Many important factors can affect the populations in an ecosystem
Example: Food
Living organisms need food in order to survive. Water is another factor important that can affect populations in an ecosystem. Without water and food animals will die off.
Example #2: Food Chain
Living organisms have a spot on the food chain, one animal will be a prey/predator to another organism.
Example #3: Temperature
Living organisms need to have a temperature that they are adaptive to. Some animals that are cold-blooded need a precise temperature to survive in.