Global patterns of moss diversity: taxonomic and molecular inferences

Taxonomic and molecular data were utilized to test the hypothesis that moss diversity is greatest near the equator. Species richness estimates from 86 taxonomic checklists representing global moss diversity do not support the hypothesis that, in general, mosses are more species-rich in the tropics than at higher latitudes. A significant latitudinal gradient was, however, detected for North, Central, and South American samples when analyzed alone. Taxonomic estimates of biodiversity patterns were compared to molecular estimates based on standing nucleotide diversity, and on phylogenetic diversity, the latter taking into account the historical information contained in a molecular phylogenetic tree for the mosses. Molecular estimates suggest that moss diversity is highest in the Southern Hemisphere and lowest in the Northern Hemisphere, with the tropics having an intermediate level. The differences, however, are slight, and analyses of molecular variance (AMOVA) indicate that there is virtually no generalized differentiation between major latitudinal zones. These results reflect the fact that virtually all moss lineages have representatives in all three latitudinal zones. At the nucleotide level, mosses best fit the pattern of everything is everywhere.