Aim The recovery of demographic history through phylogeographical analysis is critical for understanding microevolutionary processes and the spatial/temporal context of lineage divergence. Palaeodistribution modelling and the fossil record might provide the spatial context for statistical phylogeographical analyses, allowing the generation of independent palaeoscenarios of demographic history that can be tested using coalescent models. In this study we generated independent demographic scenarios to examine geographical barriers to gene flow in a Neotropical swamp palm, Mauritia flexuosa, and assessed how climatic changes during the Pleistocene influenced its geographical distribution and genetic diversity. Location Neotropical wetlands.Methods We sampled 257 adult individuals of M. flexuosa from 26 localities in the Amazon, Araguaia/Tocantins, Paraguai, Paran a and São Francisco basins. The analyses were based on statistical phylogeography, ecological niche modelling and the fossil pollen record. The genetic data were based on polymorphisms in three chloroplast non-coding regions.Results Mauritia flexuosa presented low genetic diversity but significant genetic differentiation among populations from different river basins. The ecological niche modelling and demographic simulations showed that the pattern of observed genetic diversity for M. flexuosa probably reflects range retraction during the Last Glacial Maximum, leading to multiple refugia. In support of this, the fossil pollen record suggests that multiple refugia were present in Brazilian savannas, where M. flexuosa often disappeared during cold and dry periods across the last glacial cycle, returning during the wet phases. The periodic dryness in this region was driven by the latitudinal displacement of the Intertropical Convergence Zone (ITCZ) across glacial/interglacial periods, which possibly affected the distributional dynamics of M. flexuosa during the Pleistocene epoch. Main conclusionsOur results provide evidence that climate changes during the last glacial cycle were important determinants of the geographical distribution and demographic history of M. flexuosa across the late Quaternary period. In addition to the geographical barriers imposed by river basins, these factors have shaped genetic differentiation, as currently observed among lineages.

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We studied genetic diversity and differentiation patterns in Neotropical plants to address effects of life history traits (LHT) and ecological attributes based on an exhaustive literature survey. We used generalized linear mixed models (GLMMs) to test the effects as fixed and random factors of growth form, pollination and dispersal modes, mating and breeding systems, geographical range and habitat on patterns of genetic diversity (HS, HeS, π and h), inbreeding coefficient (FIS), allelic richness (AR) and differentiation among populations (FST) for both nuclear and chloroplast genomes. In addition, we used phylogenetic generalized least squares (pGLS) to account for phylogenetic independence on predictor variables and verify the robustness of the results from significant GLMMs. In general, GLMM revealed more significant relationships among LHTs and genetic patterns than pGLS. After accounting for phylogenetic independence (i.e., using pGLS), FST for nuclear microsatellites was significantly related to pollination mode, mating system and habitat. Plants specifically with outcrossing mating system had lower FST. Moreover, AR was significantly related to pollination mode and geographical range and HeS for nuclear dominant markers was significantly related to habitat. Our findings showed that different results might be retrieved when phylogenetic non-independence is taken into account and that LHTs and ecological attributes affect substantially the genetic pattern in Neotropical plants, hence may drive key evolutionary processes in plants.

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Resumo A região Neotropical, detentora da maior riqueza de espécies no globo, ocorre do México Central ao sul do Brasil. Neste trabalho, buscamos sumarizar as principais informações disponíveis na literatura que caracterizam os biomas neotropicais de Florestas Sazonalmente Seca (FTSS), Chaco e Savanas. Revisamos hipóteses biogeográficas concernentes a esses ambientes que buscam explicar sua dinâmica histórica. Nosso objetivo é oferecer uma caracterização desses biomas como etapa principal para o entendimento das principais hipóteses biogeográficas a eles associadas. Ainda que comporte como um cenário atraente para pesquisa, as espécies neotropicais são pouco estudas, sendo questões referentes a seus aspectos ecológicos, origem, história evolutiva e manutenção da elevada biodiversidade desconhecidas ou, ainda, pouco compreendidas. Embora, nossa revisão apresente pesquisas com diferentes pontos de vista quanto à dinâmica biogeográfica das formações vegetais, há consenso de que é produto de complexa interação entre os processos históricos, ecológicos e biológicos. Os estudos em biodiversidade de regiões ameaçadas, como os Neotrópicos, são norteadores para simulações e previsões de impactos, planos e estratégias de pesquisa.

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