Download Chapter 12: Biodiversity

Chapter 12:
Biodiversity
Lesson Objectives:
To define the terms species, habitat and
biodiversity
To explain how biodiversity may be
considered at different levels (habitat,
species and genetic)
Biodiversity
Biodiversity, which is short
for biological diversity, is
the term used to describe
the whole variety of life on
Earth (first used by Wilson
in 1986).
‘the variety of habitats, communities and species in an area, and the
genetic diversity within populations’
We still have not documented/discovered all living
organisms on Earth
At the moment ~1.5 million species have been described
Estimates of total number of species range from 2 to
100 million … but we don’t really know!
Dr Terry Erwin (1980s)
In Panama, 19 trees were ‘fogged’ with
insecticide and the dead individuals were
collected
Erwin and his team were sampling arthropod
diversity (mosquitoes, dragonflies etc.)
1,200 different species of beetle alone were
collected
Of these ~80% were not previously known
Beetles are the largest group of known
arthropods (40%) … Erwin extrapolated from his
findings to estimate that the number of
arthropods is around 30 million!!!
But who really cares?
… does it really matter if we document all species?
The more we understand about the organisms around us
(how and where they live etc.), then the more we should
be able to protect them and their environment
Ecology
• The study of interactions that take place between
organisms and their environment.
• It explains how living organisms affect each other
and the world they live in.
• Habitat is the place a plant or
animal lives
• Niche is an organism’s total way
of life
• What is a SPECIES? (recap from
Chapter 13!)
Ecology – levels of organisation in living things
•
•
•
•
•
•
•
Atom
Molecule
Organelle
Cell
Tissue
Organ
System
– organism
Ecologists have organized
the interactions an
organism takes part in
into different levels
according to complexity.
Levels of Organisation
Organism:
An individual living thing that is
made of cells, uses energy,
reproduces, responds, grows,
and develops
Population:
A group of organisms, all of the same
species, which interbreed and live in
the same place at the same time.
Biological Community:
All the populations of different
species that live in the same place
at the same time.
Levels of Organisation
Organism
Population
Ecosystem:
Populations of plants and animals
that interact with each other in
a given area with the abiotic
components of that area.
(terrestrial or aquatic)
Community
Levels of Organisation
Organism
Population
Community
Biosphere:
The portion of
Earth that
supports life.
Biosphere
Ecosystem
Discussion time …
Can biodiversity be considered
at different levels?
(habitat, species and genetic)
Can biodiversity be considered at different levels?
Species diversity
The variety of living species within a geographic area
This can be measured using species richness (the
number of species within a particular sample area)
together with species evenness (the evenness in
numbers of individuals of each species in the area)
Ecosystem (habitat) diversity
The broad differences in ecosystem types and the
diversity of habitats and processes within each type
Species distribution and community patterns
The role and function of key species
Not understood very well as
interactions are very complex … you
are trying to understand all of the
species in an ecosystem, the
effects they have on each other
and their surroundings whilst also
being affected themselves
Diverse ecosystems include
rainforests
Genetic diversity
The differences in genetic make-up between distinct
species and genetic variation within a species (the least
visible and arguably the least studied level of diversity)
Variety in alleles, genes and
chromosome structure
More genetic diversity in a
species/population means a
greater ability for individuals to
adapt to environmental changes …
which leads to natural selection
and therefore evolution!!!
Monoculture in farming =
genetically identical plants which
could lead to problems in the
event of a disease
PLENARY – define the following key words!
1.Species
2.Population
3.Community
4.Habitat
A group of organisms, all of the same species, which
interbreed and live in the same place at the same
time.
All the populations of different species that live
in the same place at the same time.
the place a plant or animal lives
5.Biodiversity
‘the variety of habitats, communities and species in an area, and the
genetic diversity within populations’
Practical Ecology
Lesson Objectives:
To find out about practical ecology
techniques
To complete a practical using quadrats –
‘Investigating the distribution of plants in
two habitats, using random sampling’
Equipment …
A quadrat – used for systematic
sampling (transects) and stratified
sampling (comparing two different
areas)
Comparing the population of daisies in two different areas
20m
Count the number of
daisies in each quadrat!
1m2 quadrat
-10 quadrats in each site
Use the random
number table to
position your
quadrat (eg: read
down the left hand
side)
-2 sites
4
2
1
5
3
0m
20m
Reviewing
practical
techniques
Lesson Objectives:
To review our practical from last lesson
To describe how to carry out simple
analysis of results
To be introduced to Simpson’s Index of
Diversity
Tasks …
STARTER – review practical techniques used last
lesson
1. Run through homework (completing tasks 10-14
from practical worksheet)
2. Complete SAQ 1 and SAQ 2 in pairs/individually
3. Peer assess
4. How to sample non-plants!
5. Start to think about a bit of Maths!
How to sample things that aren’t plants!
Longworth Traps …
http://www.youtube.com/watch?v=FDqpXlClJTw
How to sample things that aren’t plants!
Kick sampling
http://www.youtube.com/watch?v=h__fLpsWxcg
How to sample things that aren’t plants!
Dye marking Salmon for a mark, release and recapture study
http://www.youtube.com/watch?v=8Q81ihjzb8U
Comparing species evenness
Which habitat had the greatest species evenness?
POND B – there is less variation in population size
between each species
If we wanted to compare relative abundance (amount) of
each species found in two habitats we can therefore
look at the information gathered and draw a conclusion
Using statistics …
Statistically analysing your results is much more powerful
than just comparing your results
In this ecology
practical, 10 quadrats
were laid randomly in
each site (Shore A and
Shore B) and the
number of individuals
from each of the
species was counted
The results are shown
in the table
Simpson’s Index of Diversity
Used to calculate a value of
Biodiversity in an area
Requires data about the number of
species in an area and their
densities
BONUS – you don’t
have to ID all species
you find, just note the
number of different
types (ie: you can
label them A, B. C
etc!)
D
Diversity Index value (0-1); 1 = high, 0 = low
n
Total number of organisms of a particular species
N
Total number of organisms of all species
‘Sum of’
It can’t be that hard – let’s have a go!
First we must calculate
n/N for each Species
found on Shore A
Then we need to square
this number
D = 1 – 0.201 = 0.799
Finally, add all of the
numbers together and
take this away from 1
Now for Shore B …
First we must
calculate n/N for each
Species found on
Shore A
Then we need to
square this number
D = 1 – 0.267 = 0.733
Finally, add all of the
numbers together and
take this away from 1
Let’s compare …
The higher the number, the
greater the diversity!
Species richness
Simpson’s Index of
Diversity
Shore A = 8 (8 different
species!)
Shore A
Shore B = 7
Shore B
More
D = 0.799 diverse!
D = 0.733