Ecology

This course is a part of AP®︎ Biology, a 38-course Topic series from Khan Academy.

Why are polar bears found only in the Arctic? Why does mildew grow in your shower and not (hopefully) in your sock drawer? Learn how ecologists study the interactions between organisms and their environment, and how these interactions affect where, and in what numbers, different types of organisms are found.

This course contains 8 segments:

Intro to ecology

Looking for an overview of core concepts in ecology? Just wondering what the heck ecology is? You're in the right place! Learn how organisms interact with each other and with their environment to make amazingly complex and beautiful networks.

Intro to population ecology

What population are you a part of? Humans, and other organisms, can be organized into populations - groups of organisms of the same species that are found in the same place. Learn about the tools ecologists use to study populations and predict how their numbers may change in the future.

Population growth & regulation

Any species could take over the Earth just by reproducing if it had unlimited resources. That includes bacteria, worms and snakes, which might not be things you want covering the Earth's surface in a four-foot layer! Learn how populations grow and why real populations in nature always have limits on their growth.

Intro to community ecology

Populations alone are cool. But what happens when you get populations of a bunch of different species together in the same place? Something way cooler – you get an ecological community! Learn more about how species interact with each in communities.

Community structure & diversity

What makes ecological communities more or less stable to disturbances? What happens when an invasive species is introduced into a new environment? Learn how we can describe the structure of an ecological community and why a more diverse ecological community is usually more stable.

Intro to ecosystems

What is an ecosystem? Well...it can be something as small as a tide pool,or as huge as the Amazon rainforest. But whatever size it may be, an ecosystem is made up of a community (populations of species interacting) plus their physical environment. Learn about different types of ecosystems and how energy flows through ecological communities.

Biogeochemical cycles

"Atoms get recycled." That may not sound too exciting. But think of it this way: some of the atoms in your body right now were once almost certainly part of trees, rocks, various animals, other human beings, and even dinosaurs! Learn more about how matter is recycled in Earth's ecosystems and why the water, carbon, nitrogen, and phosphorous cycles are so important to living things.

Biogeography

Have you ever noticed that different types of animals and plants are found in different places? Learn about some of the factors behind patterns of species distribution and abundance.