population ecology. what is ecology? study of organisms, their environment and interactions...
TRANSCRIPT
Population Ecology
What is Ecology?
• Study of organisms, their environment and interactions
• Different types of ecology
• Not environmentalists!
What is Ecology?
• Abiotic factors:– Water– Sun– Temperature– Wind– Soil– Disturbance
What is Ecology?• Organismal responses:
– Physiological – acclimation– Anatomical– Behavioral
Population Ecology
• Characteristics of Populations
• Described by demographics
– Size
– Age structure
– Density
– Dispersion pattern
Dispersion – Clumped
• Common
• Patchy resources c
lumped
Dispersion – Random
• Uniform conditions
Dispersion – Uniform
• Harsh competition
Determining Population Size
• Direct counts
• Sampling
– Plants
– Mark and recapture
Changes in Population Size
• Adds:
– Births
– Immigration
• Subtract:
– Death
– emigration
Exponential Growth
Limits on Growth
• Environmental conditions
• Limiting factors: Predation, food
supply, etc.
Carrying Capacity (K)• Sustainable resource supply for a
population
Logistic Growth
• As size of the population increases, rate of reproduction decreases
• When the population reaches carrying capacity, population growth ceases
Density-Dependent Controls
• Disease,
predation,
competition,
toxicity of waste
Density-Independent Controls
• Natural disasters,
climate events
LE 18-20a
Decreasing birth rate with increasing density
LE 18-20b
Increasing death rate with increasing density
LE 18-22
Exponentialgrowth
Suddendecline
Human Population Growth
• 6 billion
• Average annual increase is 1.26%
• Increase exponentially
Human Population Growth
Future Growth
• 2 Million yrs for population to reach
1 billion
• Only 12 yrs to reach 5th billion
• 1.26% growth is not sustainable
Ecological Footprints
16
14
12
10
8
6
4
2
00 2 4 6 8 10 12 14 16
Available ecological capacity (ha per person)
Eco
log
ica
l fo
otp
rint
(ha
pe
r p
ers
on
)
Japan
UK
Spain
Germany
NetherlandsNorway
USA
World
ChinaIndia
Sweden
Canada
Australia
New Zealand
Figure 36.9B
Traffic in downtown Cairo, Egypt
Manhattan,New York City
Refugee camp in ZaireFigure 36.9C
Age Structure DiagramsShow age distribution of a population
Rapid Growth
Slow Growth
Zero Growth
Negative Growth
Resource Consumption
• U. S. has 4.7% world’s population
• India has 16%
• U.S. uses 25% of processed minerals and energy and produces 25% of global pollution
• India is mere 3%
Life History Patterns
• Patterns of survival and reproduction
Survivorship Curves
• Graph of age-specific survivorship
Type I – K selected
Type III – r selected
Table 18.2
Life Tables
• Population is divided into age
categories
• Birth rates and mortality risks are
calculated for each age category
Table 18.1
Life Tables
Question of the Day