Parallel origins of apomixis in two diverged evolutionary lineages in tribe Potentilleae (Rosaceae)

Oxford

1990

S. 214–229

Bandaufführung

12159S

202633

We synthesized the results from a flow cytometric seed screen and the literature to infer the phylogenetic origin and the geographical and taxonomic distribution of apomixis in tribe Potentilleae (Rosaceae). We distinguished between regular sexuality and apomixis, the zygotic and parthenogenetic origin of the embryo, and the pseudogamous (i.e. sexual) versus autonomous origin of the endosperm. The combined evidence provides information on reproductive modes for 11 genera and 120 species. For the first time records on reproductive mode are provided for the genus Farinopsis, 29 species (from five genera), and seven series of Potentilla. Regular sexuality was observed in Aphanes, Argentina, Comarum, Dasiphora, Drymocallis, Farinopsis, Fragaria, Horkeliella, Potentilla, and Sibbaldia. Reliable evidence for apomixis is restricted to two evolutionary lineages of Potentilleae: the Potentilla core group and Alchemilla/Aphanes. Early evolutionary divergence of these lineages (approximately 50 Mya), characterized by pseudogamous and autonomous apomictic seed formation, respectively, suggests parallel origins of apomixis. Apomixis is shown to be taxonomically widespread in the whole Northern Hemisphere distribution range of Potentilla, a pattern that is explained by hybrid transfer and repeated intercontinental dispersals. Taxonomic and geographical coverage is discussed with reference to species diversity centres of genera.evolution – FCSS – flow cytometry – phylogeny – Potentilla – reproduction – seed – sexuality.