RAPID RADIATION OF NORTH-AMERICAN DESERT GENERA OF THE PAPAVERACEAE -EVIDENCE FROM RESTRICTION SITE MAPPING OF PCR-AMPLIFIED CHLOROPLAST DNA FRAGMENTS

Phylogenetic relationships of a group of North American desert genera of the Papaveraceae subfam. Papaveroideae and Platystemonoideae were i nvestigated with an RFLP analysis of three PCR-amplified chloroplast g enome regions. In agreement with earlier results it was found that sub fam. Platystemonoideae is nested within subfam. Papaveroideae. The gro up under study is characterized by a large number of generic autapomor phies but only few informative synapomorphies. This is interpreted as strong evidence for a rapid radiation event caused by major climatic c hanges in the past. Poor phylogenetic resolution seems to reflect biol ogical reality and not to be an experimental artifact. There is also e vidence for accelerated morphological evolution under arid climatic co nditions.