Answer: By either emigration or natural increase.
Explanation: Natural increase is where in a population, the birth rate, or number of live births per year, is greater than the death rate, or deaths per year. Emigration is when individuals leave their region to move to another, often due to economic or political reasons. Eventually, a population will reach its carrying capacity, where the land the population occupies is only just able to support the population. Once the carrying capacity is breached, the population will start to collapse.