The evolutionary processes underlying the high diversity and endemism in the Cerrado, the most extensive Neotropical savanna, remain unclear, including the factors promoting the presence and evolution of savanna enclaves in the Amazon forest. In this study, we investigated the effects of past climate changes on genetic diversity, dynamics of species range and the historical connections between the savanna enclaves and Cerrado core for Qualea grandiflora, a tree species widely distributed in the biome. Totally, 40 populations distributed in the Cerrado core and Amazon savannas were analyzed using chloroplast and nuclear DNA sequences. We used phylogeographic, coalescent and ecological niche modeling approaches. Genetic data revealed a phylogeographic structure shaped by Pleistocene climatic oscillations. An eastern-western split in the Cerrado core was observed. The central portion of the Cerrado core harbored most of the sampled diversity for cpDNA. Ecological niche models predicted the presence of a large historical refuge in this region and multiple small refuges in peripheral areas. Relaxed Random Walk (RRW) models indicated the ancestral population in the north-western border of the central portion of the Cerrado core and cyclical dynamics of colonization related to Pleistocene climatic oscillations. Central and western ancient connections between Cerrado core and Amazonian savannas were observed. No evidence of connections among the Amazonian savannas was detected. Our study highlights the importance of Pleistocene climatic oscillations for structuring the genetic diversity of Q. grandiflora and complex evolutionary history of ecotonal areas in the Cerrado. Our results do not support the recent replacement of a large area in the Amazon forest by savanna vegetation. The Amazonian savannas appear to be fragmented and isolated from each other, evolving independently a long ago.

Identifying the environmental factors that shape intraspecific genetic and phenotypic diversity of species can provide insights into the processes that generate and maintain divergence in highly diverse biomes such as the savannas of the Neotropics. Here, we sampled Qualea grandiflora, the most widely distributed tree species in the Cerrado, a large Neotropical savanna. We analyzed genetic variation with microsatellite markers in 23 populations (418 individuals) and phenotypic variation of 10 metamer traits (internode, petiole and corresponding leaf lamina) in 36 populations (744 individuals). To evaluate the role of geography, soil, climate, and wind speed in shaping the divergence of genetic and phenotypic traits among populations, we used Generalized Dissimilarity Modelling. We also used multiple regressions to further investigate the contributions of those environmental factors on leaf trait diversity. We found high genetic diversity, which was geographically structured. Geographic distance was the main factor shaping genetic divergence in Qualea grandiflora, reflecting isolation by distance. Genetic structure was more related to past climatic changes than to the current climate. We also found high metamer trait variation, which seemed largely influenced by precipitation, soil bulk density and wind speed during the period of metamer development. The high degree of metamer trait variation seems to be due to both, phenotypic plasticity and local adaptation to different environmental conditions, and may explain the success of the species in occupying all the Cerrado biome.

Background and aims Hybridisation is increasingly recognised as an integral part of the dynamics of species range expansion and contraction. Thus, it is important to understand the reproductive barriers between co-occurring species. Extending previous studies that argued that the rare Eucalyptus risdonii was expanding into the range of the surrounding E. amygdalina by both seed and pollen dispersal, we here investigate the long-term fitness of both species and their hybrids and whether expansion is continuing. Methods We assessed the survival of phenotypes representing a continuum between the two pure species in a natural hybrid swarm after 29 years, along with seedling recruitment. The performance of pure species as well as artificial and natural hybrids was also assessed over 28 years in a common garden trial. Key results In the hybrid zone, E. amygdalina adults showed greater mortality than E. risdonii and the current seedling cohort is still dominated by E. risdonii phenotypes. Morphologically intermediate individuals appeared to be the least fit. Similar results were observed after growing artificial first generation and natural hybrids alongside pure species families in a common garden trial. Here, the survival, reproduction, health and growth of the intermediate hybrids were significantly less than either pure species, consistent with hybrid inferiority, although this did not manifest until later reproductive ages. Among the variable progeny of natural intermediate hybrids, the most E. risdonii-like phenotypes were the most fit. Conclusions This study contributes to the increasing number of reports of hybrid inferiority in Eucalyptus, suggesting postzygotic barriers contribute to the maintenance of species integrity even between closely related species. However, with fitness rapidly recovered following backcrossing it is argued that hybridisation can still be an important evolutionary process, in the present case appearing to contribute to the range expansion of the rare E. risdonii in response to climate change.

To evaluate the distribution of asymptomatic infection by Leishmania infantum in a metropolis in Brazil with different relative risks (RRs) for disease and risk factors associated with the infection, an ecological study was conducted using a Bayesian approach to estimate the RR of human visceral leishmaniasis (HVL) based on cases between 2008 and 2011. The areas were categorized and selected according to disease incidence: low (area-1), medium (area-2) and high (area-3). Cross-sectional study enrolling 935 children was used to estimate the prevalence of infection by L. infantum. Volunteers from these three areas were tested for L. infantum infection by ELISA (rK39 and soluble antigens). Infection prevalence rates were estimated and compared with the RR of disease. Multilevel logistic regression model evaluated the relationship between infection and the analysed variables. The RR of HVL was distributed heterogeneously in the municipality. The infection prevalence rates were: 34·9% in area-1; 29·3% in area-2; and 33·6% in area-3, with no significant differences between these areas. The variables 'Presence of backyards in the neighbourhood' and 'Younger children' were associated with L. infantum infection. We conclude that infection by L. infantum affects a significant proportion of the infant population regardless of the RR of disease.

Aim:The centre-periphery hypothesis (CPH) states that peripheral populations exhibit lower genetic diversity, abundance and size, and higher differentiation compared to central populations, due to a decline in environmental suitability towards range margins. Here, we tested if neutral genetic diversity and functional leaf trait diversity fit the predicted patterns of the CPH.Location: Cerrado, Brazil.Taxon: Qualea grandiflora (Vochysiaceae) and Annona crassiflora (Annonaceae).Methods: Variation in eight functional leaf traits and nine or eight microsatellite loci were analysed in 37 populations (777 individuals) of Q. grandiflora and 21 populations (397 individuals) of A. crassiflora. We tested CPH using three distinct centres of species' range: geographical (centre of species' geographic occurrence), historical (centre of species' refugia) and ecological (centre of species' current suitability areas).Generalised linear regressions were performed between genetic diversity and differentiation, coefficients of variation and means of leaf metamer traits of populations and their distances from each centre.Results: A decrease in allele richness was observed from central towards peripheral populations for ecological (both species) and geographical centres (Q. grandiflora).Overall, the results for both species pointed to a decrease in metamer vigour towards marginal populations, pattern consistent with a decrease in environmental suitability towards periphery as predicted by CPH. Besides geographical and ecological centres, leaf traits fitted CPH considering historical centre.Main Conclusions: Results for leaf traits and genetic diversity of two phylogenetically distant species indicate the consistency of the CPH for Cerrado species. Our results highlight the importance of considering distinct centres and a great number of populations along species' range to better determinate the processes underlying the distribution of genetic diversity and functional traits. The low genetic diversity and metamer vigour in marginal populations can explain the Cerrado endemism of studied species and suggest that the ongoing climatic changes can be critical for their survival. | 2259 PFEILSTICKER ET aL.