By Jane Elith and Catherine Graham
ESI Special Topics,
May 2007
Citing URL - http://www.esi-topics.com/nhp/2007/may-07-Elith_Graham.html
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Jane Elith and Catherine Graham
answer a few questions about this month's
new hot paper in the field of Environment & Ecology.
The author has also
sent along images of their work.
From
•>>May 2007
Field:
Environment & Ecology
Article Title: Novel methods improve prediction of
species' distributions from occurrence data
Authors:
Elith, J;Graham, CH;Anderson, RP;Dudik,
M;Ferrier, S;Guisan, A;Hijmans, RJ;Huettmann,
F;Leathwick, JR;Lehmann, A;Li, J;Lohmann, LG;Loiselle,
BA;Manion, G;Moritz, C;Nakamura, M;Nakazawa, Y;Overton,
JM;Peterson, AT;Phillips, SJ;Richardson, K;Scachetti-Pereira,
R;Schapire, RE;Soberon, J;Williams, S;Wisz,
MS;Zimmermann, NE
Journal: ECOGRAPHY
Volume: 29
Issue: 2
Page: 129-151
Year: APR 2006
* Univ Melbourne, Sch Bot, Parkville, Vic 3010,
Australia.
* Univ Melbourne, Sch Bot, Parkville, Vic 3010,
Australia.
* SUNY Stony Brook, Dept Ecol & Evolut, Stony Brook,
NY 11794 USA.
* CUNY City Coll, New York, NY 10031 USA.
* Princeton Univ, Princeton, NJ 08544 USA.
* Dept Environm & Conservat, Armidale, NSW,
Australia.
* Univ Lausanne, CH-1015 Lausanne, Switzerland.
* Univ Calif Berkeley, Berkeley, CA 94720 USA.
* Univ Alaska Fairbanks, Fairbanks, AK USA.
* NIWA, Hamilton, New Zealand.
* Swiss Ctr Faunal Cartog, Neuchatel, Switzerland.
* CSIRO Atherton, Atherton, Qld, Australia.
* Univ Sao Paulo, BR-05508 Sao Paulo, Brazil.
* Univ Missouri, St Louis, MO 63121 USA.
* CIMAT, Mexico City, DF, Mexico.
* Univ Kansas, Lawrence, KS 66045 USA.
* Landcare Res, Hamilton, New Zealand.
* AT&T Labs Res, Florham Pk, NJ USA.
* McGill Univ, Montreal, PQ H3A 2T5, Canada.
* James Cook Univ N Queensland, Townsville, Qld 4811,
Australia.
* Natl Environm Res Inst, Roskilde, Denmark.
* Swiss Fed Res Inst WSL, Birmensdorf, Switzerland.
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Why
do you think your paper is highly cited?
Presence-only data from museum and herbarium collection
records are being used increasingly to model the world’s
biodiversity patterns and to make important decisions about
conservation priorities. Results are also used to test
theoretical predictions about factors influencing diversity
patterns and to target future field programs.
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“Managing
the use of the world’s resources and related
conservation and biosecurity issues are closely
entwined in social, economic and political
frameworks.” |
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Despite this wide application, there has been no clear
consensus on which analytical methods work best. Achieving such
a consensus is difficult because of the effort involved in
collating the extensive data sets required to test methods
thoroughly.
The research in our paper resulted from a large international
collaboration, where we were able to collate data for more than
200 species across six regions of the world. These data included
not only species records and environmental data for modeling,
but also data that had been independently collected to evaluate
model predictions.
We think that part of the attraction of this paper is that it
presents a very thorough and robust test of most currently used
modeling methods on a scale that few if any researchers could
carry out on their own.
Another important feature is that the methods tested include
several only recently introduced to ecology. Some of these
considerably out-performed more traditional techniques.
Together, these features appeal to a wide range of people,
including those working in both pure and applied branches of
ecology.
Does
it describe a new discovery, methodology, or synthesis of knowledge?
It certainly is a new synthesis of knowledge, because of the
breadth of the study and its robust comparison of both
traditional and relatively new statistical modeling techniques.
The knowledge we gained will encourage new research agendas as
researchers across a broad spectrum of applied and basic
sciences use these modeling techniques more routinely.
Could
you summarize the significance of your paper in layman’s terms?
Many people in the world are concerned about changes in
biodiversity and particularly those that are caused by human
activities. However, there are limits to the time and money
available to collect new data to describe species’
distributions. Given this tension, predictive models linking
species records with relevant environmental or geographic data
play a useful role in enabling us to map distributions across
sometimes large areas of land and to predict distributions
reliably in places we haven’t had time to visit.
To create useful predictions, it is important that we use
modeling methods that suit the data, that make sense
ecologically, and that are well-tested. Our testing of 16
modeling methods with diverse species data from six regions
around the globe provides some clear guidance on which modeling
methods perform best. The results will promote additional
research to help managers and policymakers make better use of
data as they address the biodiversity crisis.
How
did you become involved in this research, and were there obstacles
along the way?
This research was funded by NCEAS, the National Center of
Ecological Analysis and Synthesis in California, in a working
group proposed by A. Townsend Peterson and Craig Moritz. Some
authors took part in the working groups that developed the
experimental design, and others supplied data, developed models,
or gave advice.
The biggest obstacles were coming to a common understanding
of what we needed to achieve. The other hurdles were practical
ones—finding appropriate data, identifying modeling experts, and
other difficulties associated with organizing a large
collaborative research program with 27 co-authors.
Data preparation is an enormous task! By the time we had
finished, each modeler had produced about 750 sets of
predictions per method, so the final analysis was a huge
undertaking.
Where
do you see your research heading in the future?
Members of the group have widely differing interests. Many of
us are involved in the practical application of these models in
supporting conservation management in our various countries or
internationally. Some primarily work on the research side; the
ecologists and evolutionary biologists are building knowledge
about why species exist where they do.
Others are developing new modeling tools relevant not only to
species modeling but also to a broad range of analytical
problems. Our priorities include understanding the historic
biogeography of species, conserving current biodiversity, and
predicting and ameliorating the effects of invasive species and
climate change on species distributions.
Many of us aim to keep working on methods we consider most
promising, perhaps teaching others how to use them or applying
them to problems we are asked to help solve. Our illustrations
provide several examples.
Are
there any social or political implications for your research?
Managing the use of the world’s resources and related
conservation and biosecurity issues are closely entwined within
social, economic, and political frameworks. It is important that
we, as scientists, present methods that are as reliable,
unbiased, and efficient as possible, so we can underpin
decisions with the best estimates and most realistic assessments
of uncertainties that we can produce. Our research is one small
contribution to this goal.
Dr Jane Elith
Research Fellow
School of Botany
The University of Melbourne
Dr. Catherine Graham
Assistant Professor
Department of Ecology and Evolution
State University of New York, Stony Brook
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A Closer Look...
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Below
are images sent in by Jane Elith and Catherine Graham which correspond with the featured
paper, or current research. |
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Figure 1:
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Figure
1: An
illustration of the modelling process used in
our study, for an Australian grass species. The
different colours on the left map indicate the
locations of the modelling presence-only data
(blue triangles) and the evaluation data (black
= present, red = absent). Eleven relevant
environmental variables were used, and the
response of the species to environment modelled
with 16 methods to produce predictions. |
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Figure 2:
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Figure
2:
An example of further
work – this is modelling the distribution of
short-finned eels in New Zealand with boosted
regression trees – a work in progress by Jane
Elith and John Leathwick, and to be used both to
understand their ecology and to manage the eel
fisheries. |
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Figure 3:
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Figure
3:
An example of further
work – Shown is a composite map of maximum
entropy distribution models for 200 species of
endemic and threatened birds in Colombia, South
America. It is a work in progress by Jorge
Velasquez-Tibata, Catheirne Graham, Paul Salaman
and the BIOMAP team and will be used to revise
conservation priorities for birds in Colombia. |
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ESI Special Topics,
May 2007
Citing URL - http://www.esi-topics.com/nhp/2007/may-07-Elith_Graham.html
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