Phylogeny and biogeography of the Daniellia clade (Leguminosae: Detarioideae), a tropical tree lineage largely threatened in Africa and Madagascar.

The legume subfamily Detarioideae is exceptionally diverse in tropical Africa and Madagascar, compared to South America or Asia, a trend contrary to that shown by most other pantropical plant groups. We aim to elucidate the process of diversification giving rise to these high diversity levels by focussing our investigations on the Daniellia clade, which is present in both Africa and Madagascar. The Daniellia clade is an early-diverging lineage of subfamily Detarioideae (Leguminosae; pea family) and consists of three genera: Daniellia, Brandzeia and Neoapaloxylon. The species belonging to this group exhibit a wide range of habitat types. The Madagascar endemics Brandzeia (1 species) and Neoapaloxylon (3 species) occupy dry woodlands and arid succulent habitats respectively. Daniellia alsteeniana and D. oliveri are found in savannahs while the remaining eight species within Daniellia all occupy rainforest habitats. Phylogenetic analyses were generated from a dense, multi-individual species level sampling of the clade. Divergence time estimates were carried out using a molecular clock method to investigate biogeographical patterns and shifts in habitat types within the Daniellia clade, and conservation assessments were conducted to determine the levels of extinction risks these species are facing. We estimate that the Daniellia clade first emerged during the Early Eocene from an ancestor present in the rainforests of North Africa at that time, reflecting an ancestral habitat preference. There was a first major split over the course of the Eocene, giving rise to both African rainforest and Madagascan savannah lineages. With the emergence of a drier climate and vegetation type in Africa during the Eocene, it is likely that a dry-climate adapted lineage from the Daniellia clade ancestor could have dispersed through suitable savannah or woodland regions to reach Madagascar, subsequently giving rise to the savannah-adapted ancestor of Brandzeia and Neoapaloxylon in the Early Miocene. The African rainforest lineage gave rise to the genus Daniellia, which is postulated to have first diversified in the Middle Miocene, while savannah species of Daniellia emerged independently during the Pliocene, coinciding with the global rise of C4-dominated grasslands. More than half of the species in the Daniellia clade are near threatened or threatened, which highlights the need to understand the threats of anthropogenic pressures and climate change these species are facing to prioritise their conservation.

High prevalence of asymptomatic Plasmodium falciparum malaria in Makenene, a locality in the forest-savannah transition zone, Centre Region of Cameroon.

Malaria transmission and prevalence is still not well documented across Cameroon particularly in medium-sized cities or localities representing high transit zone. Different risk factors could be associated with persistence malaria transmission such as population movement from high to low transmission settings. A cross-sectional community-based study was carried out to determine malaria prevalence and risk factors in Makenene, a small city in a forest-savannah which is a crossroads between different parts of the country where travellers usually stop-over day and night to rest. Using malaria diagnostic test (mRDTs from SD-BIOLINE) and microscopy (thin and thick blood smears), 406 participants from 237 households were tested for malaria infection. The prevalence of malaria was high irrespective of the detection method: mRDT (41.87%) or microscopy (38.42%). At household level, 46.41% of households had at least one case of malaria with an average of 1.41 infected individuals per household. Parasite density was also high with the majority of infected individuals (64.74%) bearing more than 500 parasites/µl. Only Plasmodium falciparum was found. The chances of being infected with malaria parasites was almost the same for all participants irrespective of the sleeping behavior, bednet usage, house type and environmental factors. The study supports high malaria transmission in the locality and the need for additional studies on vectors bionomics and transmission patterns.

Pollen-vegetation richness and diversity relationships in the tropics.

Tracking changes in biodiversity through time requires an understanding of the relationship between modern diversity and how this diversity is preserved in the fossil record. Fossil pollen is one way in which past vegetation diversity can be reconstructed. However, there is limited understanding of modern pollen-vegetation diversity relationships from biodiverse tropical ecosystems. Here, pollen (palynological) richness and diversity (Hill N 1) are compared with vegetation richness and diversity from forest and savannah ecosystems in the New World and Old World tropics (Neotropics and Palaeotropics). Modern pollen data were obtained from artificial pollen traps deployed in 1-ha vegetation study plots from which vegetation inventories had been completed in Bolivia and Ghana. Pollen counts were obtained from 15 to 22 traps per plot, and aggregated pollen sums for each plot were > 2,500. The palynological richness/diversity values from the Neotropics were moist evergreen forest = 86/6.8, semi-deciduous dry forest = 111/21.9, wooded savannah = 138/31.5, and from the Palaeotropics wet evergreen forest = 144/28.3, semi-deciduous moist forest = 104/4.4, forest-savannah transition = 121/14.1; the corresponding vegetation richness/diversity was 100/36.7, 80/38.7 and 71/39.4 (Neotropics), and 101/54.8, 87/45.5 and 71/34.5 (Palaeotropics). No consistent relationship was found between palynological richness/diversity, and plot vegetation richness/diversity, due to the differential influence of other factors such as landscape diversity, pollination strategy, and pollen source area. Palynological richness exceeded vegetation richness, while pollen diversity was lower than vegetation diversity. The relatively high global diversity of tropical vegetation was found to be reflected in the pollen rain.