scholarly journals River Reorganization Affects Populations of Dwarf Cichlid Species (Apistogramma Genus) in the Lower Negro River, Brazil

2021 ◽  
Vol 9 ◽  
Author(s):  
Carolina Sousa de Sá Leitão ◽  
Érica M. S. Souza ◽  
Carlos H. A. Santos ◽  
Pedro Val ◽  
Adalberto L. Val ◽  
...  
Keyword(s):  
Ribosomal Rna ◽  
Amazon Basin ◽  
Aquatic Biota ◽  
Species Dispersal ◽  
Cichlid Species ◽  
Negro River ◽  
Capture Event ◽  
Evolutionary Significant Units ◽  
River Capture ◽  
History Of

Alterations, such as drainage network reorganization, in the landscape in the Amazon basin influence the distribution range and connectivity of aquatic biota and, therefore, their evolution. River capture is a geomorphic mechanism of network reorganization by which a basin captures large portions of the network of a neighboring basin, thus creating a barrier against species dispersal. In this study, the influence of river capture on the genetic differentiation and structuring of two dwarf cichlids species (Apistogramma pertensis and Apistogramma gephyra) is investigated in two tributaries of the lower Negro River. The analysis of 11 loci microsatellite and three mitochondrial DNA genes (Cytochrome b, Citochrome c Oxidase subunit I and 16S ribosomal RNA) confirmed the populational isolation of two dwarf cichlids species, suggesting that they represent evolutionary significant units (ESU) that have been isolated—probably due to the river capture event. The paleovalley that resulted from the river capture is therefore an important physical barrier that separates the populations of the Cuieiras and Tarumã-Mirim Rivers. The findings herein provide evidence of a mechanistic link between the isolation and differentiation of fish populations and the drainage evolution of the Amazon basin, and indicate that the dynamic geological history of the region has promoted species diversification. The process described here partially explains the high diversity in the genus Apistogramma and the information obtained is beneficial to conservation programs.

Lateglacial and early-Holocene palaeohydrological changes in the upper reaches of the Ūla River: An example from southeastern Lithuania

The Holocene ◽  
2012 ◽  
Vol 23 (1) ◽  
pp. 117-126 ◽  
Author(s):  
Lauras Balakauskas ◽  
Julius Taminskas ◽  
Jonas Mažeika ◽  
Miglė Stančikaitė
Keyword(s):  
Water Level ◽  
Water Level Fluctuations ◽  
Loss On Ignition ◽  
Capture Event ◽  
River Capture ◽  
New Information ◽  
Aeolian Sediments ◽  
History Of ◽  
The 19Th Century ◽  
Weichselian Glaciation

A reconstructed pattern of Lateglacial and Holocene hydrological changes in the area of the former lakes Dūbas, Pelesa and Matara is presented. The investigated basin is situated in southeastern Lithuania, beyond the marginal ridge of the Weichselian Glaciation, on the margin of the sandy plain that is the watershed between the Ūla and Katra rivers. Pollen analysis, radiocarbon dating, loss-on-ignition measurements and GIS-based simulation of water level fluctuations have been applied in order to obtain new information on the development of the Ūla–Katra watershed area. The results of multiproxy investigations revealed the history of the development and extinction of Dūbas, Pelesa and Matara lakes. A single basin, covering a large part of the study area, had formed after the retreat of the continental ice sheet from southeastern Lithuania. This basin was divided into three separate lakes during the Allerød Interstadial as a result of a drop in water level. Blocking of the drainage by aeolian sediments around the early Boreal caused another rise in the water-table and the successive merging of the separate lakes. Probably as a result of river capture, the single lake was drained abruptly after c. 2000 years. Another river-capture event in the 19th century caused abrupt drainage of the study area, which led to the final extinction of the three lakes.

scholarly journals Amazonia as the Origin and Diversification Area of Didelphidae (Mammalia: Metatheria), and a Review of the Fossil Record of the Clade

2021 ◽  
Author(s):  
Mariela C. Castro ◽  
Murilo J. Dahur ◽  
Gabriel S. Ferreira
Keyword(s):  
South America ◽  
Amazon Basin ◽  
Parametric Models ◽  
Isthmus Of Panama ◽  
Biogeographic History ◽  
Early Diversification ◽  
Northern Portion ◽  
History Of ◽  
Environmental Events ◽  
Fossil Records

AbstractDidelphidae is the largest New World radiation of marsupials, and is mostly represented by arboreal, small- to medium-sized taxa that inhabit tropical and/or subtropical forests. The group originated and remained isolated in South America for millions of years, until the formation of the Isthmus of Panama. In this study, we present the first reconstruction of the biogeographic history of Didelphidae including all major clades, based on parametric models and stratified analyses over time. We also compiled all the pre-Quaternary fossil records of the group, and contrasted these data to our biogeographic inferences, as well as to major environmental events that occurred in the South American Cenozoic. Our results indicate the relevance of Amazonia in the early diversification of Didelphidae, including the divergence of the major clades traditionally ranked as subfamilies and tribes. Cladogeneses in other areas started in the late Miocene, an interval of intense shifts, especially in the northern portion of Andes and Amazon Basin. Occupation of other areas continued through the Pliocene, but few were only colonized in Quaternary times. The comparison between the biogeographic inference and the fossil records highlights some further steps towards better understanding the spatiotemporal evolution of the clade. Finally, our results stress that the early history of didelphids is obscured by the lack of Paleogene fossils, which are still to be unearthed from low-latitude deposits of South America.

Streptococcus pluranimalium meningoencephalitis in a horse

2021 ◽  
pp. 104063872110234
Author(s):  
Dah-Jiun Fu ◽  
Akhilesh Ramachandran ◽  
Craig Miller
Keyword(s):  
Ribosomal Rna ◽  
Cross Sections ◽  
Nucleotide Sequencing ◽  
Formalin Fixed Paraffin ◽  
Quarter Horse ◽  
Formalin Fixed Paraffin Embedded ◽  
History Of ◽  
The Brain ◽  
Gram Positive Cocci ◽  
Formalin Fixed

A 3-y-old, female Quarter Horse with a history of acute neurologic signs was found dead and was submitted for postmortem examination. Areas of petechial and ecchymotic hemorrhage were present on cross-sections of the cerebrum, cerebellum, and brainstem. Histologic examination of the brain revealed severe, purulent meningoencephalitis and vasculitis with a myriad of intralesional gram-positive cocci. Streptococcus pluranimalium was identified from formalin-fixed, paraffin-embedded tissue obtained from sites with active lesions by PCR and nucleotide sequencing of bacterial 16S ribosomal RNA. S. pluranimalium should be considered as a cause of meningoencephalitis in a horse.

scholarly journals Genetic variation in native and farmed populations of Tambaqui (Colossoma macropomum) in the Brazilian Amazon: regional discrepancies in farming systems

2013 ◽  
Vol 85 (4) ◽  
pp. 1439-1447 ◽  
Author(s):  
Jonas Aguiar ◽  
Horacio Schneider ◽  
Fatima Gomes ◽  
Jeferson Carneiro ◽  
Simoni Santos ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Dna Sequences ◽  
Amazon Basin ◽  
Farming Systems ◽  
Wild Populations ◽  
The West ◽  
Colossoma Macropomum ◽  
Breeding Stock ◽  
History Of

The tambaqui, Colossoma macropomum, is the most popular fish species used for aquaculture in Brazil but there is no study comparing genetic variation among native and farmed populations of this species. In the present study, we analyzed DNA sequences of the mitochondrial DNA to evaluate the genetic diversity among two wild populations, a fry-producing breeding stock, and a sample of fish farm stocks, all from the region of Santarém, in the west of the Brazilian state of Pará. Similar levels of genetic diversity were found in all the samples and surprisingly the breeding stock showed expressive representation of the genetic diversity registered on wild populations. These results contrast considerably with those of the previous study of farmed stocks in the states of Amapá, Pará, Piauí, and Rondônia, which recorded only two haplotypes, indicating a long history of endogamy in the breeding stocks used to produce fry. The results of the two studies show two distinct scenarios of tambaqui farming in the Amazon basin, which must be better evaluated in order to guarantee the successful expansion of this activity in the region, and the rest of Brazil, given that the tambaqui and its hybrids are now farmed throughout the country.

scholarly journals Analysis of Suspended Sediment in the Anavilhanas Archipelago, Rio Negro, Amazon Basin

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1073 ◽  
Author(s):  
Rogério Ribeiro Marinho ◽  
Naziano Pantoja Filizola Junior ◽  
Édipo Henrique Cremon
Keyword(s):  
Suspended Sediment ◽  
Amazon Basin ◽  
Water Discharge ◽  
Left Bank ◽  
River Channels ◽  
Total Suspended Sediment ◽  
Negro River ◽  
Discharge Velocity ◽  
The Mean ◽  
The Right

This article analyzes the flows of water and total suspended sediment in different reaches in the lower course of the Negro River, the largest fluvial blackwater system in the world. The area under study is the Anavilhanas Archipelago, which is a complex multichannel reach on the Negro River. Between the years 2016 and 2019, data about water discharge, velocity, and concentration of total suspended solids (TSS) were acquired in sample sections of the Negro River channels located upstream, inside, and downstream of the Anavilhanas Archipelago. In the study area, the Negro River drains an area greater than 700,000 km2, and the mean water discharge observed before the Anavilhanas was about 28.655 m3·s−1, of which 97% flows through two channels of the Archipelago close to the right and left banks. The mean TSS concentration of the Negro River upstream and downstream the Archipelago was 3.28 mg·L−1 and 1.63 mg·L−1, respectively. Within the Archipelago, we observed more TSS in the channel on the left bank of the Negro River (mean of 4.50 mg·L−1). The total suspended sediment discharge of the Negro River before (3.14 Mt·year−1) and after (1.43 Mt·year−1) the Anavilhanas Archipelago indicates a 55% retention of the suspended load due to the low water slope and reduced flow velocity caused by the backwater effect of Solimões River on the Negro River. The hydro-sedimentary scenario of the low course of the Negro River characterized in this study indicates a slow and continuous sedimentation process in the Anavilhanas Archipelago. The results presented will serve as a baseline to assess the impacts of the dams on the Branco River, the main tributary for both water and sediment in the Negro River basin.

Recent History of the Agriculture of the Brazilian Amazon Basin

2005 ◽  
Vol 34 (4) ◽  
pp. 215-223 ◽  
Author(s):  
Carlos C. Cerri ◽  
Jerry M. Melillo ◽  
Brigitte J. Feigl ◽  
Marisa C. Piccolo ◽  
Christopher Neill ◽  
...  
Keyword(s):  
Amazon Basin ◽  
Research Work ◽  
No Till ◽  
Early Results ◽  
Gas Fluxes ◽  
Trace Gas Fluxes ◽  
History Of ◽  
Homogeneous Area ◽  
Four Blocks ◽  
Economic Analyses

Land-use change for human settlement and agricultural purposes, especially pasture establishment, has caused major impacts on the Amazon Basin's environment. Development of strategies for reformation and restoration of already degraded pastures constitutes the main goal of the authors' research work. For some of this work, a homogeneous area of land in terms of soil characteristics was selected at Nova Vida ranch in Rondônia state to conduct a multidisciplinary experiment, which included agronomic, environmental and economic analyses. Since July 2001, the authors have monitored five treatments: control, herbicide, tillage, no-till rice and no-till soybean, arranged in four blocks. Early results on carbon and nitrogen stocks, nitrogen mineralization, trace-gas fluxes, dissolved organic carbon and microbial biomass are briefly presented.

scholarly journals The "Crustacean Seas" — an evolutionary perspective on the Ponto–Caspian peracarids

2005 ◽  
Vol 62 (3) ◽  
pp. 505-517 ◽  
Author(s):  
Melania EA Cristescu ◽  
Paul DN Hebert
Keyword(s):  
Ribosomal Rna ◽  
Adaptive Radiation ◽  
Nuclear Gene ◽  
Taxonomic Status ◽  
Mitochondrial Genes ◽  
Evolutionary Perspective ◽  
Intraspecific Divergence ◽  
Geographic Structure ◽  
Colonization Event ◽  
History Of

A spectacular adaptive radiation of crustaceans has occurred in the Black, Caspian, and Aral seas. This study tests several evolutionary scenarios based on the extent of genetic differentiation and the phylogenetic relationships among endemic mysids and gammarid amphipods from the Black and Caspian seas. Molecular phylogenies for these taxa were based on two mitochondrial genes: cytochrome c oxidase subunit I and the large ribosomal RNA subunit (16S), and one nuclear gene, the large ribosomal RNA subunit (28S). The results support the monophyly of the Ponto–Caspian gammarids (genera Dikerogammarus, Echinogammarus, Obesogammarus, and Pontogammarus), suggesting their origin from one colonization event. By contrast, several colonization events preceded the radiation of the Ponto–Caspian mysids (genera Limnomysis and Paramysis). Levels of intraspecific divergence were variable, with mysids showing either no geographic structure or deep genetic splits reflecting a long history of reproductive isolation between populations in marine settings and those in fresh waters. These findings suggest that the diversity of the Ponto–Caspian crustaceans has been underestimated and that species regarded as euryhaline are often composed of distinct evolutionary groups whose taxonomic status should be reevaluated.

Fiscal Incentives for Regional Development

1976 ◽  
Vol 18 (3) ◽  
pp. 357-378 ◽  
Author(s):  
Dennis J. Mahar
Keyword(s):  
Economic History ◽  
Amazon Basin ◽  
Tropical Rainforest ◽  
Rubber Market ◽  
Fiscal Incentives ◽  
The World ◽  
Boom And Bust ◽  
History Of ◽  
Late Nineteenth ◽  
Monopoly Position

Intermittent cycles of boom and bust based on one product have long characterized the economic history of Brazil. In this respect, the immense tropical rainforest comprising the Amazon Basin has been no exception. Economic activity reached its peak in the late nineteenth and early twentieth centuries when this region held a virtual monopoly position in the world rubber market. Manaus, strategically located at the confluence of the Negro and Solimões (Amazonas) Rivers, became the hub of the rubber industry and was transformed from an obscure river town of 3,000 inhabitants to a prosperous, cosmopolitan city of 50,000 in less than forty years. Due to an influx of Asian plantation-grown rubber, though, world prices started declining after 1910 and the Brazilian monopoly was broken—between 1910 and 1934, the Amazon's share of the world rubber market fell precipitously from 60 percent to 1 percent (Andrade, 1950: 23).

Uncovering spatial patterns in the natural and human history of Brazil nut (Bertholletia excelsa ) across the Amazon Basin

2015 ◽  
Vol 42 (8) ◽  
pp. 1367-1382 ◽  
Author(s):  
Evert Thomas ◽  
Carolina Alcázar Caicedo ◽  
Crystal H. McMichael ◽  
Ronald Corvera ◽  
Judy Loo
Keyword(s):  
Spatial Patterns ◽  
Amazon Basin ◽  
Human History ◽  
Brazil Nut ◽  
Bertholletia Excelsa ◽  
History Of

scholarly journals Pinnularia caprichosa sp. nov.: a diatom from a black water Brazilian Amazon system

Phytotaxa ◽  
2015 ◽  
Vol 239 (3) ◽  
pp. 280 ◽  
Author(s):  
Andreia Cavalcante Pereira ◽  
Lezilda Carvalho Torgan ◽  
Ana Luiza Burliga ◽  
John Patrick Kociolek ◽  
Carlos E. Wetzel ◽  
...  
Keyword(s):  
New Species ◽  
River Basin ◽  
Amazon Basin ◽  
Brazilian Amazon ◽  
New Taxon ◽  
Middle Portion ◽  
Black Water ◽  
Negro River ◽  
Electron Microscopical ◽  
Scanning Electron

While possessing a remarkable diversity in the acidic and oligotrophic waters of the Amazon basin, the genus Pinnularia appears underdescribed in the region. In this study, we present light and scanning electron microscopical observations on Pinnularia caprichosa sp. nov. from Tupé Lake, a dendritic lake located on the floodplain of the Negro River basin. This new taxon has a large axial area and transapical striae that are slightly radiate to parallel and longer in the middle portion of the valve. The species was compared with Pinnularia elliptica, P. instabilis, P. lacunarum, P. montana, P. permontana and P. subflexuosa, all of which closely resemble P. caprichosa but differ from the new species in specific details of size, striae density and valve shape.

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