The potential distribution of Grimmia (Grimmiaceae) in Mexico

Hypothetically, the alpine and high elevation moss flora reached central Mexico by migration from northern latitudes following the western mountain ranges. Study of 774 specimens belonging to eighteen species of Grimmia identified four patterns of distribution in Mexico: species restricted to the Neovolcanic Belt, those mainly distributed in the northwestern states, widely distributed taxa, and endemic species. Track analysis showed that the generic distribution indeed followed the western mountains. Modeling was introduced to determine the potential ranges for most Mexican species of Grimmia and review the migration hypothesis. The resulting potential distribution maps using maximum entropy show that several species have discontinuous ranges in the northwestern states. Other taxa are restricted to the Neovolcanic Belt, and still others extend their potential distribution to stations in southern Mexico and Guatemala. Although the original hypothesis proposed that the high altitude moss flora was derived from temperate North America may still be acceptable, the South American distribution of various species indicate that migration may have also proceeded from the south.