Figure 8

Fluorescent in situ hybridisation of metaphase chromosomes and interphase nuclei of species that evolved unlinked arrangement of rRNA genes. The individual slides show merged 26S and 5S signals: (A) Dahlia pinnatta (2n = 64), (B) Helianthus annuus (2n = 34); (C) Chrysanthemum zawadskii (2n = 54), (D) Aster alpinus (2n = 18); (E) Calendula officinalis (2n = 28); (F) Tragopogon mirus (2n = 24). Note that the 26S loci are mostly terminal whereas the 5S sites are mostly interstitial. Arrowheads in (A) indicate juxtaposition of 35S and 5S arrays without physical linkage of units.