ISSN:
1615-6110
Keywords:
Pelargonium
;
sect.Hoarea
;
Chromosomes
;
B chromosomes
;
Robertsonian translocation
;
centric fusion
;
evolution
;
systematics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Chromosome numbers of 65 species of sect.Hoarea have been determined. These show three basic chromosome numbers, x = 11, 10 and 9. Only a few species are tetraploid. In five species both diploid and tetraploid cytotypes are reported. Several cases of deviations in chromosome numbers and cytological abnormalities were found, most of these being related to the presence of B chromosomes that occur in eight species. Evidence is presented to suggest that the basic chromosome numbers of x = 10 and x = 9 are derived from x = 11 by centric fusion. Although variation in basic chromosome number withinPelargonium has been the subject of detailed study, this is the first time that evidence has been found for a mechanism of change in basic number, that of centric fusion by Robertsonian translocation. For the species of sect.Hoarea with x = 9, where the evidence for Robertsonian translocation is greatest, this process has probably taken place quite recently. In contrast to results from other sections of the genusPelargonium, the three different basic numbers of sect.Hoarea do not contradict its delimitation as a natural taxon.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00985241
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