Phylogenetic relationships among Japanese flowering cherries (Prunus subgenus Cerasus) based on nucleotide sequences of chloroplast DNA

Six primers for the amplification of three non-coding regions of chloroplast DNA via the polymerase chain reaction (PCR) have been designed. In order to find out whether these primers were universal, we used them in an attempt to amplify DNA from various plant species. The primers worked for most species tested including algae, bryophytes, pteridophytes, gymnosperms and angiosperms. The fact that they amplify chloroplast DNA non-coding regions over a wide taxonomic range means that these primers may be used to study the population biology (in supplying markers) and evolution (inter- and probably intraspecific phylogenies) of plants.

Species in the columbine genus, Aquilegia, are known for their broad variation in ecology and floral morphology. Aquilegia is also known for the large degree of intercompatibility among its species, which has led to the suggestion that the genus has arisen recently. However, intercompatibility does not always imply recent divergence and the widespread distribution pattern of the genus has suggested an older age. We constructed phylogenies for Aquilegia plus its close relatives by using nucleotide sequence data from both nuclear and chloroplast DNA. The sequence data averaged over 1250 bp per species. Among the 14 columbine species sampled from Europe, Asia, and North America only 16-bp changes and one insertion/deletion event were detected. In contrast, related genera had from 3 to 45 times this level of variation. The phylogenies derived from the chloroplast and nuclear DNA sequences were highly concordant and suggest that the columbines are the result of a recent, rapid radiation. In contrast to other examples of species flocks, Aquilegia has radiated on a widespread geographical scale. By comparison with their related taxa, we suggest that the evolution of the nectar spur in Aquilegia was a key innovation for this genus and allowed rapid speciation through specialization to specific pollinators.