Search results for "Glacial period"
showing 10 items of 196 documents
A new Diplura species from Georgia caves, Plusiocampa (Plusiocampa) imereti (Diplura, Campodeidae), with morphological and molecular data
2021
A new dipluran species, Plusiocampa (Plusiocampa) imereti Sendra & Barjadze sp. nov., from the deep zone in three caves in the Imereti region, Georgia, is described. This new troglobitic Plusiocampa is an addition to four others known Diplura from around the Black Sea region, two Dydimocampa and two Plusiocampa s. str. The present study also provides the first CO1 sequences for the Plusiocampinae taxa and the first molecular data for cave-dwelling Plusiocampa species. Although bootstrap values were low, the maximum-likelihood phylogenetic tree grouped Plusiocampa (P.) imereti Sendra & Barjadze sp. nov. with two Plusiocampa s. str. species from Eastern Europe. Morphologically, P. (P.…
Evidence for cryptic glacial refugia from North American mountain sheep mitochondrial DNA
2006
The separation of populations by ice sheets into large refugia can account for much of the genetic diversity found in present day populations. The evolutionary implications of small glacial refugia have not been as thoroughly explored. To examine refugial origins of North American mountain sheep Ovis spp., we analyzed a 604 bp portion of the mitochondrial DNA (mtDNA) control region from 223 O. dalli and O. canadensis. Major refugia were identified in eastern Beringia and southern North America, and we found evidence for two smaller refugia situated between the Laurentide and Cordilleran glaciers. Our results are the first to demonstrate support for survival of any organism in the latter two…
Submarine canyons of north-western Sicily (Southern Tyrrhenian Sea): Variability in morphology, sedimentary processes and evolution on a tectonically…
2014
Special issue Submarine Canyons: Complex Deep-Sea Environments Unravelled by Multidisciplinary Research.-- 13 pages, 11 figures, 2 tables
How complex is the evolution of small mammal communities during the Late Glacial in southwest France?
2016
11 pages; International audience; The Late Glacial was a slow gradual warming associated with short, cold events that occurred between 18.0 and 11.7 ka cal. BP. Pollen analyses from deep-sea and lacustrine cores have well documented the evolution of floral communities in western Europe and suggest that climatic fluctuations influenced the evolution of terrestrial ecosystems. However, the exact impact of these climate changes on small faunal communities in southwest France is still poorly documented. Peyrazet Cave is an archaeological site located in the Lot (France) that has been excavated since 2008 and has yielded a Late Glacial sequence dated between 15.5 and 11.1 ka cal. BP. Thousands o…
Genetic structure of wildcat (Felis silvestris) populations in Italy
2013
Severe climatic changes during the Pleistocene shaped the distributions of temperate-adapted species. These species survived glaciations in classical southern refuges with more temperate climates, as well as in western and eastern peripheral Alpine temperate areas. We hypothesized that the European wildcat (Felis silvestris silvestris) populations currently distributed in Italy differentiated in, and expanded from two distinct glacial refuges, located in the southern Apennines and at the periphery of the eastern Alps. This hypothesis was tested by genotyping 235 presumed European wildcats using a panel of 35 domestic cat-derived microsatellites. To provide support and controls for the analy…
Small ice particles at slightly supercooled temperatures in tropical maritime convection
2020
In this paper we show that the origin of the ice phase in tropical cumulus clouds over the sea may occur by primary ice nucleation of small crystals at temperatures just between 0 and −5 ∘C. This was made possible through use of a holographic instrument able to image cloud particles at very high resolution and small size (6 µm). The environment in which the observations were conducted was notable for the presence of desert dust advected over the ocean from the Sahara. However, there is no laboratory evidence to suggest that these dust particles can act as ice nuclei at temperatures warmer than about −10 ∘C, the zone in which the first ice was observed in these clouds. T…
Ecological implications of Cousinia Cass. (Asteraceae) persistence through the last two glacial–interglacial cycles in the continental Middle East fo…
2012
10p. gráficas
Surface–bottom relationships in the Gulf of Salerno (Tyrrhenian Sea) over the last 34 kyr: Compositional data analysis of palaeontological proxies an…
2009
The palaeontological, geochemical and mineralogical records of core GNS84-C106 were analysed in order to reconstruct palaeohydrological changes and palaeoproductivity patterns in the Gulf of Salerno for the last 34 kyr. This approach, including compositional analysis of planktonic and benthic assemblages, gave an insight into the relationships between continental, sea surface and bottom environmental changes. The main source of variability of planktonic and benthic assemblages is related respectively to sea surface temperature and palaeobathymetry. Interrelated changes in surface salinity, nutrients, density gradient in the water column and organic fluxes at the bottom act as a secondary fa…
Significance of the Tambien Group (Tigrai, N. Ethiopia) for Snowball Earth events in the Arabian–Nubian Shield
2003
Abstract Juvenile continental crust of the Arabian–Nubian Shield (ANS) formed within a Neoproterozoic supercontinent cycle. Subsequent late Neoproterozoic deposition overlapped a series of dramatic climatic events that are unparalleled in subsequent Phanerozoic time, as proposed by the “Snowball Earth” hypothesis. In particular, extreme negative δ 13 C excursions coincident with glacial diamictite and cap carbonate sequences imply that profound carbon flux changes accompanied widespread glacial transitions (Snowball Events). Such a succession appears to be partially preserved in metasediments of the diamictite-bearing Tambien Group of northern Ethiopia (Negash syncline). Here, a pronounced …
South Pole glacial climate reconstruction from multi-borehole laser particulate stratigraphy
2013
AbstractThe IceCube Neutrino Observatory and its prototype, AMANDA, were built in South Pole ice, using powerful hot-water drills to cleanly bore>100 holes to depths up to 2500 m. The construction of these particle physics detectors provided a unique opportunity to examine the deep ice sheet using a variety of novel techniques. We made high-resolution particulate profiles with a laser dust logger in eight of the boreholes during detector commissioning between 2004 and 2010. The South Pole laser logs are among the most clearly resolved measurements of Antarctic dust strata during the last glacial period and can be used to reconstruct paleoclimate records in exceptional detail. Here we use…