fig. 52-2 organismal ecology population ecology community ecology ecosystem ecology landscape...
TRANSCRIPT
Fig. 52-2
Organismalecology
Populationecology
Communityecology
Ecosystemecology
Landscapeecology
Globalecology
Introduction to Ecology Populations
• Population ecology– Abundance– Dynamics Density, dispersion, demographics, interrelationships with other populations
Population density
• The number of individuals per unit area or volume
Fig. 52-1a, p. 1128
(a) Random dispersion
Pattern of dispersion
• Refers to how individuals are spaced relative to one another
Fig. 52-1b, p. 1128
(b) Clumped dispersion
Pattern of dispersion
• Patchiness in resources
• Family groups• Reduce risk of
predation
Fig. 52-1c, p. 1128
(c) Uniform dispersion
Pattern of dispersion
• Aggressive interactions
• Competition
Population dynamics
• 4 primary factors that influence population size– Births– Deaths– Immigration– Emigration
• How do these factors affect the rate at which populations change?
Fig. 53-3
Births
Births and immigrationadd individuals toa population.
Immigration
Deaths and emigrationremove individualsfrom a population.
Deaths
Emigration
Fig. 53-3
Births
Births and immigrationadd individuals toa population.
Immigration
Deaths and emigrationremove individualsfrom a population.
Deaths
Emigration
– The age at which reproduction begins– How often the organism reproduces– How many offspring are produced during each
reproductive cycle
• evolutionary outcomes reflected in the development, physiology, and behavior of an organism – based on trade-offs
Life History
Age (years)20 4 86
10
101
1,000
100
Num
ber o
f sur
vivo
rs (l
og s
cale
)
Males
Females
A survivorship curve is a graphic way of representing the data in a life table
relatively constant death rate
Fig. 53-6
1,000
100
10
10 50 100
II
III
Percentage of maximum life span
Num
ber o
f sur
vivo
rs (l
og s
cale
) I
Fig. 53-9
(a) Dandelion
(b) Coconut palm
Fig. 52-2, p. 1130
Num
ber o
f bac
teria
(N)
Hours
Dynamics - Population growth
r = unchecked population growth
Fig. 52-13, p. 1139
2006: 6.5 billion
Hum
an p
opul
ation
(bill
ions
)
Black Death
Time (years)
Fig. 52-3, p. 1131
Carrying capacity of the environment (K)
Num
ber o
f ind
ivid
uals
(N)
Time
The Logistic Model and Life Histories
• Life history traits favored by natural selection may vary with population density and environmental conditions
• K-selection, or density-dependent selection, selects for life history traits that are sensitive to population density
• r-selection, or density-independent selection, selects for life history traits that maximize reproduction
• Density-dependent– Density of population alters the affect of an
environmental condition• Density-independent– Effect of an environmental factor is not affected
by the density of a population
Factors influencing population size
Density-dependent factors
• Competition – interaction in which individuals try to use the same resource– Intraspecific– Interspecific
Density-dependent factors
Density-independent factors
Metapopulations
• Environments are heterogeneous– Resources are patchy– Several small populations
rather than 1 large • Not all patches are equal
– Less desirable may result in lower b or higher d
– More productive may lead to higher b and lower d
Fig. 52-12, p. 1138