Download Genetic diversity - THE GEOGRAPHER ONLINE

Enquiry Question 1
Defining Biodiversity
What is the nature
and value of biodiversity?
Learning Objectives –
* To know & understand what ‘biodiversity’ is
* To be able to explain the three ways in which
biodiversity can be measured
* To evaluate the advantages and disadvantages of
each measure
TASK: Look at the words around the room – and
come up with 2 sentences that define the word
‘biodiversity’
There are 3 measures of biodiversity!!
Answer: Biodiversity is the degree of variation
of all life forms – plants, animals and microorganisms – within a given place. It is the main
measure of health for biological systems, like
ecosystems.
Genetic diversity is the range of species found within a species.
This means that it refers to the total number of genetic characteristics within
the DNA of a species.
http://www.bbc.co.uk/lear
ningzone/clips/6244.html
http://www.youtube.com/
watch?v=y4bIcswVZMU
Why is genetic variation important?
Example – Giraffe or you can use Darwin’s
finches with their different beaks
Task: Watch the clip, then describe how genetic
variation has helped this species to survive and
adapt
Model answer:
1. Genetic variation exists among individuals
within giraffes – some have short necks
like a horse, others have slightly longer
necks.
2. All the giraffes have competition for
resources (food and space)
3. This competition would lead to the death
of some individuals (mainly shorter necked
ones, as their food is also eaten by all the
other short necked animals). Whereas
others would survive (the longer necked
ones have an advantage as they can reach
the juicy leaves at the top!)
4. Individuals that have advantageous
variations are more likely to survive and
reproduce.
Therefore, it is important because…
• Genetic diversity and biodiversity are dependent upon each other –
genetic diversity within a species is necessary to maintain
biodiversity.
• Genetic diversity plays a very important role in survival and
adaptability of a species because when a species’ environment
changes, slight gene variations are necessary for it to adapt and
survive. A species that has a large degree of genetic diversity
among its population will have more variations from which to choose
the most fit genes.
• Species that have very little genetic variation are at a great risk. With
very little gene variation within the species, healthy reproduction is
difficult.
Task: Sum the above up into only 2
sentences in your own words!!
Species diversity is the range between different species.
Commonly given via the Simpson's Diversity Index:
D = (n / N)2
n = species abundance (the total number of organisms of a particular species;
which shows how common or rare they are relative to other species in the same
area)
N = species richness (the number of organisms of all species in an area)
A value of 0 indicates infinite diversity, a value of 1 indicates
no diversity
• Why are species diversity
important!?
• The Bio Da Versity Code!
• http://assets.panda.org/custo
m/flash/daversitycode/
http://www.youtube.com/watc
h?v=BXXczLhzlHA
• TASK: What is meant by the
‘web of life’ and how does it
show the importance of
species diversity? Watch the
clip carefully then draw a
diagram to support your
answer.
Ecosystem diversity is
the interdependence and
interactions of species
within their
environments. This
refers to the diversity of
a place in terms of its
variety of ecosystems or
habitats i.e. what is the
diversity of different
ecosystems within the
UK, as opposed to the
diversity of species
within these ecosystems.
Task: Describe and compare two continent examples
– what ecosystem diversity do they have?
Advantages
GENETIC
Diversity
SPECIES
Diversity
ECOSYSTEM
Diversity
Disadvantages
Advantages
Disadvantages
GENETIC
Diversity
•Allows an accurate picture of
diversity within a population (2)
•Helps explain how isolated
species eg birds have adapted
to new environments (10)
•Difficult to assess without
high level biological skills as
DNA is required (11)
SPECIES
Diversity
•A good general measure (4)
•Better to use a range of
indicator species (8)
•Better to use taxonomic
diversity eg 1 rodent, 2 bird, 1
lizard species = better than 4
bird species (7)
•Must compare similar sized
areas for a fair test (3)
ECOSYSTEM
Diversity
•A more complex measure as it
considers the interaction of
species within their
environment (1)
•Possibly more useful when
deciding which areas to protect
as has a wider focus (5)
•Difficult to know where the
boundary of the ecosystem
is (6)
•Must compare similar sized
areas for a fair test (3)
•Species richness does not
cover species distribution or
interaction between species
•(9)
Vote
Which measure is the best and why:
• Genetic diversity?
• Species diversity?
• Ecosystem diversity?