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Four representatives of the closely related and controversial genera Alstroemeria and Bomarea are studied: Alstroemeria psittacina, A. isabellana, Bomarea boliviensis and B. edulis. The cytological studies include karyotypes and meiotic observations, mostly made on populations growing in their natural habitats. A. isabellana (n = 8) and B. boliviensis (n = 9) had not been studied previously. Total chromosome length (TCL) calculated for A. psittacina is 183.14 ± 1.76 μm, for A. isabellana, 174.01 ± 6.43 μm, for B. edulis is 160.59 ± 1.82 μm and 165.01 ± 7.21 μm for B. boliviensis. Although the Bomarea species have an additional chromosome pair (2n = 18), the Alstroemeria species (2n = 16) possess longer TCL. The karyotypes of Alstroemeria species are asymmetric with large chromosomes. On the other hand, the species of Bomarea have more symmetrical karyotypes, which is clearly shown by their lower A2 indexes and the higher values of the quotient shortest pair/longest pair. The karyological results show considerable differences in chromosome number and karyotype symmetry between Alstroemeria and Bomarea and support the criterium of considering them as separate genera. It is hypothesized that the tendency would have been towards a diminution of the basic number (x = 9 8), a greater degree of karyotype asymmetry and an increase of TCL and DNA content. |
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