Origin and evolution of the endemic Macaronesian Inuleae (Asteraceae): evidence from the internal transcribed spacers of nuclear ribosomal DNA

Abstract

The tribe Inuleae (Asteraceae) has 10 species endemic to the Macaronesian islands, including the three endemic genera Allagopappus, Schizogyne, and Vierea. Phylogenetic analyses of DNA sequence data from the internal transcribed spacers (ITS) of the nuclear ribosomal DNA of 47 taxa were performed using all Macaronesian endemics and representative species from 21 of the 36 genera of the Inuleae. The resulting ITS phylogeny reveals that Allagopappus is sister to a large clade that contains all genera with a predominantly Mediterranean distribution. This finding suggests thatAllagopappus may represent an ancient lineage that found refuge in the Canary Islands following the major climatic and/or geologic changes in the Mediterranean basin after the Tertiary. The Macaronesian endemic genus Schizogyne is sister to Limbarda from the Mediterranean. The third Macaronesian endemic genus, Vierea, is sister toPerralderia , which is restricted to Morocco and Algeria. Pulicaria canariensis is sister to P. mauritanica, a species endemic to Morocco and Algeria. In contrast, P. diffusa from the Cape Verde Islands is sister to a broadly distributed species, P. crispa, that occurs from North Africa to the Arabian peninsula. Based on the ITS data, the genera Blumea, Inula, and Pulicaria are not monophyletic. The ITS trees suggested thatBlumea mollis belongs to the tribe Plucheeae, a finding that is congruent with recent morphological evidence. A possible southern African origin for the core of the Laurasian taxa of the Inuleae is also suggested.