Olga Ramilijaona

Evidence for recent gene flow between north-eastern and south-eastern Madagascan poison frogs from a phylogeography of the Mantella cowani group

BackgroundThe genus Mantella, endemic poison frogs of Madagascar with 16 described species, are known in the field of international pet trade and entered under the CITES control for the last four years. The phylogeny and phylogeography of this genus have been recently subject of study for conservation purposes. Here we report on the studies of the phylogeography of the Mantella cowani group using a fragment of 453 bp of the mitochondrial cytochrome b gene from 195 individuals from 21 localities. This group is represented by five forms: M. cowani, a critically endangered species, a vulnerable species, M. haraldmeieri, and the non-threatened M. baroni, M. aff. baroni, and M. nigricans.ResultsThe Bayesian phylogenetic and haplotype network analyses revealed the presence of three separated haplotype clades: (1) M. baroni, M. aff. baroni, M. nigricans, and putative hybrids of M. cowani and M. baroni, (2) M. cowani and putative hybrids of M. cowani and M. baroni, and (3) M. haraldmeieri. The putative hybrids were collected from sites where M. cowani and M. baroni live in sympatry.ConclusionThese results suggest (a) a probable hybridization between M. cowani and M. baroni, (b) a lack of genetic differentiation between M. baroni/M. aff. baroni and M. nigricans, (c) evidence of recent gene-flow between the northern (M. nigricans), eastern (M. baroni), and south-eastern (M. aff. baroni) forms of distinct coloration, and (d) the existence of at least three units for conservation in the Mantella cowani group.

The Challenge of Conserving Amphibian Megadiversity in Madagascar

Highly diverse and so far apparently untouched by emergent diseases, Malagasy frogs nevertheless are threatened by ongoing habitat destruction, making pro-active conservation actions especially important for preserving this unique, pre-decline, amphibian fauna.

Sensory Basis of Food Detection in Wild Microcebus murinus

Very little is known about how nocturnal primates find their food. Here we studied the sensory basis of food perception in wild-caught gray mouse lemurs (Microcebus murinus) in Madagascar. Mouse lemurs feed primarily on fruit and arthropods. We established a set of behavioral experiments to assess food detection in wild-born, field-experienced mouse lemurs in short-term captivity. Specifically, we investigated whether they use visual, auditory, and motion cues to find and to localize prey arthropods and further whether olfactory cues are sufficient for finding fruit. Visual cues from motionless arthropod dummies were not sufficient to allow reliable detection of prey in choice experiments, nor did they trigger prey capture behavior when presented on the feeding platform. In contrast, visual motion cues from moving prey dummies attracted their attention. Behavioral observations and experiments with live and recorded insect rustling sounds indicated that the lemurs make use of prey-generated acoustic cues for foraging. Both visual motion cues and acoustic prey stimuli on their own were sufficient to trigger approach and capture behavior in the mouse lemurs. For the detection of fruit, choice experiments showed that olfactory information was sufficient for mouse lemurs to find a piece of banana. Our study provides the first experimental data on the sensory ecology of food detection in mouse lemurs. Further research is necessary to address the role of sensory ecology for food selection and possibly for niche differentiation between sympatric Microcebus species.

SEASONAL FOOD HABITS OF FIVE SYMPATRIC FOREST MICROCHIROPTERANS IN WESTERN MADAGASCAR

Abstract We determined the foods habits of 5 species of microchiropteran bats (Hipposideros commersoni, Triaenops rufus, Triaenops furculus, Myotis goudoti, and Miniopterus manavi) in the austral winter and summer in a dry deciduous forest in western Madagascar using fecal analysis. We also assessed food availability and bat activity in 4 forest microhabitats. Despite overlap in dietary composition, H. commersoni consumed mainly Coleoptera; M. goudoti consumed mainly Hymenoptera, Neuroptera, and Araneae; M. manavi consumed mainly Hemiptera; and T. rufus and T. furculus consumed mainly Lepidoptera. Diptera were the most abundant insects in traps but were rarely encountered in feces. H. commersoni was not netted during the austral winter, but the other 4 species changed their diet according to seasonal availability, with lepidopterans the most important diet items in winter and coleopterans in summer. We consistently trapped a higher abundance of potential bat prey at the forest edge, whereas the forest interior was low in both food availability and bat activity. The 5 microchiropterans studied partitioned the available food mainly through dietary specialization, although spatial and temporal partitioning also may play a role. More research is needed to assess levels of dependency on forest by these bats, and to investigate the seasonal ecology of H. commersoni and interspecific competition between T. rufus and T. furculus.

Individual variation in alkaloid content of poison frogs of Madagascar (Mantella; Mantellidae).

Brightly colored Malagasy poison frogs, Mantella spp., sequester lipophilic, basic alkaloids from arthropod prey for their own chemical defense. Consequently, microsympatric prey diversity is expected to influence alkaloid diversity observed in poison frogs. Twenty-two specimens of three Mantella species from four localities in moist forests of southeastern Madagascar were analyzed individually via gas chromatography-mass spectrometry, revealing that they contain over 80 known alkaloids. Frogs within a locality possessed significantly similar alkaloid content and diversity, while frogs from areas that varied in disturbance, elevation, and/or species showed greater differences. Based on dietary data, the larger frog species Mantella baroni consumed more and larger prey, and showed greater diversity in skin alkaloids than significantly smaller Mantella bernhardi. Additionally, frogs from the most pristine locality had the greatest number of alkaloids, whereas individuals from the most disturbed localities had the least. In a comparison of frog alkaloid profiles over a 10- to 14-yr period, alkaloid turnover, and thus presumably alkaloid-source arthropod turnover, was high in a disturbed locality and low in the pristine primary forest locality. We demonstrate that the nonlethal transcutaneous amphibian stimulator (TAS) is effective for harvesting alkaloids from poison frogs; future studies using this device could obtain larger sample sizes without harming local frog populations.

Feeding ecology, habitat use and reproduction of Rousettus madagascariensis Grandidier, 1928 (Chiroptera: Pteropodidae) in eastern Madagascar

Abstract We studied the diet, habitat use and biology of Rousettus madagascariensis, a relatively small (∼55–77 g) fruit bat endemic to Madagascar, between July 2004 and May 2005. Faecal analysis revealed few seeds in the diet, suggesting that the bats either feed extensively on nectar, flowers and leaves or on fruits with seeds too large to ingest. However, bats were captured near fruiting Ficus sp. inside relatively intact forest and Ficus sp. seeds were found in the faeces during March and April. Defecated Ficus rubra seeds germinated significantly faster than seeds from ripe fruits under controlled conditions, but germination rates were similar. Radio tracking and observations of light-tagged individuals revealed that R. madagascariensis travelled a straight line distance of at least 8 km between the roost and feeding locations, with round trip foraging routes of up to 27 km. Most juveniles were trapped between March and July and we infer that weaning of young started before 8 weeks of age. The features used to distinguish juveniles from adults were no longer evident in December and it appears therefore that R. madagascariensis reaches somatic maturity within a single year. Pregnancy, lactation and weaning in this species coincide with the austral summer when food availability is higher.

Characterization of 22 microsatellite marker loci in the Madagascar rousette (Rousettus madagascariensis)

Twenty-two nuclear microsatellite loci were isolated from a genomic DNA library derived from Madagascar’s Rousettus madagascariensis. Marker characteristics were determined from a single population (37 individuals) from Fort Dauphin (southeastern Madagascar). Sixteen of the 22 loci were within Hardy–Weinberg expectations. These loci are highly informative with polymorphic information content values ranging between 0.757 and 0.916. These loci will provide valuable information for the study of population genetics and gene flow within this species of bats. Due to the dramatic reduction and alteration of their habitat, data generated utilizing this marker suite will potentially provide additional information for the effective long-term management of this near-threatened bat species.

Characterization of 20 microsatellite marker loci in the Malagasy tree boa (Sanzinia madagascariensis madagascariensis)

The Madagascar tree boa, Sanzinia madagascariensis madagascariensis, is one of four snakes in the family Boidae living in Madagascar. This species is considered ‘vulnerable’ due to habitat loss and utilization as a food source by locals. Twenty species-specific microsatellite loci were isolated and characterized from Sanzinia m. madagascariensis to assess population genetic parameters. Individuals were collected from two populations in the east and the northeastern coast of Madagascar: Torotofotsy wetlands and Mananara-Nord Biosphere Reserve, respectively. This marker suite will provide a useful tool for future research to determine and validate the taxonomic status of the tree boa with samples collected extensively throughout the island.