Modern Occurrences Research Articles

Diversity, environments, and biogeography of Homoloida (Decapoda: Brachyura) from the Late Jurassic to the present

ABSTRACT The section Homoloida with the sole superfamily Homoloidea comprises both extinct and extant brachyuran crab taxa, with records ranging from the Tithonian (Jurassic) to the present. Examination of fossil and modern occurrence records for this clade provides insight into the biogeography, biodiversity, and environmental preference of the homoloid crabs over time. The fossil record of Homoloidea, comprised of the families Tithonohomolidae, Mithracitidae, Homolidae, Latreilliidae, and Poupiniidae, is global in distribution and peaks in diversity during the uppermost Cretaceous with the most recent fossils known from the Miocene. Modern homoloids are absent from only a handful of regions globally, with particularly high diversity and abundance in the tropical Indo-West Pacific. Comparison of interpreted depositional environments for fossil occurrences and depth records for modern occurrences sheds light on the environmental preferences and potential spatial sampling biases of this clade. By assessing both fossil and modern records of Homoloidea, patterns (e.g., absence from cold-water latitudes, Oligo-Miocene disappearance from the northeastern Pacific) emerge that may have important implications for future study of this clade, particularly in relation to dispersal/turnover events and environmental constraints.

Longitudinal population dynamics of Mediterranean-Atlantic Arbutus during the last 30 ka

The current distribution of the genus Arbutus in the Old World prompts questions about its long-term population dynamics, location and extent of refuge areas, and modern vulnerability in relation to climate change and human activity. Our work aims to address these questions by combining modern occurrence data with a comprehensive survey of pollen and macrofossil records. Range maps of past distribution have been produced for the last 32 ka to investigate geographical trends in population dynamics and the timing of the appearance of Arbutus across different biogeographical regions. In the Atlantic domain, Arbutus has been consistently present during the last 32 ka, even during the Last Glacial Maximum. In the central and eastern Mediterranean regions, it progressively increased since the beginning of the Holocene, appearing along the coasts of the Black Sea and in the Levant during the Middle Holocene. In addition, the dynamics of Arbutus in a number of peripherals stands (Ireland, Canary Islands, Cyrenaica, Crimea, and Black Sea coasts) is discussed. The palaeobotanical evidence suggests that the delayed emergence of eastern populations and peripheral stands in the fossil record may be ascribed to a very low population density, rather than to a sequential migration process from the western sectors of the range. The comparison of fossil records and modern occurrences highlights an overall temporal continuity between long-term persistence areas and current centers of gravity and calls for density-weighted ecological models that may contribute to an informed assessment of conservation actions and strategies.

A combined palaeomodelling approach reveals the role as selective refugia of the Mediterranean peninsulas

The northern Mediterranean reptiles and amphibians show contrasting biogeographic histories during the Plio-Pleistocene. The influence of European climate changes on the evolution of the biogeographic ranges of taxa with a rich fossil record is determined herein combining different proxies to obtain well-supported palaeoclimatic scenarios. Ecological Niche Modelling through the ensemble modelling approach was used to reconstruct the climatic niche of selected reptile and amphibian genera, combining modern occurrences with seven independent bioclimatic variables. The obtained model was then projected on past scenarios using fossil data to crosscheck the validity of the climatic explanation for the selective extirpations. Palaeobotanical proxies and the hypsodonty of mammals were used to reconstruct the humidity pattern of the last million years in the studied area. The climate of the Italian Peninsula during the Last Glacial Maximum was proved herein to be unsuitable for many reptile taxa, which persisted in this area until the Early or Late Pleistocene, whereas they survived till the present day in the Iberian and/or Balkans peninsulas. On the contrary, all the proxies agree that Italy was comparably more humid than the other peninsulas during the Pliocene and Pleistocene, therefore allowing the prolonged survival of amphibian taxa (including the still living Salamandrina and Speleomantes), which became extinct or extirpated elsewhere in Europe. An intensification of the conservation efforts concerning amphibians, particularly sensitive to the global climate change, is recommended in the Italian Peninsula, which acted as an amphibian refugium for Europe due to its peculiar climatic history.

Dissolved silica‐driven dolomite precipitation in the Great Salt Lake, Utah, and its implication for dolomite formation environments

AbstractSince the discovery of dolomite, numerous attempts have been made to understand its precipitation mechanism at Earth's surface conditions. One such mechanism relies on a relationship with microbial life, where laboratory synthesis experiments have shown that specific organic molecules, such as polysaccharides, exopolymeric substances and hydrogen sulphide can promote dolomite precipitation. Other mechanisms for precipitating dolomite focus on abiotic chemical environments, such as adding dissolved silica, which lower the dehydration energy barrier for the surface Mg2+‐water complex and promote disordered dolomite precipitation. Modern occurrences of dolomite in the Great Salt Lake, Utah, have been studied since the early 20th Century. The distribution of primary dolomite in the Great Salt Lake is spatially heterogeneous, with only the carbonate mud in the South Arm and ridge‐site between desiccation cracks in the North Arm being dominated by dolomite and calcite, while stromatolites in both Arms and ooidal sands in the North Arm are composed entirely of aragonite. It was proposed that dolomite precipitation in the Great Salt Lake was possibly induced by microbial activities such as organic degradation, bacteria sulphate reduction, or other microbial metabolic by‐products. However, these hypotheses could not explain the lack of dolomite in microbial mats, especially in the North Arm, which is constituted by mostly aragonite with no dolomite. Our results suggest that dissolved silica concentration is the primary control for dolomite and Mg‐clay formation in the Great Salt Lake. Even though the North Arm has a much more concentrated Mg and Ca water from lack of freshwater input, dissolved silica levels in the South Arm (>0.5 mm) and the Ridge‐site (ca 0.5 mm) are much higher than in the North Arm (<0.2 mm). Our finding could also provide a new proxy for reconstructing climate changes in the Great Salt Lake area based on dolomite content variation. Phanerozoic dolomite abundance variations may be linked to global CO2 level that facilitates global chemical weathering and dissolved silica input into palaeo‐ocean.

A millennium of climatic and floristic dynamics in the Eastern Cordillera of the Colombian Andes

AbstractAimThe transition from the Medieval Climate Anomaly (MCA, 950–1250 CE) to the Little Ice Age (LIA, 1350–1800 CE) is the largest pre‐industrial climate shift within the last two millennia, offering an opportunity to study how vegetation responds to rapid climate change. We analysed a sedimentary record from the Colombian Andes to reconstruct regional vegetation dynamics during this time interval, identify the modern environmental distribution of taxa present in the fossil record and provide a reference for modern regional temperature change.LocationLake Tota, Eastern Cordillera, Colombian Andes.TaxonAngiosperm and Gymnosperms.MethodsA sediment core was analysed for organic geochemistry and pollen to reconstruct environmental and vegetation variability between 800 and 1800 CE. Modern occurrences of individuals of the genera found in the fossil record were used to model the distribution of taxa across gradients of mean annual temperature and precipitation. These models were used to reconstruct temperature and precipitation across time and evaluate the probability of occurrence of taxa from the fossil record across the contemporary landscape.ResultsReconstructed regional vegetation dynamics were highly coupled with global temperature patterns. Reconstructed climate showed that conditions were warm and dry during the MCA, and cold and relatively wet during the LIA, although quantitative estimations might have been amplified by human disturbances. Rates of temperature change during the MCA‐LIA transition were substantially lower than those calculated for the last two decades. Vegetation turnover between 800 and 1800 CE resembled those expressed through a transect extending ~30 km southeast from the lake.Main conclusionsAround lake Tota, modern rates of temperature change have no precedent within the last two millennia. The modern environmental affinities of taxa involved in vegetation turnover during the MCA‐LIA transition point to the importance of landscape diversity and connectivity for rapid vegetation response to climate change.

Formation of Zn and Pb sulfides in a redox-sensitive modern system due to high atmospheric fallout

Human activities have led to a considerable increase in trace metal cycling in recent times. The mobilized elements get subjected to a variety of processes leading eventually to their re-concentration. The polluted sites, transformed by Earth's surface processes, become similar to metal accumulations known from geological records. This study examines authigenic metal sulfide mineralization in two peatlands polluted by atmospheric deposition from a nearby Pb-Zn smelter. We use the polluted peatlands as a small-scale model of Zn-Cd-Pb sulfide deposit to determine the role of organic matter in ore genesis and the textural and structural organization of biogenic precipitates.The study shows that the air-derived metal enrichment (up to 2.3 g Zn kg−1, 1.1 g Pb kg−1, and 62 mg Cd kg−1) is retained in a thin layer (∼30 cm) around 10–15 cm below the peat surface. A combination of focused ion beam (FIB) technology and scanning (SEM) and transmission (TEM) electron microscopy reveals that micrometric spheroids are most characteristic for ZnS and (Zn,Cd)S, although the sulfides readily form pseudomorphs after different plant tissues resulting in much larger aggregates. The aggregates have a complex polycrystalline sphalerite structure much more advanced than typically obtained during low-temperature synthesis or observed in other modern occurrences. Platy highly-disordered radially-aggregated submicrometre crystals develop within the time constraints of several decades in the cold (∼15 °C) and acid (pH 3.4–4.4) peat. The less abundant Pb sulfides occur as small cube-like crystals (<1µm) between ZnS or as flat irregular or square patches on plant root macrofossils. All PbS are crystalline and defect-free. Pb ion complexation with dissolved and solid organic matter is probably responsible for the low number and equilibrium shape of PbS crystals. Iron is absent in the authigenic sulfide mineralization and occurs entirely as organically bound ferric iron (Fe3+), as revealed by Mössbauer spectroscopy. The different affinity of metals to organic matter enhances the precipitation of Zn and Cd as sulfides over Pb and Fe. Our findings demonstrate that human activities lead to the formation of near-surface stratiform metal sulfide accumulations in peat, and the polluted sites can be of use to understand and reconstruct ancient ore deposits' genesis and mechanisms of formation.

Past, present, and future climate space of the only endemic vertebrate genus of the Italian peninsula

The two extant Salamandrina species represent a unique case of morphology, ecology, and ethology among urodeles. The range of this genus is currently limited to Italy, where it represents the only endemic vertebrate genus, but its past range extended over a much broader area of Europe, including the Iberian and Balkan peninsulas. ENM analyses using modern occurrences of Salamandrina demonstrate that the current climate of the majority of Europe, and especially areas where fossils of this genus were found, is currently not suitable for this genus, neither was it suitable during the last 3.3 million years. This result allows possible assumptions about the climatic influence on the former extirpation of this salamander from several areas of Europe. Furthermore, it shows that, during Pliocene–Pleistocene climatic oscillations, Mediterranean peninsulas, despite being generally considered together because of similar latitude, had different potential to effectively become glacial refugia for this salamander, and possibly for other species as well. Future projections using different CO2 emission scenarios predict that climatic suitability will be even more drastically reduced during the next 50 years, underlining once more the importance of conservation strategies and emission-reducing policies.

Late Pleistocene–Holocene flood history, flood-sediment provenance and human imprints from the upper Indus River catchment, Ladakh Himalaya

Abstract The Indus River, originating from Manasarovar Lake in Tibet, runs along the Indus Tsangpo suture zone in Ladakh which separates the Tethyan Himalaya in the south from the Karakoram zone to the north. Due to the barriers created by the Pir-Panjal ranges and the High Himalaya, Ladakh is located in a rain shadow zone of the Indian summer monsoon (ISM) making it a high-altitude desert. Occasional catastrophic hydrological events are known to endanger lives and properties of people residing there. Evidence of such events in the recent geologic past that are larger in magnitude than modern occurrences is preserved along the channels. Detailed investigation of these archives is imperative to expand our knowledge of extreme floods that rarely occur on the human timescale. Understanding the frequency, distribution, and forcing mechanisms of past extreme floods of this region is crucial to examine whether the causal agents are regional, global, or both on long timescales. We studied the Holocene extreme flood history of the Upper Indus catchment in Ladakh using slackwater deposits (SWDs) preserved along the Indus and Zanskar Rivers. SWDs here are composed of stacks of sand-silt couplets deposited rapidly during large flooding events in areas where a sharp reduction of flow velocity is caused by local geomorphic conditions. Each couplet represents a flood, the age of which is constrained using optically stimulated luminescence for sand and accelerator mass spectrometry and liquid scintillation counter 14C for charcoal specks from hearths. The study suggests occurrence of large floods during phases of strengthened ISM when the monsoon penetrated into arid Ladakh. Comparison with flood records of rivers draining other regions of the Himalaya and those influenced by the East Asian summer monsoon (EASM) indicates asynchronicity with the Western Himalaya that confirms the existing anti-phase relationship of the ISM-EASM that occurred in the Holocene. Detrital zircon provenance analysis indicates that sediment transportation along the Zanskar River is more efficient than the main Indus channel during extreme floods. Post–Last Glacial Maximum human migration, during warm and wet climatic conditions, into the arid upper Indus catchment is revealed from hearths found within the SWDs.

AMELIORATION OF MACHINE LEARNING AND ARTIFICIAL INTELLIGENCE IN MEDICAL MANAGEMENT (A CASE STUDY ON THE PANDEMIC OF COVID 19 CASES IN ASIA)

Machine learning is seeing increasingly utilized in medical management for different reasons: tremendous sums of information are being captured and made accessible carefully; handling of vast sums of information has gotten to be cost-effective due to the expanded computing control presently accessible at reasonable costs; and different open source systems, toolkits, and libraries are accessible that can be utilized to construct and execute ML applications. Particularly in healthcare, ML has driven to energizing modern improvements that may rethink COVID-19 treatment and vaccination within a long time to come. With modern occurrences of the brand modern coronavirus clutter, COVID-19, creating day through the day, it is common to compare the unused affliction to other flare-ups in current history. Machine learning can offer assistance to anticipate three sorts of restorative dangers - disease, seriousness, and result. Whereas it is still it is early for COVID-19 with machine learning, but early applications seem promising. Machine learning is utilized when a computer has been instructed to recognize designs by giving it with information and a calculation to assist get it that information. This method of learning from the information is called training and the yield that we accomplish is through testing. Machine learning-based robotic surgery is changing the way surgery is performed nowadays. Machine learning in healthcare is getting to be more broadly utilized and is making a difference in patients and clinicians in numerous diverse ways. Cybersecurity and protection are major concerns and open challenges in healthcare which are yet to be addressed.

A Series of Data-Driven Hypotheses for Inferring Biogeochemical Conditions in Alkaline Lakes and Their Deposits Based on the Behavior of Mg and SiO2

Alkaline (pH &gt; 8.5) lakes have been common features of Earth’s surface environments throughout its history and are currently among the most biologically productive environments on the planet. The chemistry of alkaline lakes favors the deposition of aluminum-poor magnesian clays (e.g., sepiolite, stevensite, and kerolite) whose chemistry and mineralogy may provide a useful record of the biogeochemistry of the lake waters from which they were precipitated. In this forward-looking review, we present six data-driven, testable hypotheses devoted to furthering our understanding of the biogeochemical conditions in paleolake waters based on the geochemical behavior of Mg and SiO2. In the development of these hypotheses, we bring together a compilation of modern lake water chemistry, recently published and new experimental data, and empirical, thermodynamic, and kinetic relationships developed from these data. We subdivide the hypotheses and supporting evidence into three categories: (1) interpreting paleolake chemistry from mineralogy; (2) interpreting the impact of diatoms on alkaline lake sedimentation; and (3) interpreting depositional mineralogy based on water chemistry. We demonstrate the need for further investigation by discussing evidence both for and against each hypothesis, which, in turn, highlights the gaps in our knowledge and the importance of furthering our understanding of the relevant geological and biological systems. The focused testing of these hypotheses against modern occurrences and the geologic record of alkaline lakes can have profound implications for the interpretation of the paleo-biogeochemistry and paleohabitability of these systems on Earth and beyond.

Ancient globetrotters-connectivity and putative native ranges of two cosmopolitan biofouling amphipods.

The geographic distributions of some coastal marine species have appeared as cosmopolitan ever since they were first scientifically documented. In particular, for many benthic species that are associated with anthropogenic substrata, there is much speculation as to whether or not their broad distributions can be explained by natural mechanisms of dispersal. Here, we focused on two congeneric coastal crustaceans with cosmopolitan distributions—the tube-dwelling amphipods Jassa marmorata and Jassa slatteryi. Both species are common elements of marine biofouling on nearly all kinds of artificial hard substrata in temperate to warm seas. We hypothesized that the two species’ modern occurrences across the oceans are the result of human shipping activities that started centuries ago. Mitochondrial DNA sequences of the CO1 fragment of specimens from distinct marine regions around the world were analysed, evaluating genetic structure and migration models and making inferences on putative native ranges of the two Jassa species. Populations of both species exhibited considerable genetic diversity with differing levels of geographic structure. For both species, at least two dominant haplotypes were shared among several geographic populations. Rapid demographic expansion and high migration rates between geographically distant regions support a scenario of ongoing dispersal all over the world. Our findings indicate that the likely former native range of J. marmorata is the Northwest Atlantic, whereas the likely former native range of J. slatteryi is the Northern Pacific region. As corroborated by the genetic connectivity between populations, shipping still appears to be the more successful vector of the two species’ dispersal when compared to natural mechanisms. Historical invasion events that likely started centuries ago, along with current ongoing dispersal, confirm these species’ identities as true “neocosmopolitans”.

The Quixotic Mother, the Female Author, and Mary Charlton's Rosella

To be a quixote is to be birthed by novels. In late eighteenth-century Britain, longstanding but newly urgent concerns around literary (re)production, the novel, female authorship, and gender roles converge within the fraught figure of the quixote who is also a mother. Focusing on quixotic mothers in general—and Mary Charlton's understudied novel Rosella, or Modern Occurrences (Minerva Press, 1799) in particular—this essay asserts that metaphors of authorship as biological maternity structure late eighteenth-century quixotic narratives' treatment of women's writing and the novel. Through creating a character who simultaneously embodies female authorship, quixotism, and maternity, Charlton suggests how late eighteenth-century quixotic figures provide a means for writers to explore, destabilize, and affirm models of maternal and authorial monstrosity.

Conchocelichnus seilacheri igen. et isp. nov., a Complex Microboring Trace of Bangialean Rhodophytes

ABSTRACTTraces of microboring microbial endoliths (euendoliths) conform closely to the outlines of their makers as they are made. This habit evolved among prokaryotic cyanobacteria and eukaryotic rhodophytes, chlorophytes, and fungi. Among eukaryotic microborers, the endolithic mode of life is often limited to a phase in the course of their development, which alternates with an epilithic leafy phase. These endolithic phases are sometimes independently described as separate genera and species. This was the case with Conchocelis rosea Batters, 1891, later identified as the endolithic phase of Porphyra and Bangia that helped in identification of fossil bangialean rhodophytes of Silurian age: Palaeoconchocelis starmachii Campbell, Kazmierczak et Golubic, 1979. However, the traces of Conchocelis phases, although conspicuous and used to characterize the resident body fossil, were never formally described. We present here the formal ichnotaxonomic description of the complex and variable Conchocelis trace as Conchocelichnus seilacheri igen. et isp. nov., based primarily on Oligocene (Tertiary) borings in molluscan shells of Mainz Basin, Germany, while consulting similar fossil borings of the Silurian and Jurassic findings and compareing them with modern occurrences in nature and culture. With the new trace name Conchocelichnus seilacheri igen. et isp. nov., we honor the work of the renowned paleontologist and ichnologist, Prof. Dr. Dolf Seilacher.

Recent Invasion of the Symbiont-Bearing Foraminifera Pararotalia into the Eastern Mediterranean Facilitated by the Ongoing Warming Trend.

The eastern Mediterranean is a hotspot of biological invasions. Numerous species of Indo-pacific origin have colonized the Mediterranean in recent times, including tropical symbiont-bearing foraminifera. Among these is the species Pararotalia calcariformata. Unlike other invasive foraminifera, this species was discovered only two decades ago and is restricted to the eastern Mediterranean coast. Combining ecological, genetic and physiological observations, we attempt to explain the recent invasion of this species in the Mediterranean Sea. Using morphological and genetic data, we confirm the species attribution to P. calcariformata McCulloch 1977 and identify its symbionts as a consortium of diatom species dominated by Minutocellus polymorphus. We document photosynthetic activity of its endosymbionts using Pulse Amplitude Modulated Fluorometry and test the effects of elevated temperatures on growth rates of asexual offspring. The culturing of asexual offspring for 120 days shows a 30-day period of rapid growth followed by a period of slower growth. A subsequent 48-day temperature sensitivity experiment indicates a similar developmental pathway and high growth rate at 28°C, whereas an almost complete inhibition of growth was observed at 20°C and 35°C. This indicates that the offspring of this species may have lower tolerance to cold temperatures than what would be expected for species native to the Mediterranean. We expand this hypothesis by applying a Species Distribution Model (SDM) based on modern occurrences in the Mediterranean using three environmental variables: irradiance, turbidity and yearly minimum temperature. The model reproduces the observed restricted distribution and indicates that the range of the species will drastically expand westwards under future global change scenarios. We conclude that P. calcariformata established a population in the Levant because of the recent warming in the region. In line with observations from other groups of organisms, our results indicate that continued warming of the eastern Mediterranean will facilitate the invasion of more tropical marine taxa into the Mediterranean, disturbing local biodiversity and ecosystem structure.

Facies patterns of a tropical heterozoan carbonate platform under eutrophic conditions: the Banc d’Arguin, Mauritania

High-nutrient tropical carbonate systems are known to produce sediments that, in terms of skeletal composition, are reminiscent of their extra-tropical counterparts. Such carbonate systems and associated carbonate grain assemblages in the tropics are rare in the present-day world. Nonetheless, it is crucial to gain a better understanding of those ecosystems, including their drivers and players because such settings potentially represent models for ancient depositional systems as well as for predicted future environmental conditions. One of the modern occurrences of eutrophic tropical carbonate systems is the northern Mauritanian Shelf. The marine environment is characterized by an eastern boundary upwelling system that pushes cool and nutrient-rich intermediate waters onto a wide epicontinental platform (Golfe d’Arguin) where the waters warm up to tropical temperatures. The resulting facies is mixed carbonate–siliciclastic with a dominant foramol association grading into bimol and barnamol grain assemblages in the shallowest areas forming the Banc d’Arguin. Besides this cool water-related heterozoan association, the carbonate sediment is characterized by tropical molluskan species, while chlorozoan biota (e.g., corals and algal symbiont-bearing foraminifers) are entirely absent. We here present a first comprehensive facies analysis of this model example of eutrophic tropical carbonates. Furthermore, we reconstruct the loci of carbonate production and provide a conclusive depositional model of the Banc d’Arguin that received little attention to date due to its poorly accessible nature.

Two-point versus multiple-point geostatistics: the ability of geostatistical methods to capture complex geobodies and their facies associations—an application to a channelized carbonate reservoir, southwest Iran

Facies models try to explain facies architectures which have a primary control on the subsurface heterogeneities and the fluid flow characteristics of a given reservoir. In the process of facies modeling, geostatistical methods are implemented to integrate different sources of data into a consistent model. The facies models should describe facies interactions; the shape and geometry of the geobodies as they occur in reality. Two distinct categories of geostatistical techniques are two-point and multiple-point (geo) statistics (MPS). In this study, both of the aforementioned categories were applied to generate facies models. A sequential indicator simulation (SIS) and a truncated Gaussian simulation (TGS) represented two-point geostatistical methods, and a single normal equation?simulation (SNESIM) selected as an MPS simulation representative. The dataset from an extremely channelized carbonate reservoir located in southwest Iran was applied to these algorithms to analyze their performance in reproducing complex curvilinear geobodies. The SNESIM algorithm needs consistent training images (TI) in which all possible facies architectures that are present in the area are included. The TI model was founded on the data acquired from modern occurrences. These analogies delivered vital information about the possible channel geometries and facies classes that are typically present in those similar environments. The MPS results were conditioned to both soft and hard data. Soft facies probabilities were acquired from a neural network workflow. In this workflow, seismic-derived attributes were implemented as the input data. Furthermore, MPS realizations were conditioned to hard data to guarantee the exact positioning and continuity of the channel bodies. A geobody extraction workflow was implemented to extract the most certain parts of the channel bodies from the seismic data. These extracted parts of the channel bodies were applied to the simulation workflow as hard data. This study showed how different sources of data can be employed in a multiple-point simulation algorithm to get reliable facies models. In addition, concerning the reproduction of curvilinear channel bodies, the modeling results revealed the strength of MPS algorithms (SNESIM in this study) in comparison with two-point geostatistical methods (including the SIS and TGS).

Channel characterization using multiple-point geostatistics, neural network, and modern analogy: A case study from a carbonate reservoir, southwest Iran

In facies modeling, the ideal objective is to integrate different sources of data to generate a model that has the highest consistency to reality with respect to geological shapes and their facies architectures. Multiple-point (geo)statistics (MPS) is a tool that gives the opportunity of reaching this goal via defining a training image (TI). A facies modeling workflow was conducted on a carbonate reservoir located southwest Iran. Through a sequence stratigraphic correlation among the wells, it was revealed that the interval under a modeling process was deposited in a tidal flat environment. Bahamas tidal flat environment which is one of the most well studied modern carbonate tidal flats was considered to be the source of required information for modeling a TI. In parallel, a neural network probability cube was generated based on a set of attributes derived from 3D seismic cube to be applied into the MPS algorithm as a soft conditioning data. Moreover, extracted channel bodies and drilled well log facies came to the modeling as hard data. Combination of these constraints resulted to a facies model which was greatly consistent to the geological scenarios. This study showed how analogy of modern occurrences can be set as the foundation for generating a training image. Channel morphology and facies types currently being deposited, which are crucial for modeling a training image, was inferred from modern occurrences. However, there were some practical considerations concerning the MPS algorithm used for facies simulation. The main limitation was the huge amount of RAM and CPU-time needed to perform simulations.

Environmental niche modelling fails to predict Last Glacial Maximum refugia: niche shifts, microrefugia or incorrect palaeoclimate estimates?

AbstractAimMany predictions of responses to future climate change utilize ecological niche models (ENMs). We assess the capacity of these models to predict species distributions under conditions that differ from the current environment by testing whether they can predict past distributions of species.LocationFrom 43° S to 31° S in south‐eastern Australia (including Tasmania).MethodsWe studied three dominant tree species of temperate Australian mesic forests, Atherosperma moschatum, Eucalyptus regnans and Nothofagus cunninghamii. Phylogeographic evidence indicates that these species each survived the Last Glacial Maximum (LGM) in multiple refugia. We modelled the current distribution of each species and projected those models onto LGM climates under six palaeoclimatic scenarios. The support for phylogeographic‐based glacial refugia was estimated under each scenario using three different thresholds for inferring species presence/absence.ResultsThe LGM models under scenarios that allowed for a realistic level of rainfall failed to predict survival of the study species in refugia identified from genetic evidence, apart from those in perhumid western Tasmania.Main conclusionsCorrect prediction of nearly all modern occurrences of the species suggests that this failure of ENMs to predict refugial survival was not methodological. Rather we conclude that the existing realized niches of these species may have changed since the LGM. Such niche changes may have involved the occurrence of non‐analogue climates in the LGM and some significant alteration of fundamental niche (for at least E. regnans). Our results emphasize that predictions of future impacts of climate change on biodiversity will benefit from awareness of the limitations of ENMs in predicting the extinction of populations/species. Greater knowledge of how niches have changed through time and how this relates to the characteristics of species is needed to improve the reliability of ENMs. Niche changes in plants may also affect palaeoclimatic estimates based on fossil pollen.

Temporal and spatial distributions of cold-water corals in the Drake Passage: Insights from the last 35,000 years

Scleractinian corals have a global distribution ranging from shallow tropical seas to the depths of the Southern Ocean. Although this distribution is indicative of the corals having a tolerance to a wide spectrum of environmental conditions, individual species seem to be restricted to a much narrower range of ecosystem variables. One way to ascertain the tolerances of corals, with particular focus on the potential impacts of changing climate, is to reconstruct their growth history across a range of environmental regimes. This study examines the spatial and temporal distribution of the solitary scleractinian corals Desmophyllum dianthus, Gardineria antarctica, Balanophyllia malouinensis, Caryophyllia spp. and Flabellum spp. from five sites in the Drake Passage which cross the major frontal zones. A rapid reconnaissance radiocarbon method was used to date more than 850 individual corals. Coupled with U-Th dating, an age range of present day back to more than 100 thousand years was established for corals in the region. Within this age range there are distinct changes in the temporal and spatial distributions of these corals, both with depth and latitude, and on millennial timescales. Two major patterns that emerge are: (1) D. dianthus populations show clear variability in their occurrence through time depending on the latitudinal position within the Drake Passage. North of the Subantarctic Front, D. dianthus first appears in the late deglaciation (~17,000 years ago) and persists to today. South of the Polar Front, in contrast, early deglacial periods, with a few modern occurrences. A seamount site between the two fronts exhibits characteristics similar to both the northern and southern sites. This shift across the frontal zones within one species cannot yet be fully explained, but it is likely to be linked to changes in surface productivity, subsurface oxygen concentrations, and carbonate saturation state. (2) at locations where multiple genera were dated, differences in age and depth distribution of the populations provide clear evidence that each genus has unique environmental requirements to sustain its population.

Buxus in Europe: Late Quaternary dynamics and modern vulnerability

Abstract The suggested location of broadleaved evergreen trees in Europe during the last full-glacial has traditionally favoured a southerly refugial model, which proposes survival in the Mediterranean peninsulas and recolonization of central and northern Europe during the Holocene. This hypothesis is not always substantiated by thorough reviews of original past and modern occurrence data, or considered in the light of plant traits and autoecology. Our approach focuses on the genus Buxus with the aim of exploring (i) the relationship between the location of refugia and post-glacial population dynamics, (ii) past processes determining density, fragmentation and local extinctions of modern populations, and (iii) the vulnerability of Buxus in the context of the undergoing environmental changes. We compiled a database of over 3600 modern occurrences and 676 fossil sites to reconstruct the distribution of Buxus in Europe since 30 ka cal BP. The location of fossil finds and the plant traits of Buxus indicate that it persisted widely across its modern distribution through the last glacial period with modes varying from region to region. The E Pyrenees, W Alps, and Jura Mts hosted dense populations, which expanded exponentially during the whole Holocene, and resulted in a modern continuous distribution area. In contrast, the Mediterranean Peninsulas hosted sparse populations, which increased exponentially only during the first half of the Holocene, clearly decreased in the last 4.5 ka BP and resulted in a highly fragmented modern distribution area, most likely in relation to the climate trends towards dry conditions of the last few millennia. These results challenge the common view that the Mediterranean regions are the exclusive and most important refuge areas for evergreen broadleaved trees and stress the importance of considering long-term population dynamics based on fossil data to evaluate the vulnerability of modern fragmented plant populations in view of conservation actions.