Tropical moist forests and savannas are iconic biomes. There is, however, a third principal biome in the lowland tropics that is less well known: tropical dry forest. Discussions on responses of vegetation in the tropics to climate and land-use change often focus on shifts between forests and savannas, but ignore dry forests. Tropical dry forests are distinct from moist forests in their seasonal drought stress and consequent deciduousness and differ from savannas in rarely experiencing fire. These factors lead tropical dry forests to have unique ecosystem function. Here, we discuss the underlying environmental drivers of transitions among tropical dry forests, moist forests and savannas, and demonstrate how incorporating tropical dry forests into our understanding of tropical biome transitions is critical to understanding the future of tropical vegetation under global environmental change.

Here, we explore the historical and contemporaneous patterns of connectivity among Encholirium horridum populations located on granitic inselbergs in an Ocbil landscape within the Brazilian Atlantic Forest, using both nuclear and chloroplast microsatellite markers. Beyond to assess the E. horridum population genetic structure, we built species distribution models across four periods (current conditions, mid‐Holocene, Last Glacial Maximum [LGM], and Last Interglacial) and inferred putative dispersal corridors using a least‐cost path analysis to elucidate biogeographic patterns. Overall, high and significant genetic divergence was estimated among populations for both nuclear and plastid DNA (ΦST (n) = 0.463 and ΦST (plastid) = 0.961, respectively, p < .001). For nuclear genome, almost total absence of genetic admixture among populations and very low migration rates were evident, corroborating with the very low estimates of immigration and emigration rates observed among E. horridum populations. Based on the cpDNA results, putative dispersal routes in Sugar Loaf Land across cycles of climatic fluctuations in the Quaternary period revealed that the populations’ connectivity changed little during those events. Genetic analyses highlighted the low genetic connectivity and long‐term persistence of populations, and the founder effect and genetic drift seemed to have been very important processes that shaped the current diversity and genetic structure observed in both genomes. The genetic singularity of each population clearly shows the need for in situ conservation of all of them.

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O objetivo deste trabalho foi determinar a distribuição potencial da espécie Lychnophora pohlli em Minas Gerais durante as flutuações climáticas no Quaternário, além de identificar a área de abrangência da espécie em Unidades de Conservação. O algoritmo Maxent foi selecionado para relacionar a ocorrência da espécie com variáveis bioclimáticas que refletem diferentes condições de temperatura, precipitação e sazonalidade. Os modelos foram validados por meio do índice AUC e a influência das variáveis sobre a distribuição das espécies foi avaliada por meio do teste Jackknife. Os mapas resultantes prevêem áreas de ocorrência restrita para a espécie, ocorrendo em uma porção da Serra do Espinhaço. Os modelos evidenciaram uma redução de área ambientalmente adequada da espécie do Holoceno para o período atual e aumento considerável dos dias atuais para o futuro. Os modelos apresentaram excelente desempenho, visto que os índices AUC variaram entre 0,971 a 0,997. A modelagem de distribuição de espécies mostrou-se bastante útil em fornecer contribuições para o estudo de questões ecológicas sobre a distribuição da espécie, além de ser uma importante ferramenta para planos de conservação da biodiversidade.  Recomenda-se o uso de outras variáveis microclimáticas que possam contribuir com a predição e interpretação da distribuição geográfica de espécies endêmicas.Palavra-chave: espécies Ameaçadas, Maxent, modelo de distribuição potencial, unidades de conservação. PREDICTIVE MODELING OF THE SPECIES LYCHNOPHORA POHLII SCH. BIP, IN THE STATE OF MINAS GERAIS ABSTRACT:The objective of this work was to determine the potential distribution of Lychnophora pohlli in Minas Gerais during climatic fluctuations in the Quaternary, in addition to identifying the area of coverage of the species in Conservation Units. The Maxent algorithm was selected to relate the occurrence of the species with bioclimatic variables that reflect different temperature, precipitation and seasonality conditions. The models were validated by AUC index and the influence of the variables on the distribution of the species were evaluated by the Jackknife test. The resulting maps provide areas of restricted occurrence for the species, occurring in a portion of the Serra do Espinhaço. The models showed environmentally adequate reduction of the Holocene species for the current period and a considerable increase from the present  to the future. The models showed excellent performance, since the AUC values ranged from 0,971 - 0,997. The modeling of species distribution has proved to be useful in providing contributions to the study of ecological issues on the species distribution, besides being an important tool for biodiversity conservation plans. It is recommended to use other microclimatic variables that may contribute to the prediction and interpretation of the geographic distribution of endemic species.Keywords: conservation units, endangered species, Maxent, potential distribution models. DOI: