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Climate and Biomes
Evolution and Adaptation
Population Ecology
Population Ecology
I. Attributes of Populations
- Population: A group of potentially interbreeding organisms at the same time
and place, that share a common gene pool.
- Population size : number of individuals
- Population Growth Rate: change in number over time, as a function of
(birth +immigration)- (death + emigration)
- Population density : number per unit area
- Range/distribution: geographic area over which the individuals are dispersed.
- Population Structure:
- age class structure
- sex ratio
- genetic structure
- spatial structure (pattern of how individuals are distributed through
the range)
Population Ecology
I. Attributes of Populations
II.Distributions
A. Determining Factors
1. Environmental Tolerance – the Niche Concept
Fremont’s Leather flower
Population Ecology
I. Attributes of Populations
II.Distributions
A. Determining Factors
1. Environmental Tolerance
performance
Realized and fundamental niches
Zones of optima, tolerance, intolerance
temperature
Population Ecology
I. Attributes of Populations
II.Distributions
A. Determining Factors
1. Environmental Tolerance
2. Barriers to Dispersal
A. Determining Factors
1. Environmental Tolerance
2. Barriers to Dispersal
3. Changes thru Time: Seasonal Migration
A. Determining Factors
1. Environmental Tolerance
2. Barriers to Dispersal
3. Changes thru Time: Seasonal Migration
4. Changes thru Time: Climate Change
A. Determining Factors
1. Environmental Tolerance
2. Barriers to Dispersal
3. Changes thru Time: Seasonal Migration
4. Changes thru Time: Climate Change
Changes in elevational range
cooler
warmer
Craig Moritz,1,2* James L. Patton,1,2 Chris J. Conroy,1 Juan L. Parra,1,2 Gary C. White,3 Steven R. Beissinger1,4. 2008. Impact of a
Century of Climate Change on Small-Mammal Communities in Yosemite National Park, USA. Science 322:261-264.
Craig Moritz,1,2* James L. Patton,1,2 Chris J. Conroy,1 Juan L. Parra,1,2 Gary C. White,3 Steven R. Beissinger1,4. 2008. Impact of a
Century of Climate Change on Small-Mammal Communities in Yosemite National Park, USA. Science 322:261-264.
A. Determining Factors
1. Environmental Tolerance
2. Barriers to Dispersal
3. Changes thru Time: Seasonal Migration
4. Changes thru Time: Climate Change
5. Niche Modeling and Invasive Species
Probabilities of three Eucalyptus species being
found in an area, mapped by climate and soil type.
Probabilities of three Eucalyptus species being
found in an area, mapped by climate and soil type.
Probabilities of three Eucalyptus species being
found in an area, mapped by climate and soil type.
Problems:
Doesn’t account for biological aspects of the environment
- maybe the native range is limited by competition/predation
- separated from that competitor/predator, the range may increase
Water Hyacinth
“Biological Control Agent”
Neochetina eichhorniae
Problems:
Doesn’t account for biological aspects of the environment
- maybe the native range is limited by competition/predation
- separated from that competitor/predator, the range may increase
Doesn’t account for the possibility of adaptation
A. Determining Factors
B. Dispersion – how organisms in a population are spaced
B. Dispersion
- Regular
Low variance
B. Dispersion
- Regular
- intraspecific competition
- allelopathy
- territoriality
B. Dispersion
- Clumped
- patchy resource
- social effects
- limited dispersal
High variance
B. Dispersion
- Random
- canopy trees, later in succession
Normal distribution
B. Dispersion
- Complexities
Varies with type of dispersal
B. Dispersion
- Complexities
Varies with life-history stage
B. Dispersion
- Complexities
Varies with spatial scale and resource distribution
C. Population Density
1. Correlates with Niche Parameters – greatest at center of range
Density of Dickcissel,
a prairie songbird
C. Population Density
2. Habitat Selection
Fretwell – Lucas model
of habitat selection
(1972)
C. Population Density
3. Maintenance of Marginal Populations
Why don’t these adapt to local
conditions?