Upload
dinhkiet
View
213
Download
0
Embed Size (px)
Citation preview
Population Ecology
Size, Growth, and Regulation
Associated Reading: 26.1 - 26.2, 26.4
Courtesy of Joe Robertson, Wikimedia Commons
Courtesy of National Oceanic and Atmospheric Administration
Terms to Know
•Habitat •Population •Community •Ecosystem •Biotic Factors •Abiotic Factors
Biotic Potential
•Biotic potential: Maximum rate of increase in a
population under ideal conditions
•Varies between species
•In nature, biotic potential is rarely reached
Population Growth Our hypothetical mouse population
•2,000 individuals
•Reproduce every month
•1,000 births every month
•200 deaths every month
•Birth rate (b) = # of births Total population size
•Death rate (d) = # of deaths Total population size
b = d = 1,000 2,000
200 2,000
= 0.5 = 0.1
Changes in a Population Over Time
Rate of change in population size during a
given period of time
•AKA: natural rate of increase
•How quickly a population is growing with each
generation
•Takes into account both births and deaths
r = b - d
r = 0.5 - 0.1 = 0.4
Growth Rate (r)
Population growth per unit time
(G)
Growth rate
(r)
Total population
(N)
x =
Population Growth (G)
G represents the number of individuals added to a population in the specified time frame
Month 1 2,000 x 0.4 = 800 mice added + 800 2,800 mice in population by month 2
Month 2 2,800 x 0.4 = 1,120 mice added +1,120 3,920 mice by month 3
Month 3 ???
Apply What You Know
TIME
PO
PU
LATI
ON
SIZ
E Exponential Growth
Population growth per unit time
(G) Growth rate
(r)
Total population size
(N) x =
Proportion of resources not
yet used x
Logistic Growth
An S-shaped growth curve stabilizes at carrying capacity
The S-Curve of Logistic Population Growth
Overshooting Carrying Capacity
= Environmental Resistance
Limits on Growth of Populations
Limiting factor: any essential resource that is in short supply
Total population size
Area of the habitat =
Malheur County 9,930 acres in the SE corner of Oregon
Home to ~10,000 deer
Image courtesy of Google Maps
Density
Images courtesy of Pixabay.com
Density-Independent Factors
•Factors unaffected by population density.
•Natural disasters, climate changes, etc.
Image courtesy of U.S. Fish and Wildlife Service
Image courtesy of U.S. Fish and Wildlife Service Public Domain
Image by Karunakar Rayker via Flickr CC BY 2.0
Density-Dependent Factors
•Logistic growth equation deals with density-dependent controls
•Limiting factors become more intense as population size increases
Images courtesy of Pixabay.com and OpenStax.org
Predator-Prey Cycles
Human Populations
Current World Population ←Awesome website alert! Click here for a
real time estimation of the earth's population
Human Population Growth
The Demographic Transition
Age Structure Diagram for Sweden
Replacement Level Fertility (RLF)