Organismal Ecology Study Guide

Introduction to Organismal Ecology

Definition of Ecology

Ecology is defined as the study of how organisms interact with their environment. This encompasses the relationships between living organisms and both their abiotic (non-living) and biotic (living) surroundings.

Abiotic Environment

  • Abiotic Factors: Non-living physical and chemical factors that impact ecosystems. Examples include:

    • Temperature

    • Light

    • Water

    • Nutrients

    • Humidity

    • pH

    • Minerals

    • Salinity

    • Sedimentation

Biotic Environment

  • Biotic Factors: These are other organisms, whether living or dead, that influence ecological interactions. Examples include:

    • Individuals of the same species

    • Individuals of different species

    • Predators

    • Competitors

    • Mutualists

    • Animals

    • Plants

    • Fungi

    • Microorganisms

Influence of Environmental Factors

Both biotic and abiotic characteristics of the environment influence:

  1. Distribution: Where organisms are found in particular habitats.

  2. Abundance/Density: The number of organisms present in a specific location.

Levels of Ecological Study

Ecology can be studied at different levels, each focusing on specific interactions and adaptations.

Organismal Ecology

  • Focus: Interactions of individual organisms with their environment.

  • Key Questions:

    • What kinds of adaptations have organisms evolved to cope with their environments?

    • How will organisms respond to climate change?

Population Ecology

  • Focus: A group of individuals of the same species living in a specific area.

  • Key Questions:

    • What factors affect population growth?

    • How can we tell if a species is at risk of extinction?

Community Ecology

  • Focus: Interactions among different species in a specific area.

  • Key Questions:

    • How do interactions with competitors, predators, and parasites affect the abundance of a particular species?

    • What factors determine the number of species that can coexist in a particular location?

Ecosystem Ecology

  • Focus: Interactions between communities and their environments.

  • Key Questions:

    • How does the biotic community affect the flow of energy and nutrients through ecosystems?

    • How do ecosystems respond to change?

Biosphere Ecology

  • Focus: The influence of energy on organisms across the planet.

  • Key Questions:

    • How does carbon capture by the Amazon rainforest affect global CO2 levels?

    • How will climate change affect ocean temperature and coral reef health?

Importance of Studying Ecology

Resource Management

Understanding ecology is critical for effective resource management in various fields:

  • Fishing/Hunting: Sustainable practices to ensure long-term viability of species.

  • Agriculture: Managing crop systems that minimize environmental impact while maximizing yield.

  • Wildlife Preservation: Protecting endangered species and their habitats.

  • Ecosystem Services: Recognizing the benefits provided by ecosystems, such as pollination and water purification.

Human Health

Key Ecological Considerations:

  • Epidemiology: Principles related to the spread of diseases.

  • Spillover of Diseases: Understanding how diseases can transfer from wildlife to humans.

  • Human Gut Ecosystems: Insights into how ecological interactions can affect human health.

Basic Science Understanding

  • Understanding the environmental factors that sustain life on Earth.

  • Comprehending the drivers of evolution, particularly in relation to ecological pressures.

Ecological Challenges

Human Impact on the Environment

There is unprecedented manipulation of the natural environment by humans, raising concerns about the long-term consequences. Challenges include:

  • Habitat Loss: Conversion of habitats to agriculture and urban areas.

  • Habitat Alteration: Includes activities such as the damming of rivers, pollution, and the introduction of exotic species.

  • Global Climate Change: Changes in the Earth's climate that affect all life forms.

Organism Adaptations

At the level of the organism, the types of adaptations include:

  • Physiological Traits: Functions of organisms, such as thermoregulation or water retention.

  • Morphological Traits: Physical characteristics, such as body shape or size suitable for a particular environment.

  • Behavioral Traits: Actions that organisms take to survive in their environment, such as migration or hibernation.

Influence of Global Processes

Latitude Effects on Climate

Latitude plays a crucial role in determining:

  • Angle of Incoming Sunlight: Affects local temperatures and precipitation patterns.

    • Equator: Receives direct sunlight, leading to higher temperatures.

    • Higher Latitudes (e.g., polar regions): Receive sunlight at a low angle, resulting in colder temperatures and reduced precipitation.

Circulation Cells

  • Atmospheric circulation cells influence patterns of wet and dry regions based on latitude

  • Hadley Cell: Warm air rises, cools, and leads to precipitation at the equator

  • Dry Descent: Cooled air descends at lower latitudes creating dry conditions

Seasons Due to Earth's Tilt

  • Earth's tilt of approximately 23.5° causes seasonal variation.

  • Seasons: Different points in Earth's trajectory lead to varying sunlight exposure and climate conditions.

  • Without the axial tilt, seasonal variations would not exist.

Local Geography and Climate

Local geography significantly impacts climate, especially in relation to:

  • Rain Shadows: Mountains can block moist air leading to arid conditions on one side.

  • Example: In Washington state, moisture-laden air from the Pacific Ocean leads to precipitation on the west side of the Cascade Mountains, creating diverse ecosystems, while the eastern side experiences desert conditions.

Biomes Defined by Abiotic Factors

Biome Definition

A biome is described as a distinctive assemblage of plants and animals that live together in a specific climate characterized by particular abiotic factors (temperature and precipitation).

Types of Biomes

  • Terrestrial Biomes: Largely determined by temperature and precipitation.

  • Aquatic Biomes: Characterized by salinity, nutrients, flow, and light availability.

Major Terrestrial Biomes

  1. Tropical Forest: Characterized by high biodiversity, high temperatures, and heavy rainfall.

  2. Savanna: Grasslands with scattered trees, experiences seasonal rainfall.

  3. Desert: Low precipitation, extreme temperature variations, unique adaptations for water conservation.

  4. Chaparral: Mild, wet winters and hot, dry summers with vegetation that is drought-resistant.

  5. Temperate Grassland: Features grasses, grazers, and periodic fires; supports a variety of herbivorous animals.

  6. Northern Coniferous Forest (Taiga): Dominated by conifers, experiences long, cold winters with moderate precipitation.

  7. Tundra: Characterized by permafrost, low temperatures, and low biodiversity.

Aquatic Biomes Overview

  • Various aquatic biomes are defined based on salinity:

    • Freshwater: Includes units like rivers, lakes, and ponds; characterized by low salinity.

    • Marine: Includes oceans, estuaries, and coral reefs; salinity impacts adaptations of resident organisms.