3,052 research outputs found
Where are you from, stranger? The enigmatic biogeography of North African pond turtles (Emys orbicularis) .
Abstract The European pond turtle (Emys orbicularis) is a
Nearctic element in the African fauna and thought to have
invaded North Africa from the Iberian Peninsula. All North
African populations are currently identified with the subspecies
E. o. occidentalis. However, a nearly range-wide sampling in
North Africa used for analyses of mitochondrial and microsatellite
DNA provides evidence that only Moroccan populations
belong to this taxon, while eastern Algerian and Tunisian pond
turtles represent an undescribed distinct subspecies. These two
taxa are most closely related to E. o. galloitalica with a native
distribution along the Mediterranean coast of northern Spain
through southern France to western and southern Italy. This
group is sister to a clade comprising several mitochondrial lineages
and subspecies of E. orbicularis from Central and Eastern
Europe plus Asia, and the successive sisters are E. o. hellenica
and E. trinacris. Our results suggest that E. orbicularis has been
present in North Africa longer than on the Iberian Peninsula and
that after an initial invasion of North Africa by pond turtles from
an unknown European source region, there was a phase of
diversification in North Africa, followed by a later re-invasion
of Europe by one of the African lineages. The differentiation of
pond turtles in North Africa parallels a general phylogeographic
paradigm in amphibians and reptiles, with deeply divergent
lineages in the western and eastern Maghreb. Acknowledging
their genetic similarity, we propose to synonymize the previously
recognized Iberian subspecies E. o. fritzjuergenobsti with E. o.
occidentalis sensu stricto. The seriously imperiled Moroccan
populations of E. o. occidentalis represent two Management
Units different in mitochondrial haplotypes and microsatellite
markers. The conservation status of eastern Algerian pond turtles
is unclear, while Tunisian populations are endangered.
Considering that Algerian and Tunisian pond turtles represent
an endemic taxon, their situation throughout the historical range
should be surveyed to establish a basis for conservation
measures
The study of luminophores base influence activated by europium on their acid-base and luminescent properties
Five samples of luminophores, activated by europium and synthesized by sol-gel and СВС methods were investigated. The researched samples have basic surface character, differing depending on the base of luminophor and percentage of europium. Excitation and photoluminescent spectra were obtained. Photoluminescent spectrum of the samples, containing Eu(III) ions have the similar character. They have 5 stripes with maximum at 580, 598, 622, 658 nm and the doublet with stripes at 702 and 706 nm which are referred to innerconfigurational 4f-4f transits if europium ion 7F0-5D4. The samples YVPO4(P10):Eu8% and YVO4:Eu10% have the most intense luminescence. Their intensity is about 60 times higher than the YPO4:Eu10% sample has
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Shock recovery experiments confirm the possibility of transferring viable microorganisms from Mars to Earth
Extract from introduction: With regard to the impact and ejection phase we tested the case for the transfer of microorganisms from Mars to Earth. Using a high explosive set-up thin layers of bacterial endospores of Bacillus subtilis, of the lichen Xanthoria elegans and of the cyanobacterium Chroococcidiopsis sp. embedded between two plates of gabbro were subjected to 10, 20, 30, 40 and 50 GPa which is the pressure range observed in Martian meteorites [1]
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Life after shock: the mission from Mars to Earth
Extract from introduction: The minerals of the Martian meteorites collected so far indicate an exposure to shock waves in the pressure range of 5 to 55 GPa [1]. As terrestrial rocks are frequently inhabited by microbial communities, rocks ejected from a planet by impact processes may carry with them endolithic microorganisms, if microbial life existed/exists on this planet
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Impact experiments in support of “Lithopanspermia”: The route from Mars to Earth
Shock recovery experiments on a Martian analogue rock (gabbro) loaded with three types of microorganisms reveal that these organisms survive the impact and ejection phase on Mars at shock pressures up to about 50 GPa with exponentially decreasing survival rates
Stand out from the crowd: Small-scale genetic structuring in the endemic sicilian pond turtle
The geographical pattern of genetic diversity was investigated in the endemic Sicilian pond turtle Emys trinacris across its entire distribution range, using 16 microsatellite loci. Overall, 245 specimens of E. trinacris were studied, showing high polymorphic microsatellite loci, with allele numbers ranging from 7 to 30. STRUCTURE and GENELAND analyses showed a noteworthy, geographically based structuring of the studied populations in five well-characterized clusters, supported by a moderate degree of genetic diversity (FST values between 0.075 and 0.160). Possible explanations for the genetic fragmentation observed are provided, where both natural and human-mediated habitat fragmentation of the Sicilian wetlands played a major role in this process. Finally, some conservation and management suggestions aimed at preventing the loss of genetic variability of the species are briefly reported, stressing the importance of considering the five detected clusters as independent Management Units
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The influence of shock pressure, pre-shock temperature, and host rock composition on the survival rate of endolithic microorganisms during impact ejection from Mars
Petrographic and biological analysis of shock recovery experiments confirms the possible life transport due to an impact from Mars to Earth
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