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RICARDO BARRAGAN CELESTINA GONZALEZ-ARREOLA ANA BERTHA VILLASEÑOR 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2004,37(3):223-234
Analyses of ammonite shell forms of two Barremian stratigraphic sections from Southwest Mexico consist of two well-defined morphotypes: (1) Small uncoiled, mostly leptoceratoid ancyloconic shells of the families Ancyloceratidae and Hamulinidae, and (2) middle-sized involute to moderately evolute oxycone to discocone shells of the family Pulchelliidae. Index taxa allow the recognition of standard ammonite biozones for the Barremian, which permit the relative dating of different processes that occurred through the water column in the environment of deposition. The vertical distribution of ammonite morphotypes and facies suggests changes of the palaeoceanographic and sedimentological conditions that prevailed in the area during Barremian time. Petrologic data, analyses of the organic carbon and carbonate contents of the rocks support the idea that oxygen-deficient bottom waters existed within a shallow marine, tectonically active area with little carbonate deposition during the early early Barremian (upper part of the Taveraidiscus hugii Zone through the base of the Nicklesia pulchella Zone). These conditions in the basin caused a proliferation of middle-water depth ammonites of Morphotype 1 but prevented the abundance of nektobenthic forms of Morphotype 2. Oxic conditions on a more calcareous and open normal marine environment seem to have been reestablished progressively during a transgressive episode from late early-early late Barremian (upper part of the Nicklesia pulchella Zone through the Gerhardtia sartousiana Zone). This environmental setting supported more facies dependent nektobenthic ammonites of Morphotype 2 to flourish within the basin. 相似文献
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Andrinajoro A. Rakotoarivelo Mahefatiana Ralisata Olga Ramilijaona Ravoahangimalala Marlène R. Rakotomalala Paul A. Racey Richard K. B. Jenkins 《African Journal of Ecology》2009,47(3):283-288
Hipposideros commersoni is a large microchiropteran bat endemic to Madagascar. We analysed fragments of its prey from faeces and from underneath feeding perches to describe its diet from four sites. Diet was similar across sites and Coleoptera was the main prey item by percentage volume (75%), followed by Hemiptera (13%). Carabidae and Scarabidae were the most frequent coleopterans found in the diet. Direct observations (n = 3) were made of bats flying short distances from perches along forest trails to prey on Cicadidae ( c. 20 mm in length) located on tree trunks. There were differences in the composition of faecal samples collected form netted bats and pellets collected under feeding perches, with the latter consisting of more Blattoptera (Blattellidae 'cockroaches'). Hipposideros commersoni appears to have a unique foraging behaviour and diet among Malagasy microchiropterans and its preference for certain Coleoptera and other large invertebrates may account for reported seasonal variation in body fattening and activity. 相似文献
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Andoniaina R. Andrianaivoarivelo Gary D. Shore Susie M. McGuire Richard K. B. Jenkins Olga Ramilijaona Edward E. Louis Jr. Rick A. Brenneman 《Conservation Genetics》2009,10(4):1025-1028
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. 相似文献
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Manjaka A. Ramanana Carolyn A. Bailey Gary D. Shore Olga Ramilijaona Rick A. Brenneman Edward E. Louis Jr. 《Conservation Genetics》2009,10(6):1953-1956
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. 相似文献
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Soanandrasana Rahelinirina Jean‐Marc Duplantier Mamy Ratsimba Jocelyn Ratovonjato Olga Ramilijaona Yves Papillon Lila Rahalison 《African Journal of Ecology》2010,48(3):662-666
The black rat is the main plague reservoir in rural foci in Madagascar, inside the villages as well as in the cultivated areas around. We have evaluated the potentialities of mass‐marking of rats, using baits containing Rhodamine B (RB) in order to get a tool to study the movements of rats and to understand the spread of plague. Laboratory experiments demonstrated that: (i) rats were more attracted by the rodent granules and peanut butter; (ii) incorporation of RB in baits did not reduce their appetence; (iii) RB lasted for 60 days in rat vibrissae and 180 days in rat hairs; and (iv) consumption of baits during a week was under the lethal dose. Field tests have been realized comparatively among 24 highland villages where plague is endemic, in different contexts: baits inside houses or around the village, baits with and without RB, rats captured 1, 2 and 3 months after the marking. No negative effect of the RB on population dynamics of rats or fleas on them was observed. The effectiveness of the marking was comparable between males and females. This technique of collective marking appears very valuable for monitoring rat movements in plague foci. 相似文献
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Abstract
The phylogenetic diversity of bacteria and cyanobacteria colonizing sediment particles in the permanent ice cover of an Antarctic
lake was characterized by analyses of 16S rRNA genes amplified from environmental DNA. Samples of mineral particles were collected
from a depth of 2.5 m in the 4-m-thick ice cover of Lake Bonney, McMurdo Dry Valleys, Antarctica. A rRNA gene clone library
of 198 clones was made and characterized by sequencing and oligonucleotide probe hybridization. The library was dominated
by representatives of the cyanobacteria, proteobacteria, and Planctomycetales, but also contained diverse clones representing
many other microbial groups, including the Acidobacterium/Holophaga division, the Green Non-Sulfur division, and the Actinobacteria. Six oligonucleotide probes were made for the most abundant
clades recovered in the library. To determine whether the ice microbial community might originate from wind dispersal of the
algal mats found elsewhere in Taylor Valley, the probes were hybridized to 16S rDNAs amplified from three samples of terrestrial
cyanobacterial mats collected at nearby sites, as well as to bacterial 16S rDNAs from the lake ice community. The results
demonstrate the presence of a diverse microbial community dominated by cyanobacteria in the lake ice, and also show that the
dominant members of the lake ice microbial community are found in terrestrial mats elsewhere in the area. The lake ice microbial
community appears to be dominated by organisms that are not uniquely adapted to the lake ice ecosystem, but instead are species
that originate elsewhere in the surrounding region and opportunistically colonize the unusual habitat provided by the sediments
suspended in lake ice.
Received: 16 August 1999; Accepted: 28 December 1999; Online Publication: 28 April 2000 相似文献
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Björn M. Siemers Holger R. Goerlitz Eric Robsomanitrandrasana Marcus Piep Jean-Baptiste Ramanamanjato Daniel Rakotondravony Olga Ramilijaona Jörg U. Ganzhorn 《International journal of primatology》2007,28(2):291-304
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. 相似文献