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Robertsonian Fusion and Centric Fission in Karyotype Evolution of Higher Plants
Vol. 64, No. 3 (Jul. - Sep., 1998), pp. 273-289
Stable URL: http://www.jstor.org/stable/4354325
Page Count: 17
You can always find the topics here!Topics: Chromosomes, Evolution, Karyotype, Species, Biological taxonomies, Diploidy, Ploidies, Plants, Genera, Cytology
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Robertsonian fusion and centric fission are uniquely detectable in comparative studies of karyotype patterns. They are the most important types of karyotype change in animals but seem to be relatively uncommon in higher plants. Both modify intra- and interchromosomal recombination and linkage relationships and consequently patterns of genetic variation. When differentiating populations or species they can produce postmating barriers to gene flow. The number of reported cases of fusion or fission in higher plants has increased over the years but remains low, and most of these are casual comparisons of karyotypes without any follow-up investigation. This review focuses on more adequate studies made in a few groups. Studies in the Tradescantieae produce the strongest evidence for fusion as a type of ortho-selection in the subfamily. Some species of Lycoris are also considered to have evolved their karyotypes in that way. Some genera of slipper orchids and the cycad genus Zamia have populations where atypical chromosome number increase can be attributed to fission probably as a result of stressful influences. It is suggested that fusion may have been involved in the evolution of many stable karyotypes and that fission is generally a secondary destabilizing mechanism which may lead to refusion in the long term. Their proven incidence remains making it unwise to suggest that they have been major influences in karyotype evolution in higher plants.
Botanical Review © 1998 New York Botanical Garden Press