Chapter 4: Populations and Communities Flashcards
Population
Members of the same species that live in the same area
Community
Different species that all live in the same area
Population growth
A change in populaion size
Equilibrium
(births + immigration) = (deaths + emigration)
Population Growth Rate
Amount the population has changed divided by the time it had to change
Exponential Growth
Growth at a constant rate of increase
Population Explosion
Results from exponential growth
J-curve
the curve of exponential growth
Logistic Growth
Some process slows growth so it levels off near carrying capacity
Carrying Capacity (K)
the maximum population of a species a habitat can support without being ruined
S-curve
Results from logistic growth
Biotic potential
The number of offspring produced under ideal conditions
Environmental Resistance
The biotic and abiotic factors that limit a population’s increase
K-strategists
Lower biotic potential
- care for and protect young
- live in stable environment
- larger, longer lived, well-adapted to normal environmental fluctuations
- populations fluctuate around carrying capacity
- equilibrian species
R-strategists
Produce lots of young, but leave their survival to nature
- low recruitment
- rapid reproduction/movement/life span
- adapted to changing environment
- “boom-and-bust”
3 Survivorship curves
Type 1 Survivorship: low mortality in early life
Type 2 Survivorship: Intermediate survivorship pattern
Type 3 Survivorship: many offspring that die young
Population Density
Number of individuals per area
Density-Dependent Factor
Increases with increased population density