Ecology and Biomes Study Guide

Lecture 35: Ecology and Biomes - Detailed Study Guide

1. Definition of Ecology

  • Ecology is the scientific study of interactions among organisms and their environment.

a. Biotic and Abiotic Interactions

  • Biotic interactions: These are interactions among living organisms. Examples include predation, competition, and symbiosis.

  • Abiotic interactions: These involve interactions between organisms and their physical environment, such as temperature, water, sunlight, nutrients, and soil composition.

2. Types of Ecology

  • 1. Population Ecology
      - Focuses on populations, aiming to understand factors affecting population growth, size, and density.   - Involves the study of species interactions, survival, and reproduction.

  • 2. Community Ecology
      - Studies how populations of different species interact and form functional communities.   - Examines differences between species-rich and species-poor areas.   - Investigates ecological succession - the process by which ecosystems change and develop over time.

  • 3. Ecosystem Ecology
      - Focuses on energy and material flow within ecosystems.   - An ecosystem consists of a community of organisms interacting with their physical environment.   - Involves studying food chains and food webs, which illustrate the feeding relationships between organisms.

  • 4. Organismal Ecology
      - Examines how individual organisms adapt to their abiotic and biotic interactions.   - Divided into two subdisciplines:     - Physiological Ecology: Studies physiological adaptations to environmental stress.     - Behavioral Ecology: Explores behavioral adaptations that organisms use to cope with their environment.

  • 5. Biosphere Ecology
      - Represents the sum of all the planet's ecosystems, emphasizing the interactions within global scales.

3. Definition of Biomes

  • Biomes are major types of habitats characterized by distinct plant and animal life.

  • Biomes can be classified into terrestrial and aquatic types.

  • The most significant influence on the distribution of organisms on Earth is climate.

4. Definition of Climate

  • Climate: The average weather conditions for a given area, shaped by both abiotic and biotic factors.

a. Major Factors Affecting Climate

  • Sunlight Intensity: Variations result from the amount of solar radiation received at different latitudes; the spherical shape of the Earth plays a crucial role.

  • Air Circulation and Precipitation Patterns: Explains terrestrial moisture distribution; global air circulation is driven by intense solar radiation, particularly near the equator.

  • Earth’s Rotation: Contributes to convection cells created by cycles of heating, cooling, and air movement; there are six large convection cells between the poles.

  • Ocean Currents: Affect temperature and climate; proximity to the equator results in less variation in climate conditions.

  • Land Formations: Geographic features like mountain ranges can create barriers affecting precipitation. The windward side receives moist air leading to rainfall, while the leeward side is usually dry.

5. Terrestrial Biomes

a. Tropical Forest

  • Physical Environment:   - Characterized by high mean annual temperatures (around 25-95 °C) and high mean annual precipitation.   - Tropical rain forests experience constant rainfall (200-400 cm); tropical deciduous forests have seasonal rainfall (150-200 cm).

  • Location: Found in equatorial and subequatorial regions.

  • Plant and Animal Life: Known as biodiversity hotspots, hosting a vast range of plant and animal species.

b. Savanna

  • Physical Environment:   - High annual temperature with a long dry season (typically 9 months).   - Low annual precipitation.

  • Location: Located in equatorial and subequatorial regions.

  • Plant and Animal Life:   - Vegetation primarily consists of fire-adapted grasses and occasional thorny trees.   - Typical animals include mammals (antelope, zebra, wildebeest, cheetahs, lions, and hyenas) and various insects.

c. Desert

  • Physical Environment:   - Mean annual temperatures vary drastically between day and night and across seasons.   - Very low precipitation.

  • Location: Found approximately 30° north and south of the equator and within the interiors of continents.

  • Plant and Animal Life:   - Dominated by drought-tolerant plants; many animals are nocturnal to escape daytime heat.

d. Temperate Deciduous Forest

  • Physical Environment:   - Characterized by seasonal temperature changes; winters are freezing, while summers are hot and humid.   - Annual precipitation is distributed evenly over the year.

  • Location: Mid-latitudes of the Northern Hemisphere, with smaller areas in Chile, South Africa, Australia, and New Zealand.

  • Plant and Animal Life:   - Dominated by deciduous trees (trees that shed leaves in winter).   - Home to a variety of birds and mammals.

e. Tundra

  • Physical Environment:   - Cold winters and relatively cool summers.   - Arctic tundra receives 20-60 cm of annual precipitation; alpine tundra experiences higher precipitation levels (up to 100 cm).

  • Location: Found in expansive areas of the Arctic and high mountains across all latitudes.

  • Plant and Animal Life:   - Vegetation includes mosses, grasses, forbs, dwarf shrubs, and lichen.   - Animals include caribou, reindeer, wolves, bears, and foxes; many migratory birds nest in summer.

6. Aquatic Biomes

  • Distinguishing Features: Aquatic biomes differ based on salinity, oxygen content, depth, current strength, and light availability.

  • Two Main Types of Aquatic Biomes:   - Freshwater Biomes
      - Saltwater Biomes

7. Freshwater Aquatic Biomes

  • Lentic habitats: Areas of standing water (e.g., lakes).

  • Lotic habitats: Areas of running water (e.g., rivers).

a. Freshwater Biomes Description

  • Wetlands: Areas that are seasonally or permanently saturated with water. They support flora adapted to saturated soils and host diverse invertebrates, birds, frogs, and alligators.

  • Estuaries: Wetlands where freshwater merges with saltwater; highly biologically rich areas on Earth with salinity varying with tides. Host marine invertebrates and fish.

  • Oligotrophic Lakes: Nutrient-poor lakes that generally possess high oxygen levels.

  • Eutrophic Lakes: Nutrient-rich lakes that support various organisms, with fish inhabiting oxygen-sufficient zones. Differentiates between littoral (near shore) and limnetic zones (open water).

  • Rivers and Streams:   - Headwater streams: Cold, clear, turbulent, and oxygen-rich; often narrow and rocky.   - Downstream waters: Warmer, more turbid, typically wider and meandering; the sediment often becomes silty.   - Salinity and nutrient levels increase from headwaters to mouths, while oxygen content generally decreases.

8. Saltwater Aquatic Biomes

a. Description of Saltwater Biomes

  • Intertidal Zone: Alternates between being submerged and exposed with tides. Exhibits significant temperature and salinity variation, and forces of waves. Generally rich in oxygen and nutrients; substrates may be rocky or sandy.

  • Coral Reefs: Comprised of calcium carbonate skeletons of marine polyps living symbiotically with algae. Corals require high oxygen levels and a solid substrate for attachment; exist as shallow reefs in warm, photic zones or deep-sea coral at depths of 200-1500 cm. High biodiversity characterizes both habitats with many fish and invertebrate species.

  • Oceanic Pelagic Zone: Encompasses 70% of Earth’s surface, constantly mixed by wind-driven currents. Rich in oxygen; phytoplankton is the dominant photosynthetic organism. Home to free-swimming animals such as squids, fish, sea turtles, and marine mammals.

  • Marine Benthic Zone: Refers to the seafloor. Animals inhabiting this zone are adapted to cold temperatures and high pressure. In dark and hot environments, especially near hydrothermal vents, producers are chemoautotrophic prokaryotes. Diverse communities include giant tube worms, arthropods, and echinoderms, thriving on organic matter and chemosynthesis.