Ecology Basics

Study Notes

The environment consists of two parts: biotic and abiotic.
The ultimate goal of Ecosystem Ecologists is to understand how ecosystems function.

A population is a group of organisms of the same species that live together in the same area at the same time.
A species is a group of similar organisms whose members freely interbreed with one another in the wild to produce fertile offspring.
A community is a natural association that consists of all the populations of different species that live and interact together within an area at the same time.
An ecosystem includes all the biotic interactions of a community as well as the interactions between organisms and their abiotic environment.

Energy is the capacity or ability to do work.
Energy exists as potential energy and kinetic energy.
Thermodynamics is the study of energy and its transformations.
The first law of thermodynamics states that energy cannot be created or destroyed, although it can change from one form to another.
The second law of thermodynamics states that when energy is converted from one form to another, some of it is degraded into heat, a less usable form that disperses into the environment.
Photosynthesis is a biological process that captures light energy and transforms it into the chemical energy of organic molecules.

Producers are plants and other photosynthetic organisms that manufacture organic molecules from carbon dioxide and water.
Consumers are organisms that consume other organisms as a source of food energy and bodybuilding materials.
Primary consumers (herbivores) eat producers.
Secondary consumers eat primary consumers.
Tertiary consumers eat secondary consumers.
Other consumers (omnivores) eat a variety of organisms.
Detritus feeders consume detritus, organic matter that includes animal carcasses, leaf litter, and feces.
Decomposers are organisms that break down dead organisms and waste products, such as bacteria and fungi.

Energy flow is the passage of energy in a one-way direction through an ecosystem.
A food chain is a sequence of energy flow from one organism to the next.
A food web is a complex of interconnected food chains in an ecosystem.
The longer the food chain, the less energy is available for organisms at the higher trophic levels.
Most of the energy going from one trophic level to the next in a food chain or food web dissipates into the environment.
Ecological pyramids often graphically represent the relative energy values of each trophic level.