Transcript Species interaction

Lake Victoria, East Africa
Nile Perch
Cichlids
Deforestation
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Competition
Predation
Symbiosis:
* parasitism
* mutualism
*commensalism
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Interspecific competition – occurs when parts of the
fundamental niches of different species overlap
Intraspecific competition – competition between the
same species
TO SURVIVE…..
Species must….
a. migrate to another area
b. shift its feeding habits or behavior through
natural selection and evolution
c. become extinct in that area
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Interference competition – one species may
limit another’s access to some resource
Defend territory – release chemicals,
chase away,
stinging
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Exploitation competition – competing species
have roughly equal access to a specific resource
but differ in how fast or efficiently they exploit
it
The faster you eat… the more you get!.
1.
2.
Some plants displace others by having leaf and
root systems that allow them to absorb more
sunlight and soil nutrients than their
competition.
Other plants produce chemicals that inhibit the
growth or germination of seeds of competing
species.
Two species that require the same resource cannot
coexist indefinitely in an ecosystem in which there
is not enough of that resource to meet the needs of
both species.
Resource Partitioning
Character Displacement
Species coexistence = neither species fully excludes the
other from resources, so both live side by side
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Resource partitioning
= species use
different resources
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Or they use shared
resources in different
ways
Ex: one species is active
at night, another in the
day
Ex: one species eats
small seeds, another
eats large seeds
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Character displacement = competing species
diverge in their physical characteristics
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Due to the evolution of traits best suited to the resources
they use
Results from resource partitioning
Birds that eat larger seeds evolve larger bills
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Birds that eat smaller seeds evolve smaller bills
Competition is reduced when two species become more different
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Fundamental niche = the full niche of a species (no
competition for resources)
Realized niche = the portion of the fundamental niche
that is actually filled
 Due to competition or other species’ interactions
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Ways to get lunch – pursuit, ambush
How to get away
Protective mechanisms – run fast, keen eye sight
 Camouflage,
 Chemical warfare
 Warning coloration
 Mimicry
 Behavioral strategies
 Protection from living in large groups
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(a) Span worm
(c) Bombardier beetle
(e) Poison dart frog
(g) Hind wings of Io moth
resemble eyes of a much
larger animal.
(b) Wandering leaf insect
(d) Foul-tasting monarch butterfly
(f) Viceroy butterfly mimics
monarch butterfly
(h) When touched,
snake caterpillar changes
shape to look like head of
snake.
Stepped Art
Fig. 5-2, p. 103
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Herbivory = animals feed on the tissues of plants
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May not kill the plant
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Widely seen in insects
But affects its growth and survival
Defenses against herbivory include:
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Chemicals: toxic or distasteful
Thorns, spines, or irritating hairs
Other animals: protect the plant
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Natural selection leads to evolution of adaptations
that make predators better hunters
Individuals who are better at catching prey:
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Live longer, healthier lives
Take better care of offspring
Prey face strong selection pressures: they are at
risk of immediate death
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Prey develop elaborate defenses against being eaten
Parasitism
Mutualism
Commensalism
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Two or more species benefit from their interactions
Symbiosis = mutualism in which the organisms
live in close physical contact
Each partner provides a service the other needs (food,
protection, housing, etc.)
 Microbes within digestive tracts
 Mycorrhizae: plant roots and fungi
 Coral and algae (zooxanthellae)
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Pollination = bees, bats, birds and others transfer
pollen from one flower to another, fertilizing its
eggs
In exchange for the plant nectar, the animals pollinate plants, which allows them to
reproduce
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Parasitism = a relationship in which one
organism (parasite) depends on another (host)
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For nourishment or some other benefit
The parasite harms, but doesn’t kill, the host
• Some are free-living
- Infrequent contact with
their hosts
- Ticks, sea lampreys
• Some live within the host
- Disease, tapeworms
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Amensalism = a relationship in which one
organism is harmed while the other is unaffected
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Difficult to confirm, because usually one organism
benefits from harming another
Allelopathy = certain plants release harmful chemicals
Or, is this a way to outcompete another for space?
Commensalism = a relationship in which one
organism benefits, while the other remains
unaffected
Succession = the predictable series of
changes in a community
Primary Succession – ecological succession in an
environment that has not previously been
inhabited. No Soil is Present Initially!
Examples:
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The first organisms to colonize a new site are
Lichens and mosses
Rock
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Secondary Succession: Succession in an area that
experiences some type of disturbance.
Soil is Already Present
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Climax Community is a community of plants and
animals that has reached a steady state because of the
development of vegetation in an area over time.
A fire levels portions
of a forest
A farmer plows
his field
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Communities experience many types of disturbance
 Removal of keystone species, spread of invasive species,
natural disturbances
 Human impacts cause major community changes
Resistance = community of organisms resists change and
remains stable despite the disturbance
Resilience = a community changes in response to a
disturbance, but later returns to its original state
A disturbed community may never return to its original
state
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Humans have dramatically changed ecological systems
 Severely degraded systems cease to function
Ecological restoration = efforts to restore communities
Restoration is informed by restoration ecology = the
science of restoring an area to an earlier condition
 To restore the system’s functionality (i.e. filtering of
water by a wetland)
 It is difficult, time-consuming, and expensive
It is best to protect natural systems from degradation in
the first place
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Prairie restoration = replanting native species,
controlling invasive species
The world’s largest project = Florida Everglades
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Flood control and irrigation removed water
Populations of wading birds dropped 90-95%
It will take 30 years
and billions of dollars
to restore natural
water flow
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What is meant by “natural”?
Is it before industrialization ? Before the
Europeans came to the New World???
Let’s say the Native Americans altered a forest
community 8,000 years ago by burning the
underbrush to improve hunting and continued
doing so until Europeans arrived 400 years ago
and cut down the forest for farming.
Should restorationist try to recreate the forest of
the Native Americans or the forest that existed
before the Native Americans arrived?
What values are involved in the decision?