Ecology

Key Terms in Ecology

• Ecology: The scientific study of interactions among organisms and between organisms and their environment.

• Ecosystem: A community of living organisms (biotic factors) interacting with non-living components (abiotic factors) in their environment.

• Environment: The sum of all external conditions affecting the life, development, and survival of an organism.

• Community: All the populations of different species living and interacting in a particular area.

• Organism: An individual living thing, such as a plant, animal, fungus, or microbe.

Biotic and Abiotic Factors

• Biotic factors: Living components of an ecosystem (e.g., plants, animals, bacteria, fungi).

• Abiotic factors: Non-living physical and chemical components (e.g., sunlight, temperature, water, soil, air).

• Example: In a pond ecosystem, fish and algae are biotic factors; water temperature and pH are abiotic factors.

Energy Flow: Food Chains and Food Webs

• Food Chain: A linear sequence showing how energy and nutrients flow from one organism to another.

• Food Web: A complex network of interconnected food chains within an ecosystem.

• Producers: Organisms (mainly plants and algae) that make their own food via photosynthesis.

• Consumers: Organisms that obtain energy by eating other organisms (herbivores, carnivores, omnivores).

• Decomposers: Organisms (bacteria, fungi) that break down dead matter, recycling nutrients.

• Example: Grass (producer) → Grasshopper (primary consumer) → Frog (secondary consumer) → Snake (tertiary consumer).

Photosynthesis and Cellular Respiration

• Photosynthesis: The process by which plants, algae, and some bacteria convert light energy into chemical energy (glucose).

• Equation:

• Cellular Respiration: The process by which living organisms convert glucose and oxygen into energy (ATP), carbon dioxide, and water.

• Equation:

Interactions in Ecosystems

• Biotic and abiotic factors interact to shape the structure and dynamics of ecosystems.

• Changes in abiotic factors (e.g., drought) can affect the survival of organisms.

• Organisms can influence abiotic factors (e.g., plants stabilizing soil).

Trophic Levels and Diet Categories

• Trophic Level: The position an organism occupies in a food chain (e.g., producer, primary consumer, secondary consumer).

• Diet Categories:

  • Herbivore: Eats plants only.

  • Carnivore: Eats animals only.

  • Omnivore: Eats both plants and animals.

  • Decomposer: Breaks down dead organic matter.

• Some organisms can occupy multiple trophic levels (e.g., omnivores).

Constructing and Analysing Food Chains and Webs

• Food chains show direct feeding relationships; food webs show complex interactions.

• Adding or removing organisms can disrupt energy flow and ecosystem balance.

• Example: Removing a top predator can lead to overpopulation of prey species.

Classification

Classification and Taxonomy

• Classification: The process of grouping organisms based on shared characteristics.

• Taxonomy: The science of naming, describing, and classifying organisms.

Levels of Classification

• Domain

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

• Mnemonic: "Dear King Philip Came Over For Good Soup"

Scientific Naming Conventions

• Binomial Nomenclature: Each species is given a two-part Latin name: Genus (capitalized) + species (lowercase), both italicized (e.g., Homo sapiens).

• Scientific names are universal, reducing confusion from common names.

Major Kingdoms and Classes

• Three Kingdoms: Animalia, Plantae, Fungi

• Five Classes of Vertebrates: Fish, Amphibians, Reptiles, Birds, Mammals

• Four Classes of Arthropods: Insects, Arachnids, Crustaceans, Myriapods

Dichotomous Keys

• Dichotomous Key: A tool that allows the identification of organisms through a series of choices between two alternatives.

• Rules for Construction:

  • Use clear, objective, and observable characteristics.

  • Each step offers two contrasting choices.

  • Avoid subjective language.

• Importance: Universal tool for scientists to identify organisms accurately.

Classification Table Example

Human Impacts on Ecosystems

Changes in Ecosystems

• Natural and human-induced changes can alter the types and numbers of organisms in ecosystems.

• Examples: Deforestation, pollution, introduction of new species.

Human Activities Affecting Ecosystems

• Pollution: Contaminants can harm organisms and disrupt ecological balance.

• Overfishing: Reduces populations, affecting food webs.

• Introduced Species: Non-native species (e.g., foxes, rabbits, cane toads in Australia) can outcompete native species and disrupt ecosystems.

Impacts of Introduced Species

• Can lead to extinction of native species, alter habitats, and change food web dynamics.

• Example: Cane toads in Australia have poisoned native predators and competed with native amphibians.

Disruption of Food Webs

• Human activities can remove or add species, altering energy flow and population sizes.

• Consequences include population booms or crashes, loss of biodiversity, and ecosystem instability.

Conservation and Ethical Perspectives

• Ethical considerations influence conservation decisions and land use.

• Communities can reduce negative impacts by protecting habitats, reducing pollution, and managing resources sustainably.

Population Changes and Ecosystem Balance

• Changes in one population can affect others through food web connections.

• Example: Removing a predator may increase herbivore numbers, leading to overgrazing.

Summary Table: Human Impacts

Additional info: Sustainable practices and ecological restoration are important for maintaining ecosystem health and resilience.