Populations and Curves Notes-- Life Sciences

Population Dynamics Overview

  • General Concept: Population dynamics explores how populations of organisms change over time, interacting within communities and ecosystems.

  • Key Learning Objective (LS. 8a-c): Investigate dynamic equilibria in populations, including:

    • Interactions within and among different populations

    • Carrying capacities and limiting factors

    • Growth curves

Definitions

  • Population: All individuals of a species living _______________________________________________________________

  • Community: A group of different species residing in the same area

Three Key Features of Populations

1. Size

  • Definition: Number of individuals in a population.

  • Growth Rate Formula: Birth Rate (Natality) - Death Rate (Mortality)

    • Understanding how many individuals are born compared to how many die.

    • Population growth can be categorized as:

      • Rapid growth

      • Slow growth

      • Zero growth/decrease

  • Example Data: Growth trends observed in different countries like Kenya (rapid growth), United States (slow growth), and Italy (zero growth/decrease).

2. Density

  • Definition: _______________________________________________________

  • Population Density Formula: Population Density = # of Individuals ÷ Unit of Space

  • Population Density Examples: Cities like Seattle, Chicago, and San Francisco demonstrate varying population densities ranging from 0 to over 250 persons per square mile.

3. Dispersion

  • Definition: _______________________________________________________

  • Types of dispersion include:

    • Clumped: Individuals grouped together in patches.

    • Even/Uniform: Individuals evenly spaced.

    • Random: Individuals spread randomly without a pattern.

Factors Affecting Population Density

1. Immigration

  • Movement of individuals ___________________________________________

2. Emigration

  • Movement of individuals ___________________________________________

3. Density-Dependent Factors

  • Definition: Biotic factors that have an increasing effect as population density increases

  • examples:________________________________________________________

  • Abiotic =___________________________________________

  • Biotic =____________________________________________

4. Density-Independent Factors

  • Definition: Abiotic factors that affect populations regardless of density

  • examples:__________________________________________________________

Limiting Factors

  • Definition: Any biotic or abiotic factor that restricts the existence of organisms in a specific environment.

    • Examples:___________________________________________________

  • Zone of Tolerance: Ranges of conditions that organisms can withstand.

Carrying Capacity

  • Definition: The maximum population size that____________________________________________________________

  • Implications: Populations will grow until they reach the carrying capacity of their environment.

  • Growth Curves:

    • J-Shaped Curve: Represents exponential growth when resources are abundant.

    • S-Shaped Curve: Represents logistic growth as it approaches carrying capacity.

Population Growth Examples

Deer Population on Walla Walla Island

  • Initial observations show fluctuations over time, trending toward carrying capacity.

Human Population Growth

  • Historical Data: Human populations have rapidly increased due to scientific advances and the industrial revolution.

  • Projected Population Growth: From 2.3 billion in 1947 to an expected 12 billion by 2050.