Transcript What is Species Diversity?

Species Diversity
Questions for Today
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What is Species Diversity?
What is the difference between
Species Richness and Species
Evenness?
What is the Theory of Island
Biogeography?
How Does Species richness affect
Biodiversity?
What is Species
Diversity?
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Species Diversity is the number of
different species an ecosystem
contains (species richness) combined
with the relative abundance of
individuals within each of those
species (species evenness).
– Species Diversity is as major component
of biodiversity.
What is Species
Diversity?
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Species Diversity varies with their
Geographic Location:
– Terrestrial plants and animals
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Highest towards the equator and lessens as
we head to the poles
– Aquatic Plants and animals
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Highest where there is more sun available.
Species Richness vs.
Evenness
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A coral reef with many different types of
species but at a low number would be
described as having high species richness
but low evenness
A aspen forest with only aspen trees and a
few individuals but at a high number would
be described as having low species richness
but high evenness.
Variations in Species Richness
and Species Evenness
The Theory of Island
Biogeography
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Created by Robert MacArthur and Edward O.
Wilson.
States that the number of different species
found on an island is determined by the
interactions of two factors:
– The rate at which new species migrate to the
island
– The rate at which species go extinct on the
island.
The Theory of Island
Biogeography
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The Model project that at some point
in time, immigration rate and
extinction rate will balance out.
– Scientists can then determine the average
number of different species over time.
The Theory of Island
Biogeography
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Two features affect the immigration
and extinction of species on an island:
– Island Size
– Distance from the Mainland
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Remember the Lizard Lab!
How does Species Richness
affect Biodiversity?
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High Species Richness creates a more
stable environment
– More Producers
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More NPP
– More complex food chains and webs
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Allows organism to adapt to environmental
stresses
– Able to bounce back from catastrophes
better.