Presentation 1: Species, Communities and Ecosystems

Science MYP5

Ecology

The study of the relationships between living organisms themselves, and between living organisms and their environment.

Species

A group of organisms that can potentially interbreed to produce fertile and viable offspring. Members of different species cannot produce fertile offspring together. For example, when horses and zebras interbreed, they produce a sterile hybrid called a zebroid.

Population

A group of organisms belonging to the same species that live in the same area at the same time. Members of different populations are considered reproductively isolated but are still the same species if they could functionally interbreed.

Community

A group of different populations living together and interacting with each other in a specific area.

Habitat

The environment where a species normally lives.

Ecosystem

 A community combined with its interactions with the abiotic (non-living) environment. The continued survival of all living things depends on sustainable ecosystems.

Autotroph

An organism that makes its own organic molecules using simple inorganic substances from the abiotic environment (like air, water, and soil). This is one of the two main methods of nutrition.

Heterotroph

An organism that gets its organic molecules by feeding on other organisms. They are also known as consumers. Heterotrophs can be classified based on their feeding patterns.

Consumer

A type of heterotroph that feeds on living or recently killed organisms through ingestion.

Detritivore

A type of heterotroph that gets organic nutrients from detritus (dead organic matter like feces and decaying material) through internal digestion.

Examples: earthworms, millipedes, woodlice

Saprotroph

A type of heterotroph that gets organic nutrients from dead organic matter by using external digestion. They secrete digestive enzymes onto the non-living material and then absorb the resulting products. They are often called decomposers because they break down dead material.
Examples: fungi like mushrooms, yeasts, and molds.

Nutrient Cycling

The process that maintains the supply of inorganic nutrients in an ecosystem. Autotrophs take inorganic nutrients from the environment, heterotrophs consume them, and saprotrophs decompose dead organisms to return the inorganic nutrients to the soil.

Sustainability (in an ecosystem)

The potential for an ecosystem to be maintained over a long period. This requires three main things: a continuous energy source (usually sunlight), the availability of nutrients (recycled by decomposers), and the recycling of wastes.