Biogeographical history of bryophytes in Chile

Abstract

Some biogeographical features of bryophytes associated with subtropical-temperate ecosystems in Chile are examined, including diversity, concentration of species richness, endemism, biogeographical composition and disjunctions. The historical-biogeographical interpretation of these characteristics considers the major evolutionary changes of the group in three different temporal scenarios, according to geological, paleobotanical and molecular evidences. First, simple- and complex-thalloids liverworts represented in Chile are examined, belonging to the Classes Haplomitriopsida and Marchantiopsida- Marchantiidae, archaic lineages linked to the pre-Cenozoic colonization of the Pangea mega-continent. Examples of simple-thalloids liverworts of Class Jungermanniopsida-Pelliidae, hornworts of the Class Anthocerotopsida and mosses of the Classes Bryopsida and Polytrichopsida illustrate the paleo-austral distribution patterns of bryophytes from the temperate region of Chile, related to the Gondwana breakup and expansion of Angiosperms during the Cretaceous/Paleogene. A second scenario, considers the final uplift of the Andes and the development of the Arid Diagonal of South America during the Neogene, processes that have played a major role in the biogeographical structure of the Chilean and South American floras. In this context, leafy liverworts associated with the relict forests of the Chilean semi- arid coast stand out, particularly epiphyllous liverworts of the two most diverse families of the Class Jungermanniopsida-Jungermanniidae, Lejeuneaceae and Plagiochilaceae, adapted to microclimates favored by coastal fogs. The last scenario discusses the significant role of the Pleistocene glacial cycles in the expansion of the sub-Antarctic temperate-cold element throughout central-southern Chile, and its effects on the concentration of bryophyte richness associated with Chile’s temperate-rain ecosystems.