AP Bio Unit 8: Population Dynamics and Growth Models

Population Ecology

The study of how populations interact with their environment and change over time.

Population

A group of individuals of the same species living in the same area, relying on the same resources.

Population Size (N)

The number of individuals in a population.

Births (B)

The number of new individuals produced in a population.

Deaths (D)

The number of individuals that die in a population.

Immigration (I)

The movement of individuals into a population from other areas.

Emigration (E)

The movement of individuals out of a population to other areas.

Exponential Growth

Population growth in an ideal environment with unlimited resources, forming a J-shaped curve.

Logistic Growth

Population growth that levels off as population size approaches carrying capacity, forming an S-shaped curve.

Carrying Capacity (K)

The maximum population size that an environment can sustain.

Density-Dependent Factors

Factors whose effects intensify as population density increases.

Density-Independent Factors

Factors that affect population size regardless of density.

Iteroparity

A reproductive strategy characterized by producing few offspring with high parental care, typical of K-selected species.

Semelparity

A reproductive strategy characterized by producing many offspring with little to no parental care, typical of r-selected species.

Type I Survivorship Curve

Characterized by low death rates early in life, with higher mortality in older age; example: humans.

Type II Survivorship Curve

Characterized by a constant death rate throughout the organism's life; example: some lizards.

Type III Survivorship Curve

Characterized by high death rates for the young, with survivors living long lives; example: oysters.

Age Structure Diagram

Visual representation of the relative number of individuals at each age in a population.

Rapid Growth Population Pyramid

Population pyramid with a broad base, indicating a large number of young individuals.

Stable Growth Population Pyramid

Population pyramid with a relatively even distribution among age groups.

Negative Growth Population Pyramid

Population pyramid with a narrow base, indicating fewer young individuals than older ones.

Maximum per capita growth rate (r_{max})

The intrinsic rate of increase in a population under ideal conditions.

dN/dt

The rate of population change over time.

Competition (Density-Dependent Factor)

Increased struggle for resources as population density rises.

Predation (Density-Dependent Factor)

Preferential targeting of abundant prey species by predators as population density increases.

Toxic Waste (Density-Dependent Factor)

Toxic substances produced by individuals which can affect population growth at high densities.

Natural Disasters (Density-Independent Factor)

Environmental events such as floods and fires that can drastically alter population size regardless of density.