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.