PARK, SEON-JOO*, JAVIER FRANCISCO-ORTEGA, ARNOLDO SANTOS-GUERRA, JOSE PANERO, AND ROBERT JANSEN. Section of Integrative Biology, University of Texas, Austin TX 78712. - Implications of chloroplast DNA variation for the evolution of the Macaronesian Endemic genus Pericallis (Asteraceae, Senecioneae).
Pericallis includes 14 species endemic to the archipelagos of the
Azores, Canary Islands, and Madeira. Species in the genus occur in
all five ecological zones except the high altitude desert and they
exhibit considerable variation in growth form and floral biology. We
have examined cpDNA restriction site variation for all species of
Pericallis and several closely related continental genera. We
detected 135 parsimony informative restriction site changes among the
403 variable sites using 22 restriction enzymes. The cpDNA data
produce highly resolved and well supported trees which are largely
congruent with previous trees generated from nuclear ITS data. We
plotted both growth form (woody versus herbaceous), ecology, and
island distribution on the combined tree from both markers. Two
evolutionary trends are evident from these comparisons. First, there
have been at least two independent origins of woodiness in the island
endemics from a herbaceous continental ancestor. Second, inter-island
colonization between similar ecological zones on different islands is
the major avenue of evolution, a pattern that we have observed
previously in several other Macaronesian endemics.
Key words: Asteraceae, Islands, Macaronesia, Pericallis, Senecioneae