Biogeographical and evolutionary considerations of Mauritia (Arecaceae), based on palynological evidence

Abstract

[EN] The available palynological evidence allows reconstruction of the principal trends in the historical biogeography and evolution of the neotropical palm genus Mauritia. Its pollen is known from the Palaeocene, and has been widespread throughout the entire neotropical region, during the Tertiary. From the Late Miocene until the Pleistocene, populations have been progressively fragmented by the Andean orogeny, thus promoting local extinction in some smaller basins and allopatric speciation in others. During the Pleistocene, Mauritia survived the repeated dry and cool periods characteristic for glaciations either by restricting its distribution to assumed Amazon forest ‘refugia’ or by forming large-scale, heterogeneous forest communities. After the last glaciation, palynological studies document a broad dispersal process of Mauritia, leading to its present range. However, Holocene climatic shifts, together with human disturbance, created a heterogeneous distribution pattern with spatial and temporal differences within this process. Therefore, biogeographical inferences based on present-day observations can only account for the most recent changes and are not suitable for generalizations. The history of Mauritia derived from the fossil record suggests opportunities for both vicariance and allopatric speciation, and reveals dispersal patterns through time. The presence of Mauritia in sediments can also be used as a reliable indicator of warm tropical lowland environments flooded by fresh (occasionally oligohalyne) waters. Several hypothesis about its biogeographical history and its palaeoecological implications are offered that can be tested with future studies.