engleski

The genus Knautia (Dipsacaceae) - insights into polyploid evolution, rapid radiation and extensive gene flow

The genus Knautia comprises ca. 60, mostly European species, with highest diversity in southern and southeastern Europe, especially the Alps and the Balkan Peninsula. It is traditionally regarded as one of the taxonomically most challenging European genera due to the widespread occurrence of polyploidy, the high incidence of hybridization and the existence of morphologically intermediate forms. The aim of this study was to provide insights into spatiotemporal diversification of the genus and to test previous infrageneric taxonomic hypotheses based on morphological and karyological traits. Using the nuclear ribosomal internal transcribed spacer (ITS) and the plastid petN(ycf6)-psbM region as well as amplified fragment length polymorphisms (AFLPs) we provide the first phylogeny of Knautia and its infrageneric classification. Our molecular data unambiguously support the monophyly of Knautia and the presence of three main lineages. The diploid annual sections Knautia and Tricheroides comprise only a few taxa ; the former is resolved at a basal position. The majority of species belong to the mostly perennial section Trichera, where polyploidisation up to the tetra- and hexaploid levels occurred within almost all traditionally recognized groups. Large-scale ploidy-level screening revealed (1) multiple cytotypes within some taxa that were previously considered ploidy-uniform as well as (2) similarity of genome sizes across different taxa belonging to the same ploidy level, with the exception of some Iberian taxa with divergent genome size. The plastid and nuclear datasets inferred a shallow genetic structure with mostly low resolution and only partial congruence, possibly due to recent rapid diversification and still ongoing hybridisation among different taxa. The genetic groups correspond to some extent with geography or ecological requirements. The wide distribution of some haplotype groups spanning large geographical areas implies recent and fast range expansion. Moreover, our results show that infrageneric classification and circumscription of traditional groups are not congruent with molecular data.

Knautia; phylogeny; polyploid evolution

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