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Silva J.S.B.,National University of Colombia | Montoya A.J.D.,National University of Colombia | Lopez D.C.,Instituto Amazonico Of Investigaciones Cientificas Sinchi | Hurtado F.H.M.,National University of Colombia
Acta Amazonica

This study was carried out in a 5-ha permanent plot established in the Amacayacu National Park, Colombian Amazonia. We assessed the extent at which floristic patterns of tree species were determined by either the environmental variation or the spatial configuration in tierra firme forests. Floristic and environmental variation was assessed on quadrants of 20×20 m. To run the analysis, four different categories of abundance (all, high, medium and low) were considered. We used Detrended Correspondence Analysis and Canonical Correspondence Analysis, followed by a variation partitioning, to analyze the patterns of species distribution in order to quantify the role played by both environmental filtering and dispersal limitation. The spatial template, which represents dispersal limitation, was evaluated in two different ways: using a third degree polynomial and using the Principal Coordinates of Neighbour Matrix (PCNM) method. Beta diversity was relatively low within the plot. PCNM appears as the most appropriate method to analyze the spatial template at this scale. The floristic differences explained along the 5-ha plot were mainly associated to biological processes, such as dispersal limitation. The largest proportion of community variation in our dataset was unexplained by either environmental or spatial data. In conclusion, these results support random processes as the major drivers of the spatial variation of tree species at a local scale on tierra firme forests in the Amacayacu National Park. Source

Correa S.B.,University of Georgia | Winemiller K.,Texas A&M University | Cardenas D.,Instituto Amazonico Of Investigaciones Cientificas Sinchi
Biota Neotropica

Isotopic variation within food sources adds uncertainty to models intended to reconstruct trophic pathways. Understanding this variation is pivotal for planning sampling protocols for food-web research. This study investigates natural variation in C and N stable isotopes among plant species in two western Amazon flooded forests with contrasting watershed biogeochemistry (white-water várzea-forest and black-water igapó -forest). Our objectives were to compare δ13C and δ15N of leaves and fruits between sites; assess the magnitude of within-site variation in δ13C and δ15N of leaves (várzea: 28 spp., igapó: 10 spp.) and fruits (várzea: 22 spp., igapó: 22 spp.); determine within-plant variation in δ13C and δ15 of leaf, wood and fruit tissues; and test whether inter-specific variation in δ13C and δ15N influence the results of a mixing model predicting the contribution of terrestrial C sources to an aquatic consumer. Mean δ13C values of leaves and fruits were not statistically different between the two sites despite regional differences in biogeochemistry and floristic composition. In contrast, mean δ15N of leaves and fruits were significantly lower at the várzea than at the igapósite. The high floristic diversity of both forests was reflected in large within-site interspecific variation in both δ13C and δ15N. Paired comparisons revealed that δ13C of wood and fruits and δ15N of fruits were generally greater than values obtained for leaves from the same plant. The predicted contribution of different carbon sources to the consumer biomass changed between models as a function of source variability. We discuss implications of source variation for designing sampling protocols, interpreting isotopic signatures, and establishing trophic links between plants and consumers. Our findings highlight the importance of in situ sampling to establish reliable primary production baselines for local food webs. © 2016, Universidade Estadual de Campinas UNICAMP. All rights reserved. Source

Sterling Armando C.,Instituto Amazonico Of Investigaciones Cientificas Sinchi | Gomez M C.A.,University of the Amazon | Campo J A.A.,University of the Amazon
Revista Colombiana de Entomologia

In the Colombian Amazon termites attack bare root stumps of the rubber tree Hevea brasiliensis. The objective of the study was to evaluate the pathogenicity of the fungus Metarhizium anisopliae on Heterotermes tenuis termites under laboratory conditions. The concentrations used were 1x10 1, 1x10 3, 3x10 5, 1x10 7 and 3x10 8 conidia/ml and the control (distilled sterile water). The dead insects were cleared with KOH at 10% and mounted on glass slides. Mortality was compared using Kaplan-Meier survival curves and the CL 50 and TL 50 were determined. The concentration of 3x10 8 conidia/ml was the most effective (100% of insects eliminated in six days). There were differences found among the six concentrations used in percent survival of H. tenuis (H 5,81=19.4; p < 0.05) and in the time (days) of survival (H 4,60=14.0; p < 0.05). The CL 50 was 9.64 x 10 3 conidia/ml after a time of six days. The TL 50 was three days for the concentration of 3 x 10 8 conidia/ml. Under laboratory conditions M. anisopliae is very effective on H. tenuis, and for this reason its use under natural conditions should be considered in the integrated management of the termites that affect the cultivation of rubber trees in the Amazonian region. This study is the first report on the in vitro biocontrol of H. tenuis in H. brasiliensis. Source

Vouilloud A.A.,National University of La Plata | Sala S.E.,Instituto Amazonico Of Investigaciones Cientificas Sinchi | Nunez-Avellaneda M.,University of Antioquia | Montoya-Moreno Y.,University of Antioquia | Duque S.R.,National University of Colombia
Diatom Research

This study focuses on the genus Brachysira Kützing from lowland waters as part of the diatom flora investigation of Colombia. Periphyton samples were collected in lentic and lotic waterbodies from different Amazonian basins and the Ayapel swamp system in the northern Atlantic plain of Colombia. Diatoms were analysed with light and scanning electron microscopy. Two new taxa, B. guarrerai and B. huitotarum, are described. These species were differentiated from their allied taxa based on the combination of: the shape of the central area; the shape and number of the areolae that delimit the central area; stria position; presence or absence of papillae on the interstriae; and degree of silicification of the ribs that delimit the raphe. In addition, five other taxa are reported and described: B. microcephala (Grunow) Compère and B. subrostrata Lange-Bertalot are recorded for the first time from Colombia, while B. manfredii Lange-Bertalot was previously found in the Sierra Nevada. The other two taxa were identified as B. aff. brebissonii Ross and B. aff. microcephala because the Colombian specimens differ slightly from the type material of these cosmopolitan species. © 2013 © 2013 The International Society for Diatom Research. Source

Avellaneda M.N.,Instituto Amazonico Of Investigaciones Cientificas Sinchi | Duque S.R.,National University of Colombia
Revista de Biologia Tropical

Diatoms from the Colombian and Peruvian Amazon: the Genera Encyonema, Encyonopsis and Gomphonema (Cymbellales, Bacillariophyceae). The diatom flora of the Colombian and Peruvian Amazon is far less studied than the flora of the Brazilian sector of the basin. Here we present results related to the genera Encyonema, Encyonopsis and Gomphonema. Plankton and periphyton samples were collected in lotic and lentic waterbodies from the Amazonian-Andean region, the Amazon River, Japurá River and Porvenir River basins during 1993, 1994, 2001 and 2003. At each sampling station pH, temperature, water transparency and conductivity were registered. Samples were analyzed with phase contrast microscope (LM) and scanning electron microscope (SEM). Ten taxa are new records for the area; Encyonema for the Peruvian and Colombian Amazon and Encyonopsis for the Colombian Sector. Encyonema neogracile var. tenuipunctatum, E. vulgare, Encyonopsis frequentis, Gomphonema augur var. sphaerophorum and G. contraturris are recorded for the first time in Colombia; Encyonema venezolanum and G. neoapiculatum in Colombia and Peru and the latter also for Amazonia. E. angustecapitatum was mentioned in Colombia before at a pond located at 3000m asl. We describe a new species from Porvenir River, Amazonas, Colombia: Encyonema amazonianum. Source

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