Studies of species relationships in several dwarf bearded irises

Species relationships were studied in several eupogoniris species. Iris pumila L. (2n = 32) is a presumed amphidiploid believed to have originated from a cross between Iris attica Boiss and Heldr. (2n = 16) and Iris pseudopumila Tineo (2n = 16). Originally thought an autotetraploid I. attica (Simonet, 1934), later investigations (Mitra, 1955; 1956) provided convincing cytological evidence of an amphidiploid origin. Reinvestigation of this speciation hypothesis was conducted with parental species collected from type locations and I. pumila clones obtained from private collections. The present study included karyotype and RFLP rRNA gene analyses as well as studies of pollen with SEM and stomata with SEM and light microscopy.; Karyotype studies establishing somatic numbers for each species also included an in depth study of chromosome morphology. C-banding and Ag-NOR staining were also attempted with questionable application. Evidence of autopolyploidy, amphidiploidy and dysploidy were observed. Structural alterations indicative of chromosomal repatterning, satellite heteromorphism and polymorphism were observed.; Ribosomal RNA gene variation assessed through RFLP analysis was conducted. Hybridization studies of EcoRI digested genomic DNA, with different probes, supported that I. attica and I. pseudopumila are two distinct species, evidenced by unique restriction patterns. I. pumila clone restriction patterns more closely resembled I. attica, having additional non-coding spacer regions.; Monocolpate pollen morphology was revealed through ultrastructural (SEM) studies; size, shape and exine pattern texture varies little among species. Epidermal peels were examined; relatively uniform sizes and appearance of stomata was recorded, increased stomatal size concomitant with increased ploidy was seen in Iris lutescens (2n = 38).; Thus, re-examination of polyploidy including amphidiploidy in Iris pumila has shown a dynamic, continuous process of change occurred at the chromosomal and molecular level through hybridization resulting in the formation of polymorphic clones in the process of speciation. Similar approaches can be utilized in the examination of mechanisms of speciation as well as serve as a model for studying the origins of other suspected allopolyploids, especially amphidiploids as well as the underlying changes that accompany it. This combined approach can serve as a model for studying the origin of other alleged amphidiploids.