scholarly journals Landscape dynamics promoted the evolution of mega-diversity in South American freshwater fishes

2021 ◽  
Author(s):  
Fernanda Cassemiro ◽  
James S Albert ◽  
Alexandre Antonelli ◽  
Andre Menegotto ◽  
Rafael O Wuest ◽  
...  
Keyword(s):  
Drainage Basin ◽  
Freshwater Fishes ◽  
Landscape Dynamics ◽  
South American ◽  
Serra Do Mar ◽  
History Of ◽  
Andean Uplift ◽  
Abrupt Shifts ◽  
Lineage Diversification

Landscape dynamics and river network rearrangements are widely thought to shape the diversity of Neotropical freshwater fishes, the most species-rich continental vertebrate fauna on Earth. Yet the effects of hydrogeographic changes on fish dispersal and diversification remain poorly understood. Here we integrate an unprecedented occurrence dataset of 4,967 South American freshwater fish species with a species-dense phylogeny to track the evolutionary processes associated with hydrogeographic events over 100 Ma. Net lineage diversification was heterogeneous through time, across space, and among clades. Three abrupt shifts in diversification rates occurred during the Paleogene (between 63 and 23 Ma) in association with major landscape evolution events, and net diversification accelerated from the Miocene to the Recent (c. 20 - 0 Ma). The Western Amazon exhibited the highest rates of in situ diversification and was also the most important source of species dispersing to other regions. All regional biotic interchanges were associated with documented hydrogeographic events and the formation of biogeographic corridors, including Early Miocene (c. 20 Ma) uplift of the Serra do Mar, and Late Miocene (c. 10 Ma) uplift of the Northern Andes and formation of the modern transcontinental Amazon River. Reciprocal mass dispersal of fishes between the Western and Eastern Amazon coincided with this phase of Andean uplift. The Western Amazon has the highest contemporary levels of species richness and phylogenetic endemism. Our results support the hypothesis that landscape dynamics were constrained by the history of drainage basin connections, strongly affecting the assembly and diversification of basin-wide fish faunas.

Ecophylogeography of the disjunct South American xerophytic tree species Prosopis chilensis (Fabaceae)

2020 ◽  
Vol 129 (4) ◽  
pp. 793-809
Author(s):  
Dana Lucía Aguilar ◽  
María Cristina Acosta ◽  
Matías Cristian Baranzelli ◽  
Alicia Noemí Sérsic ◽  
Jose Delatorre-Herrera ◽  
...  
Keyword(s):  
Tree Species ◽  
Disjunct Distribution ◽  
Climatic Data ◽  
South American ◽  
Prosopis Chilensis ◽  
Relative Contribution ◽  
Adaptive Processes ◽  
History Of ◽  
Central Western Argentina

Abstract The intraspecific evolutionary history of South American xerophytic plant species has been poorly explored. The tree species Prosopis chilensis has a disjunct distribution in four South American regions: southern Peru, southern Bolivia, central–western Argentina and central Chile. Here, we combined phylogeographical (based on chloroplast and nuclear markers), morphological and climatic data to evaluate the relative contribution of historical demo-stochastic and adaptive processes in differentiating the disjunct areas of distribution. The results obtained with the two molecular markers revealed two closely related phylogroups (Northern and Southern, predominating in Bolivian Chaco and in Argentine Chaco/Monte, respectively), which would have diverged at ~5 Mya, probably associated with transgression of the Paranaense Sea. Bolivia and Argentina have a larger number of exclusive haplotypes/alleles and higher molecular diversity than Chile, suggesting a long-lasting in situ persistence in the former and a relatively recent colonization in the latter, from the Bolivian and Argentinian lineages. The two main lineages differ in morphology and climatic niche, revealing two significant, independent evolutionary units within P. chilensis promoted by local adaptation and geographical isolation.

Grass development in the Amazon drainage basin, evidence from the fossil and phytochemical record

2020 ◽  
Author(s):  
Carina Hoorn ◽  
Judith Kirschner ◽  
Maxine Beer ◽  
Caixia Wei ◽  
Tyler Kukla ◽  
...  
Keyword(s):  
Drainage Basin ◽  
Electron Microscopy Analysis ◽  
Heated Debate ◽  
Neogene Sediments ◽  
History Of ◽  
Andean Uplift ◽  
Staged Model ◽  
Land Surfaces ◽  
Glacial Periods ◽  
Fluvial Environments

<p>The Poaceae (the grass family) includes over 11000 species and covers large part of the Earth land surfaces. Their history is rooted in the Cretaceous, but this group only expanded fully over the globe during the late Miocene. In the Amazon drainage basin (ADB) grasses were at the core of a heated debate, in which it was hypothesized that during the Pleistocene glacial periods grasses replaced vast extents of the Amazon rainforest. Although this hypothesis is now rejected, the history of grasses in the ADB still remains to be resolved. In this paper we propose a 3-staged model for grass development in the ADB: (1) from c. 23 to 9 Ma western Amazonia was dominated by a megawetland (the ‘Pebas system’) that harboured large amounts of (aquatic?) grasses; (2) from c. 9 Ma Andean uplift prompted megafan and fluvial environments on the Andean slopes and in the Amazon lowlands respectively, these environments created new settings for grass colonization; (3) from c. 5 Ma grasses were firmly established in the tropical alpine vegetation (páramo), the tropical lowland floodplains (várzeas), and savannas (cerrado). To test these scenarios we analysed Neogene and extant Andes-Amazonian grasses by means of Fourier Transform Infrared spectroscopy, we performed a Light- and Scanning Electron Microscopy analysis, and compared the results with existing biomarker data from the Neogene sediments. Here we report on the preliminary results that, among others, suggest that in the middle Miocene aquatic (C3) taxa were comon in the Amazon lowlands. Although further study will have to confirm the precise nature of the ADB grass history, we anticipate that abiotic processes during the Neogene and Quaternary left a strong imprint in the grass phytogeography of northern South America.</p><p> </p>

Evolution of the Paran drainage basin and its relation to the Plio-Pleistocene history of the Arava Rift western margin, Israel

2000 ◽  
Vol 49 (4) ◽  
pp. 215-238 ◽  
Author(s):  
Hanan Ginat ◽  
Yoav Avni ◽  
Zvi Garfunkel ◽  
Hanan Ginata ◽  
Yosef Bartov
Keyword(s):  
Drainage Basin ◽  
Western Margin ◽  
History Of

scholarly journals North polar trough formation due to in-situ erosion as a source of young ice in mid-latitudinal mantles on Mars

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. Alexis P. Rodriguez ◽  
Kenneth L. Tanaka ◽  
Ali M. Bramson ◽  
Gregory J. Leonard ◽  
Victor R. Baker ◽  
...  
Keyword(s):  
Katabatic Wind ◽  
Spiral Pattern ◽  
Near Surface ◽  
Valuable Source ◽  
History Of ◽  
North Polar ◽  
Human Exploration ◽  
Erosional Event

AbstractThe clockwise spiral of troughs marking the Martian north polar plateau forms one of the planet’s youngest megastructures. One popular hypothesis posits that the spiral pattern resulted as troughs underwent poleward migration. Here, we show that the troughs are extensively segmented into enclosed depressions (or cells). Many cell interiors display concentric layers that connect pole- and equator-facing slopes, demonstrating in-situ trough erosion. The segmentation patterns indicate a history of gradual trough growth transversely to katabatic wind directions, whereby increases in trough intersections generated their spiral arrangement. The erosional event recorded in the truncated strata and trough segmentation may have supplied up to ~25% of the volume of the mid-latitude icy mantles. Topographically subtle undulations transition into troughs and have distributions that mimic and extend the troughs’ spiraling pattern, indicating that they probably represent buried trough sections. The retention of the spiral pattern in surface and subsurface troughs is consistent with the megastructure’s stabilization before its partial burial. A previously suggested warm paleoclimatic spike indicates that the erosion could have occurred as recently as ~50 Ka. Hence, if the removed ice was redeposited to form the mid-latitude mantles, they could provide a valuable source of near-surface, clean ice for future human exploration.

scholarly journals Development of a Field Deployable Firebrand Flux and Condition Measurement System

2020 ◽  
Author(s):  
Simone Zen ◽  
Jan C. Thomas ◽  
Eric V. Mueller ◽  
Bhisham Dhurandher ◽  
Michael Gallagher ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Time History ◽  
Infrared Camera ◽  
Thermal Conditions ◽  
Particle Characterization ◽  
Fire Dynamics ◽  
Rate Of Spread ◽  
New Instrument ◽  
History Of

AbstractA new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

scholarly journals In Situ exploration of the giant planets

2021 ◽  
Author(s):  
O. Mousis ◽  
D. H. Atkinson ◽  
R. Ambrosi ◽  
S. Atreya ◽  
D. Banfield ◽  
...  
Keyword(s):  
Solar System ◽  
Giant Planets ◽  
Atmospheric Composition ◽  
Formation History ◽  
History Of ◽  
Composition Structure ◽  
Galileo Probe ◽  
Probe Measurements

AbstractRemote sensing observations suffer significant limitations when used to study the bulk atmospheric composition of the giant planets of our Solar System. This impacts our knowledge of the formation of these planets and the physics of their atmospheres. A remarkable example of the superiority of in situ probe measurements was illustrated by the exploration of Jupiter, where key measurements such as the determination of the noble gases’ abundances and the precise measurement of the helium mixing ratio were only made available through in situ measurements by the Galileo probe. Here we describe the main scientific goals to be addressed by the future in situ exploration of Saturn, Uranus, and Neptune, placing the Galileo probe exploration of Jupiter in a broader context. An atmospheric entry probe targeting the 10-bar level would yield insight into two broad themes: i) the formation history of the giant planets and that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. An atmospheric probe could represent a significant ESA contribution to a future NASA New Frontiers or flagship mission to be launched toward Saturn, Uranus, and/or Neptune.

scholarly journals Gaia DR1 completeness within 250 pc & star formation history of the Solar neighbourhood

2017 ◽  
Vol 12 (S330) ◽  
pp. 148-151 ◽  
Author(s):  
Edouard J. Bernard
Keyword(s):  
Star Formation ◽  
Star Formation History ◽  
Solar Neighbourhood ◽  
The Sun ◽  
Thick Disc ◽  
Formation History ◽  
Magnitude Diagram ◽  
History Of

AbstractWe took advantage of the Gaia DR1 to combine TGAS parallaxes with Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique. We present the determination of the completeness within this volume, and compare the resulting SFH with that calculated from the Hipparcos catalogue within 80 pc of the Sun. We also show how this technique will be applied out to ~5 kpc thanks to the next Gaia data releases, which will allow us to quantify the SFH of the thin disc, thick disc and halo in situ, rather than extrapolating based on the stars from these components that are today in the solar neighbourhood.

scholarly journals The merger-driven evolution of massive early-type galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 62-66
Author(s):  
Carlo Cannarozzo ◽  
Carlo Nipoti ◽  
Alessandro Sonnenfeld ◽  
Alexie Leauthaud ◽  
Song Huang ◽  
...  
Keyword(s):  
Mass Velocity ◽  
Selection Criteria ◽  
Velocity Dispersion ◽  
Ex Situ ◽  
Scaling Relations ◽  
Early Type ◽  
History Of ◽  
Kinematic Properties ◽  
Shed Light

AbstractThe evolution of the structural and kinematic properties of early-type galaxies (ETGs), their scaling relations, as well as their stellar metallicity and age contain precious information on the assembly history of these systems. We present results on the evolution of the stellar mass-velocity dispersion relation of ETGs, focusing in particular on the effects of some selection criteria used to define ETGs. We also try to shed light on the role that in-situ and ex-situ stellar populations have in massive ETGs, providing a possible explanation of the observed metallicity distributions.

Uretero-Iliac artery fistula: a rare cause of haematuria

2020 ◽  
Vol 13 (9) ◽  
pp. e232189
Author(s):  
Natalia Hernandez ◽  
Bethany Desroches ◽  
Eric Peden ◽  
Raj Satkunasivam
Keyword(s):  
Iliac Artery ◽  
Percutaneous Nephrostomy ◽  
Arterial System ◽  
Endoscopic Evaluation ◽  
Stent Removal ◽  
Retrograde Pyelogram ◽  
History Of ◽  
Gross Haematuria ◽  
Multiple Episodes

A woman in her mid-forties with a history of cervical cancer requiring chemoradiation presented with bilateral ureteral strictures secondary to radiation therapy. The ureteral obstruction was initially relieved with bilateral percutaneous nephrostomy tubes, and subsequently, bilateral ureteral stents. Over the course of 8 months, she presented with multiple episodes of severe gross haematuria. This persisted even after stent removal and conversion back to percutaneous nephrostomy tubes. The initial evaluation, done with concern for an uretero-iliac artery fistula, which included bilateral retrograde pyelograms and CT angiography was non-diagnostic. Given continued haematuria, repeat endoscopic evaluation was undertaken; on retrograde pyelogram, brisk contrast was seen to pass into the arterial system, consistent with a left ureteroarterial fistula. The patient underwent endovascular iliac artery stent placement. Subsequently, the patient underwent resection of the iliac artery with endovascular graft in situ, left distal ureterectomy with proximal ureteral ligation following femoral-to-femoral bypass. This allowed for complete resolution of the patient’s gross haematuria episodes.

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