Population ecology is a major sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment.[1]

The first journal publication of the Society of Population Ecology, titled Population Ecology (originally called Researches on Population Ecology), was released in 1952.[1] Population ecology is concerned with the study of groups of organisms that live together in time and space. One of the first laws of population ecology is the Thomas Malthus' exponential law of population growth.[2] This law states that:

"...a population will grow (or decline) exponentially as long as the environment experienced by all individuals in the population remains constant."[2]:18

At its most elementary level, interspecific competition involves two species utilizing a similar resource. It rapidly gets more complicated, but stripping the phenomenon of all its complications, this is the basic principal: two consumers consuming the same resource.[3]:222

This premise in population ecology provides the basis for formulating predictive theories and tests that follow. Simplified population models usually start with four key variables including death, birth, immigration, and emigration. Mathematical models used to calculate changes in population demographics and evolution hold the assumption (or null hypothesis) of no external influence. Models can be more mathematically complex where "...several competing hypotheses are simultaneously confronted with the data."[4] For example, in a closed system where immigration and emigration does not take place, the per capita rates of change in a population can be described as:

dN / dT = B − D = bN − dN = (b − d)N = rN,

where N is the total number of individuals in the population, B is the number of births, D is the number of deaths, b and d are the per capita rates of birth and death respectively, and r is the per capita rate of population change. This formula can be read as the rate of change in the population (dN/dT) is equal to births minus deaths (B - D).[2][3]

Using these techniques, Malthus' population principal of growth was later transformed into a mathematical model known as the logistic equation:

dN / dT = aN(1 − N / K),

where N is the biomass density, a is the maximum per-capita rate of change, and K is the carrying capacity of the population. The formula can be read as follows, the rate of change in the population (dN/dT) is equal to growth (aN) that is limited by carrying capacity (1-N/K). From these basic mathematical principals the discipline of population ecology expands into a field of investigation that queries the demographics of real populations and tests these results against the statistical models. The field of population ecology often uses data on life history and matrix algebra to develop projection matrices on fecundity and survivorship. This information is used for managing wildlife stocks and setting harvest quotas [3][5]

The first journal publication of the Society of Population Ecology, titled Population Ecology (originally called Researches on Population Ecology), was released in 1952.[1] Population ecology is concerned with the study of groups of organisms that live together in time and space. One of the first laws of population ecology is the Thomas Malthus' exponential law of population growth.[2] This law states that:

"...a population will grow (or decline) exponentially as long as the environment experienced by all individuals in the population remains constant."[2]:18

At its most elementary level, interspecific competition involves two species utilizing a similar resource. It rapidly gets more complicated, but stripping the phenomenon of all its complications, this is the basic principal: two consumers consuming the same resource.[3]:222

This premise in population ecology provides the basis for formulating predictive theories and tests that follow. Simplified population models usually start with four key variables including death, birth, immigration, and emigration. Mathematical models used to calculate changes in population demographics and evolution hold the assumption (or null hypothesis) of no external influence. Models can be more mathematically complex where "...several competing hypotheses are simultaneously confronted with the data."[4] For example, in a closed system where immigration and emigration does not take place, the per capita rates of change in a population can be described as:

dN / dT = B − D = bN − dN = (b − d)N = rN,

where N is the total number of individuals in the population, B is the number of births, D is the number of deaths, b and d are the per capita rates of birth and death respectively, and r is the per capita rate of population change. This formula can be read as the rate of change in the population (dN/dT) is equal to births minus deaths (B - D).[2][3]

Using these techniques, Malthus' population principal of growth was later transformed into a mathematical model known as the logistic equation:

dN / dT = aN(1 − N / K),

where N is the biomass density, a is the maximum per-capita rate of change, and K is the carrying capacity of the population. The formula can be read as follows, the rate of change in the population (dN/dT) is equal to growth (aN) that is limited by carrying capacity (1-N/K). From these basic mathematical principals the discipline of population ecology expands into a field of investigation that queries the demographics of real populations and tests these results against the statistical models. The field of population ecology often uses data on life history and matrix algebra to develop projection matrices on fecundity and survivorship. This information is used for managing wildlife stocks and setting harvest quotas [3][5]