Population growth

Population definition

A group of organisms of the same species living in the same geographical area at the same time.

Population reproduction

Individuals in a population can reproduce with other mature members of the same species.

Four ways population size changes

Births, immigration, deaths, emigration.

Births (B) definition

New individuals added to a population through reproduction.

Immigration (I) definition

Movement of individuals into a population.

Deaths (D) definition

Removal of individuals due to mortality.

Emigration (E) definition

Movement of individuals out of a population.

Population increase equation

Population change = (Births + Immigration) - (Deaths + Emigration)

Population size definition

Total number of individuals in a population.

Population density definition

Number of individuals per unit area.

Population growth definition

Change in number of individuals in a population.

Population growth rate definition

Change in population size per unit time.

Positive population growth

Births and immigration exceed deaths and emigration.

Negative population growth

Deaths and emigration exceed births and immigration.

Ideal environmental conditions for population growth

Abundant food, no predators, no disease, optimal temperature, no competition.

Population growth curve definition

S-shaped curve showing changes in population over time.

Lag phase definition

Slow population growth due to few individuals and difficulty finding mates.

Lag phase characteristics

Low reproduction and slow increase in numbers.

Log phase definition

Rapid population growth at maximum rate.

Log phase characteristics

Birth rate exceeds death rate and population grows quickly.

Biotic potential definition

Maximum reproductive capacity of a population under ideal conditions.

Environmental resistance definition

Factors that limit population growth.

Diminishing growth phase definition

Growth slows as environmental resistance increases.

Diminishing phase characteristics

Increased competition and reduced resources.

Stationary phase definition

Population stabilizes at carrying capacity.

Stationary phase characteristics

Birth rate equals death rate.

Carrying capacity definition

Maximum number of individuals an environment can support.

Carrying capacity symbol

K

Shape of population growth curve

S-shaped or sigmoid curve.

Factors that increase population size

Adequate food, water, space, low predation, stable conditions.

Factors that decrease population size

Limited food, water, space, high predation, unstable conditions.

Adequate food effect on population

Increases survival and reproduction.

Limited food effect on population

Reduces survival and reproduction.

Adequate water effect on population

Supports growth and metabolism.

Limited water effect on population

Causes death and migration.

Habitat space importance

Provides shelter and breeding areas.

Predation effect on population

Increases death rate.

Disease effect on population

Reduces survival rate.

Reproductive rate importance

Determines population growth speed.

Abiotic stability effect

Supports steady population growth.

Unstable abiotic conditions effect

Causes population decline.

Density-dependent factors definition

Factors that depend on population size.

Examples of density-dependent factors

Food, disease, predation, competition.

Density-independent factors definition

Factors that affect populations regardless of size.

Examples of density-independent factors

Hurricanes, droughts, floods, earthquakes.

Biotic potential components

Age of maturity, litter size, reproductive events, survival rate.

Age of reproductive maturity effect

Earlier maturity increases population growth.

Litter size effect

Larger litter increases population growth.

Number of reproductive events effect

More events increase population size.

Survival rate effect

Higher survival increases population growth.

Environmental resistance factors

Limited food, disease, predation, disasters.

Environmental resistance role

Limits exponential population growth.

Biotic potential vs environmental resistance

Biotic potential increases population while environmental resistance limits it.

Immigration in plants

Occurs through seed and spore dispersal.

Immigration in animals

Occurs through movement into new areas.

Population density equation

Population density = Number of individuals / Area

Population growth rate equation

Growth rate = Change in population / Time

Net population change equation

(B + I) - (D + E)

Exponential growth definition

Rapid population increase under ideal conditions.

Sigmoid growth definition

S-shaped growth reaching carrying capacity.

Carrying capacity importance

Prevents overuse of resources.

Environmental resistance and carrying capacity

Environmental resistance keeps population near carrying capacity.

Example of density-dependent control

Disease spreads faster in crowded populations.

Example of density-independent control

Hurricane destroys habitat regardless of population size.

Why populations cannot grow indefinitely

Resources become limited and environmental resistance increases.

Relationship between biotic potential and carrying capacity

High biotic potential increases growth until carrying capacity is reached.

Population regulation definition

Processes that control population size.

Importance of population studies

Helps in conservation and resource management.

Carrying capacity definition

Maximum population size that an environment can support over a long period.

Environmental carrying capacity definition

Maximum sustainable population supported without degrading resources.

Carrying capacity symbol

K

Carrying capacity equilibrium

Population stabilizes when birth rate equals death rate.

Carrying capacity importance

Prevents environmental degradation and resource depletion.

Overpopulation definition

Population exceeds environmental carrying capacity.

Effects of overpopulation

Resource depletion, habitat damage and pollution.

Carrying capacity and sustainability

Ensures resources are available for future generations.

Boom-and-bust population definition

Population overshoots carrying capacity and crashes.

Overshoot definition

Population exceeds carrying capacity temporarily.

Boom phase

Rapid increase in population size.

Bust phase

Rapid population decline due to lack of resources.

Overshoot effects

Environmental damage and reduced carrying capacity.

Factors affecting carrying capacity

Water, space, nutrients, food and climate.

Water availability effect

Limited water reduces carrying capacity.

Space availability effect

Limited habitat reduces population size.

Nutrient availability effect

Limits plant and animal growth.

Extreme weather effect

Droughts and floods reduce carrying capacity.

Environmental resistance role

Keeps population near carrying capacity.

Biotic potential and carrying capacity

Biotic potential increases population while environmental resistance limits it.

Why populations cannot exceed carrying capacity indefinitely

Resources become limited and environmental resistance increases.

Human carrying capacity definition

Maximum human population supported without harming environment and society.

Human carrying capacity complexity

Includes social, cultural and environmental factors.

Carrying capacity and sustainable development

Supports long-term human survival.

Two schools of thought on carrying capacity

Boserup and Malthus.

Ester Boserup theory

Technology increases carrying capacity.

Boserup main idea

Population growth leads to technological innovation.

Boserup example

Artificial fertilizers increase food production.

Boserup view on resources

Resources can be expanded using technology.

Boserup population-resource relationship

Technology raises carrying capacity.

Thomas Malthus theory

Population grows faster than resources.

Malthus main idea

Population increases exponentially while resources increase linearly.