XVI International Botanical Congess

Most genera and higher level groups in the bryophytes are disjunct across multiple continents, and individual morphologically defined species are often widespread in both the New and Old Worlds. Many species have ranges that appear to result from ancient vicariance events (e.g., E. Asia - E. North America), but are morphologically uniform across huge ranges. Case studies in the Sphagnaceae indicate that boreal species are not differentiated between continents but complexes of tropical taxa form well marked clades that are endemic to specific continental areas. In the aquatic moss, Fontinalis, population-level genealogical studies indicate that widespread species are paraphyletic because of independent speciation events in the New and Old Worlds. Infraspecific circum-subantarctic disjunctions offer exciting opportunities to assess area relationships among the southern continents.