Vicariance, dispersal, and hybridization in a naturally fragmented system: the afro-alpine endemics Carex monostachya and C. runssoroensis (Cyperaceae)

摘要: The naturally fragmented habitat on the tallest African mountains provides a good model system to study vicariance, dispersal, and hybridization. Many are separated by lowland that likely was unsuitable for high-alpine plants even during cold climatic periods. We explore relative importance of these processes using two endemic sister species: widespread Ethiopian/eastern East Carex monostachya mainly western C. runssoroensis. These bog-forming sedges co-occur in some hypothesized hybridize. species were distinctly differentiated genome-wide amplified fragment length polymorphisms (AFLPs), also one mountain where they co-occur. However, from another showed strong signals admixture. results suggest initial divergence into northern/eastern lineage, followed long-distance dispersal resulting secondary contact zones. In addition within genetic diversity was clearly structured with distinct groups some, but not all mountains. Differentiation levels varied considerably did always correspond extent between narrow Rift Valley otherwise nearly contiguous highlands Ethiopia appears present much stronger barrier than extensive lowlands separating Africa. This may be general pattern since it has been documented other afro-alpine species.