Download Ecosystem Notes of biology that studies the interactions between

Ecosystem Notes
_____________Branch of biology that studies the interactions between organisms and
their environment
_____________All of the locations on Earth that can support life
Abiotic
• Non living factor in an environment
Examples
Biotic
• Living factors in an environment
Examples
Levels of Life
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Ecologists look at individual organisms (level 1)
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organisms that have similar characteristics can mate and produce fertile offspring
are a ________________
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______________Group of organisms of a single species that live in a given area
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______________A collection of interacting populations in a given area
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______________Collection of organisms that interact with each other and with
abiotic factors in the environment
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________________ a group of ecosystems which affect one another
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________________ a transition area between ecosystems, with blended
characteristics
1
Ecotones are sometimes due to:
Why are ecotones more diverse?
Energy in the ecosystem
__________-make own food producers
__________-must get nutrients from outside sources consumers
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__________: break down dead organisms into simple molecules
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__________: feed off dead animals
2
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________________Feeding level on food, energy, or biomass pyramid
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Starts with ___________
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Ends with highest level ____________
Food Chain
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One set of organisms moving up through the trophic levels
Example
Food Web
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Interconnecting food chains in an ecological community
More than one food chain
Energy Pyramid
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Illustrates that energy decreases at each succeeding trophic level
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Only 10% energy moves up
Populations
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Group of organisms of the same species living in the same location
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Change in population size is called growth rate (can be + or -)
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Population size governed by
–
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–
–
Population change =
3
Growing Populations
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Ideal conditions
Healthy organisms reproduce faster
Birth rate is higher than death rate
Species have different reproductive Patterns
r-selected species
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Characteristics of r-selected reproductive species
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k-selected species
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Characteristics of K-selected reproductive species
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Carying capicity (K)
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Largest number of individuals that can survive over long periods of time in a given
environment
Size of population is stabilized
What factors determine carrying
capacity?
Why do populations decrease if
they grow above carrying
capacity?
Why do populations increase if
the population goes below
carrying capacity?
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Boom and Bust
Some species exponential growth and then fast crash
can rise again or wait for some time before another boom
What would cause a population to
boom?
What would cause a population to
bust?
How does the predator prey relationship prevent “boom and bust”
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Density Dependent Limiting Factors
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Operate more strongly on large populations
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Usually works on stable populations
Examples
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Density Independent Limiting Factors
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Coevolution
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_______________the evolution of complementary adaptations in two or more
species of organisms because of a special relationship that exists between them
Example: Predator/prey
Batesian Mimicry
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Mullerian Mimicry
Population Interactions Influence Abundance
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When populations of different species interact, the effects on one on the other
may be positive (+), negative (-) or neutral (0).
By comparing populations living alone and together, several types of interactions can be
identified
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+=
COMMENSALISM (+/0)
MUTUALISM (+/+)
COMPETITION (-/-)
PARASITISM (+/-)
PREDATION (+/-)
- =
0=
The symbols +, - and 0 refer to the effect of one species on another when both are living
together.
Competition
LIVING ALONE
LIVING TOGETHER
COMPETITION
[When both populations live together, abundance of each is lower.]
Law of Competitive Exclusion
• No two species will occupy the same niche and compete for exactly the same
resources for an extended period of time.
• One will either migrate, become extinct, or partition the resource and utilize a subset of the same resource.
• Given resource can only be partitioned a finite number of times.
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Resource Partitioning
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___________ - Competition between members of different species.
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___________ - Competition among members of the same species.
– Often intense due to same space and nutritional requirements.
• Territoriality - Organisms defend specific area containing resources,
primarily against members of own species.
• Resource Allocation and Spacing
Intraspecific Competition
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Resource depletion may result in too many individuals in the population. Thus, the
population crashes.
Prevention
1.
2.
3.
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Reindeer on Saint Matthews Island died off as the result of depletion of lichens
(food).
Reindeer on St Mathews
Island
7000
6000
4000
3000
2000
Number
5000
6000
1350
1000
0
1940
29
1950
1960
Year
42
1970
What caused a boom in the reindeer population?
Why did the reindeer population bust after reaching a population size of 6000?
What could have prevented the “boom and bust”?
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A seed company tells gardeners that planting plants too far apart or too close
together will only produce a few seeds. Why?
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Territorial behavior has evolved in many species as a response to intraspecific
competition.
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Male red wing blackbirds stake out a territory in defense of nests and mates.
How does the territorial behavior reduce intraspecific competition?
What changed when these two
species were grown separately
verses when they were grown
together?
Which species is a better
competitor at obtaining resources?
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Predation
LIVING ALONE
LIVING TOGETHER
PREDATION
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Feeds directly upon another living organism
Prey most successfully on slowest, weakest, least fit members of target population.
Effect of predation
1.
2.
3.
Symbiosis
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Intimate living together of members of two or more species.
Three types of symbiosis
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_____________ - One member benefits while other is neither benefited nor
harmed.
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Example: Cattle and Cattle Egrets
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____________ - Both members benefit.
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Example: Bees and flowers
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_____________- One member benefits at the expense of other.
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Example: Humans and Tapeworms
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COMMENALISM
LIVING ALONE
A
LIVING TOGETHER
B
A
B
COMMENALISM
Example
• The cattle egret and cattle or other grazing African ungulate species.
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The egret benefits from catching insects that cattle “scare-up” while grazing.
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Cattle unaffected.
Mutualism
LIVING ALONE
A
LIVING TOGETHER
B
A
B
MUTUALISM
Example
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pollination of flowering plants by an insect or humming bird.
The pollinator benefits from the interaction by receiving nectar.
The plant gets its pollen transferred from one plant to another.
Parasitism
LIVING ALONE
LIVING TOGETHER
A
A
B
B
Parasitism
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Example
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Tick feeds off mammal benefitting the tick but harming the mammal.
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How would this ecosystem be affected if the butterfly population decreased?
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How would this ecosystem be affected if the coyote population decreased?
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How would this ecosystem be affected if the raven population increased?
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Limitations of where a species can live
1.
2.
3.
4.
5.
Physiological stress due to environmental conditions
Competition with other species
Predation
Parasitism and disease
luck
Critical Environmental Factors
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Single factor in shortest supply relative to demand is the critical determinant in
species distribution.
– Example: a cactus species can not survive if temperature drops below 30º F
for more than 12 hours.
Tolerance Limits
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Each environmental factor has both minimum and maximum levels, tolerance limits,
beyond which a particular species cannot survive
– Combination of many factors: temperature range, food availability,
competitors, predators
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Limits of Range
1. Physical Barriers
a.
b.
c.
2.
3.
4.
5.
6.
Indicators
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If we know the tolerance range of species, we can deduce the conditions in the
environment based on the presence of a particular species
– Example: trout require cool, clean well oxygenated water; if you see an
abundance of trout, what does that tell you about the environment?
Ecological Niche
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Habitat - Place or set of environmental conditions where a particular organism lives.
Ecological Niche
– Role a species plays in a biological community (e.g. large grassland herbivore)
– Total set of environmental factors that determine a species’ distribution.
– Generalists – Specialists When generalists and specialists collide, ____________________.
Example of generalists
Example of specialists
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Keystone Species
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A keystone species is a species that plays a critical role in maintaining the
structure of an ecological community and whose impact on the community is greater
than would be expected based on its relative abundance or total biomass
– Large predators
– Critical food organisms (bamboo and pandas)
– Often, many species are intricately interconnected so that it is difficult to
tell which is the essential component.
Example of Keystone Species:
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