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The article reports the AMS (accelerator mass spectrometry) radiocarbon investigation of the historic Grand Baobab of Mahajanga. The largest African baobab of Madagascar exhibits a cluster structure, which consists of 6 fused ordinary stems and of 3 small binding stems. Two samples were collected from the largest stem and from a primary branch, out of which several tiny segments were extracted and dated by radiocarbon. The oldest dated sample segment had a radiocarbon date of 214 ± 17 BP, which corresponds to a calibrated age of 265 ± 25 calendar years. The dating results indicate that the Grand Baobab of Mahajanga is 275 ± 25 years old. [ABSTRACT FROM AUTHOR]

It is commonly accepted that species should move toward higher elevations and latitudes to track shifting isotherms as climate warms. However, temperature might not be the only limiting factor determining species distribution. Species might move to opposite directions to track changes in other climatic variables. Here, we used an extensive occurrence data set and an ensemble modelling approach to model the climatic niche and to predict the distribution of the seven baobab species (genus Adansonia) present in Madagascar. Using climatic projections from three global circulation models, we predicted species' future distribution and extinction risk for 2055 and 2085 under two representative concentration pathways (RCPs) and two dispersal scenarios. We disentangled the role of each climatic variable in explaining species range shift looking at relative variable importance and future climatic anomalies. Four baobab species (Adansonia rubrostipa, Adansonia madagascariensis, Adansonia perrieri¸ and Adansonia suarezensis) could experience a severe range contraction in the future (>70% for year 2085 under RCP 8.5, assuming a zero‐dispersal hypothesis). For three out of the four threatened species, range contraction was mainly explained by an increase in temperature seasonality, especially in the North of Madagascar, where they are currently distributed. In tropical regions, where species are commonly adapted to low seasonality, we found that temperature seasonality will generally increase. It is, thus, very likely that many species in the tropics will be forced to move equatorward to avoid an increase in temperature seasonality. Yet, several ecological (e.g., equatorial limit, or unsuitable deforested habitat) or geographical barriers (absence of lands) could prevent species to move equatorward, thus increasing the extinction risk of many tropical species, like endemic baobab species in Madagascar. [ABSTRACT FROM AUTHOR]

Baobab (genus Adansonia , family Malvaceae) comprises nine species distributed worldwide of which seven are present in Madagascar. Six are endemic to Grande Ile and are distributed in two sections: Brevitubae and Longitubae. The aim of this study was to distinguish the qualitative and quantitative characters of floral emissions by different species of Malagasy baobabs and to propose hypotheses on their modes of pollination. Floral fragrance was analysed using gas chromatography and mass spectrometry. The study revealed two sections which were distinguishable by the quality and quantity of the compounds they emitted. Species belonging to the Longitubae section all emit a large quantity of compounds with aromatic structures, dominated by 2-phenylacetonitrile, whereas the fragrances of the two species of Brevitubae are rich in compounds with aliphatic structures, particularly 8-heptadecene. The majority of chemicals identified in the Longitubae section are common components of a wide array of scented flowers pollinated by moths such as Sphingidae. However, in the Brevitubae section, no clear relation was found between chemical composition of the fragrance and a particular type of pollinator. The presence of common components in the fragrances in every Longitubae species made it possible to analyse the action of common pollinators and to explain the cases of genetic introgression between the species in this section. [ABSTRACT FROM AUTHOR]

We extended our research on the architecture, growth and age of trees belonging to the genus Adansonia, by starting to investigate large individuals of the most widespread Malagasy species. Our research also intends to identify the oldest baobabs of Madagascar. Here we present results of the radiocarbon investigation of the two most representative Adansonia rubrostipa (fony baobab) specimens, which are located in south-western Madagascar, in the Tsimanampetsotse National Park. We found that the fony baobab called “Grandmother” consists of 3 perfectly fused stems of different ages. The radiocarbon date of the oldest sample was found to be 1136 ± 16 BP. We estimated that the oldest part of this tree, which is mainly hollow, has an age close to 1,600 yr. This value is comparable to the age of the oldest Adansonia digitata (African baobab) specimens. By its age, the Grandmother is a major candidate for the oldest baobab of Madagascar. The second investigated specimen, called the “polygamous baobab”, consists of 6 partially fused stems of different ages. According to dating results, this fony baobab is 1,000 yr old. This research is the first investigation of the structure and age of Malagasy baobabs. [ABSTRACT FROM AUTHOR]

Background and Aims Adansonia comprises nine species, six of which are endemic to Madagascar. Genetic relationships between the Malagasy species remain unresolved due to conflicting results between nuclear and plastid DNA variation. Morphologically intermediate individuals between distinct species have been identified, indicative of interspecific hybridization. In this paper, microsatellite data are used to identify potential cases of hybridization and to provide insights into the evolutionary history of the genus on Madagascar. Methods Eleven microsatellites amplified with new primers developed for Adansonia rubrostipa were used to analyse 672 individuals collected at 27 sites for the six Malagasy species and morphologically intermediate individuals. Rates of individual admixture were examined using three Bayesian clustering programs, STRUCTURE, BAPS and NewHybrids, with no a priori species assignment. Key Results Population differentiation was coherent, with recognized species boundaries. In the four Malagasy species of section Longitubae, 8·0, 9·0 and 9·5 % of individuals with mixed genotypes were identified by BAPS, NewHybrids and STRUCTURE, respectively. At sites with sympatric populations of A. rubrostipa and A. za, NewHybrids indicated these individuals to be F2 and, predominantly, backcrosses with both parental species. In northern Madagascar, two populations of trees combining A. za and A. perrieri morphology and microsatellite alleles were identified in the current absence of the parental species. Conclusions The clear genetic differentiation observed between the six species may reflect their adaptation to different assortments of climate regimes and habitats during the colonization of the island. Microsatellite variation reveals that hybridization probably occurred in secondary contact between species of section Longitubae. This type of hybridization may also have been involved in the differentiation of a local new stabilized entity showing specific microsatellite alleles and morphological characters, suggesting a potential role of hybridization in the recent history of diversification on Madagascar. [ABSTRACT FROM AUTHOR]

Highlights: [•] We provide new estimates of abundance and distribution of three endangered baobab species in Madagascar. [•] Very high resolution satellite images from GoogleEarth were used to identify species presence. [•] Two baobab species are highly vulnerable to climate change (significant habitat loss). [•] Due to shift in species distribution, present protected areas should not be effective in the future. [•] Alternative strategies (e.g. ecological restoration) should be adopted to save biodiversity. [Copyright &y& Elsevier]

The article presents research which assessed the association between the Phesulma standingi and the Adansonia in Madagascar. The researchers examined the role played by the Phesulma standingi in offering secure refuge as well as climbing surfaces for the large day geckos. They also found that the association between baobab and the Phesulma standingi is only related with large mature trees that belong to the species of Adansonia za, Adansonia grandidieri and the Adansonia rubrostipa. The authors suspected that Phesulma standingi is widely distributed in Madagascar despite the claims that it is only known to occupy the river drainages Fiherenana, Mangoky and Onilahy.

The African baobab ( Adansonia digitata L.) is an emblematic, culturally important, and physically huge tropical tree species whose natural geographical distribution comprises most of tropical Africa, but also small patches of southern Arabia, and several Atlantic and Indian Ocean islands surrounding the African continent, notably including Madagascar. We analysed the polymerase chain reaction–restriction fragment length polymorphism of five chloroplast DNA fragments obtained from 344 individuals of A. digitata collected from 74 populations covering the entire extant distribution range of the species. Our goal was to reconstruct the phylogeographical history of the species and, if possible, to identify its centre of origin, which has been a subject of controversy for many decades. We identified five haplotypes whose distribution is clearly geographically structured. Using several species of Adansonia and of closely related genera as outgroups, the haplotypes showed a clear phylogeographical pattern of three groups. Two are phylogenetically related to the outgroup taxa, and are distributed in West Africa. The third group is substantially more differentiated genetically from outgroup species, and it corresponds to southern and eastern Africa, Arabia and the Indian Ocean islands, including Madagascar. According to our results, the tetraploid A. digitata, or its diploid progenitor, probably originated in West Africa and migrated subsequently throughout the tropical parts of that continent, and beyond, by natural and human-mediated terrestrial and overseas dispersal. [ABSTRACT FROM AUTHOR]

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B1 and B2 vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B1 88 mg 100 g-1, B2 187 mg 100 g-1, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Crossspecies grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations. [ABSTRACT FROM AUTHOR]

Baobab trees are often cited in the literature as water-storing trees, yet few studies have examined this assumption. We assessed the role of stored water in buffering daily water deficits in two species of baobabs ( Adansonia rubrostipa Jum. and H. Perrier and Adansonia za Baill.) in a tropical dry forest in Madagascar. We found no lag in the daily onset of sap flow between the base and the crown of the tree. Some night-time sap flow occurred, but this was more consistent with a pattern of seasonal stem water replenishment than with diurnal usage. Intrinsic capacitance of both leaf and stem tissue (0.07–0.08 and 1.1–1.43 MPa−1, respectively) was high, yet the amount of water that could be withdrawn before turgor loss was small because midday leaf and stem water potentials (WPs) were near the turgor-loss points. Stomatal conductance was high in the daytime but then declined rapidly, suggesting an embolism-avoidance strategy. Although the xylem of distal branches was relatively vulnerable to cavitation (P50: 1.1–1.7 MPa), tight stomatal control and minimum WPs near −1.0 MPa maintained native embolism levels at 30–65%. Stem morphology and anatomy restrict water movement between storage tissues and the conductive pathway, making stored-water usage more appropriate to longer-term water deficits than as a buffer against daily water deficits. [ABSTRACT FROM AUTHOR]

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Cover description: Malagasy communities call the baobab tree the “mother of the forest,” as it plays an essential role in the local ecosystem and also as the seeds and the bark are used by local communities for making oil and ropes. Six out of the eight species of baobab in the world are endemic to Madagascar, and all six are classifi ed as threatened. Many of the baobabs in Madagascar have survived in sacred sites. [ABSTRACT FROM AUTHOR]