Essential Concepts of Species Interactions and Population Dynamics

Specialist vs. Generalist Species

  • Differences:

    • Specialists:

    • Narrow ecological niche; specific resource requirements.

    • More prone to extinction; less adaptable to changes.

    • Advantageous in constant habitats.

    • Generalists:

    • Broad ecological niche; adaptable to many environments.

    • Less prone to extinction; can be invasive.

    • Advantageous in changing habitats.

K-selected vs. r-selected Species

  • Differences:

    • K-selected species:

    • Large size; few offspring; high parental care.

    • Long lifespan; mature slowly; stable environments; low biotic potential.

    • r-selected species:

    • Small size; many offspring; little to no care.

    • Short lifespan; mature quickly; unstable environments; high biotic potential.

  • Impact of Invasive Species:

    • K-selected species are more negatively impacted by r-selected invasive species due to competition for resources.

Survivorship Curves

  • Types:

    • Type I: High survival early, rapid decline in older age (e.g., humans).

    • Type II: Steady survival rate throughout life (e.g., birds).

    • Type III: High mortality early, few survive to adulthood (e.g., insects).

Carrying Capacity

  • Definition: Maximum population size an ecosystem can support based on resources.

  • Overshoot Consequences: Leads to resource depletion, die-off, and population crashes.

Population Growth & Resource Availability

  • Influence of Resources:

    • Growth is limited by the availability of resources.

    • Rapid population growth occurs with abundant resources; decline occurs when resources are depleted.

Age Structure Diagrams and Human Population Dynamics

  • Interpretation: Shape indicates growth rates; wider base indicates rapid growth, narrower base indicates declining populations.

Total Fertility Rate (TFR)

  • Factors Influencing TFR:

    • Age of first child; educational opportunities for females; access to family planning.

    • Higher infant mortality rates associated with higher TFR due to replacement child needs.

Demographic Transition

  • Stages:

    1. Pre-Industrial: High birth/death rates; little growth.

    2. Transition/Developing: Declining death rates; high birth rates; rapid growth.

    3. Industrialized: Low birth/death rates; stable population.

    4. Post-Industrial: Birth rates below replacement; possible population decline.