Madagascar Dry Forest Research Articles

Hot bats change torpor game rules

In just the same way that turning off the furnace in your house in the middle of a cold winter night causes the property to cool, when hibernating mammals stop generating heat during winter to conserve energy, their temperature also drops to match that of their environment. But not all animals turn down the inner thermostat for an entire season. A shorter version of hibernation is torpor, where animals stop keeping their body warm for a few hours or days when it is cold or when food is scarce. However, most of our understanding of how animals use torpor has been gleaned from research done in colder regions, where there is little spare heat and an animal's body temperature drops as soon as they turn down their inner furnace. But what happens when animals resort to this form of energy conservation in warmer climes? Stephanie Reher and Kathrin Dausmann, from the University of Hamburg, Germany, recently studied a species of bat (Macronycteris commersoni) in Madagascar and found that when these bats slow down their rate of energy usage, their body temperature actually increases.Reher and Dausmann found this new flavour of torpor by measuring both the bats’ skin temperature and metabolism when the animals were resting during the day. Unexpectedly, their skin temperature increased when the bats reduced their metabolism. In other words, the bats had been actively using energy to stay cooler than the surrounding air temperatures, and as soon they stopped putting effort in, their bodies heated up. In fact, the air temperature in the dry forests of Madagascar is often hotter than the bat's body temperature, sometimes as high as 41°C, and the bats’ body temperatures even reached 42.9°C on one occasion. Reher and Dausmann think that this ‘hot torpor’ saves the bats energy and allows them to better tolerate hotter temperatures.In addition to this unusual form of torpor, the bats did a second unique thing on cooler days, around 34°C; some bats entered many micro-spells of torpor throughout their daytime resting period, almost like cat-napping when you are supposed to be listening to a presentation. During these micro-spells of torpor, the bats used less energy, essentially pausing their metabolism for only a few minutes at a time (3–53 min). Because these micro-spells were so short, the body temperature did not have time to reach that of the local air; it only changed a little, shifting toward the air temperature. The researchers think this penny-pinching attitude saves the bats energy over time, but allows them to remain alert to any threats while they are roosting, compared with traditional lengthier periods of torpor when bats are lethargic or even unconscious – imagine being woken from a very deep sleep.In addition, this discovery of a novel mode of torpor reveals the importance of studying species in the tropics, where high temperatures can cause major physiological differences relative to species that reside in cooler climes. This finding, that some species do not follow the traditional rules of torpor, may also suggest that the rules were not right to begin with. The fact that body temperatures can increase when the metabolism is reduced may force us to reconsider our previous understanding of torpor and rewrite what, until now, was an accepted rule of thermal physiology.

A Synthetic Butenolide Diterpene is now a Natural Product Isolated from Metaporana sericosepala, a Plant from the Madagascar Dry Forest [1a

Antiproliferative bioassay-guided fractionation of the ethanolic extract of the endemic Madagascan plant Metaporana sericosepala led to the first natural product isolation of a butenolide diterpene, which was synthesized during an anti-inflammatory study in 1988. The structure of the compound was elucidated as 3-homofarnesyl-4-hydroxybutenolide (1) by analysis of its spectroscopic data, including 1D- and 2D-NMR data and chemical evidence. The once synthetic compound can now also be considered as a natural product. Compound 1 had modest antiproliferative activity towards the A2780 ovarian cancer cell line,with an IC50 value of 8 µM.

Antiproliferative Diterpenes from a Malleastrum sp. from the Madagascar dry forest [1

An ethanol extract of leaves of the plant species Malleastrum sp. collected in northern Madagascar afforded the new clerodane diterpene 18-oxo-cleroda-3,13-dien-16,15-olide (1), together with the three known clerodane diterpenes 16,18-dihydroxykolavenic acid lactone (2), solidagolactone (3) and (-)-kolavenol (4), and the known labdane diterpene 3-oxo-ent-Iabda-8(17),13-dien-15,16-olide (5). Compounds 1, 3, and 4 showed moderate antiproliferative activities against the A2780 ovarian cancer cell line, with the IC50 values of 3.01 ± 0.8, 7.84 ± 0.2, and 17.9 ± 3 µM, respectively. The structure elucidations of all compounds were carried out based on analysis of NMR and mass spectroscopic data. The relative stereochemistry of compound 1 was determined by NOESY NMR spectrum.

Calling Activity of an Anuran Assemblage in a Temporary Pond in a Dry Forest of Madagascar

Abstract: Temporary pools are important resources for animals that have aquatic stages during their life history, and particularly for those living in dry climate regions. We investigated the breeding activity of an anuran assemblage in a small temporary pond in the Ampijoroa dry forest of Ankarafantsika National Park, northwestern Madagascar, during the first half of the rainy season from 2000 to 2001 and during the entire rainy season and the beginning of the dry season from 2003 to 2004. We also surveyed the anuran fauna of Ampijoroa throughout the long-term research conducted from 1999 to 2014. We estimated the breeding activity based on the calling intensity of male frogs. A total of 12 species of frogs was recorded, and eight out of them were confirmed to breed in the temporary pond. These eight species consisted of five families, including one introduced species. The initiation of calling activity seemed to be affected by rainfall in several species. Five of the eight species (Ptychadena mascarenie...

A New Species of Operculicarya H. Perrier (Anacardiaceae) from Western Dry Forests of Madagascar

Abstract Randrianasolo, A. & P. P. Lowry II (2015). A new species of Operculicarya H. Perrier (Anacardiaceae) from western dry forest of Madagascar. Candollea 70: 57–60. In English, English and French abstracts. A new species of Operculicarya H. Perrier (Anacardiaceae) is described from material collected in dry forest on karstic limestone in western Madagascar, bringing the total number of species in the genus to nine. Operculicarya calcicola Randrian. & Lowry is distinguished from the other members of the genus by the size and shape of its leaves and leaflets, the structure of its infructescence, and the size of its fruits. An illustration is provided along with a distribution map and preliminary assessment of its risk of extinction following the IUCN Red List criteria, which indicates a status of Least Concern.

Bioactive Oleanane Glycosides from Polyscias duplicata from the Madagascar Dry Forest [1

As part of the International Cooperative Biodiversity Group (ICBG) program, in a search for antiproliferative compounds, an ethanol extract of Polyscias duplicata was investigated due to its antiproliferative activity against the A2780 human ovarian cell cancer line (IC50 6 µg/mL). Seven known oleanane glycosides, 3β-[(α-L-arabinopyranosyl)oxy]-16α-hydroxyolean-12-en-28-oic acid (1, IC50 8 µM), 3β-[(α-L-arabinopyranosyl)oxy]-16α,23-dihydroxyolean-12-en-18-oic acid (2, IC50 13 µM), 3β-[(O-β-D-glucopyranosyl-(t-->3)-α-L-arabinopyranosyl)oxy]-16α-hydroxyolean-12-en-28-oic acid (3, IC50 7 µM), 3β-[(O-α-L-rhamnopyranosyl-(1-2)-α-L-arabinopyranosyl)oxy]-16α-hydroxyolean-12-en-28-oic acid (4, IC50 2.8 µM), 3β-[(O-β-D-glucopyranosyl-(l-->3)-α-L- arabinopyranosyl)oxy]-23-hydroxyolean-12-en-28-oic acid (5, IC50 10 µM), β-[(O-α-L-rhamnopyranosyl-(-1.2)-α-L-arabinopyranosyl)oxy]-23-hydroxyolean-12-en-28-oic acid (6, IC50 3.4 µM), and 3β-[(α-L-arabinopyranosyl)oxy]-23-hydroxyolean-12-en-28-oic acid (7, IC50 3.4 µM) were isolated, and their structures determined using spectroscopic methods.

Antiproliferative compounds from Ocotea macrocarpa from the Madagascar dry forest

Bioassay-directed fractionation of an antiproliferative ethanol extract of the roots of Ocotea macrocarpa (Lauraceae) afforded the new butanolide macrocarpolide A (1), and the two new secobutanolides macrocarpolides B (2) and C (3), together with the known butanolides linderanolide B (4), and isolinderanolide (5). The structure elucidation of all compounds was carried out based on NMR and mass spectroscopic data analyses. The absolute configurations of all compounds isolated were determined by comparison of their optical rotation values with those found in literature. Compounds 1–5 showed good antiproliferative activities against the A2780 ovarian cell line, with IC50 values of 2.57±0.12 (1), 1.98±0.23 (2), 1.67±0.05 (3), 2.43±0.41 (4), and 1.65±0.44μM (5), respectively.

Feeding Behavior on Tree Sap and Planthopper-derived Honeydew by a Fish-scale Gecko (Geckolepissp.) in a Dry Forest of Madagascar

Abstract: Although most geckos are carnivorous, a number of examples of occasional observations on plant consumption have been reported in recent years. Moreover, previous research has reported that several Madagascan geckos lick honeydew excreted from planthoppers. Here, I report feeding on tree sap and honeydew by Geckolepis sp., a fish-scale gecko from northwestern Madagascar. Although, in the previous report, the planthopper showed specific abdomen movement after stimulation by a gecko, the planthopper and the gecko in my observation did not show any specific behavioral interaction. Honeydew milking without a specialized behavioral interaction, which was observed in Geckolepis sp., might be the intermediate stage of the evolutionary transition from simple feeding on plant sap to the highly specialized behavioral interaction that enhances honeydew milking.

Bioactive compounds from Stuhlmannia moavi from the Madagascar dry forest

Bioassay-directed fractionation of the leaf and root extracts of the antiproliferative Madagascar plant Stuhlmannia moavi afforded 6-acetyl-5,8-dihydroxy-2-methoxy-7-methyl-1,4-naphthoquinone (stuhlmoavin, 1) as the most active compound, with an IC50 value of 8.1μM against the A2780 human ovarian cancer cell line, as well as the known homoisoflavonoid bonducellin (2) and the stilbenoids 3,4,5′-trihydroxy-3′-methoxy-trans-stilbene (3), piceatannol (4), resveratrol (5), rhapontigenin (6), and isorhapontigenin (7). The structure elucidation of all compounds was based on NMR and mass spectroscopic data, and the structure of 1 was confirmed by a single crystal X-ray analysis. Compounds 2−5 showed weak A2780 activities, with IC50 values of 10.6, 54.0, 41.0, and 74.0μM, respectively. Compounds 1−3 also showed weak antimalarial activity against Plasmodium falciparum with IC50 values of 23, 26, and 27μM, respectively.

Antiproliferative and antiplasmodial dimeric phloroglucinols from Mallotus oppositifolius from the Madagascar Dry Forest (1).

Bioassay-guided fractionation of an ethanol extract of the leaves and inflorescence of Mallotus oppositifolius collected in Madagascar led to the isolation of the two new bioactive dimeric phloroglucinols mallotojaponins B (1) and C (2), together with the known mallotophenone (3). The structures of the new compounds were determined on the basis of spectroscopic evidence, including their 1D- and 2D-NMR spectra, mass spectrometry, and an X-ray crystal structure. Compounds 1 and 2 showed potent antimalarial activity against chloroquine-resistant Plasmodium falciparum, with IC50 values of 0.75 ± 0.30 and 0.14 ± 0.04 μM, while 3 was inactive in this assay. Compounds 1-3 also displayed strong antiproliferative activity against the A2780 human ovarian cancer cell line (IC50 1.10 ± 0.05, 1.3 ± 0.1 and 6.3 ± 0.4 μM, respectively).

Antiproliferative compounds from the fabaceae family from the Madagascar dry forest

As a part of the International Cooperative Biodiversity Group (ICBG) program, ethanol extracts of the leaves and roots of a plant initially identified as Bussea sakalava (Fabaceae) were selected for evaluation as potential anticancer agents based on activity against the A2780 ovarian cancer cell line. Recent taxonomic studies have indicated that the plant is not B. sakalava. Bioassay-directed fractionation of the leaf extract afforded the new naphthoquinone (1), and a combination separation methods on the root extract afforded the known isoflavonoid bonducellin (2), one new stilbenoid (3) and the four known stilbenoids piceatannol (4), resveratrol (5), rhapontigenin (6), and isorhapontigenin (7). The structure elucidations of all compounds were based on NMR spectra and mass spectroscopic data, and the structure of 1 was confirmed by single crystal X-ray analysis. Compounds 1-5 showed antiproliferative activity against the A2780 human ovarian cancer cell line as shown.

Isolation, synthesis, and bioactivity of Calamenene sesquiterpenoids from Sterculia Capuronii from the Madagascar dry forest

Isolation, synthesis, and bioactivity of Calamenene sesquiterpenoids from Sterculia Capuronii from the Madagascar dry forest

Antiproliferative acetogenins from a Uvaria sp. from the Madagascar dry forest.

Investigation of the endemic Madagascan plant Uvaria sp. for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of two new acetogenins. The structures of these two compounds were elucidated on the basis of analysis of their 1D and 2D NMR spectra, circular dichroism, and mass spectrometric data, together with chemical modification. The two acetogenins display weak antiproliferative activity against the A2780 ovarian cancer, the A2058 melanoma, and the H522 lung cancer cell lines.

Astrotricoumarin, an antiproliferative 4′-hydroxy-2′,3′-dihydroprenylated methylcoumarin from an Astrotrichilia sp. from the Madagascar dry forest[1

Bioassay guided fractionation of the ethanol extract of a new endemic species of the genus Astrotrichilia led to the isolation of the new antiproliferative 3-(4'-hydroxy-2',3'-dihydroprenyl)-4,6-dimethoxy-5-methylcoumarin, named astrotricoumarin (8) with an IC50 value of 6.8 microM against the A2780 cell line. The structure of compound 8 was elucidated on the basis of its physical and spectroscopic data, including extensive 1D- and 2D-NMR analysis.

Antiproliferative compounds from Pongamiopsis pervilleana from the Madagascar Dry Forest.

Bioassay-guided fractionation of an ethanol extract of the roots of the endemic Malagasy plant Pongamiopsis pervilleana led to the isolation of the three new compounds (2'R)-4'-hydroxyemoroidocarpan (1), pongavilleanine (3), and epipervilline (4) together with two known compounds, identified as emoroidocarpan (2) and rotenolone (5). The structures of all compounds were determined by physical, chemical, and spectroscopic evidence. The stereochemistry at C-2' of the previously reported compound emoroidocarpan was determined to be R by the observation of a negative Cotton effect at 474 nm in the CD spectrum of its osmate ester derivative. Compounds 2-5 displayed moderate antiproliferative activity against the A2780 human ovarian cancer cell line, and rotenolone also showed micromolar antiproliferative activity toward the breast cancer BT-549, prostate cancer DU 145, NSCLC NCI-H460, and colon cancer HCC-2998 cell lines.

Saponins and a lignan derivative of Terminalia tropophylla from the Madagascar Dry Forest

A study of an EtOH extract obtained from the roots of the Madagascan plant Terminalia tropophylla H. Perrier (Combretaceae) led to isolation of the oleanane-type triterpenoid saponin 1, the lignan derivative 2, and the two known saponins arjunglucoside I ( 3) and sericoside ( 4). The structures of compounds 1 (terminaliaside A) and 2 (4′- O-cinnamoyl cleomiscosin A) were elucidated using 1D and 2D NMR experiments and mass spectrometry. Compound 1 showed antiproliferative activity against the A2780 human ovarian cancer cell line with an IC 50 value of 1.2 μM.

Morphometric Variation and Phylogeographic Structure in Macrotarsomys bastardi (Rodentia: Nesomyidae), an Endemic Malagasy Dry Forest Rodent

Recent field and revisionary studies of Madagascar's endemic rodents (Muroidea: Nesomyidae: Nesomyinae) have dramatically improved our understanding of species-level diversity within this group. However, such studies have generally focused on taxa from the island's relatively well-studied eastern humid forests and have relied solely on morphometric comparisons. Herein, we undertake a study of morphometric and genetic variation within Macrotarsomys bastardi, a rodent endemic to Madagascar's dry forest habitats. In particular, we evaluate existing subspecific boundaries using comparisons of cranial and external measurements from 84 museum specimens. We then assess phylogeographic structure across the geographic range of the species using sequence variation in the mitochondrial cytochrome-b gene from a subset of these specimens. We conclude that there is little basis for recognizing established subspecies, but that molecular data reveal novel patterns of diversity and geographic structure within this species. These results, coupled with emerging patterns of diversity in other endemic Malagasy mammals, suggest that there is underestimated diversity and biogeographic structure within Madagascar's western habitats.

The impact of burning on the microhabitat used by two species of couas in the western dry forest of Madagascar

Habitat structure — an important consideration in all ecological studies of relationships between animals and their environment — can be studied at different scales. This topic was studied at the microhabitat scale in burned and unburned plots of a dry forest of Madagascar. The response of two endemic terrestrial coua (Coua coquereli and C. ruficeps) to burning was studued, at a microhabitat scale (involving the definition of several microhabitat variables relating to foraging sites of the two species), by comparing burned and unburned plots in a dry forest of Madagascar. There were significant differences between burned and unburned plots in terms of the microhabitat variables that were measured. The two species responded differently to the burning effect. In unburned forest, Coquerel's Coua (Coua coquereli) was restricted to places where tree dispersion and stem density were the most important variables in their foraging sites. The Redcapped Coua Coua ruficeps foraged more often at places where understorey vegetation was not well developed. Burning was not beneficial for Coquerel's Coua, because this species was restricted to favourable foraging sites and had to increase its territory size to find its food. Burning may be favourable for the Red-capped Coua, by increasing prey detectability.

Natural history of Phelsuma madagascariensis kochi from a dry forest in Madagascar

AbstractNatural history of the diurnal gecko, Phelsuma madagascariensis kochi, was investigated with mark-and-recapture and census methods from the end of the dry season to the middle of the rainy season in a dry forest of Madagascar. Males were larger than females in snout-vent length, tail length, and body mass, and also had relatively larger head widths. Hatchlings were observed only in the rainy season. The geckos passively followed ambient temperatures, rarely basked, but had lower cloacal temperature than air temperature at high air temperatures. They preferred high and thick trees. The frequency of sighting decreased in the rainy season. Foraging mode was sit-and-wait. Home ranges of male P. madagascariensis kochi did not overlap with each other, but partially overlapped with those of females and unsexed individuals. Several ecological traits of P. madagascariensis kochi such as male-biased sexual size dimorphism and possible home range defense, seemed more similar to those of diurnal, arboreal lizards (some iguanids and agamids) relying on the visual modality, rather than to those of nocturnal geckos.

The impacts of logging on the microhabitats used by two species of couas in the western forest of Madagascar

Habitat structure is important to consider in all ecological studies considering the relationships between animals and their environment. Habitat structure can be studied at different scales, from landscape to microhabitat. I studied here the response of two endemic terrestrial birds living in the dry forest of Madagascar. These birds belong to the genus Coua. The study is made at the microhabitat scale in a gallery forest, which has been logged selectively in order to limit the degradation of the forest. Selective logging is promoted to be respectful of the environment by allowing us to exploit the forest without destroying it and the wildlife encountered here. At the microhabitat scale, I underline that selective logging does not affect the Coquerel's coua, which can exploit new microhabitats and increase its density. On the other hand, the giant coua was affected by the restriction of optimal microhabitats for foraging. This species could be adapted to the new habitat by modifying its favourite foraging sites, but by decreasing also the population density. This species was affected by forest degradation, even considered as not destroying. At last, I considered how Coquerel's coua could be used as umbrella species for the endangered mesite. To cite this article: P. Chouteau, C. R. Biologies 327 (2004).