Natural selection is the process in nature by which organisms better adapted to their environment tend to survive and reproduce more than those less adapted to their environment. For example, treefrogs are sometimes eaten by snakes and birds.
The dependant variable would be the salmon, because they depend on the water and pollution levels to give a result.
Carrying compacity affects communities because there is usually limited resources. If a population gets too high, they may die out.
The answer to the question above is a cell.
The burning of fossil fuels releases carbon dioxide and other greenhouse gases these carbon emissions raise global temperatures by trapping solar energy in the atmosphere.
