Communities: Interdependence, Competition and Abiotic Factors
An organism in a community depends on others for food, shelter and reproduction, and competes with them for whatever is scarce. Alongside that sit the non-living conditions of the place, and separating the two kinds of factor is what makes an ecological explanation testable.
What a learner can do afterwards
- Sort the influences on a named population into abiotic and biotic factors
- Explain what two species are competing for and predict what happens when one is removed
- Describe an adaptation of an organism and link it to a specific factor in its habitat
1 · Read
You saw how a rainforest web holds together when many living things share food and shelter. A biotic factor is a living part of that place, like a plant, an animal, a fungus, or gut bacteria that help digest food. An abiotic factor is a non-living part, like sunlight, temperature, water, soil, or wind. Rain decides which plants can grow, and the plants decide which animals find food and shelter.
A community is all the populations of all the species living together in one area. Species interact in set ways: in competition both lose, in predation one gains and one loses, in mutualism both gain, in commensalism one gains and the other is unaffected, and in parasitism one gains and the other is harmed.
In competition, two species use the same limited resource, like grazing bison sharing prairie grass, and each would do better if the other were gone. If you remove one competitor, the other usually grows. Over time, competing species may split resources so their needs overlap less.
A cactus survives the desert because it handles strong sun, high heat, and very little rain. The Karner blue butterfly depends on wild lupine, since females lay eggs only on that plant and caterpillars feed solely on it. Each adaptation links to one factor in its habitat.
Name what is living and what is not, then link each organism to its factors.
2 · Watch
Take it off screen
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.