Fig. 1.

a In the easternmost Alps, the 3 main cytotypes of Senecio carniolicus (Asteraceae) occur in mixed populations, where they separate into different microhabitats: diploids (b) grow in open, rocky patches (foreground), tetraploids (c) are found on mostly north-exposed slopes with longer snow-cover (left side of the ridge), and hexaploids (d) occur in dense grass swards (right side of the ridge). The 3 cytotypes also differ morphologically with respect to overall size (scale bars in b–d approximately 5 cm), dimensions of the synflorescence and the flowering head, indumentum and leaf shape. e In Melampodium sect. Melampodium (Asteraceae), sequential allopolyploidization involved (maternal parent indicated in blue) diploid M. glabribracteatum and likely M. americanum (f), giving rise to allotetraploid M. strigosum, which in turn together with diploid M. linearilobum (g) resulted in the allohexaploids M. pringlei and M. sericeum (h). Whereas no gross karyotypic change is evident during allopolyploid evolution (karyotypes are given for each species), evolution of rDNA loci is characterized by loci loss and conversion (chromosomes carrying rDNA loci are shown for each species, 5S and 35S rDNA indicated by green and red fluorescence signals, respectively), which differ in the independently originated allohexaploids despite their identical parentage. (Photo credits: a M. Winkler, b– d M. Sonnleitner, f– h T.F. Stuessy and E. Ortiz.)