RECOMBINATION IN SIX HOMOPTEROUS FAMILIES

@article{Halkka1964RECOMBINATIONIS,
  title={RECOMBINATION IN SIX HOMOPTEROUS FAMILIES},
  author={O. Halkka},
  journal={Evolution},
  year={1964},
  volume={18}
}
At any point in the evolution of a given species there must be an optimum recombination rate. The obvious necessity for regulation implies the existence of various mechanisms for restricting recombination. These may take many forms, but cytogenetically they can be said to involve a change in either the number, absolute size, or size variation of the effective units of recombination. The number of these units (or "effective factors," Mather, 1949) is given by Darlington's (1937) recombination… Expand
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References

SHOWING 1-10 OF 17 REFERENCES
The Biology of Crossing-over
SEXUAL reproduction consists of two alter-nating processes: fertilization, by which two germ cells containing each a single set of chromosomes fuse and produce a zygote with the double number ofExpand
Chromosomal Variation and Adaptation in Insects
TLDR
According to Thoday's definition, the biological mechanisms which improve the adaptation of the organisms to their present environ­ ments and which increase the probability of perpetuation of their kind by reproduction through environment changes are progressive. Expand
Variation of chiasma frequency in and between natural populations of acrididae
TLDR
Natural populations of grasshoppers have been examined by analysis of metaphase chiasma frequencies in males to see whether variation is to be found in the genetic stability and variability of populations. Expand
PRINCIPLES OF NATURAL COEXISTENCE INDICATED BY LEAFHOPPER POPULATIONS
TLDR
Drawing significant conclusions indicating that certain of the concepts of species ranges and ecological occupancy have been unnatural are found. Expand
FURTHER COMMENTS ON NICHES AND NATURAL COEXISTENCE
TLDR
It is pointed out that the functional concept of the ecologic niche is a most important idea to the understanding of modern community ecology and its use adds several dimensions to the concept of ecologic adaptation. Expand
POLYGENIC INHERITANCE and NATURAL SELECTION
TLDR
It is now known that both of these conditions are fulfilled, and all the available facts of evolution are in accord with the genetical theory of variation and selection. Expand
Variation and Evolution in Plants
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology andExpand
Environmental effects on the distribution of chiasmata among nuclei and bivalents and correlation between bivalents
TLDR
Environmental effects on the distribution of chiasmata among nuclei and bivalents and correlation between bivalented particles and nuclei are studied. Expand
Uber die Arten Rhopalopyx preyssleri
  • 1962
Chromosome studies on the Hemiptera Homoptera Auchenorrhyncha
  • The regulation of recombination in plants . Cold Spring Harbor Symp . Quant . BioI .
  • 1959
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