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Transcript
Ecology
Ecology
• Scientific study of the interactions
between organisms and their
environment
Levels of Study
• Organism
– Individual
– 1 turtle
Levels of Study
• Population
• Individuals of
the same
species living in
the same area
• All the turtles of
the same
species
Levels of Study
• Community
• All the organisms
living in an area
• All the turtles,
plants, insects,
algae, bacteria
Levels of Study
• Ecosystem
• All the organisms
and all the
abiotic factors
• All the organisms
& the soil, water,
gases, minerals
Levels of Study
• Biosphere
• All the
organisms & all
the abiotic
factors on
Earth
• Earth
Abiotic Factors
• Nonliving
• Temperature
• Climate
• Soil type
• Rainfall
• Gases
• Minerals
Biotic Factors
• Living
• Predators
• Parasites
• Herbivores
• Carnivores
• Decomposers
Biomes
• Tropical rainforest
• Tall trees
• High temperature
• Heavy rainfall
Biomes
•
•
•
•
•
•
Savannas
Tropical
Grasslands
Scattered trees
High temperature
Less rainfall than
tropical rain forest
Biomes
• Temperate grasslands
• Grasses
• Seasonal droughts
• Occasional fires
• Lower temperature &
less rainfall than
savannas
Biomes
• Deciduous forests
• Deciduous trees
• Oak, maple
• Warm summers
• Cold winters
• Moderate rainfall
Biomes
• Taiga
• Coniferous forests
• Pines & firs
• Cold winters
• Heavy snowfall
Biomes
• Tundra
• Grasses & sedges
• Very cold winters
• Permafrost
• High winds
• Little rain
Population Characteristics
• Density
• Number of
individuals per unit
area or volume
Population Characteristics
• Dispersal Patterns
• Spacing between
individuals
• Clumped
• Uniform
• Random
Population Characteristics
• Dispersal Patterns
• Clumped
Population Characteristics
• Dispersal Patterns
• Uniform
Population Characteristics
• Dispersal Patterns
• Random (ferns)
Population Characteristics
• Demographics
• Study of vital statistics
• Age structure
– Groupings by age
– Graphed
• Sex ratio
– % of females
compared to males
Population Characteristics
Survivorship Curves
• Graph of # of survivors vs. relative age
Survivorship Curves
• Type I
• Most
survive to
middle
age
• Humans
Survivorship Curves
• Type II
• Likelihood
of death
same at
any age
• Squirrel
Survivorship Curves
• Type III
• Most die
young
• Oyster
Limiting Factors
• Prevent population from reaching
biotic potential
• Types
– Density dependent
– Density independent
Limiting Factors
• Density dependent
• Effect becomes more intense with
increased density
• Examples
–
–
–
–
Parasites & diseases
Competition for resources
Toxic effect of waste products
Predation
Limiting Factors
• Density independent
• Occur independently of density
• Examples:
– Natural disasters
– Climate extremes
Population Growth Models
• Exponential Growth
• Change in # of individuals (N) over
time (t) is equal to the growth rate (r)
times the number of individuals (N)
N
 rN
t
Population Growth Models
• Exponential Growth
• J-shaped curve
Population Growth Models
• Logistic Growth
• When limiting factors restrict size of
population to carrying capacity
• Carrying capacity (K) = max. # of
individuals of a population that can be
sustained by the habitat
N
KN
 rN 

t
 K 
Population Growth Models
• Logistic Growth
• Sigmoid (S) shaped curve
Life-History Strategies
•
•
•
•
r-selected species
Exhibit rapid growth (J-curve)
Examples – grasses, insects
Characterized by opportunistic species
– Quickly invade habitat
– Quickly reproduce
– Then die
• Produce many offspring that are small, mature
quickly, require little parental care
Life-History Strategies
• k-selected species
• Population size remains relatively
constant
• Example - humans
• Produce small number of relatively
large offspring that require extensive
parental care
• Reproduction occurs repeatedly during
lifetime
Community Interactions
• Interspecific Competition
• Competition between different species
• When 2 species compete for same
resources one will be more successful
• To survive, the less successful species
– Must use slightly different resources
– Must use resources during different
time of day
Community Interactions
• Predation
• Any animal that totally or partly
consumes a plant or animal
• True predator kills and eats another
animal
• Parasite lives in and off a host
• Herbivore is an animal that eats plants
Community Interactions
• Symbiosis
• Two species that live together in close
contact
• Types
– Mutualism
– Commensalism
– Parasitism
Community Interactions
• Mutualism
• Both species benefit from relationship
• Examples
– Bacteria in root nodules
– Lichens – algae & fungus living
together
Community Interactions
• Commensalism
• One species benefits
while the other is
neither harmed nor
helped
• Examples
– Birds building nests in
trees
– Egrets that eat
insects around cattle
Community Interactions
• Parasitism
• One species benefits while the other is
harmed
• Examples
– Tapeworm inside animal
– Ticks on dog
Ecosystems – Trophic Levels
• Primary producers
• Plants
• Photosynthetic
bacteria
• Algae
Ecosystems – Trophic Levels
• Primary consumers
• Herbivores
• Eat producers
Ecosystems – Trophic Levels
• Secondary
consumers
• Carnivores
• Eat primary
consumers
(herbivores)
Ecosystems – Trophic Levels
• Tertiary consumers
• Secondary
carnivores
• Eat secondary
consumers
Ecosystems – Pyramids
• Pyramid of
numbers
• Most = producers
• Least = top level
consumers
Ecosystems – Pyramids
• Pyramid of energy
• Most = producers
• Least = top level consumers
Ecosystems – Pyramids
• 10% rule
• Only 10% of
energy
available at
each trophic
level is
converted
into new
biomass at
the next level
Ecosystems – Food Chain
Ecosystems – Food Web
Nitrogen Cycle
Water Cycle
Carbon Cycle
Human Impact
• Greenhouse effect
• Ozone depletion
• Acid rain
• Deforestation
• Pollution
• Species extinction