PANERO, JOSE L.*, JAVIER FRANCISCO-ORTEGA, A. SANTOS-GUERRA, AND ROBERT K. JANSEN. Department of Botany, The University of Texas, Austin, TX 78713; Departamento de Ciencias Agrarias, Universidad de La Laguna, Tenerife, Canary Islands, Spain and Jardin de Aclimatacion de La Orotava, 38400. Tenerife, Canary Islands, Spain. - Molecular evidence for the origin and evolution of the Macaronesian endemic genus Pericallis.
Pericallis includes 14 species endemic to the archipelagos of
Azores, Canary Islands, and Madeira. Species in the genus occur in
all five ecological zones except the high elevation desert and they
exhibit considerable variation in growth form and floral biology. We
have sequenced the internal transcribed spacer (ITS) region of the
nuclear ribosomal DNA for all species of Pericallis and its
putative continental relatives to examine the origin and evolution of
the genus. The ITS trees indicate a close relationship between
Pericallis and the African genera Dendrosenecio and
Cineraria and also to the New World genera Pseudogynoxys
and Dorobaea. This represents the first phylogenetic evidence
linking a member of the Macaronesian Flora with taxa from the New
World. Patterns of evolution in Pericallis were also assessed
within Macaronesia using the ITS trees. The major trend is that
species from the same ecological zones on different islands form
monophyletic groups. This indicates that inter-island colonization
between similar ecological zones on different islands is the major
avenue of evolution, a pattern which we have observed in several other
Macaronesia endemics (i.e., Argyranthemum, Crambe,
Silene).
Key words: Asteraceae, ITS phylogeny, Macaronesian flora, Pericallis, Senecioneae