Contribution to the cytotaxonomical knowledge of the genusGageaSalisb. (Liliaceae). III. New karyological data from the central Mediterranean area

Calochortus and the family Liliaceae s.s. have often been considered each other's closest relatives, based partly on their shared possession of bulbs, visually showy flowers, winged wind-dispersed seeds, and narrow parallel-veined leaves. We present a well-supported molecular phylogeny for these groups and their close relatives in the core Liliales, based on sequence variation in the chloroplast-encoded rbcL and ndhF genes. This analysis identifies Liliaceae s.s. as monophyletic. including one clade (((Lilium, Fritillaris, Nomocharis), Cardiocrinum), Notholirion) that appears to have diversified in the Himalayas roughly 12 million years ago and another ((Erythronium, Tulipa), (Gagea, Lloydia)) that arose in East Asia at about the same time. Medeola and Clintonia are sister to Liliaceae s.s. and bear rhizomes, inconspicuous flowers, fleshy animal-dispersed fruits, and broad reticulate-veined leaves. Calochortus is sister to Tricyrtis; both Tricyrtis and the neighboring clade of Prosartes-Streptopus-Scoliopus share several of the traits seen in Medeola-Clintonia. The core Liliales thus provide compelling examples of both concerted convergence and phylogenetic niche conservatism. Invasion of open, seasonal habitats was accompanied by the independent evolution of bulbs, showy flowers, wind-dispersed seeds, and narrow parallel-veined leaves in Calochortus and Liliaceae s.s. Conversely, persistence in shady habitats was accompanied by the retention of rhizomes, inconspicuous flowers, animal-dispersed seeds, and broad reticulate-veined leaves in their sister groups. We advance arguments for the context-specific adaptive value of each of these traits, as well as evidence of parallel trends in other groups. Concerted convergence--convergence in several different traits, favored by the same shared set of ecological conditions, in two or more lineages--is an important evolutionary process that can mislead evolutionary analyses based solely on phenotypic variation.

Our study represents the first phylogenetic analyses of the genus Gagea Salisb. (Liliaceae), including 58 species of Gagea and 6 species of the closely related genus Lloydia Salisb. ex Rchb. Our molecular results support the infrageneric classification of the genus Gagea in sections according to Levichev and demonstrate that Pascher's subdivision of this genus into two subgenera can no longer be upheld. Certain Gagea sections (e.g., Gagea, Minimae, and Plecostigma) are well supported by cpDNA and nrDNA data. Gagea sect. Fistulosae is closely related to G. sect. Didymobolbos. Gagea sect. Graminifoliae and G. sect. Incrustatae are closely related to G. sect Platyspermum. The analyses support the monophyly of Gagea and Lloydia collectively. The molecular analyses reveal the basal position of G. graeca in proportion to all other species of Gagea and Lloydia investigated. Minor morphological differences could be established between both genera which support their close relationship.