How To Define Biodiversity? Jacques Baudry 1, Françoise Burel 2, and Agnès Ricroch 3 1 INRA of...
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Transcript of How To Define Biodiversity? Jacques Baudry 1, Françoise Burel 2, and Agnès Ricroch 3 1 INRA of...
How To Define Biodiversity?
Jacques Baudry1, Françoise Burel2, and Agnès Ricroch3
1INRA of Rennes, 2University of Rennes / CNRS,
3University of Orsay / CNRS, France
Biodiversity, agriculture and environmental justice: a meeting to discuss and debate issues in interdisciplinary research.
University of the Western Cape, November 5, 2007
Edward O.Wilson, editor, Frances M.Peter, associate editor, Biodiversity, National Academy Press, March 1988
The word biodiversity first appeared in a publication in 1988 when
entomologist E. O. Wilson used it as the title of the proceedings of
National Forum on Biological Diversity.
Definitions
As defined in the proposed US Congressional Biodiversity Act, HR1268
(1990), « biological diversity means the full range of variety and
variability within and among living organisms and the ecological
complexes in which they occur, and encompasses ecosystem or
community diversity, species diversity, and genetic diversity. »
This covers distinct populations of the same species such as
the thousands of traditional corn varieties in America
or genetic variation within a population or a metapopulation
high among Indian rhinos, and very low among cheetahs.
1- Genetic diversity refers to the variation of genes within species.
South Africa is a global hotspot of tortoise diversity.
A juvenile anglulated tortoise (Geochelone pardalis) in Cape fynbos.
If the gene is the fundamental unit of natural selection, according to
E.O. Wilson, the real biodiversity is genetic diversity.
• For genetists, biodiversity is the diversity of genes and organisms.
They study processes such as natural selection (survival of the
fittest), selection pressure, mutations, migration, gene exchanges,
and genome dynamics, recombination that occur at the DNA level
and generate evolution.
• For ecologists, biodiversity is also the diversity of durable
interactions among species. It not only applies to species, but also to
their immediate environment (biotope) and their larger landscape. In
each ecosystem, living organisms are part of a whole, interacting
with not only other organisms, but also with the air, water, and soil
that surround them and humans.
2- Species diversity refers to the variety of species within a region.
The number of species in a region - its species richness - is one
often-used measure (Simberkoff, 1999), but a more precise
measurement, taxonomic diversity, also considers the
relationship of species to each other.
For example,
an island with two species of birds and one
species of lizard
has a greater taxonomic diversity than
an island with three species of birds but no
lizards.
Species richness and diversity of species in an agro-ecosystem can be measured
at different time scales
May 2005 May 2006 In Selommes, France
1km
Species richness
d = 2000
-2.5 -1.5 -0.5 0.5 1.5
d = 2000
-3 -1 1 3
Oilseed rape populations studied in 30 field margins
Rich
Poor
Plant diversityhigh
low
41 km2 area Open field landscape
Local evolution of biodiversity over a long time using the richness of pollen taxon
Motte BertierVieux-Viel
(Brittany, West France)
XV-XVIe s.
II-IVe s.17,5
28,7
20,5
Example of time scale
(Jacques Baudry’s courtesy)
(Jacques Baudry’s courtesy)
sunfloweralfala carrot clover
00.000050.00050.0010.0050.010.020.050.10.20.50.60.71missing data1. Exploring:
Simulation models
2. Biological data:
Parameter estimation
1+2= 3:
Some quantitative predictions
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
exponential, Case 2 exponential power, Case 2 geometric, Case 2
exponential, Case 1 exponential power, Case 1 geometric, Case 1
In meters from the source
OSR pollen dispersal in an agro-ecosystem can be measured
at different spatial scales
3- Ecosystem diversity is harder to measure than species or genetic diversity because the "boundaries" of communities - associations of
species - and ecosystems are elusive.
Nevertheless, as long as a consistent set of criteria is used to define
communities and ecosystems, their numbers and distribution can
be measured.
Indices of diversity to measure biodiversity are
Species richness ; Simpson index ; Shannon index
H’= Σ-n
i=1Σ-
n
i=1
Ni
NNi
Nx log2
Ni
NNi
ND= Σ
n
i=1
Ni x (Ni - 1)N x (N - 1)
and Alpha diversity refers to diversity within a particular area, community or
ecosystem, and is measured by counting the number of taxa within the ecosystem
(usually species).
Beta diversity is species diversity between ecosystems; this involves comparing the
number of taxa that are unique to each of the ecosytems.
Gamma diversity is a measure of the overall diversity for different ecosystems within
a region.
A variety of objective measures have been created in order to empirically measure biodiversity.
Each measure of biodiversity relates to a particular use of the data.
Dense hedgerow network landscape
(Pleine-Fougères)
Open hedgerow network landscape
(Pleine-Fougères)
OpenfieldLandscape
(Selommes)
An OSR pollen dispersal can be measured in various ecosystems
at different spatial scales
an oilseed rape grain pollen
10 µm
0.4 km 1.5 km 2.0 km
(Jacques Baudry’s courtesy) (Jacques Baudry’s courtesy)
Ecosystem components are the inhabiting species in all their variety and richness.
i.e. wild and domesticated genetic resources as defined by Jean Pernès (1984).
Ecosystem structure refers to the physical patterns of life forms.
There is more structure in a multilayered forest (herbs, shrubs, young trees, canopy trees) than in a single sagebrush grassland, or salt marsh...
sagebrush grassland salt marsh
Reed NossHe portrays ecosystems as having three primary attributes:
composition, structure, and function. Indicators for Monitoring Biodiversity: A Hierarchial Approach.
Conservation Biology 1990. 4(4):355-364
multilayered forest
Ecosystem functions are more difficult to see in action
as time and space scales can be large.
• Ecological processes create landscapes (hedgerow vs. openfield).
Hedgerow network landscape Openfield landscape
Phtomontage showing the evolution of a landscape in Pleine-Fougères (France)(Doc: CNDP/La Cinq - Jacques Baudry’s courtesy)
1955 19801965 1993
• Different forms produced or threatened by agricultural activities can be
examined through species richness (weeds, varieties of crop, pollinators)
and life traits (annual vs perienal plants).
A field can be examined as
a spatial unit
or a functional unit.
• Natural disturbances also play a role.
Wildfires release nutrients to the soil and weed out weak trees.
Ecosystem components, structures, and functions are all interdependent.
Local patterns and dynamics of species and communities are different at larger spatial scales.
Function involves ecological and evolutionary processes,
including gene flow, disturbances, and nutrient cycling
Composition has to do with the identity and variety of elements in a
collection, and includes species lists and measures of species diversity and genetic diversity.
Structure is the physical organization or pattern of a system, from habitat complexity as measured within communities to the pattern of patches and other elements at a landscape scale.
Biodiversity can be considered either as a biological heritage of wildlife to be conserved or a unit of management
(including domesticated forms of organisms).
The United Nations (UN) Earth Summit in Rio de Janeiro has recognized the close and
traditional dependence of many indigenous and local communities on biological
resources, notably in the preamble to the Convention on Biological Diversity.
There is also a broad recognition of the contribution that traditional knowledge can
make to both the conservation and the sustainable use of biological diversity, two
fundamental objectives of the Convention.
in 1992
in 2000
The Millennium Ecosystem Assessment (MA) was called for by UN Secretary-General Kofi Annan in a report to the General Assembly entitled We the Peoples: The Role of the United Nations in the 21st Century.
Initiated in 2001, the objective of the MA was to assess the consequences of ecosystem change for human well-being and the scientific basis for actions needed to enhance the conservation and sustainable use of those systems and their contribution to human well-being.