Download Biodiversity

Biodiversity
Biodiversity and Conservation

Variation in three levels:



Genetic – the variety of genes within a species
Species – the number of species per area
Habitat –the variety of places where life exists
Genetic Diversity

Range of genes for a particular trait



May be different from another population of the same
species
Definitely different from another species
Cause – sexual reproduction and mutations
Why is genetic diversity important?



Allows for survival from disease, changes in
climate or other local environmental conditions
Provides the basis for evolution by natural
selection
A healthy population has a high genetic diversity.
Habitat Diversity

The range of different habitats
Includes microhabitat or a major community

Cause – Atmospheric circulation

Why is habitat diversity important?


Provides different niches
Provides a variety of services





CO2 Fixation
Pest Control
Nitrogen Fixation
Soil Binding
Air Pollution Absorption




Oxygen Production
Water Purification
Nutrient Storage
Pollination
Species Diversity


Species – organisms that interbreed and produce
fertile offspring
How many different species are there?


~ 1.75 million known
Many more unknown

5 – 50 million or more
Interconnection of Diversity

Increases in types of habitat leads to increase in
different species which in turn increases genetic
variation.
Natural Selection

Natural Selection


Darwin proposed that population changes are based
on natural differences.
“Survival of the fittest”
Five main propositions for the theory
of evolution by natural selection
1.
More offspring are produced than will survive
and reproduce.

2.
There are more individuals than can be supported by
resources of the habitat
There is competition for resources among
offspring.

Struggle for survival based on environmental
pressure
Five main propositions for the theory
of evolution by natural selection
3.
There is variation of traits within populations of
organisms.

4.
There is variety between individuals
Some of these traits are more helpful than
others.
Five main propositions for the theory
of evolution by natural selection
5.
Because organisms with certain traits have greater
chance of reproducing, there offspring will make up a
larger part of the population

Those more fit (able)to survive, do and pass their
genes on to the next generation

Changes in gene frequency lead to changes in
population over time.

Over long periods of time consistent selective
pressure along with reproductive isolation can lead
to speciation (new species
Example of Natural Selection

Black and gray peppered moths in 19th century
England