University of Antananarivo

About: University of Antananarivo is a education organization based out in Antananarivo, Madagascar. It is known for research contribution in the topics: Population & Lemur. The organization has 1561 authors who have published 1703 publications receiving 30922 citations. The organization is also known as: Tananarive University & Antananarivo University.

Host Ecology Rather Than Host Phylogeny Drives Amphibian Skin Microbial Community Structure in the Biodiversity Hotspot of Madagascar.

Abstract: Host-associated microbiotas of vertebrates are diverse and complex communities that contribute to host health. In particular, for amphibians, cutaneous microbial communities likely play a significant role in pathogen defense; however, our ecological understanding of these communities is still in its infancy. Here we take advantage of the fully endemic and locally species-rich amphibian fauna of Madagascar to investigate the factors structuring amphibian skin microbiota on a large scale. Using amplicon-based sequencing, we evaluate how multiple host species traits and site factors affect host bacterial diversity and community structure. Madagascar is home to over 400 native frog species, all of which are endemic to the island; more than 100 different species are known to occur in sympatry within multiple rainforest sites. We intensively sampled frog skin bacterial communities, from over 800 amphibians from 89 species across 30 sites in Madagascar during three field visits, and found that skin bacterial communities differed strongly from those of the surrounding environment. Richness of bacterial operational taxonomic units (OTUs) and phylogenetic diversity differed among host ecomorphs, with arboreal frogs exhibiting lower richness and diversity than terrestrial and aquatic frogs. Host ecomorphology was the strongest factor influencing microbial community structure, with host phylogeny and site parameters (latitude and elevation) explaining less but significant portions of the observed variation. Correlation analysis and topological congruency analyses revealed little to no phylosymbiosis for amphibian skin microbiota. Despite the observed geographic variation and low phylosymbiosis, we found particular OTUs that were differentially abundant between particular ecomorphs. For example, the genus Pigmentiphaga (Alcaligenaceae) was significantly enriched on arboreal frogs, Methylotenera (Methylophilaceae) was enriched on aquatic frogs, and Agrobacterium (Rhizobiaceae) was enriched on terrestrial frogs. The presence of shared bacterial OTUs across geographic regions for selected host genera suggests the presence of core microbial communities which in Madagascar, might be driven more strongly by a species’ preference for specific microhabitats than by the physical, physiological or biochemical properties of their skin. These results corroborate that both host and environmental factors are driving community assembly of amphibian cutaneous microbial communities, and provide an improved foundation for elucidating their role in disease resistance.

Decline of the Madagascar radiated tortoise Geochelone radiata due to overexploitation

Abstract: To avoid the risk of misapplying conservation effort the correct diagnosis of the agent causing a population to decline requires scientific approaches. The radiated tortoise Geochelone radiata, endemic to southern Madagascar, is heavily harvested for food and for the pet trade. Fearing overexploitation, the tortoise was protected under Malagasy law and placed on Appendix I of CITES, yet scientific evidence that the radiated tortoise is declining, and that exploitation is the agent driving any decline, is lacking. Interviews with tortoise harvesters, a comparison of the size of the tortoise's range through time, and estimates of tortoise abundance at 14 sites under different levels of harvest intensity were used to seek evidence of overexploitation. In the first study to attempt to quantify the size of the illegal harvest of radiated tortoises, we estimated that up to 45,000 adult radiated tortoises are harvested each year. The species is declining, with its range having contracted by one-fifth over the last 25 years. Three pieces of evidence strongly suggest that overexploitation is driving this decline. Firstly, commercial harvesters reported travelling increasingly far, up to 200 km, to find sufficient densities of tortoises. Secondly, tortoises were either absent or at very low abundance at sites subject to commercial harvesting, but in remote, unharvested regions, tortoises persisted at densities of up to 2,500 km−2. Thirdly, tortoise abundance increased significantly with distance from urban centres of high demand for tortoise meat. If current rates of harvesting continue, the radiated tortoise will go extinct in the wild.

Paleoenvironment and paleoecology of majungasaurus crenatissimus (theropoda: abelisauridae) from the late cretaceous of madagascar

Abstract: The abelisaurid theropod Majungasaurus crenatissimus inhabited the plains of northwestern Madagascar during the Late Cretaceous. It lived alongside other nonavian dinosaurs, including a small-bodied noasaurid theropod (Masiakasaurus knopfleri) and a titanosaurian sauropod (Rapetosaurus krausei). Although an inhabitant of the expansive floodplains of the Mahajanga Basin, M. crenatissimus also frequented the broad and sandy channel belts that drained Madagascar's central highlands. These shallow rivers were populated by a variety of aquatic and semi-aquatic animals, including fish, frogs, turtles, and several species of both large and small crocodyliforms. These animals were likely adapted for seasonal fluctuations in water availability because the sediments that entomb their remains (fine-grained debris flow deposits intercalated with stream flow deposits) indicate a strongly variable discharge regime. Associated oxidized calcareous paleosols with localized accumulations of carbonate nodules sugge...

Bioclimatic envelope models predict a decrease in tropical forest carbon stocks with climate change in Madagascar

Abstract: Summary Recent studies have underlined the importance of climatic variables in determining tree height and biomass in tropical forests. Nonetheless, the effects of climate on tropical forest carbon stocks remain uncertain. In particular, the application of process-based dynamic global vegetation models has led to contrasting conclusions regarding the potential impact of climate change on tropical forest carbon storage. Using a correlative approach based on a bioclimatic envelope model and data from 1771 forest plots inventoried during the period 1996–2013 in Madagascar over a large climatic gradient, we show that temperature seasonality, annual precipitation and mean annual temperature are key variables in determining forest above-ground carbon density. Taking into account the explicative climate variables, we obtained an accurate (R2 = 70% and RMSE = 40 Mg ha−1) forest carbon map for Madagascar at 250 m resolution for the year 2010. This national map was more accurate than previously published global carbon maps (R2 ≤ 26% and RMSE ≥ 63 Mg ha−1). Combining our model with the climatic projections for Madagascar from 7 IPCC CMIP5 global climate models following the RCP 8.5, we forecast an average forest carbon stock loss of 17% (range: 7–24%) by the year 2080. For comparison, a spatially homogeneous deforestation of 0.5% per year on the same period would lead to a loss of 30% of the forest carbon stock. Synthesis. Our study shows that climate change is likely to induce a decrease in tropical forest carbon stocks. This loss could be due to a decrease in the average tree size and to shifts in tree species distribution, with the selection of small-statured species. In Madagascar, climate-induced carbon emissions might be, at least, of the same order of magnitude as emissions associated with anthropogenic deforestation.