Ecology Lecture Notes

Introduction

• Topic: Ecology
• Goals: Understanding the main content of ecology, relating it to exam questions for better preparation.

Definition of Ecology

• Ecology: Study of interactions between living things and their environment.
• Environment: All external factors affecting organisms.
• Habitat: Place where an organism lives (e.g., deserts, grasslands, woodlands).
• Ecosystem: Interrelationships between living organisms and their environment.

Types of Ecosystems

• Deserts: Low rainfall (e.g., Sahara Desert, Gobi Desert).
• Grasslands: Mild temperatures, low rainfall (e.g., Steppes of Asia).
• Freshwater Ecosystems: Non-salty water (e.g., rivers, lakes, wetlands).

Environmental Factors Affecting Ecosystems

• Abiotic Factors: Non-living factors (e.g., weather, soil).
• Biotic Factors: Living factors (e.g., competition, predation).
• Climatic Factors: Weather-related conditions.
• Adaptive Factors: Soil characteristics.

Examples of Factors

• Abiotic Factors: Temperature, light, soil pH, soil moisture.
• **Biotic Factors: Competition: Animals compete for food & mates, plants compete for light & space. Predation: Predators control prey population.
• Climatic Factors: Temperature, rainfall, wind, humidity.
• Adaptic Factors: Soil type, pH, moisture content.**

Energy Flow in Ecosystems

• Producers: Organisms that make their own food (e.g., plants).
• Consumers: Organisms that consume other organisms.
  • Primary Consumer: Consumes producers (e.g., herbivores).
  • Secondary Consumer: Consumes primary consumers.
  • Tertiary Consumer: Top consumer in most cases.

Food Chains

• Food Chain: Linear sequence of organisms where nutrients and energy pass.
• Arrows: Point towards the organism that's doing the consuming.
• **Example: **Leaf -> Caterpillar -> Chameleon -> Snake -> Mongoose.

Food Webs

• Food Web: Network of interconnected food chains.
• Example: Plant -> Insect -> Bird -> Hawk, Plant -> Cow -> Human.
• Importance: Shows interdependence among organisms.

Trophic Levels

• First Trophic Level: Producers (plants).
• Second Trophic Level: Primary consumers.
• Third Trophic Level: Secondary consumers.
• Fourth Trophic Level: Tertiary consumers.
• Energy Flow: Significant energy loss (90%) at each level.

Pyramids of Numbers and Energy

• Pyramid of Numbers: Represents the number of organisms at each trophic level.
• Standard Pyramid: Large number of producers, fewer consumers.
• Inverted Pyramid: Fewer producers with large biomass or presence of parasites.
• Pyramid of Energy: Always pyramid shaped due to energy loss.

Habitat Study

• **Equipment Used: **Quadrat, Sweep net, Pitfall trap, Pooter.
  • Quadrat: For counting plants, placed randomly.
  • Sweep Net: For collecting insects from long grass.
  • Pitfall Trap: For capturing ground-dwelling insects.
  • Pooter: For collecting small insects.

Identifying Organisms

• Key: Used to identify collected plants and animals.

Quantitative vs. Qualitative Studies

• Qualitative Study: Data collected using words (presence/absence).
• Quantitative Study: Data collected using numbers (counts, percentages).
  • Percentage Frequency: (Number of Quadrats present / Total Quadrats) * 100.
  • Percentage Cover: (Presence in Small Squares / Total Small Squares) * 100.

Errors in Habitat Studies

• Human Error: Misrecording data, interpreting keys incorrectly.
• Changing Conditions: Weather affecting presence.
• Accidental Discovery: Uncommon presence of rare organism.
• Sample Size: Larger sample sizes give more accurate results.

Adaptations, Competition, and Interdependence

Adaptations

• Physical Adaptations: Body structure (e.g., thick fur, layer of fat).
• Behavioral Adaptations: Actions taken (e.g., migration, hibernation).

Interdependence

• Definition: Two organisms depend on each other for survival.
• Example: Bees and plants (pollen for honey and pollination).

Competition

• Definition: Struggle between organisms for resources.
• Types: Contest and Scramble competition.

Population Control

• Factors Affecting Population:
  • Competition: Active physical struggle or scramble for resources.
  • Predation: Predator and prey dynamics.
  • Parasitism: One organism benefits at the expense of another.
  • Symbiosis: Mutual benefit between two organisms.

Exam Preparation and Resources

• Importance: Relating content to exam questions helps in preparation.
• Tools: Video tutorials, quizzes, resource packs, exam builds.
• Subscription: Monthly plans, discounts for multiple subjects.