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Population
A group of organisms of the same species that inhabit a defined geographic area at the same time
Population Density
Number of individuals of a population that inhabits a certain unit of land or water area
Population / Area
Population Dispersion
How individuals of a population are spaced within a region
Uniform Dispersion
Dependent on the position of other members of the population
Random Dispersion
Independent of the position of other members of the population
Clumped Dispersion
Migration / dispersion in groups; most common
Biotic Potential
The amount that the population would grow if there were unlimted resources
Carrying Capacity
Variable K; maximum population size for the species that can be sustained by the environment
Exponential Population Growth
Unrestricted growth
dN/dt = rmax(N)
Logistic Population Growth
Restricted growth dictated by the carrying capacity
dN/dt = rmax(N)(K-N/K)
Overshoot
When a population exceeds its carrying capacity
Rule of 70
The time it takes in years for a population to double
70 / Growth rate in percent = Amount of years
Doubling Time
Amount of years for any variable to double
r-selected Organisms
Populations below the carrying capacity of their environment with high fecundity
Competition: Low
K-selected Organisms
Populations with growth limited by the carrying capacity and low fecundity
Competition: High
Survivorship Curves
The number of individuals in a population born at a given time that remain alive as time goes on
Cohort
Number of individuals in a population born at a given time
Type 1 Curve
K-selected; sharp increase of mortality at the end
Type 2 Curve
Mortality and survival rates are constant throughout time
Type 3 Curve
r-selected organisms; sharp increase of mortality near the start
Crude Birth Rate
Live births per 1,000 members of the population
Crude Death Rate
Deaths per 1,000 members of the population in a year
Actual Growth Rate
(birth rate - death rate) / 10
Population Change Over Time
(birth rate + immigration rate) - (death rate + emigration rate) / 10
Emigration
Movement of people out of a population
Immigration
Movement of people into a population
Total Fertility Rate (TFR)
The number of children a woman will bear during her lifetime
Replacement Birth Rate
The number of children a couple must have in order to replace themselves in a population
Infant Mortality Rate
The number of deaths of children under the age of 1 per 1,000 live births
Rapid Growth Age-Structure Pyramid / Diagram
Pre-reproductive >> Reproductive, Post-reproductive
Slow Growth Age-Structure Pyramid / Diagram
Pre-reproductive > Reproductive, Post-reproductive
Zero Growth Age-Structure Pyramid / Diagram
Pre-reproductive = Reproductive
Negative Growth Age-Structure Pyramid / Diagram
Pre-reproductive < Reproductive, Post-reproductive
Population Growth Rate (As Percent)
((B - D)/Number of people) * 100
Malthusian Catastrophe
The theory of overshooting the carrying capacity of the Earth resulting in a catastrophe
Macronutrients
Nutrients needed in large amounts
Micronutrients
Nutrients needed in smaller amounts
Hunger
Occurs when insufficient calories are taken in to replace those being expended
Malnutrition
Poor nutrition that results from an insufficient or poorly balanced diet
Undernourished
Those who do not receive sufficient resources
Food Deserts
Lack of access to fresh, healthy food
Niche
Total sum of a species’ use of the biotic and abiotic resources in its environment
Habitat
The area of environment where an organism or ecological community normally lives or occurs
Specialist
A species that has a narrow niche and can only live in a certain habitat
Generalist
A species that has a broad niche, is highly adaptable, and can live in varied habitats
Intraspecific Competition
Competition within a species
Interspecific Competition
Competition between species
Competitive Exclusion
When two different species in a region compete and one species wins due to better adaptation
Gause’s Principle
No two species can occupy the same niche at the same time and that the species that is less fit to live in the environment will relocate, die out, or occupy a smaller niche
Realized Niche
Occupation of a niche due to competition
Fundamental Niche
Occupation of a niche without competition
Resource Partitioning
When different species use slightly different parts of the habitat but rely on the same resources
