Global Ecology pt 3

Ecology Overview

Seasons and Rain Shadows

  • Seasons are influenced by:

    • Earth's tilt (23.5°) and orbit around the sun.

    • Rain shadows occur when mountains block moist air, resulting in wet conditions on one side and dry conditions on the other.

Types of Influencing Factors

  • Biotic Factors:

    • Interactions with other living organisms including food availability and predator-prey relationships.

  • Abiotic Factors:

    • Non-living components like temperature, water, sunlight, and soil composition that affect where species can thrive.

Upwelling Process

  • Definition: Upwelling is the movement of nutrient-rich water from the ocean depths to the surface.

  • Causes: Typically caused by winds that push surface waters away, allowing deeper water to rise.

  • Effects on Nutrient Availability: This process increases productivity in marine ecosystems by providing nutrients necessary for photosynthetic organisms.

Factors Influencing Species Distribution

Adaptation

  • Species adapt to their environments based on:

    • Abiotic Factors: Such as climate and geology.

    • Biotic Factors: Including food availability and presence of predators.

  • Populations need sufficient genetic variability and competition to respond to environmental changes.

Environmental Influences

  • Temperature:

    • Organisms function within specific temperature ranges; deviations require extra energy.

    • Example: Kangaroo rats have behavioral adaptations to survive in temperature extremes.

  • Physical Attributes:

    • Example: Whale blubber for insulation against cold.

    • Rising ocean temperatures contribute to ecological events such as coral bleaching.

Light and Sunlight

  • Importance of Sunlight:

    • Limits distribution of photosynthetic organisms; excessive light may damage DNA.

    • Intense competition for light in forest ecosystems.

  • Aquatic Photosynthesis: Most happens near the surface known as the photic zone where light penetrates.

Water and Its Role

  • All life forms require water for metabolic activities.

  • Adaptations to prevent water loss include:

    • Physical: Lizard skin that reduces water evaporation.

    • Behavioral: Animals retreating during dry conditions.

Salinity Effects

  • Salinity affects aquatic organisms’ water balance; species may restrict to either fresh or saltwater depending on their ability to manage osmotic pressure.

Oxygen Availability

  • Factors Impacting Oxygen Levels:

    • Warm aquatic habitats generally hold less oxygen than cold ones, impacting species survival.

    • Some species are adapted to anaerobic conditions, but many require oxygen.

Soil and Rocks

  • Soil structure can influence which species can thrive.

  • Influential factors include:

    • pH levels, mineral composition, and nutrient availability affecting growth and survival.

Biotic Factors

  • Competition and Predation:

    • Presence of competitors can limit species' habitat availability.

    • E.g., Mantis shrimp as fierce competitors in their niche.

  • Habitat Selection:

    • Organisms may occupy only specific parts of otherwise suitable habitats (e.g., spawning salmon).

Dispersal and Geographic Isolation

  • Species might not occupy suitable habitats due to:

    • Dispersal: Movement of individuals away from their origin; barriers lead to geographic isolation.

    • Adaptive Radiation: When species colonize unoccupied areas, they may evolve significantly (e.g., Darwin's finches).

Factors Limiting Species Distribution

  • Assessing species absence from an area involves:

    • Dispersal Limits: Geographic barriers or insufficient time to reach.

    • Behavioral Limits: Avoidance due to predation or competition.

    • Abiotic Limits: Including water, oxygen, salinity, pH, and nutrient availability.

Environmental Challenges in Tundra

  • Adaptations expected in arctic tundra include:

    • Mechanisms for surviving extreme cold, limited rainfall, and intense summer sunlight.

  • Abiotic Factors Limiting Distribution:

    • Temperature extremes, light availability, and moisture levels impact where species can live.

Population Dynamics

Key Population Parameters

  • Four Factors:

    • Density, dispersion, demographics, and dynamics.

  • Density-Independent Factors:

    • Size of the population does not influence birth or death rates (mostly abiotic).

    • Example: Fixed mortality rates in dune fescue unrelated to population size.