Population Ecology Flashcards
What is population ecology?
- science that deals with measuring changes in population size and composition
- identify the factors that cause the changes
It consists of all the individuals of a species in a given area
Population
It describes the age distribution of individuals, and how those individuals are spread over the environment
Population structure
Why is it important for scientist to describe natural populations?
- to asses the health of population
- to determine the endangered or threatened status
- to predict the population dynamics
- study how and why population size changes over time
- study the factors affecting growth, stability and decline of populations
Population Dynamics
3 phases in life cycle
- growth
- stability
- decline
Characteristics of Dynamics
- size
- density
- dispersal
- immigration
- emigration
- births
- deaths
- survivors
The _____ of a population is measured as the number of individuals per unit area
density
The _______ of a population is the patten of spacing among individuals within the geogrpahic boundaries
dispersion
It is a way to estimate the size of a population
Mark and recapture method
Three general patterns of population distribution
- Clumping
- Uniform distibution
- Random dispersion
- also known as aggregated distribution
- individuals aggregate in patches
Clumped distribution
Clump Distribution
Caused by:
environment where the resources concentrated in patches
Clumped Distribution
Other factors:
- mating
- limited seed dispersal
Clumped Distribution
Importance:
- for protection
- reducing competition
- increasing feeding efficiencies
- patterm of equallyspaced individuals
- used the resources found immediately around them
Uniform Distribution
Unifrom Distribution
Caused by:
the ability to survive anywhere in the habitat
Uniform Distribution
Importance:
able to set up the zone of territories for feeding, nesting, breeding
Individuals in a population are spaced all over an area in a way that in unrelated to the presemce of others
Random Dispersion
Random Dispersion
Spacing pattern:
based on total unpredictability
Random Dispersion
Caused by:
the ability to live anywhere in a given area except, they are limited to grow whenever they are first set root (for plants)
3 factors to determine population changes
- births
- deaths
- migration (immigration & emigration)
Population of organism able to change ____ ____
over time
Increase in population size usually due to _______ (birth rate)
natality
Decrease in population size as a result of ______
mortality
Population growth can be describe by using a growth curves, what are those?
- Exponential Growth
- Logistic Growth
It is called an S-curve necause of its shape
Growth curve
Factors that tend to reduce population growth rates
Environmental resistance
- the growth rate is always positive
- NO upper limit to population size
Exponential Growth
- mode of population that assume birth rate and death rate remain constant over time
- describing an idealized population in an unlimited population
- ignoring immigration and emigration
Exponenetial Growth Curve
The result in exponential growth
b >d , r > 0
Population growth is therefore regulated by _____ ______ (K), which is the maximum stable population size a particular environment can support
carrying capacity
Population Growth Rate
- Logistic Growth Rate
- Carrying Capacity
- S-shaped curve
- the rate of population growth slows as the population size approches carrying capacity, leveling to a constant level
Logistic Growth Rate
Factors influencing population density
- interaction of density-dependent factors
- interaction of density-independent factors
Density-dependent Factors
- limiting resources (eg., food & shelter)
- production of toxic waste
- infectious disease
- predation
- stress
- emigration
Density-independent Factors
- severe storms and flooding
- sudden unpredictable severe cold spells
- earthquakes and volcanoes
- catastrophic meteorite impacts
General types of population fluctuations
- Stable
- Irruptive
- Chaotic Behavior
- Cyclic
Population size fluctuates slightly above and below carrying capacity
Stable
General types of population fluctuations:
Stable, usually found in
- undisturbed areas
- little change in climate
- a population explosion but then rather return to a lower size rather than quickly
- impacted by favorable weather, increase in food supply, decrease in predators
Irruptive
Irregular changes in size with no real pattern seen
Chaotic Behavior
Changes occur in a pattern over a period of time
Cyclic
