Transcript Biodiversity

How To Define Biodiversity?
Jacques Baudry1, Françoise Burel2, and Agnès Ricroch3
1INRA
of Rennes,
of Rennes / CNRS,
3University of Orsay / CNRS, France
2University
Biodiversity, agriculture and environmental justice:
a meeting to discuss and debate issues in interdisciplinary research.
University of the Western Cape, November 5, 2007
Definitions
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.
Edward O.Wilson, editor, Frances M.Peter, associate editor,
Biodiversity, National Academy Press, March 1988
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. »
1- Genetic diversity refers to the variation of genes within species.
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.
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
1km
41 km2 area
d = 2000
d = 2000
-2.5
-1.5
-0.5
0.5
1.5
-3
May 2005
Rich
Poor
Oilseed rape populations studied in 30 field margins
Open field landscape
-1
Plant diversity
low
3
In Selommes, France
high
Species richness
1
May 2006
Local evolution of biodiversity over a long time using the richness of pollen taxon
Example of time scale
20,5
28,7
XV-XVIe s.
Motte Bertier
Vieux-Viel
(Brittany, West France)
(Jacques Baudry’s courtesy)
17,5
II-IVe s.
(Jacques Baudry’s courtesy)
alfala
sunflower
carrot
clover
OSR pollen dispersal in an agro-ecosystem can be measured
at different spatial scales
missing data
1
0.7
0.6
0.5
0.2
0.1
0.05
0.02
0.01
0.005
0.001
0.0005
0.00005
0
1. Exploring:
Simulation models
2. Biological data:
Parameter estimation
In meters from the source
0
500
1000
1500
2000
2500
3000
3500
4000
4500
1.E+00
1.E-01
1.E-02
1+2= 3:
Some quantitative predictions
1.E-03
1.E-04
1.E-05
1.E-06
1.E-07
1.E-08
exponential, Case 2
exponential, Case 1
exponential power, Case 2
exponential power, Case 1
geometric, Case 2
geometric, Case 1
5000
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.
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.
Indices of diversity to measure biodiversity are
Species richness ;
Simpson index ;
n
D=
Σ
i=1
Ni x (Ni - 1)
N x (N - 1)
Shannon index
n
H’= -
Σ NN x log
i
2
i=1
Ni
N
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.
An OSR pollen dispersal can be measured in various ecosystems
at different spatial scales
(Jacques Baudry’s courtesy)
(Jacques Baudry’s courtesy)
Dense hedgerow
network landscape
Open hedgerow
network landscape
Openfield
Landscape
(Pleine-Fougères)
(Pleine-Fougères)
(Selommes)
0.4 km
1.5 km
10 µm
an oilseed rape grain pollen
2.0 km
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
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...
multilayered forest
sagebrush grassland
salt marsh
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
1955
1965
Openfield landscape
1980
Phtomontage showing the evolution of a landscape in Pleine-Fougères (France)
(Doc: CNDP/La Cinq - Jacques Baudry’s courtesy)
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.
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.
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.
Function involves ecological and
evolutionary processes,
including gene flow, disturbances,
and nutrient cycling
Local patterns and dynamics of species
and communities are different at larger spatial scales.
Biodiversity can be considered either as a biological heritage of
wildlife to be conserved or a unit of management
(including domesticated forms of organisms).
in 1992
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 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.