Population biology essay example

According to Wilson and Bossert, population biology is the study of how populations of organisms change through time, essentially dealing with births, deaths, emigration, and immigration and the factors that affect these four variables (Wendell, 2012). The characteristic change in population of organisms can significantly be attributed to the competition between species that fight for scarce resources. This competition shapes the biological population and causes extinction of some species. The objective of this paper is to understand how competition between different species is important in the shaping of biological populations, including the possibility of such competition leading to extinction. Broadly, the paper deals with the competition process between different species, the survival of fittest and the extinction of the weak ones.

Competition between species becomes inevitable when resources are common and scarce. In real life resources are always limited and have a tendency to become scarce when population rises. The common examples of a limited resource that support the growth of most of the species are carrying capacity of the earth, water, sunlight and food. Population growth is rapid when these resources are in abundance and other growth conditions are favourable. In fact, favourable growth conditions cause immigration of species from less favourable environment leading to increase in population. Similarly, discouraging external environment causes emigration of species. When the population is sparse, fewer resources are used up. But as the population increases, the common resources begin to deplete or get used up at a faster pace. This phenomenon puts a pressure on the available resources and the fight for survival begins. But, the supplying capacity of the resource is limited, different species initiate their struggle for survival.

In the competition between different species, the growth rate of both the species is affected. But, the impact on both the species is not the same. One of the species is usually dominant or stronger than the other species. Thus, the stronger species will reduce the growth rate and size of population of the weaker species significantly. The population size of stronger species may also slightly get impacted in the process. Overall, competition reduces the growth rate of a population and increases the death rate, reducing or controlling the size of a given population.

When stronger species compete with very weak species, there are chances that the latter gets gradually extinct. Also, the species that are less capable of adapting themselves to changing environment have a probability to get extinct. This is a process of natural selection and the species that is the fittest will remain. Species still manage to co-exist because they are able to create a micro-environment for themselves that is less interfered by other species.

Overall, competition is a key element that shapes the biological population of an area. By its virtue of reducing the growth and reproduction of a population, it adversely affects a population of a species. Its dynamic impact is also felt in terms of birth, death, immigration and emigration. While favourable environment supports birth and immigration, it also increases competition. Competition increases death and emigration. Thus, competition is a natural control mechanism that keeps the population pressure within limits. It also influences extinction of weaker species from time to time. In spite of these influences, species do co-exist in reality given their ability to create a micro-environment for themselves where they can avoid competition from other species in a given geographical area.


Wendell, Roger J. (2012). Defending 3. 8 Billion Years of Organic Evolution. Retrieved from http://www. rogerwendell. com/biology. html