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Learning Objectives
 Understand biodiversity
Success criteria
Learners should be able to demonstrate and apply their knowledge and
understanding of:
(a) how biodiversity may be considered at different levels
To include habitat biodiversity (e.g. sand dunes, woodland, meadows,
streams), species biodiversity (species richness and species evenness) and
genetic biodiversity (e.g. different breeds within a species).
(c) how to measure species richness and species evenness in a habitat
(d) the use and interpretation of Simpson’s Index of Diversity (D) to
calculate the biodiversity of a habitat
To include the formula: D = 1 – (Σ(n/N)2)
AND
the interpretation of both high and low values of Simpson’s Index of Diversity (D).
Biodiversity
The number and variety of living things to be found in
the world/ecosystem/habitat.
Biodiversity is essential in maintaining a balanced
ecosystem for all organisms.
Measuring biodiversity
 Plays an important role in conservation.
 Environmental Impact Assessments (EIA) are
undertaken to predict the positive and negative effects
of a project on the biodiversity of an area.
Biodiversity can be measured at 3 levels:
 Habitat biodiversity
 Species biodiversity
 Genetic biodiversity
Habitat
Biodiversity
Number of different habitats in an area.
Greater the habitat diversitythe greater the species
diversity.
UK – large number of habitat types e.g. Meadow,
woodland, stream, sand dune - large habitat
biodiversity.
Antarctica – low number of habitat types e.g. ice
sheet – low habitat biodiversity.
Species
Biodiversity
Number of different species and the abundance of
each species in an area.
 Species richness
 Number of species present in habitat
 Species evenness
 Measure of abundance of individuals in each species
(ACFOR)
The greater the species richness and evenness the
higher the biodiversity
Genetic
Biodiversity
Genetic variation between individuals of the same
species (variation of alleles).
The greater the genetic biodiversity within a
species the more adaptable it is to changing
environments.
Suggest why greater genetic biodiversity increases
a species chances of survival for the long term?
Simpson’s Index of Diversity
 Measure biodiversity of a habitat taking into account
species richness and species evenness
D=
2
1-(Σ(n/N) )
 n = number of individuals of a particular species (or
percentage cover for plants)
 N = total number of all individuals of all species (or
percentage cover for plants)
Simpson’s Index of Diversity
 Simpson’s index is always a value between 1 and 0.
 Significance of high values of D (close to 1)
 Diverse habitat
 Small change in habitat may only affect one species
 Habitat stable and can withstand change
 Significance of low values of D (close to 0)
 Habitat dominated by just a few species
 Small change in habitat may effect one of the key species
and damage whole habitat
Simpson’s Index of Diversity
Species
n
A
12
B
7
C
2
D
6
E
5
F
8
n=N=
(n/N)2
n/N
(n/N)2 =
What is the species richness?
Simpson’s Index of Diversity
Species
n
A
12
B
7
C
2
D
6
E
5
F
8
n=N=
n/N
(n/N)2
(n/N)2 =
Work out n (N=sum of all the species present)
Simpson’s Index of Diversity
Species
n
A
12
B
7
C
2
D
6
E
5
F
8
n=N=40
(n/N)2
n/N
(n/N)2 =
Work out n (N=sum of all the species present)
Then work out n/N for all species
Simpson’s Index of Diversity
Species
n
n/N
A
12
0.300
B
7
0.175
C
2
0.050
D
6
0.150
E
5
0.125
F
8
0.200
n=N= 40
(n/N)2
(n/N)2 =
Work out (n/N)2 for all species
Then add them all up for (n/N)2
Simpson’s Index of Diversity
Species
n
n/N
(n/N)2
A
12
0.300
0.09
B
7
0.175
0.031
C
2
0.050
0.003
D
6
0.150
0.023
E
5
0.125
0.016
F
8
0.200
0.040
n=N= 40
(n/N)2 = 0.203
D = 1 - (Σ(n/N)2)
D = 1 - 0.203 = 0.797
Biodiversity values
Habitat feature
Low biodiversity
High biodiversity
Number of successful
species
Relatively few
A large number
Nature of the
environment
Stressful and/or extreme
with relatively few
ecological niches
Not stressful with more
ecological niches
Adaptations of species to
the habitat
Relatively few species in
habitat, often with very
specific adaptations for
the environment
Many species in habitat,
often with few specific
adaptations to the
environment
Types of food webs
Relatively simple
complex
Effect of a change to the
environment on
ecosystem as a whole
Major effects on the
ecosystem
Often relatively small
effect
Task
 Complete the questions
N = 15
 D = 1 - (Σ(n/N)2)
 D = 1 – 0.349 = 0.651
0.133
0.018
0.533
0.284
0.067
0.004
0.067
0.004
0.200
0.040
Σ(n/N)2 =
0.349
Species richness - number of different species present
number of individuals of each species
in each habitat
species
a
b
c
d
e
f
g
h
i
j
k
l
species richness
total number of
insects (N)
Simpson’s Index
of Diversity (D)
barley
field
32
78
0
0
0
0
0
0
0
0
86
0
3
wheat
field
4
0
126
5
0
0
25
10
0
0
56
0
6
under
hedge
0
1
2
12
8
9
3
3
2
5
0
7
10
196
226
52
0.62
0.61
0.86
n/N
(n/N)2
0.163
0.398
0.027
0.158
0.439
0.193
0.378
Learning Objectives
 Understand biodiversity
Success criteria
Learners should be able to demonstrate and apply their knowledge and
understanding of:
(a) how biodiversity may be considered at different levels
To include habitat biodiversity (e.g. sand dunes, woodland, meadows,
streams), species biodiversity (species richness and species evenness) and
genetic biodiversity (e.g. different breeds within a species).
(c) how to measure species richness and species evenness in a habitat
(d) the use and interpretation of Simpson’s Index of Diversity (D) to
calculate the biodiversity of a habitat
To include the formula: D = 1 – (Σ(n/N)2)
AND
the interpretation of both high and low values of Simpson’s Index of Diversity (D).