Title: Ch. 52 Warm-Up
1Ch. 52 Warm-Up
- (Review) Sketch an exponential population growth
curve and a logistic population growth curve. - What is an ecological footprint?
- What are ways that you can reduce your ecological
footprint?
- Define
- Demography
- Semelparity
- Iteroparity
- Carrying capacity
- Exponential growth curve
- Logistic growth curve
- K-selection
- r-selection
- Ecological footprint
2Population Ecology
3You Must Know
- How density, dispersion, and demographics can
describe a population. - The differences between exponential and logistic
models of population growth. - How density-dependent and density-independent
factors can control population growth.
4Introduction
- Population group of individuals of a single
species living in same general area - Density individuals / area
- Dispersion pattern of spacing between individuals
5Determining population size and density
- Count every individual
- Random sampling
- Mark-recapture method
6Patterns of Dispersal
- Clumped most common near required resource
- Uniform usually antagonistic interactions
- Random not as common as you would think
7Demography the study of vital statistics that
affect population size
- Additions occur through birth, and subtractions
occur through death. - Life table age-specific summary of the survival
pattern of a population - Represent data with a survivorship curve.
- Plot of individuals in a cohort still alive at
each age.
8Life Table
9Survivorship Curves
- Type I curve low death rate early in life
(humans) - Type II curve constant death rate over lifespan
(squirrels) - Type III curve high death rate early in life
(oysters)
10Life History traits that affect an organisms
schedule of reproduction and survival
- 3 Variables
- Age of sexual maturation
- How often organism reproduces
- offspring during each event
- Note These traits are evolutionary outcomes, not
conscious decisions by organisms
11Semelparity
- Big-bang reproduction
- Many offspring produced at once
- Individual often dies afterwards
- Less stable environments
Agave Plant
12Iteroparity
- Repeated reproduction
- Few, but large offspring
- More stable environments
Lizard
Critical factors survival rate of offspring and
repeated reproduction when resources are limited
13Change in Population Size
- ?N/?t B-D
- N population size
- t time
14- Zero population growth B D
- Exponential population growth ideal conditions,
population grows rapidly
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16- Unlimited resources are rare
- Logistic model incorporates carrying capacity
(K) - K maximum stable population which can be
sustained by environment - dN/dt rmax((K-N)/K)
- S-shaped curve
17Laboratory Populations
18Factors that limit population growth
- Density-Dependent factors population matters
- i.e. Predation, disease, competition,
territoriality, waste accumulation, physiological
factors - Density-Independent factors population not a
factor - i.e. Natural disasters fire, flood, weather
19- K-selection pop. close to carrying capacity
- r-selection maximize reproductive success
K-selection r-selection
Live around K Exponential growth
High prenatal care Little or no care
Low birth numbers High birth numbers
Good survival of young Poor survival of young
Density-dependent Density independent
ie. Humans ie. cockroaches
20- Populations fluctuate due to biotic and abiotic
factors
1975-1980 peak in wolf numbers 1995 harsh
winter weather (deep snow)
21- What do you notice about the population cycles of
the showshoe hare and lynx?
22Boom-and-bust cycles
- Predator-prey interactions
- Eg. lynx and snowshoe hare on 10-year cycle
23Human Population Growth
- 2 configurations for a stable human population
(zero population growth) - High birth / high death
- Low birth / low death
- Demographic transition occurs when population
goes from A ? B
24Age-Structure Diagrams
25Global Carrying Capacity
- UN predicts 7.8 to 10.8 billion people by the
year 2050 - 2012 7 billion
- Estimated carrying capacity 10-15 billion?
- Ecological footprint total land water area
needed for all the resources a person consumes in
a pop. - 1.7 hectares (ha)/person is sustainable
- U.S. 10 ha/person ? over K??
- Limitations? Consequences? Solutions?
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27Map of ecological footprint of countries in the
world (proportional sizes shown)