Download Population Ecology

Population Ecology
Chapter: 52
What you need to know!
1.
2.
3.
How density, dispersion, and demographics
can describe a population.
The differences between exponential and
logistic growth models.
How density-dependent and density
independent factors can control population
growth.
Levels of Organization
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From small to large:
Organism (individual)
Population – group of organisms of the same
species that interact with one another
Community
Ecosystem/Biome
Biosphere
Population Characteristics
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Size* (N) = total number of individuals
Density* = number of individuals per area or
volume (100 buffalo/km2)
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*Dynamic – births/deaths & migration
Dispersion = grouping of
individuals in area
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Clumped (humans in cities)
Uniform (nesting penguins)
Random (trees in a forest)
Demographics – Life Tables
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Demographics is the study of vital population statistics
Life Tables are age-specific summaries of survival patterns
of a population
Demographics - Survivorship Curves
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Graph of Life Table
Idealized survivorship
curves show 3 common
patterns of the relationship
between age and death:
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Type I = Long Life
Type II = intermediate;
little to no relationship
between age and death
Type III = Infanticide with
longevity after adolescence
Demographics – Reproductive
Table
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A fertility schedule
that includes the
relationship between
age and reproductive
success
Life History
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Traits that impact reproduction and survival
1.
2.
3.
Maturation
Frequency of reproduction
Clutch size
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Fecundity is the combination of 2 & 3
Two evolutionary patterns:
1. Semelparity (big-bang reproduction)
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2.
One massive reproductive event followed by death
Iteroparity (repeated reproduction)
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Several reproductive events throughout lifetime
Exponential Growth
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Maximum growth in ideal conditions
Logistic Growth
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Realistic Model of
Growth
Carrying capacity (K)
is the maximum
amount of life an
ecosystem can
support
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Usually density
dependent and/or
limiting factors
Fluctuations common
Logistic Model & Life Histories
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r-selected species:
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Quick reproduction time leads to rapid increase
in number (semelparity)
Widespread death when K is reached
K-selected species:
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Steady population around K
Small number of large offspring needing
intensive parenting
Multiple reproductive events in lifetime
(iteroparity)
Limiting Factors
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Anything that reduces population growth
Density-dependent factors apply as populations increase in
density:
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Competition: food, water, territory, etc.
Health (disease, waste)
Predation
Intrinsic factors
Density-independent (abiotic)
factors apply to all populations,
regardless of size
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Weather
Climate change
Natural disasters
Population Dynamics
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Complex interactions between
biotic and abiotic factors that
cause variation in the size of a
population
Population are not stable; they
fluctuate
Metapopulation includes the
migration between more than
one population
Human Population
Age Structure