in this way, it should be accompanied
by an undergraduate text in Earth system science.
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0169-5347/$ – see front matter ß 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tree.2007.03.005
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Social butterflies
The Other Insect Societies by James T. Costa, The Belknap Press of Harvard University Press, 2006. £38.95, hbk (602 pages) ISBN 978
067402163 1
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William A. Foster
Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB3 2EJ, UK
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The aim of James Costa in writing The
Other Insect Societies is to convert us to his
concept of the ‘big tent’ of insect societies.
We traditionally think of social insects as
occupying an important, but modestly proportioned, tent that houses an exclusive
clientele of eusocial Hymenoptera and
termites, with a few thrips and aphids
squeezed in under the guy-ropes. However,
Costa’s social insects occupy a massive
tent: a vast sprawling yurt, thronging with species from
every Order. The eusocial species, although included, are
outnumbered by crickets and caterpillars, barklice and
beetles, sawflies and stick-insects, pondskaters and praying
mantids. It is about these insects that this book is written.
The Other Insect Societies is a stunning feat of
scholarship. At the most basic level, any reader will
encounter a whole new world of social phenomena and
fascinating animals. We learn about thornbugs (Membracidae), where the mothers make spiral slits on stems to
help their young to feed; sawfly larvae that construct a
communal pupal nidus; and blister beetles that group
together to persuade bees to mate with them. Costa’s range
Corresponding author: Foster, W.A. ([email protected]).
Available online 23 March 2007.
www.sciencedirect.com
is awesome: over habitats and continents, over hundreds of
insect taxa, and deep into the early history of entomology.
It is impressive enough to have assembled all this information, but to make it accurate requires genuine dedication. As far as I can judge, Costa has succeeded. Most
insects that I have ever worked on are ‘social’ in Costa’s
terms, and it is gratifying to find this work not only
included here, but also discussed with a thoroughness
and clarity that is hard to fault.
But Costa makes stern demands on his readers. There
are a set of ravishing colour plates and numerous delightful
line drawings of insects, but otherwise all we are offered is
prose. There are no figures, tables, phylogenies or summaries and few bullet points. This is tough. After reading
the cockroach chapter, I felt I had learnt a lot, but I was
muddled. Phylogeny is really vital here, as Costa himself
emphasizes, and I was longing for a cladogram, a succinct
summary or even just an ordered list of taxa. At the end of
the book, Costa again starves us of overview and goes for the
tangled-bank approach: elegant lace bug mums chaperoning
their tiny jewel-like brood among the lush rhododendrons,
and so on. This is nicely done, but I was getting desperate
to know what general conclusions the author had drawn
about the organization and evolution of these beasts.
The Other Insect Societies does have important general
themes. One is that these presocial insects are important