Download Energy and Biomass Pyramid (together)

Energy and Biomass Pyramid (together)
Represents amount of energy
available at each level as well
as amount of living tissue—
both decrease with each
increasing trophic level
V. Ecological Interactions between organisms
A. Competition—when two organisms of the same or
different species attempt to use an ecological resource
in the same place at the same time.
Ex: food, water, shelter
Monkeys compete
with each other and
other animals for food.
Rams compete with
each other for mates.
Until Americans introduced gray squirrels into parts of
England in the early 20th century, red squirrels had been
the only species of squirrel in the country. The gray
squirrels were larger and bred faster and successfully
competed for resources. Within a couple years of overlap
in an area, the red squirrels disappeared.
B. Niche—the ecological niche involves both the
place where an organism lives and
the roles that an organism has in its habitat.
Example: The ecological niche of a sunflower growing in the
backyard includes absorbing light, water and nutrients
(for photosynthesis), providing shelter and food for other
organisms (e.g. bees, ants, etc.), and giving off oxygen
into the atmosphere.
The ecological niche of an organism depends not only on
where it lives but also on what it does. By analogy, it may
be said that the habitat is the organism’s “address”, and
the niche is its “profession”, biologically speaking.
“Address”—Soil, Ground, etc.
Worm’s Niche
“Profession”– Mix-up soil
C. Predation—one organism captures and feeds on
another organism
1. Predator—one that does the killing
2. Prey—one that is the food
D. Symbiosis—any relationship in which two
species live closely together
1. Mutualism—both species benefit (WIN-WIN)
a. Ex: insects and flowers
Can you think of any other examples that we’ve talked about in class?
2. Commensalism—one member of the association
benefits and the other is
neither helped nor harmed.
(WIN-0)
Example: barnacles on a whale
The Remora fish attaches to
the shark and gets a free ride.
Commensalism
Birds build nests in trees.
3. Parasitism—one organisms lives on or inside
another organism (host) and harms it.
The parasite obtains all or part of its nutritional
needs from the host. (WIN-LOSE)
Example: fleas on a dog
Wasp eggs on back of
caterpillar.
Parasitism
Sea lampreys feed on
fluids of other fish.
Mosquito biting a
human.
Mutualism, Commensalism or Parasitism??
Parasitism
Mutualism
Ecological Levels
Density and Distribution of
Populations
• Population Density - Number of
individuals per unit area or volume.
• Population Distribution - Pattern of
dispersal of individuals within the
area of interest.
Uniform Distribution
Random Distribution
Clumped Distribution
Characteristics of Populations
• They tend to grow
• Intrinsic Rate of Natural Increase
(r)
Population Growth Models
• Exponential Growth
• Biotic Potential
• Environmental Resistance
Exponential Growth Curve
Logistic Growth
• Logistic growth—indicated by an S-shaped
curve
• Difference between logistic and exponential
due to environmental resistance
Logistic Growth
Carrying Capacity
• Carrying Capacity is the maximum number of
individuals of a given species the environment
can support.
– The closer the population to the carrying capacity,
the greater the environmental resistance.
• Biotic potential is having full effect and birthrate is a
maximum during exponential growth.
St. Paul Island
Reindeer
Population
Mortality Patterns
• Cohort --- all the members of a population
born at the same time.
• Survivorship---the probability of newborn
individuals of a cohort surviving to particular
ages.
• Illustrated by Survivorship Curves
Survivorship Curves
Survivorship Curves
Age Distributions
• What proportion of population
is in each cohort?
• Age Structure Diagrams
U.S. Age Distributions
Regulation of Population Size
• Density - Dependent Factors
• Density - Independent Factors
Factors That Affect
Population Size
Density Dependent Factors
1.


2.
Competition
Intraspecific
Interspecific
Predation
3. Parasitism
4. Disease
Factors That Affect
Population Size
Density Independent Factors
1. Abiotic factors
2. Unpredictable,
catastrophic
events
Life History Patterns
• r - Strategists (Opportunistic)
• Remember r=reproduction
Life History Patterns
• k - Strategists (Equilibrium)
• Remember k=Karrying kapacity
Human Population Growth
• Human population has had an exponential
growth pattern.
– Doubling time currently estimated at 53 years.
• Population Size
– 1800
– 1930
– 1960
– 2000
1 Billion
2 Billion
3 Billion
6 Billion
World Population Growth
Country Development
• More-Developed Countries (MDCs)
GR=0.1%
• Less-Developed Countries (LDCs)
GR= 1.6%
– LDC population expected to
increase from 5-8b by 2050
Age Distributions
• Age Structure Diagrams divide
populations into three age
groups.
–Pre-Reproductive
–Reproductive
–Post-Reproductive
The Demographic Transition
• Stage I: high birthrates and death rates
• Stage II: continued high birthrates, declining
death rates
• Stage III: falling birthrates and death rates,
eventually stabilizing
More-Developed Countries
Less-Developed Countries
Age Distribution of the World’s Population
Population Structures by Age and Sex, 2005
Millions
Less Developed
Regions
More Developed
Regions
Age
Male
300 200 100
Female
0
100 200 300
80+
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
17-19
10-16
5-9
0-4
Male
300
Female
100
100
300
Source: United Nations, World Population Prospects: The 2002 Revision (medium scenario), 2003.
World Population Distribution
by Region, 1998 and 2050
Environmental Impact
• Measured in terms of:
–Population Size
–Resource Consumption Per
Capita
–Resultant Pollution
Environmental Impact
Review
•
•
•
•
•
•
•
•
Scope of Ecology
Population Density and Distribution
Population Growth Models
Survivorship Curves
Age Distributions
Regulation of Population Size
Life History Patterns
Human Population Growth
– Environmental Impact
• facstaff.bloomu.edu/.../Ecology%20of%20Pop
ulations%20online%20