Biogeographic patterns and cryptic speciation in bryophytes
Author: Jonathan Shaw
Source: Journal of Biogeography, Volume 28, Number 2, 1 February 2001 , pp. 253-261(9)
Bryophytes (mosses, liverworts, hornworts) typically have broad geographical distributions that span two or more continents. Many species show classic patterns of disjunction that are similar to those found in many other groups of organisms (e.g. eastern Asiaeastern North America), and which are thought to result from fragmentation of previously continuous ranges (i.e. vicariance). However, in the bryophytes, these disjunctions often occur at the infra-specific level and suggest that morphological uniformity may belie complex underlying genetic structure. Recent demonstrations of cryptic speciation, revealed by analyses of isozymes and DNA sequence variation, support the interpretation that genetic subdivision has occurred within some morphologically uniform species. Evidence for cryptic or nearly cryptic speciation exists for seven species of liverworts and seven mosses. In most (but not all) cases, cryptic species have broadly overlapping geographical ranges, although many are ecologically differentiated. Future work should focus on species that display `classic' patterns of disjunction at higher taxonomic levels in other organisms (e.g. eastern North Americaeastern Asia, eastern or western North AmericaEurope, Gondwanic), and should utilize explicitly phylogenetic approaches.
Document Type: Research article
Publication date: 2001-02-01