干旱区生态环境知识资源中心

Iris sect. Oncocyclus species generally occur in small populations or locally scattered over rocky hillsides, steppes, and deserts from the north Caucasus to the eastern Mediterranean. Species of this section are easily recognized by their inflorescences of a single, large, spherical flower and sepals with a dark signal spot and adjacent beard of multicellular hairs. We present here results of the first phylogenetic study of sect. Oncocyclus based on one low-copy nuclear and six plastid markers from 33 of approximately 42 species and infraspecific taxa. Gene trees are congruent and nuclear markers are more potentially parsimony informative than plastid markers. We identify clades that do not correspond to previously described species groups based on size, color, and shape of perianth parts and show that hypotheses of species monophyly are not supported. In general, diversification is greatest along terminal branches suggesting that species diversified in isolation. The Caucasus is suggested as the ancestral area for sect. Oncocyclus and the eastern Mediterranean as an important area of diversification.