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Biodiversity
2 Components of Species Diversity:
• Species RichnessNumber of species
• Species Evenness
Relative abundance of each species.
Diversity in Ecosystems
• Species richness seems to increase productivity
and stability or sustainability.
Better able to withstand environmental
disturbances.
• How much species richness is needed is
debatable
Ecological Niche vs. Habitat
Habitat: the location that a species is found in an ecosystem.
Niche: the ___________________ of a species in an ecosystem.
includes:
• conditions (physical & chemical);
• resources (such as nutrients or food);
• interactions with biotic & abiotic components of the ecosystem;
• role in flow of energy cycling of matter.
Habitat is like "address" of an organism.
Niche is like "occupation" of an organism.
Generalists vs. Specialists
Generalists: have __________ niches (for
example eat many types of food);
Examples: cockroaches, coyotes, humans
Specialists: have __________ niches (for
example require a specific type of habitat);
Examples: giant pandas, which eat primarily
bamboo
Discuss with your table partner the advantages and
disadvantages of being either a specialist or a generalist.
Fill in your answers on the next slide.
Is it better to be a generalist or a specialist?
Specialists may have the advantage
when environmental conditions are
more constant because may be able to
_____________ other species for
specific resources; ____________
___________________________
Generalists may have the advantage
when environments are rapidly
changing, because ____________
________________; but __________
_______________________________
Native species: species that normally live in a
particular ecosystem.
Nonnative species: (also called exotic, alien,
or ____________ species) originate in other
ecosystems;
May enter an ecosystem by migration or by
deliberate or accidental introduction by humans;
•example: "killer bees"
Addressing Invasive Species
•Prevention- Customs controls etc.
•Containment
•Removal
•Encouraging _________________ of invasive species
Example- promotion of nutria as a fur and meat source.
Endemic species: Species that
are found nowhere else on Earth
(type of native species).
Often, there are many endemic
species on __________
because they are isolated.
Examples: Austrian ghost bat,
Galapagos marine iguana,
Madagascar lemur
Indicator species: species that
serve as ________________ that a
community or ecosystem is being
damaged:
Examples:
•Decline of migratory songbirds in
North America indicates loss/
fragmentation of habitat;
• Presence of trout in mountain
streams is an indicator of good
water quality;
• Presence of spotted owls is
indicator of healthy old–growth
forest.
Case of the Vanishing Frogs
• Habitat loss and fragmentation
• Prolonged drought
• Pollution
• Increase in UV radiation
• Parasites
• Viral and fungal diseases
• Climate change
• Overhunting
• Nonnative predators and competitors
•https://www.youtube.com/watch?v=_lWQLd5U0g8
Vanishing Frogs Video (2 min.)
Keystone species: species that play
a critical role in an ecosystem:
_____________ and ____________
are often keystone species.
Examples:
• Sea otters prevent sea urchins from
depleting kelp beds;
• Dung beetles remove animal waste;
"The loss of a keystone species is like
a drill accidentally striking a power
line. It causes lights to go out all
over.“ –– E.O. Wilson
Foundation Species:
Create or enhance their habitat in a way
which benefits other species.
Examples:
Beaver
Elephant
Discuss with your table partner:
Sea stars eat mussels, and urchins in tide pools.
These animals have no other natural predator. The
graph below indicates the biodiversity with and
without sea stars present. Determine if this
demonstrates that the sea star is an endemic species,
indicator species or keystone species.
_________________________________________
_________________________________________
An experiment by Robert
Paine showed that without
Pisaster (Sea stars)
biodiversity decreased.
Types of Species Interactions
Biotic Interactions:
• Predation: members of one species
(predator) feed on another species
(prey);
• Interspecific competition: when two
or more species use the same limited
resource and adversely affect each
other
Example: fire ants and native ants in
North America; fire ants are better
competitors; sharply reduce
populations of native species.
Intra = _____________
Inter = ______________
Review with your table partner
___________
___________
___________
___________
___________
http://www.youtube.com/watch?v=yjqIvKKMGSY
Is the video showing inter or intraspecies
competition?
When gulls chase away an eagle from their
territory, is it inter or intraspecies competition?
___________________________________
Interspecific competition results because of niche
overlap = overlap in requirements for limited resources.
Types of Competition:
• Interference competition: one
species limits another species'
__________ to a resource; e.g.,
hummingbirds defending feeding
territories.
• Exploitation competition:
competing species both have
access to a limited resource, but
one exploits the resource more
__________ or ____________.
Discuss with your table partner:
After watching the following two video clips
determine whether each type of plant competition for
light is exploitation competition or interference
competition.
Strangler Fig: Private Life of Plants (3:30 minutes)
http://www.youtube.com/watch?v=UCUtpmwacoE
Giant Water Lilies: Private Life of Plants (to 2 min.)
http://www.youtube.com/watch?v=igkjcuw_n_U
Principle of Competitive Exclusion
G.P. Gausse, in a classical
experiment (1934), showed
that two species with
identical niches can not
coexist indefinitely. This is
called the principle of
competitive exclusion.
Note that when grown
together, Paramecium
aurelia outcompetes
Paramecium caudatum.
Discuss with your table partner:
The graph below shows the seed size consumed by two
different species. Predict how this type of interspecific
competition might shape the natural selection of each
species. How might the distribution of each species for
this resource use be affected? Draw new graph for results.
Hint: what subset of each species is most likely to
survive?
•Species 1 might adapt by_____________________.
•Species 2 might adapt by_____________________.
Resource Partitioning
This process of different species _______________
_____________________is called resource petitioning.
It can allow species with similar resource requirements
can coexist because they use limited resources at
different times, in different ways, or in different places.
Resource petitioning is an ____________
process. When the niche of two species
overlap, organisms in each species may be
likely to survive using the resource in a way
that is not in direct competition.
Examples of Resource Partitioning
Sharing the Wealth
Competition AND the environment can limit distributions
of organisms
Types of Species Interactions
Symbiosis: a long–lasting
relationship in which species
live together in intimate
association.
Mutualism
Commensalism
Parasitism
3 Types of Symbiosis
Mutualism: two species interacting in a way that
benefits both.
Example: ants live in type of swollen thorn acacia.
Tree provides nectar food source and ants defend
tree from predators.
Symbiosis Cont.
Commensalism: one organism benefits from
another, but neither helps nor harms that other
organism
Example: epiphyte growing on a tree (epiphyte
benefits & tree not usually affected).
Symbiosis cont.
Parasitism: one organism (parasite) lives on part
of another organism (host), host is harmed,
Endoparasite:
lives inside host (tapeworm)
Ectoparasite:
lives outside host
(lamprey eel,
mistletoe)
Succession
Succession: gradual & fairly predictable
change in ___________________________.
•Pioneer species: the first species to colonize
•The progression of species that colonize with
time are commonly termed early, mid, & late
successional species.
Discuss with your table partner:
Compare the characteristics of two different trees
below and predict which would come earlier in the
succession process. Predict which type of tree
would tend to be more dominant in the later stage of
succession. Be able to explain your answers.
Primary Succession
Primary succession occurs in
an area where _________
____________________.
Examples:
• newly formed islands
• after the retreat of a glacier
•Typically lichens & mosses first colonize bare rock;
•Latter small herbs & shrubs colonize;
•Next faster growing tree species that have high light
requirements become established
•Finally, trees with lower light requirements establish
mature community and are able to ___________
earlier species.
Primary Succession on the Galapagos Islands
Secondary Succession
Secondary succession
occurs where an area has
been disrupted, but ______
_______________________.
Example: abandoned field
According to the classic view, succession proceeds
until an area is occupied by a climax community (or
mature communities).
Discuss with your table
partner:
Through the process of succession, predict what generally
happens to each of the following factors over time (from
early succession to late succession):
o Plant size
o Diversity
o Number of Ecological Niches
o Net Primary Productivity
Be able to explain your answers.
Discuss with your table partner:
Go to the website
www.treebenefits.org
Enter the school’s zip code (98040) to get growth data
for trees in our area.
Select the tree type Fir, Douglas and compare the CO2
reduced from the atmosphere from the following three
sizes of trees.
Douglas Fir Diameter
12 inches
25 inches
45 inches (reaching maximum size)
Explain this pattern.
lb. of CO2 Reduced in year
Ecosystem Changes During Succession
Characteristic
Plant size
Species diversity
Trophic structure
Early Succession
small
low
mostly producers
Ecological niches
few, more
generalized
low
Late Succession
large
high
mixture of producers,
consumers, &
decomposers
many, more
specialized
high
low
high
high
low
simple
low
complex
high
low
high
Community
organization (# links)
Biomass
Net Primary
Productivity
Food web
Efficiency for nutrient
cycling
Efficiency of energy
use
As plants become larger and growth rate slows down, the NPP
decreases.
Theory of Island Biogeography
• Species equilibrium model of
island biogeography
• Developed by Robert MacArthur &
Edward O. Wilson.
• Based on the idea that the number
of species on an island is
determined by the ____________
___________________________.
• This theory is applied not only to
islands, but any isolated
ecosystem.
Example: A wildlife preserve surrounded by pavement.
Effect of Island Distance from Mainland on
Species Diversity
Distant islands typically have lower species
diversity because of decreased immigration to
island.
•Note that the lower
immigration rate means the
immigration and extinction
rates intersect for a lower
species diversity equilibrium.
Discuss with you table partner:
How does a smaller island size affect species
diversity.
__________ species diversity on smaller island
How and WHY does a smaller island size effect
both the immigration and emigration rates?
_______ rate of immigration
because smaller island = ______
___________
_______ rate of extinction
because ___________________
_______________.
Stability of Ecosystems
Two key aspects of stability:
•Inertia (or persistence): the
ability of a system to resist being
disturbed or altered;
•Resilience: the ability of a living
system to recover after a
disturbance;
Discuss with your table partner whether the following
ecosystems would have a high or low inertia and high or
low resilience.
Tropical rainforest (high biodiversity, poor soil)
•_______ inertia- _____________________________
___________________________.
•______ resilience- ____________________________
__________________________.
Grasslands (low biodiversity, prone to fires, nutrient
rich soil and deep rooted plants)
•_____ inertia- ____________________________
________________________.
•_____resilience-______________________________
_____________________________.
In a rainforest, the biotic
matter is quickly decomposed
and the nutrients are ______
________. Most of the
nutrients are ___________
____________________.
Rainforest have poor soil.
In the grasslands, there is a
cold/ or dry season where
there is a _________
______________. This
allows for a ___________
____________in the soil.
Grasslands have rich soil.