Micrometeorites are dust-sized (i.e., 10 to 2000 µm in size) extraterrestrial particles reaching the Earth’s surface [1]. We report the discovery of hundreds of micrometeorites during the 2017-2018 BELAM (Belgian Antarctic Meteorites) expedition that took place in the south to south-east area up to 40 km away from the Belgian Princess Elisabeth Station (71°57Ļ00ļS; 23°20Ļ49ļE). Two types of micrometeorite traps were targeted on the glacially eroded tops of Vengen, Walnumfjellet, Widerøfjellet, Svindland and Smalegga Mountains, consisting of 1/ seven samples of soils that have potentially been exposed for long periods of times (up to several Ma), similarly to samples collected in the Atacama Desert [2] and 2/ five samples of wind catchment areas, such as the base of large boulders or within cracks. The lee-sides of three lateral and supraglacial moraines were also sampled, totalling eleven samples. In all cases, the sampled material, weighing 80 kg, consisted of moderately sorted finegrained rock detritus. Preliminary results suggest that the distribution of micrometeorites varies according to the type of trap, with glacial moraines exhibiting the lowest concentrations, followed by wind-catchment areas and soils from the top of the glacially eroded summits of mountains. Samples exposed on the border of the Sør Rondane Mountains with the Antarctic Plateau exhibit concentrations one order of magnitude greater than in moraines. Similarly to the Larkman Nunatak micrometeorite collection [3], the micrometeorite accumulation mechanism in moraine and wind-catchment areas seems to be mainly controlled by wind. Conversely, direct infall of micrometeorites may contribute significantly as an accumulation mechanism in exposed soil samples, as evidenced by the presence of large micrometeorites (>400 µm in size). Thus, this new collection, comprising various sampling site types, may serve as the basis to understand micrometeorite distribution patterns in Antarctica.
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RBINS Staff Publications 2018
Terrestrial pulmonate slugs are hermaphroditic and often are capable of both outcrossing and self-fertilization. This mixed breeding system may severely affect population genetic structuring and taxonomic differentiation. Currently little is known about the breeding system(s) of Banana slugs (Ariolimax), a group of taxonomically ill-defined slugs living along the West Coast of North America, from California to southern Alaska. Based on genital morphology and mtDNA sequence data (COI, 16S and CytB), the genus Ariolimax is nowadays interpreted as a group of eight species level taxa, viz Ariolimax columbianus, A. buttoni, A. stramineus, A. californicus, A. dolichophallus, A. brachyphallus and two undescribed species. These species ap-pear to be closely related as 19 microsatellite DNA loci identified from A. californicus consistently amplify in all of the de-scribed taxa and share many alleles. Hence, these microsatellites can help to clarify Ariolimax taxonomy. To this end, four microsatellite loci were used to study potential interspecific crosses of A. californicus x A. dolichophallus. This showed that none of these crosses produced hybrid offspring and that A. californicus reveals multiple paternity under natural conditions. Conversely, a panel of 28 microsatellites applied to cross-breeding experiment between two populations of A. buttoni, showed that all the parental specimens involved only three homozygous multilocus genotypes (MLG) and that offspring of pairs in which both parents had a different genotype, always were monomorphic for the same homozygous MLG of one of the parents. This confirms that A. buttoni is able to self-fertilize. Yet, to what extent self-fertilization is common in natural condi-tions remains to be investigated.
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