Population Growth Models Flashcards
Population density
the average number of organisms in a population per unit of area or volume
Random distribution
a pattern of spacing between members of a species where each individual’s position is independent of the others
Uniform distribution
a spatial arrangement of organisms where individuals are spaced out in a fairly regular pattern
Clumped distribution
a spatial pattern where individuals of a population are grouped together in small areas, rather than being spread out evenly or at unpredictable distances
Age structure
the proportions of individuals at different life stages within a population
Birthrate
the number of live births in a population over a given period of time, usually a year
Death rate
he number of deaths in a population over a period of time, usually expressed per 1000 or 100,000 people
Immigration rate
The number of individuals of a similar species that have invaded the habitat who have come from elsewhere during specific period
Emigration rate
The number of individuals of a similar species that have left the habitat and have migrated elsewhere in specific period
Sigmoid growth curve
A growth pattern in which an organism’s population density rises slowly originally in a fresh setting, in a favorable acceleration stage ; then rises quickly approaching an exponential growth rate as in the J-shaped curve ; but then decreases in a negative acceleration stage
Lag phase
the initial stage of growth when the population remains constant while adjusting to the environmental conditions
Exponential phase
a period when growth is at a constant, maximum rate, ususally doubling in shorter periods of time
Stationary phase
a stage of growth where the increase in populations stops as birth and death rates become equal
Death phase
the final stage of growth, when the population decreases exponentially due to limiting factors
Carrying capacity
the maximum number of organisms that an ecosystem can support without degrading the habitat
Limiting factor
a condition or variable that can slow or stop a population from growing, or limit the rate of a reaction
Life-history plan
the pattern of an organism’s survival and reproduction, and the traits that affect it. Life history theory is the study of how organisms use their energy to grow, maintain their bodies, defend themselves, reproduce, raise their young, and avoid death.
Density dependent limiting factors
factors that affect a population’s growth rate based on the population’s density
Density independent limiting factors
factors that impact population sizes regardless of the population’s size. These factors are often associated with non-living things, or abiotic factors, and can include: weather, climate, natural disasters, and human activity
