Living organisms in the course of evolution are undergoing various changes.Due to this, the population of these organisms adapt to changing environmental conditions.It is very important demographic characteristics of the population such as fertility, mortality, age structure of individuals, but none of them individually can not be judged on the dynamics of the general population.
Growth of individuals - an important dynamic process.It occurs when the development of new habitats after successfully undergoing disaster.
Growth may be different.In populations with normal age structure of the pattern of growth is usually rapid, rapid, explosive.But populations with complex age structure grows slowly and smoothly.
With the growth of the number of individuals of the population density increases to the point, do not take effect until the constraints of the environment (eg, resource limitations).As a result, it achieved a balance to be stored for a long time afterwards.Fluctuations in the number of
In that phase, when the population maintains a balance, its population fluctuates around a constant value.Often these variations are caused by seasonal changes in living conditions.Possible to consider such variations like fluctuations.
Fluctuations in the number of certain populations are cyclical.For ligaments "predator-prey" characterized by a cycle of three to four years.During this cycle, in different periods of its population is dominated by predators, their victims.
Another striking example of cyclical fluctuations - periodic outbreaks of insects.For example, locusts, living mainly in the deserts, does not make migrations over the years.However, from time to time in the population of locusts is an explosion in numbers.And then these insects develop long wings, and the locusts begin to fly in the areas of agriculture, devouring everything in its path.Apparently, the reasons for these explosions are caused by unstable environmental factors.