Population ecology

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The population ecology (of Latin populus 'people') is a branch of the ecology and the biology that deals with the interactions of the population of a kind busy with other populations of the same or a different kind. She also examines the interaction of a population with its environment.


The term demecology (from the Greek demos 'people') was used temporarily in the German-speaking area . This designation came from the title of the 2nd volume of the formerly widespread ecology textbook by the forest entomologist Fritz Schwerdtfeger . The motivation for the new name formation was the alignment of the prefix to those of the two sister terms autecology and synecology (see under ecology ), which were also Greek and not Latin. Despite this internal logic, the term has largely disappeared and has never found its way into other languages.

Traditionally, population ecology is divided into static population description and population dynamics . In the case of complex communities, one also speaks of demography insofar as one characterizes the composition and change in population size, age structure or gender ratio. Another important aspect is the interaction of populations in the context of competition and predator-prey relationships . Long-term changes as a result of evolutionary processes traditionally no longer belong in population ecology, but in population biology and evolutionary ecology .


Population ecology deals with the structure, change and interaction of the population of a species with other populations and with the environment . It records the structure and dynamics of populations, their age composition, their growth and their development under the influence of the biotic and abiotic influencing variables of the ecosystem. Taking into account genetic aspects or aspects of island biogeography leads to population biology .

Typical applications are population densities and population numbers for wild animals , parasites , hunted animals or endangered species. For example, for sustainable fisheries it is essential to determine the fishing quotas and fishing techniques in such a way that the population of the species being fished does not collapse, which requires an understanding of population ecological principles.

The size of a population depends on several factors:

If the rate of reproduction is higher than the death rate, the population will grow, if it is smaller, the population will shrink.

Depending on the complexity of the species and its habitat, there are models of different complexity for describing population size and population growth

  • In the simplest case (bacterial colony without restrictions) the population grows exponentially .
  • If one takes into account the limitations of the living space (space, resources), a simple example is the logistical growth of bacteria and many unicellular organisms that multiply through cell division .
  • As soon as sexual reproduction plays a role in reproduction, calculating or estimating the reproductive rate becomes more complex.
  • The effects of a predator-prey relationship on both populations are described by the Volterra rules .

In addition to the immediate population dynamics aspects, indirect aspects also play a role, e.g. B.


  • Michael E. Begon, Martin Mortimer, David J. Thompson: Population Ecology . Spektrum Akademischer Verlag, Heidelberg 1997, ISBN 978-3-86025-258-1
  • Fritz Schwerdtfeger : Ecology of the animals. A teaching and manual in 3 parts . Volume 2: Demecology. Structure and dynamics of animal populations . 2nd Edition. Parey, Hamburg / Berlin 1979, ISBN 3-490-07518-8
  • Bruno Streit : Ecology. A short textbook . G. Thieme, Stuttgart 1980. ISBN 3-13-583501-4