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The study of spatial and temporal patterns in the abundance and distribution of organisms and of the mechanisms that produce those patterns. Species differ dramatically in their average abundance and geographical distributions, and they display a remarkable range of dynamical patterns of abundance over time, including relative constancy, cycles, irregular fluctuations, violent outbreaks, and extinctions. The aims of population ecology are threefold: (1) to elucidate general principles explaining these dynamic patterns; (2) to integrate these principles with mechanistic models and evolutionary interpretations of individual life-history tactics, physiology, and behavior as well as with theories of community and ecosystem dynamics; and (3) to apply these principles to the management and conservation of natural populations.
In addition to its intrinsic conceptual appeal, population ecology has great practical utility. Control programs for agricultural pests or human diseases ideally attempt to reduce the intrinsic rate of increase of those organisms to very low values. Analyses of the population dynamics of infectious diseases have successfully guided the development of vaccination programs. In the exploitation of renewable resources, such as in forestry or fisheries biology, population models are required in order to devise sensible harvesting strategies that maximize the sustainable yield extracted from exploited populations. Conservation biology is increasingly concerned with the consequences of habitat fragmentation for species preservation. Population models can help characterize minimum viable population sizes below which a species is vulnerable to rapid extinction, and can help guide the development of interventionist policies to save endangered species. Finally, population ecology must be an integral part of any attempt to bring the world's burgeoning human population into harmonious balance with the environment. See Ecology, Theoretical ecology
a branch of ecology that studies a population as the elementary form of existence of a species. The main objective of population ecology is to investigate the structure and dynamics and the sex and age distribution of animal populations, which determine fecundity and fertility. Varying with the conditions of existence, fecundity and fertility have an adaptive function, because they ensure a balance between the birth and death rates. Fluctuations in the rate of reproduction determine the density of a population, as well as the animal population dynamics and waves of life.
Population ecology also studies the ethological structure of a population. This structure reflects the nature of a population’s organization and is expressed by various associations of individuals, such as families, flocks, herds, and colonies among animals, colonies among microorganisms and lower plants, and groups of trees or shrubs and clumps of grasses among higher plants. These associations ensure propagation, systematic use of the territory and its resources, and mutual help and protection against enemies and unfavorable conditions. The development of the ethological structure of a population is based on animal communication, which is established between animals by chemical, acoustical, optical, mechanical, electromagnetic, and other signals carrying specific information. These signals are picked up by receptors and influence the metabolism and behavior of the organisms. Genetic polymorphism is an important adaptive trait of a population that serves to broaden the range of fluctuations in environmental conditions that a population can tolerate.
REFERENCESNaumov, N. P. Ekologiia zhivotnykh, 2nd ed. Moscow, 1963.
Shmal’gauzen, I. I. Faktory evoliutsii, 2nd ed. Moscow, 1968.
Shvarts, S. S. Evoliutsionnaia ekologiia zhivotnykh. Sverdlovsk .
Timofeev-Resovskii, N. V., A. V. Iablokov, and N. V. Glotov. Ocherk ucheniia o populiatsii. Moscow, 1973.
Naumov, N. P. “Signal’nye (biologicheskie) polia i ikh znachenie dlia zhivotnykh.” Zhurnal obshchei biologii, 1973, vol. 34, no. 6.
N. P. NAUMOV