6.1 Ecology

Introduction to Ecology
  • Definition: Ecology is the study of interactions between living organisms and their environment.
  • Focus Areas: The module will cover:
    • Organismal ecology
    • Population ecology
    • Community ecology
    • Ecosystem ecology
    • Biodiversity
Organismal Ecology
  • Definition: Focuses on individual organisms and their adaptations to specific environments.
  • Example: Carpenter blue butterfly, a specialist species that relies exclusively on one plant for laying eggs (wild lupine).
    • Life Stages:
    • Eggs and larvae depend on wild lupine.
    • Adult butterflies are not restricted to this plant.
Population Ecology
  • Definition: Study of a group of interbreeding organisms in the same geographic area.
  • Key Terms:
    • Population: A group of conspecifics capable of interbreeding in a defined area.
  • Focus:
    • Changes in population size over time (birth rates, death rates, migrations).
    • Example: Karner blue butterflies studying population dynamics.
Community Ecology
  • Definition: Examines the interactions among different species in a given area.
  • Components: All living organisms in a habitat, including plants, animals, and microorganisms.
  • Interactions Types:
    • Conspecific Interactions: Interactions within the same species (e.g., competition).
    • Heterospecific Interactions: Interactions between different species (e.g., predation, parasitism).
  • Example: Mutualistic relationship between caterpillars and ants, where both species gain benefits (defense and nourishment).
Ecosystem Ecology
  • Definition: Encompasses both the biotic (living) and abiotic (nonliving) components of ecosystems.
  • Abiotic Factors: Nonliving components such as water, soil nutrients, and atmospheric gases.
  • Example Study: Understanding how soil nutrient availability affects plant distribution and consequently the butterflies that rely on those plants.
Biogeography
  • Definition: Study of the distribution of life across Earth and the factors influencing this distribution.
  • Factors Affecting Distribution:
    • Abiotic Factors: Temperature, precipitation, latitude, and elevation.
    • Example: Local ecosystems in Central Valley transitioning to Shaver Lake’s cooler temperatures and higher precipitation with elevation change.
Types of Species
  • Endemic Species: Species with a limited geographic range (e.g., kangaroos found only in Australia).
  • Generalist Species: Widespread species, able to thrive in various environments (e.g., mockingbirds, house mice).
Abiotic Factors
  • Temperature: Significantly impacts species distribution; warmer temperatures generally allow for greater biodiversity.
  • Water Availability: Different species adapt to varying water types (freshwater vs. saltwater).
  • Nutrient Availability: Nutrient-rich environments support diverse ecosystems.
Ocean Upwelling and Lake Turnover
  • Ocean Upwelling:
    • Wind patterns cause nutrient-rich water from the ocean's depths to surface, enhancing productivity.
    • Example of community dynamics influenced by nutrient cycling.
  • Lake Turnover:
    • Occurs biannually (spring and fall) due to temperature changes, redistributing oxygen and nutrients.
    • Spring Turnover: Warmer water at four degrees Celsius sinks, bringing nutrients from the bottom to the surface.
    • Fall Turnover: Similar process as spring, with colder water sinking and mixing nutrients and oxygen.
Climate Change Overview
  • Weather vs. Climate:
    • Weather: Short-term atmospheric conditions.
    • Climate: Long-term patterns and trends over decades.
Factors Driving Climate Change
  • Milankovitch Cycles: Natural Earth orbital variations; not affected by human activity.
  • Solar Radiation Variations: Subtle fluctuations in solar output; also not controllable by humans.
  • Volcanic Eruptions: Can cause short-term cooling by emitting ash and gases.
  • Greenhouse Gases: Human-emitted gases (e.g., CO2 from fossil fuels) are the primary driver of current climate change.
Greenhouse Effect
  • Mechanism: Greenhouse gases trap heat in the atmosphere, preventing it from radiating into space.
  • Major Gases: Carbon dioxide, methane, nitrous oxide, which have increased due to human activities like burning fossil fuels and deforestation.
  • Carbon Cycle: Fossil fuel combustion releases trapped carbon into the atmosphere, contributing to climate change.
Impact of Climate Change
  • Observable Trends: Average global temperatures rising, shifts in ecological zones, melting glaciers, and rising sea levels.
  • Long-term Consequences: Even if fossil fuel use stopped, atmospheric carbon will continue warming the planet for decades due to existing levels.
Summary
  • Understanding ecology involves studying biotic and abiotic interactions across various levels, from organisms to ecosystems, and how these are being affected by global changes such as climate change. Key concepts include levels of ecology, species types, abiotic influences, and implications of human activity on the environment.