Answer:
Key points
- Ecology is the study of how organisms interact with one another and with their physical environment.
- The distribution and abundance of organisms on Earth is shaped by bothbiotic, living-organism-related, and abiotic, nonliving or physical, factors.
- Ecology is studied at many levels, including organism, population, community, ecosystem, and biosphere.
Biotic and abiotic factors
One core goal of ecology is to understand the distribution and abundance of living things in the physical environment. For instance, your backyard or neighborhood park probably has a very different set of plants, animals, and fungi than the backyard of a fellow Khan Academy learner on the opposite side of the globe. These patterns in nature are driven by interactions among organisms as well as between organisms and their physical environment.
As an example, let's go back to our shower mold. Mold is more likely to appear in your shower than, say, your sock drawer. Why might this be the case?
Maybe the mold needs a certain amount of water to grow, and this amount of water is found only in the shower. Water availability is an example of an abiotic, or nonliving, factor that can affect distribution of organisms.
Maybe mold feeds off of dead skin cells found in the shower, but not in the dresser. Availability of nutrients provided by other organisms is an example of a biotic, living-organism-related, factor that can influence distribution.
Ecology at many scales
Within the discipline of ecology, researchers work at five broad levels, sometimes discretely and sometimes with overlap: organism, population, community, ecosystem, and biosphere.
Let's take a look at each level.
Organism: Organismal ecologists study adaptations, beneficial features arising by natural selection, that allow organisms to live in specific habitats. These adaptations can be morphological, physiological, or behavioral.
Population: A population is a group of organisms of the same species that live in the same area at the same time. Population ecologists study the size, density, and structure of populations and how they change over time.
Community: A biological communityconsists of all the populations of different species that live in a given area. Community ecologists focus on interactions between populations and how these interactions shape the community.
