SCHNEEWEISS, GERALD M.1*, PETER SCHOENSWETTER1, SYLVIA KELSO2, and HARALD NIKLFELD1. 1Dep. of Chorology and Vegetation Science, Institute of Botany University of Vienna, Rennweg 14, A-1030 Vienna, Austria; 2The Colorado College, Biology Department, 14 East Cache La Poudre Street, Colorado Springs, CO 80903, USA. - Patterns of disjunction and relationships within Androsace (Primulaceae).
Androsace, the second-largest genus within Primulaceae, is
distributed mainly in the northern hemisphere. The largest of the
sections, Chamaejasme, is distributed mainly in mountain ranges
over the entire broad region. Other groups are the similarly
widespread sect. Andraspis, comprising the annual or biennial
taxa, and the European endemic sect. Aretia. The
morphologically most primitive group, sect. Pseudoprimula, is
restricted to Eastern Asia. The amphi-Beringian sect. Douglasia
and the monotypic European sect. Vitaliana are often treated as
separate genera, Douglasia and Vitaliana, due to their
divergent morphological features. The most surprising result of a
phylogenetic analysis of DNA-sequences (nuclear ITS, plastid
trnL-intron plus trnL-trnF-spacer) concerns sect. Douglasia,
which nests within the European sect. Aretia, being closely
related to species of subsect. Dicranothrix (sect.
Aretia) characterized by multi-flowered, scapous
inflorescences. This is supported by cytotaxonomic data. The same base
chromosome number, x = 19, is found in sect. Douglasia
and in subsect. Dicranothrix, whereas subsect. Aretia
has x = 20. The wide geographic gap between the amphi-Beringian
sect. Douglasia and the European sect. Aretia is bridged
not by Central- or East-Asian species, but by the high-arctic Siberian
A. triflora. Such an arctic connection might help to explain
similar disjunct distributional patterns seen in some groups of
Primula (Primulaceae) or in Ranunculus glacialis
(Ranunculaceae). Furthermore, the results indicate that
Androsace sect. Vitaliana, morphologically unique within
Androsace by its heterostylous flowers, is nested within sect.
Aretia. Similarly, A. chaixii, endemic to the Western
Alps and currently placed in sect. Andraspis, falls within
sect. Aretia. Sect. Andraspis is highly polyphyletic.
This is comparable to similar situations in other genera, whereby the
annual (to biennial) life-form has developed independently on several
occasions.
Key words: Androsace, biogeography, disjunctions, phylogeny, Primulaceae