Transcript ESS 4.1 Biodiversity

Diversity
What is Diversity?
• Diversity is often considered as a function of
two components:
A) the number of different species and
B) the relative numbers of individuals of each
species.
There are 3 main types of Diversity we need to
know about:
Species Diversity,
Genetic Diversity,
Habitat Diversity
We can measure diversity so that we can
quantify and compare different ecosystems
using a Diversity index.
Species Diversity
• The variety of species per unit area. This
includes both the number of species present
and their relative abundance.
Genetic Diversity
• The range of
genetic material
present in a gene
pool or population
of a species.
Habitat Diversity
• The range of different habitats or number of ecological
niches per unit area in an ecosystem, community or
biome.
How did this
diversity of
species come
about?
First we need to know about how
organisms can change……. Lets use a
giraffe as an example
How Natural Selection works…..
We have to start with 2 main ideas and look at their
consequences:
• Populations tend to produce more offspring than
an environment can support.
• There is variation in members of a species.
1. Populations tend to produce more offspring than
an environment can support.
http://www.senescence.info/overpopulation.jpg
We can
remember this
from our look
at rabbits in
Australia, and
human
population.
http://www.cartoonstock.com/directory/o/over_population_gifts.asp
2. There is variation in members of a species.
Just look around you……
But you need to note that:
Variation within our species is
the result of different
selection pressures operating
in different parts of the world,
yet this variation is not so vast
to justify a construct such as
race having a biological or
scientific basis.
http://news.softpedia.com/images/news2/12-ofthe-DNA-Differs-Amongst-Human-Races-andPopulations-2.jpg
• This leads to a struggle for existence…….
Who is
struggling
here?
http://www.wildlifeart.org/artImages/large/struggle_for_existence.jpg
Some organisms within the population have
characteristics that make them better at overcoming
these struggles
The prize for winning
is that they get to
pass on more of their
genes (that gave
them those
characteristics) to the
next generation.
Each habitat has different conditions
so different organisms succeed. So
does each Biome and Niche.
So how come biomes in different areas
of the world have different species?
How do different species come about?
In order to answer these questions we
need to consider speciation.
Speciation or how do new species
appear?
6.
…Eventually
enough
change
up that
the
2the
groups
5.
…so
varieties
survive
on
side
ofdifferent.
••• 3.
4.
on
either
side
ofbuilds
the
divide
are
1.Conditions
In adifferent
space
there
are
some
organisms.
2.
There
is natural
variety
within
the
species.
The
space
gets
divided.
Soeither
does
the
population.
can’t interbreed…..a new species has been formed.
divide.
Different ways that populations
can get separated……
This is called continental
drift.
Pick a continent. What
impact will the land
movements shown affect:
1.
Geology?
2.
Movement of
animals
and trees?
3.
Climate?
4.
Isolation?
5.
Biodiversity?
Go back to your succession work….
• What happened to Biodiversity through the
stages of succession? Why?
• What impact will ecosystem stability have on
biodiversity? Are more diverse habitats more
resilient to change? Why?
• What will happen to Biodiversity if humans
keep interfering with succession? (Eg Logging,
grazing, farming, burning.)
• What happens to Biodiversity with
Fragmentation of habitats?
Discussion
• Conservation of habitat diversity usually leads
to the conservation of species and genetic
diversity.
• Why should we conserve habitats?
• If we are going to conserve them which ones
should we prioritize and why?