When a population is
small in a habitat, its population growth is exponential. This means it doubles
its population with every generation. This is because there is plenty of resources
and little competition between individuals of the population. However, as the population
grows bigger, the population reaches carrying
capacity (the maximum number that the ecosystem can hold). The growth slows and
stagnates as stiff competition results to an equal death rate as birth rate.
Natural selection is a process that causes heritable/favorable traits that are helpful for survival and reproduction to become more common as time goes on, and it gets passed from generation to generation.