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Biodiversity
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Biodiversity
Genetic diversity,
Species diversity
Habitat diversity.
Biodiversity comes from the phrase biological diversity. It is now used to
mean the variety of life on Earth.
‘Bio’ makes it clear that we mean the biological parts of the ecosystem
and ‘diversity’ means variety.
Biodiversity can be used to evaluate both the complexity of an area and
how healthy that area is.
Biodiversity is measured in three ways: species diversity, habitat diversity
and genetic diversity.
Species Diversity
• The variety of species per unit area. This
includes both the number of species present
and their relative abundance.
Species diversity is the variety or number of different
species in a unit of area e.g. a km2.
It includes the number of species present and their
abundance (how many of each one there are).
The higher the species diversity of a community, the
greater the complexity.
Areas of high species diversity are also more likely to be
undisturbed by people e.g. primary rainforest.
*Species richness means only the number of species.
Genetic Diversity
• The range of
genetic material
present in a gene
pool or population
of a species.
Genetic diversity means the range of genetic material
present in a gene pool or in a population of a species.
Gene pool refers to all the different genes found in all
the individuals of the species in that area.
A large gene pool leads to a high genetic diversity and a
small gene pool leads to a low genetic diversity.
Gene pool can refer to the diversity of genes in all species
within an area.
Habitat Diversity
• The range of different habitats or number of ecological
niches per unit area in an ecosystem, community or
biome.
Habitat diversity means the range of different habitats in
an ecosystem.
Habitat diversity is often connected to the variety of
ecological niches.
So, for example:
A woodland has many different niches, such as a rivers, trees and soil, and so it has a
high habitat diversity.
A desert has few habitats, maybe sand and occasional vegetation, and so has a low
habitat diversity.
Check understanding
1. Are species with a high or a low genetic diversity more prone
to extinction and why? Think about what would happen if
the environment changes.
2. How could we increase the genetic diversity of an area?
3. How could we increase habitat diversity?
4. How could we increase species diversity?
5. As an environmentalist, which of the three methods of
increasing biodiversity will be the most successful and why?
6. How could we measure biodiversity in any given area?
Measuring diversity? Which ones…
• Quadrat
• Lincoln
• Simpson’s - how does it work? PAIRS
• Communities with individuals evenly distributed between different species
are said to have high evenness and have high diversity. This is because
many species can co-exist in the many available niches within a complex
ecosystem.
• Communities with one dominant species have a low diversity which shows
a poorer ecosystem not able to support as many types of organism.
• Measures of diversity in communities with few species can be unreliable
as relative abundance between species can misrepresent true patterns.
4.1.1 Define the terms biodiversity, genetic diversity, species diversity and
habitat diversity.
So, why conserve species?
Preservation of habitats as
people live there e.g.
indigenous people in
rainforest areas
Insects for pollination of
crops and other plants
Plants to remove carbon dioxide and add
oxygen to air
Mammals and birds for seed
dispersal
Pleasure / aesthetic value
from seeing species and
habitats
Food such as rice and wheat
all come from wild plants
Need diversity so we can increase scientific
knowledge
Genes preserved in case pests
wipe out our food species now
Some organisms control
other species – biological
control rather than chemical
control e.g. ladybirds eat
greenfly
Natural products e.g. timber,
oil palm, guano (seabird
droppings – fertilizer), cotton,
rubber etc
Ethical reasons – humans as dominant
species should be protecting other areas,
biorights – species have their own rights
regardless of how they help us
Holidays in national parks and
areas of beauty improve the
quality of people’s lives
Products such as medicine –
the first antibiotics such as
penicillin came from fungi,
the rosy periwinkle in
Madagascar’s forest gave us a
drug for leukaemia and a rare
yew tree has a chemical that
may help to fight cancer
Indicator species needed to
show if ecosystem is being
Plants to regulate climate by keeping water
in local area and providing shade
Tourism may bring in revenue
for local economy e.g. GBR
1a) Identify, giving reasons, two actions which
will promote species diversity.
(2)
1b) Explain why species diversity is considered
to be an advantage to an ecosystem.
(3)
IB questions:
1. Distinguish between the term biodiversity and abundance.
2. How can species diversity in an area be measured?
3. Discuss the characteristics of an ecosystem that would allow it to support
high biodiversity and explain what the threats are to this ecosystem.
Are humans still evolving?