3 - 15.1 Species Abundance and Ecological Tolerance

Introduction

• The evolution and adaptation of species over time affect their abundance in various habitats.

Ecological Tolerance

• Definition: Refers to the range of conditions under which organisms can exist.

• Exists for both individual organisms and entire species.

• Optimal environments exist for every species, influenced by:

  • Biotic Factors

    • Interactions with other living organisms.

  • Abiotic Factors

    • Non-living environmental conditions like temperature and soil quality.

    • Optimal environments allow for better species performance.

Niche Generalists vs. Niche Specialists

• Niche Generalists:

  • Can survive under a wide range of abiotic and biotic conditions.

    • Example: Stickleback fish can reproduce in various temperatures.

  • Exhibit broad distribution in their habitats (wide tolerance curve).

  • Found in environments with gradient changes, such as successional forests.

    • Example: White pine trees thrive in various stages of forest succession.

• Niche Specialists:

  • Have specific environmental requirements or food sources.

  • Examples:

    • Leaf beetle: Specializes in feeding on goldenrod plants.

    • Koala: Feeds exclusively on eucalyptus leaves.

Adaptation and Vulnerability

• Specialists:

  • Thrive in stable environments.

  • Vulnerable to changes in habitat or food sources.

• Generalists:

  • More resilient to environmental changes.

  • Possess multiple food options if primary sources decline.

Global Climate Change Considerations

• Climate change may alter temperatures and precipitation, affecting habitats.

• Niche generalists are expected to be more adaptable and resilient to these changes.