Download Community - El Camino College

Two processes that affect the world's current biodiversity are
A) breeding and ecotourism
B) invasion and competition
C) mutation and succession
D) extinction and speciation
E) endemism and climate change
When they were fist sold, aerosols insecticides were highly effective in killing flies and mosquitoes.
Today, some 30 years later, a much smaller proportion of these insects die when sprayed. The
reason fewer insects are being killed is that ________.
A) the original spraying has caused a permanent mutation, giving the insects genetic resistance to
the spray
B) mosquitoes are deliberately adapting themselves to this man-made change in the environment
C) many mosquitoes today are descendants of mosquitoes with insecticide-resistant characteristics
D) insecticides cause a mutation on the DNA of the mosquitoes making them resistant
E) none of the choices are correct
From your knowledge of evolution, which of the following populations has the highest chances of
surviving in a changing environment?
A) a small population since there is less competition between the individuals
B) a population that has been restocked with individuals reared in captivity
C) a population that is genetically diverse
D) a population of genetically identical individuals
E) a population with a specialized niche
Community Ecology
What is the difference between
a population and a community?
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Each species has a niche in the community
• If a species is naturally found in a specific area or habitat,
it is because it is adapted to it
• This individuals of this species are adapted to
the abiotic (climate) and
biotic factors (community) of this area.
• This species has specific niche (a place in the community):
resources it uses (food or shelter)
role in the community (interactions with others)
Caribou and the Arctic National Wildlife Refuge
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The Community of ANWR
Interspecific interactions in the community
interaction of two species over evolutionary time
has developed special relationships between the two
Competition
Predation
Symbiosis
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Competition relationship:
When two or more species compete for the same resource
(when species have a similar niche)
How do two competitors solve competition?
When two species compete it can result in:
competitive exclusion or resource partitioning
competition leads to elimination of
one of the species from the area
competition drives a species
to differ by one or more factors
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Predation Relationship:
Interaction where
the consumer is the predator
and the food species is the prey
How does predation affect the prey population?
In the predator species, what traits will evolution select for?
In the prey species, what traits will evolution select for?
Prey Adaptations
Plant’s defenses:
can be Mechanical or Chemical
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Prey adaptations
Animal’s defenses
warning coloration
cryptic coloration
mimicry
Predator Adaptations
Predators adaptations to ambush or to pursuit
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Identify the adaptation!
Coyote and horned lizard
Sargassum fish
Nudibranch
Symbiotic Relationships
An interaction in which two species live in close physical contact
Types of symbiosis depending on benefits-harm:
Parasitism
Mutualism
Commensalism
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Parasitism
The parasite lives in or on the host
Parasite benefits and host is harmed
Commensalism
The commensalist gets a benefit
and the host is not harmed or benefited
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Mutualism
Both organisms get a benefit
•
Nitrogen fixing bacteria
in roots of bean plants
(plant and bacteria)
•
Pollination
(plant and animal)
Identify the type of symbiosis
Bats, seeds, and agoutis
Thorn trees and ants
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Can humans borrow some of these
interactions for our own benefit?
when the human is NOT one of the
species in the relationship
Humans have been able to use these
relationships for their own benefit
Use of chemical defenses against predation:
Use of predation or parasitism:
Use of a mutualistic relationship:
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Can humans harm
interactions in a community?
Introducing new species in the community
Removing species from the community
Habitat Restoration
Restore an area to its original community structure by:
removing invasive species
planting native species
Restoration projects in our area:
Madrona Marsh
Ballona Wetlands
Palos Verdes Peninsula Land Conservancy
Bolsa Chica Wetlands
Alondra Park
SEA Lab
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Predator removal can harm the environment
By decreasing diversity
By leading to deforestation
Wolves in Yellowstone
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Season
Vegetation
Climate
What happens after a fire?
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A disturbance event can start
an Ecological Succession
ECOLOGICAL SUCCESSION
Sequential replacement of species
by immigration of new species and local extinction of older ones
Why ?
Every species has a set of environmental conditions for ideal growth
Are disturbances to a community good or bad?
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Why do we have fires?
1st
Right ingredients
- climate 
- the amount of fuel 
- source of ignition 
2nd ecosystem depends on fires
- not enough moisture for bacteria
and fungi to recycle nutrients
- fire acts as __________
3rd community is adapted and depends on fire:
•
Grasses and some Shrubs:
Seeds are in the soil and
need fire to stimulate germination
•
Shrubs and some trees:
resprout from underground storage organs
•
Conifer trees:
store their seed in their cones
seeds are released after the fire opens them
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Human Impact on
this ecological succession
What do you think is the consequence of these
approaches?
 Fire suppression
 Expansion of timber-homes into fire prone areas
•
Prescribed fires
Other alternatives:
- Defensible space or “firescaping”
- Fire resistant construction
- Land use planning and growth restrictions
If we have enough time..
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Biome
Group of areas with similar communities and similar climate
Why are there different biomes?
•
Climate: rainfall (precipitation) and temperature have a patchy distribution
These climate diagrams show
monthly temperature and
precipitation for an area
•
Adjacent areas have different climates and
distant areas have similar climate
•
Plants and animals (community) found in a specific area have been
subjected to a specific climate and they are adapted to it
•
Implication: areas with similar climate
will have communities with similar adaptations
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Dry Biomes: Climate
Temp warm in most,
variable b/w day and night
Rain extremely low
Temp cold, seasonally variable
Rain very low, soil water mostly frozen
(permafrost)
S Warm dry / W cold dry
S Short, dry, cold / W Long, dry, colder
Dry Biomes: Adaptations and Human Impact
Plants:
shallow wide spread roots,
dormant seeds
Animals: hibernation, active at dusk,
food provides water
Human impact: urbanization- recreation
Plants:
Short and grouped together
No trees
Animals:
Hibernation and migration
Human impact: oil, mines, climate
change
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Treeless, Fire dependent biomes: Climate
Temp seasonally variable
Temp more variable
Temp warm
Rain seasonally variable
Rain sparse but stable
Hot, dry / mild, s wet
Summer fires
Hot, mild wet / cold, wet (s)
Summer fires
Rain highly seasonally
variable
Warm, wet / warm, dry
Winter fires
Treeless, Fire dependent biomes: Adaptations and Human Impact
P: Shrubs w/ hard leaves,
and adaptations to fire
P: Grasses with buds
underground
P: Grasses w/ trees
A: dusk active, food
source of water
A: Grazers form herds,
ground dwelling animals
A: grazers, migration
during dry season
HI: urbanization
HI: farmland
HI: poaching, farmland
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Forest biomes: Climate
Temp cool,
seasonally variable
Rain low to moderate
Temp moderate,
seasonally variable
Rain stable all year
Temp warm,
seasonally stable
Rain high
Short, mild wet (fire)/
Long, cold (snow)
Mild war, wet / cold, wet (s)
Long, very wet, warm/
short, less wet, warm
Forests biomes: Adaptations and Human Impact
P: needles, evergreen
trees
P: broad leaves that are
shed during winter
P: competition for light,
no thick bark
A: thick fur,
hibernation, thick fur,
tree life
HI: Deforestation
A: hibernation, migration
Tree life
A: tree life. Many niches
HI: acid rain
HI: Deforestation for
farmland, wood, mining
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