Taxonomy of allopolyploid species complexes of Sphagnum: evolutionary and ecological significance of polyploidy

Peat mosses (Sphagnum) has historically attracted much attention from systematists, and the taxonomy of many groups has been controversial. An important obstacle to achieving a stable taxonomy has been the abundant environmentally induced variation in mor phology, making it difficult to delimit distinct genetic entities. Allopolyploids are formed by hybridisation and subsequent chromosome doubling. This is a rapid speciation process, and a new reproductively isolated unit can be formed in just one generati on. Particular problems exist for species delimitation within allopolyploid complexes, as the allopolyploid and its progenitors have a large part of the genome in common. Further, several hypotheses regarding the ecological and evolutionary significance of allopolyploidy exist, including increased ecological amplitude and less phenotypic plasticity. This study will contribute to more reliable species demarcations, and reveal relationships between allopolyploids and their most likely progenitors. Moreove r, questions regarding recurrent origins are tried solved in a wide geographical perspective. Also whether allopolyploids have wider ecological tolerances, and whether this is caused by general or special purpose genotypes will be addressed through cultiv ation experiments of haploids and polyploids.