At the molecular level, the study of ecology focuses on the production of proteins, how those proteins affect the organism and the environment, and how the environment in turn affects the production of various proteins. In all known organisms, DNA gives rise to various proteins, which interact with each other and the environment to replicate the DNA. These interactions lead to some very complex organisms. Molecular ecologist study how these proteins are created, how they affect the organism and environment, and how the environment in turn affects them.
The study of organismal ecology deals with individual organisms and their interactions with other organisms and the environment. While organismal biology is a division of ecology, it is still a huge field. Each organism experiences a huge variety of interactions in its lifetime, and to study all of them is impossible. Many scientist studying organismal ecology focus on one aspect of the organism, such as its behavior or how it processes the nutrients of the environment.
Populations are groups of organisms of the same species. Due to the wide variety of life on Earth, different species have developed many different strategies for dealing with their conspecifics, or organisms of the same species. Some species directly compete with conspecifics, while other organisms form close social bonds and work cooperatively to secure resources.
Different populations that live in the same environment create communities of organisms. These communities create niches
, or various spaces, for organisms to occupy.
The largest scale of organismal organization is the ecosystem. An ecosystem is network of interconnected biological communities. The largest ecosystem, the biosphere, encompasses all ecosystems inside of it. Ecosystem ecologist study the complex patterns produced by interacting ecosystems and the abiotic factors of the environment. They may study water, nutrients, or other chemical that cycle through the ecosystem.