WATSON, LINDA E.1*, TIMOTHY M. EVANS2, MATTHEW M. UNWIN1, and AMY B. KORKVEN. 1Department of Botany, Miami University, Oxford OH 45056 USA; 2Biology Department, Hope College, Holland, MI 49422 USA. - Origin and Diversification of Tribe Anthemideae (Asteraceae), based on molecular phylogenies of ndhF and ITS.
The Anthemideae is primarily an Old World tribe that occurs mostly in
north temperate regions, with centers of endemism in Mediterranean
climates including the Iberian Peninsula of Europe and North Africa,
as well in as the Cape Province of South Africa. It contains numerous
cultivars, such as daisies and chrysanthemums, and also includes
ecologically-important and widespread species such as sagebrush. The
tribe is composed of 109 genera and 1700 species, however, the
majority of species comprise five large core genera of 100+ species
each, including Artemisia/Seriphidium, Tanacetum, Achillea and
Anthemis. Molecular phylogenies based on chloroplast gene ndhF
and the internal transcribed spacers (ITS) of nrDNA place several
South African genera in a basal grade. The phylogenies also support an
early divergence between members that occur in Far East Asia and the
western Eurasian region. These two major clades are sister to clades
that are also centered in South Africa. A South African origin for the
Anthemideae is in contrast to previous hypotheses that the tribe
originated in Eurasia, with an early vicariant event resulting in
relictual members occurring in South Africa. In addition, derived
placements of all five core genera indicate that these large and
geographically-widespread genera are recent. There is little
congruence with taxonomy and morphologically-based phylogenies, with
considerable homoplasy in the morphological characters.
Key words: Anthemideae, Asteraceae, phylogeny, South Africa