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the free crossbreeding of individuals within a population or some other intraspecific group.

Complete panmixia exists only when each individual has the possibility to mate with any individual of the opposite sex. However, in nature pairs do not form for crossbreeding by chance. The choice of partners is conditioned chiefly by similarity in behavior and physiology; the partner chosen also inhabits the same part of the area of distribution. In the latter case, divergences from complete panmixia may be the result of crossbreeding between close relatives (inbreeding). Therefore, when one refers to panmixia in natural groups of individuals, and first and foremost in populations, what is usually meant is the extent to which panmixia occurs: it must be more common within a given group than among individuals of neighboring groups.

The extent to which panmixia occurs varies among species and depends on differences in the manner of reproduction. Some species form long-term, sometimes lifelong, pairs; other species form pairs only for the reproductive season. Some species, such as many galliforms, do not form lasting pairs; in other species, for example, many insects and arachnids, the females are fertilized only once in their lives. Species in which fertilization takes place externally, such as fishes and amphibians, do not form pairs. Here, a cluster of eggs from a single female may be fertilized by spermatozoa from different males. To whatever extent it occurs, panmixia safeguards the genetic and evolutionary unity of intraspecific groupings and of the species as a whole. The term “panmixia” was introduced in 1885 by A. Weismann.


Weismann, A. Die Continuität des Keimplasmas als Grundlage einer Theorie der Vererbung, 2nd ed. Jena, 1892.


References in periodicals archive ?
2013: Population genetics of the American eel (Anguilla rostrata): FST = 0 and North Atlantic Oscillation effects on demographic fluctuations of a panmictic species.
The results of mitochondrial DNA and AFLP implied that around distribution area should be considered to be a single panmictic population, which is opposed to the conclusion of sagittal otoliths analysis by Xie and Watanabe (2007).
Keywords: Geometric morphometrics, Procrustes Analysis, MANOVA, panmictic unit, fore-wing and hindwing shape
To address these questions, and determine whether the ETP comprises one large, panmictic population with high demographic connectivity, or whether gene flow is low along this coastline and populations demographically distinct, we use microsatellite and mtDNA markers to characterize genetic structure and estimate migration rates.
Multiple-locus departures from panmictic equilibrium within and between village gene pools of Amerindian tribes at different stages of agglomeration.
If an ecosystem harbors a single panmictic population of the affected species, the entire population may develop resistance.
Results support the idea of a single panmictic population favored by the reproductive isolation produced by geological events during the formation history of the basin, the absence of geographic barriers and the migratory behavior of the species.
Another distinction of this approach is that the crossover operator is modified to allow panmictic reproduction, in which several parents generate a single child (instead of having two parents generate two children as in the traditional genetic algorithm).
The resulting resistance frequency would be only slightly higher than the frequency one year previous if populations on cotton were to make a minor contribution to the panmictic population.
More generally, Ehrlich and Raven (1969) argued strongly that there was so little gene flow between populations that it was not useful to think of species as panmictic.
They explained that the possible reason for the panmictic population along the peninsula is the intensified coastal countercurrent during the spawning season, influencing the larval transport.
If we assume that all 500 animals are part of 1 large panmictic population, and we have 95% confidence that if EBOV were circulating in >0.