The Afromontane and Afroalpine areas constitute some of the main biodiversity hotspots of Africa. They are particularly rich in plant endemics, but the biogeographic origins and evolutionary processes leading to this outstanding diversity are poorly understood. We performed phylogenomic and biogeographic analyses of one of the most species-rich plant genera in these mountains, Helichrysum (Compositae-Gnaphalieae). Most previous studies have focused on Afroalpine elements of Eurasian origin, and the southern African origin of Helichrysum provides an interesting counterexample. We obtained a comprehensive nuclear dataset from 304 species (≈50% of the genus) using target-enrichment with the Compositae1061 probe set. Summary-coalescent and concatenation approaches combined with paralog recovery yielded congruent, well-resolved phylogenies. Ancestral range estimations revealed that Helichrysum originated in arid southern Africa, whereas the southern African grasslands were the source of most lineages that dispersed within and outside Africa. Colonization of the tropical Afromontane and Afroalpine areas occurred repeatedly throughout the Miocene-Pliocene. This timing coincides with mountain uplift and the onset of glacial cycles, which together may have facilitated both speciation and intermountain gene flow, contributing to the evolution of the Afroalpine flora.

• Keywords
• Afroalpine, Afromontane, Asteraceae, Helichrysum, biogeography, evolution, long-distance dispersal, phylogeny, target-enrichment,
• Publication type
• Journal Article MeSH

Polyploidy has played a crucial role in the evolution of many plant taxa, namely in higher latitudinal zones. Surprisingly, after several decades of an intensive research on polyploids, there are still common polyploid species whose evolutionary history is virtually unknown. Here, we addressed the origin of sweet vernal grass (Anthoxanthum odoratum) using flow cytometry, DNA sequencing, and in situ hybridization-based cytogenetic techniques. An allotetraploid and polytopic origin of the species has been verified. The chromosome study reveals an extensive variation between the European populations. In contrast, an autopolyploid origin of the rarer tetraploid vernal grass species, A. alpinum, has been corroborated. Diploid A. alpinum played an essential role in the polyploidization of both European tetraploids studied.

• Keywords
• FISH, GBSSI, GISH, Poaceae, flow cytometry, genome size, polyploidy,
• MeSH
• Biological Evolution * MeSH
• Chromosomes, Plant genetics   MeSH
• Diploidy MeSH
• Phylogeny MeSH
• Hybridization, Genetic * MeSH
• In Situ Hybridization MeSH
• Poaceae cytology   genetics   MeSH
• Evolution, Molecular * MeSH
• Polyploidy MeSH
• Base Sequence MeSH
• Tetraploidy MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH