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?
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
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.
Niches and Roles
Questions for Today
 What is a Niche?
 What are the differences between Generalist
Species and Specialist Species?
 What are the different roles Species can play
in the environment?
Ecological Niches
 Each species in an ecosystem has a specific
role or way of life
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Ecological Niche = a species way of life or role
in the community
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Includes everything that affects its survival and
reproduction
Generalist Species vs. Specialized
Species
 Some species have broad ecological roles
and others have narrower or more
specialized roles.
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Generalized species – species that can have
broad niches.
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Extremely adaptable to a changing environment
Flies, Rats, Cockroaches, white-tailed deer,
raccoons, coyotes, humans, and many weeds.
Generalist Species vs. Specialized
Species
 Specialist species – species that occupy narrow
niches.
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May only live in a certain habitat, use only one type
of food, or tolerate a certain climate condition.
More Prone to extinction
 Tiger Salamanders – must live in fishless ponds
 Giant Panda – habitat loss, low birth rate
 Shorebirds
 Is it better to be a generalist or a specialist?
Roles for Organisms
 Niches can be divided into the roles species
play in their community:
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Native
Non-native
Indicator
Keystone
Foundation
Native vs. Non-native
 Native species are those individuals that
normally live and thrive in a particular
ecosystem.
 Non-native species are those individuals that
migrate or are accidentally or deliberately
introduced to a particular ecosystem.
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Invasive, alien, or exotic
Native vs. Non-native
 Non-native species can be good or bad.
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Good NN
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Cows, chickens, and other domesticated animals
Bad NN
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Kudzu Vine, Water Hyacinth, and Killer Bees
Indicator Species
 When an ecosystem or community starts to
collapse, ecologist look at indicator species
for the first warning signs.
 Indicator species are, generally, specialist
species that are affected by a change in one
or more key abiotic factors in the
environment.
Indicator Species
 Examples of Indicator Species:
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Trout for water quality
Birds for air quality
Frogs a general measure of productivity in a
region.
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Tropical Regions
Keystone and Foundation Species
 Keystone species have a large effect on the types
and abundances of other species in an ecosystem.
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Keystone species are low in number and are usually
prone to extinctions
Extremely important
 Two major roles of Keystone Species
 Pollinator
 Top Predator
 Loss of Keystone Species usually lead to a
population crash and other extinctions
Keystone and Foundation Species
 Foundation species play a major role in
shaping communities by creating and
enhancing their habitats in ways that benefit
other species.
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Elephants push over trees and uproot plants
to help new plants take root.
Beavers create dams and cut down trees.