23736 research outputs found
Sort by
Climate change effects on population dynamics of three species of Amazonian lizards
No full textThe scarcity of data on natural history and ecology of lizards still limits the understanding of population dynamics for many species. We attempt to evaluate possible effects of climate change on the population dynamics of three lizard species (Ameiva ameiva, Gonatodes humeralis and Norops fuscoauratus) in two Amazonian localities (Caxiuanã National Forest and Ducke Reserve). We calculated a tolerance index combining environmental thermal adequacy with the b-d model, which consider survival and reproductive rates to calculate population dynamics. Thus, we simulated population growth rates based on current and future environmental operative temperatures, considering an optimistic and a business-as-usual scenario of greenhouse gases emissions (GGE), and evaluate if the sensitivity of life history traits to population growth rate are likely to be trigged by climate change. Our results demonstrated that both populations of G. humeralis and the Ducke population of N. fuscoauratus may become locally extinct under both scenarios of GGE, while both populations of A. ameiva are likely to decrease, but without reaching a scenario of local extirpation. This study represents the first effort to evaluate the sensitivity of lizard populations and elasticity to climate change and demonstrate the geographic variability of these traits in three widespread and habitat-generalist species. We highlight the need of new studies focusing on species with different biological trait patterns, such as endemic distributions and habitat-specialists, to provide the theoretical and empirical basis for biologically informed conservation strategies and actions, in order to minimize the potential extinction of populations due to climate change. © 2019 Elsevier Inc
Trece especies nuevas de los milpiés del género Haematotropis Jeekel, 2000 (Polydesmida: Aphelidesmidae: Aphelidesminae)
No full textMicrotriatoma trinidadensis (Lent, 1951) (Hemiptera, Reduviidae, Triatominae): first record in the state of Amazonas, Brazil
Get PDFMicrotriatoma trinidadensis (Lent, 1951), previously known from Venezuela, Colombia, Suriname, Peru, Bolivia, and the Brazilian states of Mato Grosso, Pará, and Tocantins, is reported for the first time in Amazonas state, Brazil. We found in the collection of the Instituto Nacional de Pesquisas da Amazônia an unidentified female specimen of Microtriatoma. The specimen was collected in April 2010, in dried straw and foliage of açai palm, Euterpe precatoria Mart., from Monte Sião, municipality of Codajás, Amazonas state. © 2019 Souza et al. All rights reserved
Morfogênese, caracterização temporal e efeito da remoção das reservas em estádios pós-embrionários de três espécies de palmeiras (Arecaceae: Arecoideae)
Get PDFThis work presents morphological and anatomical data to understand the process of organogenesis during the initial growth of three Amazonian palms: Astrocaryum acaule, Attalea attaleoides and Attalea microcarpa. These species present differences in the type of post-germinative development, as well as in their internal morphology, being these more pronounced among species of different genera. In Astrocaryum acaule the germination is adjacent, with formation of a coleoptile above the cotyledonary sheath. The germination is unequal, varying from 14 to 250 days for emission of the germinative bud. The initial root system differs in the hypocotyl-radicle region, below the insertion of the leaf primordia, forming first a lateral root, whereas the primary root has posterior emergence. The first eophyll, bifid, is expanded to 120 days after the protrusion of the germinative button. Attalea species differ in the time of emergence of the germinative bud, with an average of 171 days for A. attaleoides and 15 days for A. microcarpa, with a wide variation in the period. Both have early initial growth, with apocole lengthening, no coleoptile present, have an evident and persistent primary root, with lateral roots traversing through the cotyledonary sheath. Attalea microcarpa can branch off the primary root and emit roots of the apocole. By means of histochemical tests mucilages, starch and proteins were detected in adventitious roots and in the primary root of the species. The first eophyll, lanceolate, is expanded about 113 days after the emission of the germinative button in A. attaleoides and 145 days in A. microcarpa. The seeds of the species have a tegument with a layer in Astrocaryum acaule and two layers in Attalea followed by an endosperm where a zone of degradation is formed, that increases with the growth of the haustorium, evidenced by the dissolution of the endosperm cell walls. In Attalea, in the phase of expansion of the first eophyll this zone of degradation is close to the integument of the seed. The centesimal composition of all species was investigated, revealing the predominance of lipids and carbohydrates as the representative reserves of the seed. The three species have similar composition by the qualitative analysis of the histochemical tests in the endosperm and haustorium. However, the detection of lipids and starch in the haustorium was evident only from the stages after the emission of the germinative button. The data presented here can support studies with the propagation of palm species for economic purposes and complementary ontogenetic studies. It is also hoped that the information in this study will broaden the database on Amazonian flora, palms, and how to conduct ontogenetic studies within the group be addressed in future works. We suggest working with different taxa in order to answer other questions related to the organogenesis of structures involved in plant growth, which may have phylogenetic, autoecological or adaptive importance.Este trabalho apresentou dados morfológicos, anatômicos para a compreensão do processo de organogênese ao longo do crescimento inicial de três palmeiras amazônicas: Astrocaryum acaule, Attalea attaleoides e Attalea microcarpa. As espécies apresentam diferenças no tipo de desenvolvimento pós-germinativo, bem como em sua morfologia interna, sendo estas mais pronunciadas entre espécies de gêneros diferentes. Em Astrocaryum acaule a germinação é adjacente, com formação de um coleóptilo acima da bainha cotiledonar. A germinação é desuniforme, variando entre 14 e 250 dias para emissão do botão germinativo. O sistema radicular inicial se diferencia na região hipocótilo-radícula, abaixo da inserção dos primórdios foliares, formando primeiramente uma raiz lateral, ao passo que a raiz primária tem emergência posterior. O primeiro eofilo, bífido, é expandido aos 120 dias após a protrusão do botão. As espécies de Attalea divergem no tempo de emergência do botão germinativo, sendo em média de 171 dias para A. attaleoides e 15 dias para A. microcarpa, com ampla variação no período. Ambas possuem crescimento inicial remoto, com alongamento do apocole, não apresentam coleóptilo, possuem uma raiz primária evidente e persistente, com raízes laterais partindo através da bainha cotiledonar. Attalea microcarpa pode ramificar a raiz primária e emitir raízes do apocole. Por meio de testes histoquímicos mucilagens, amido e proteínas foram detectadas em raízes adventícias e na raiz primária da espécie. O primeiro eofilo, lanceolado, é expandido em cerca de 113 dias após a emissão do botão germinativo em A. attaleoides e 145 dias em A. microcarpa. As sementes das espécies possuem tegumento com uma camada em Astrocaryum acaule e duas camadas em Attalea seguidas de um endosperma onde se forma uma zona de degradação que aumenta com o crescimento do haustório, evidenciada pela degradação das paredes celulares do endosperma. Em Attalea, na fase de expansão do primeiro eofilo esta zona de degradação se encontra próxima ao tegumento da semente. A composição centesimal de todas as espécies foi investigada, revelando a predominância de lipídios e carboidratos como as reservas representativas da semente. As três espécies têm composição similar pela análise qualitativa dos testes histoquímicos no endosperma e haustório. No entanto, a detecção de lipídios e amido no haustório foi evidente apenas a partir das fases posteriores à emissão do botão germinativo. Os dados apresentados aqui podem subsidiar estudos com a propagação das espécies com finalidades econômicas e complementar estudos ontogenéticos. Espera-se também que as informações deste estudo ampliem a base de dados sobre a flora amazônica, sobre as palmeiras, e sobre como a forma de conduzir estudos ontogenéticos com o grupo seja abordada. Sugere-se que trabalhos futuros com diferentes táxons visem responder outras questões relativas à organogênese de estruturas envolvidas no crescimento da planta, que possam ter importância filogenética, autoecológica ou adaptativa
Effects of sublethal Cd, Zn, and mixture exposures on antioxidant defense and oxidative stress parameters in early life stages of the purple sea urchin Strongylocentrotus purpuratus
No full textOxidative stress parameters were evaluated during the first 72 h of embryonic development of purple sea urchin Strongylocentrotus purpuratus continuously exposed to control conditions, to cadmium alone (Cd, 30 μg/L), to zinc alone (Zn, 9 μg/L) or to a Cd (28 μg/L) plus Zn (9 μg/L) mixture. These sublethal concentrations represent ∼ 10% of the acute EC50. Bioaccumulation, antioxidant capacity against peroxyl radicals (ACAP), total glutathione (GSH) level, glutathione-S-transferase (GST), glucose-6-phosphate dehydrogenase (G6PDH) and superoxide dismutase (SOD) activity, and lipid peroxidation (LPO) were analyzed at 24 h (blastula), 48 h (gastrula), and 72 h (pluteus) stages of development. Zinc (an essential metal) was well-regulated, whereas Cd (non-essential) bioaccumulated and whole-body [Cd] increased from blastula to pluteus stage in sea urchin larvae. In controls, ACAP progressively declined from 24 h to 72 h, while LPO reciprocally increased, but other parameters did not change. Cd alone was more potent than Zn alone as a pro-oxidant, with the major effects being decreases in SOD activity and parallel increases in LPO throughout development; GST activity also increased at 24 h. Zn alone caused only biphasic disturbances of ACAP. In all cases, the simultaneous presence of the other metal prevented the effects, and there was no instance where the oxidative stress response in the presence of the Cd/Zn mixture was greater than in the presence of either Cd or Zn alone. Therefore the sublethal effects of joint exposures were always less than additive or even protective, in agreement with classical toxicity data. Furthermore, our results indicate that SOD and Zn can play important roles in protecting sea urchin embryos against Cd-induced lipid peroxidation. © 2019 Elsevier B.V
Moina micrura Kurtz 1874, (Crustacea: Anomopoda): Alternativa de alimento vivo para larvicultura de peixes amazônicos
Get PDFAs far as we know about live feeds production, it has always been the most limitation
factor to large-scale zooplankton cultivation in aquaculture practices. The sites
designated for the zooplankton production are usually tanks that are fertilized with
organic or inorganic nutrients to provide the development of microalgae to feed and
support the growth of zooplankton. Microalgae composition and density has been
reported to be one of the main controlling factors for zooplankton’s population growth
during cultivation, knowing that the low availability of this resource decreases the
number of produced progenies and can even change the cladocera’s reproduction
type, from asexual reproduction to sexual, where the females produce at most two
progenies, that go into dormancy. Resting eggs production leads to several
implications involving both the production of zooplankton itself and zooplankton as a
living food for the success of larviculture stage. That way, understanding the role of
these forms for the zooplankton’s production as a live feed, besides of perceiving under
what conditions the zooplankton produces dormant forms, was the purpose of this
study. To understand this role of resting eggs in the cultivation process, a tank
(9.6x4.8x0.9m) of INPA was used. In the tank, sampling was done and used to
estimate density of phytoplankton, sediment sampling for both density estimation and
daily hatching of resting eggs, as well as the collection of resting eggs produced by the
active community in the tank. In order to understand under what conditions
zooplankton starts producing this eggs, the effect of different densities of
phytoplankton were tested (A1 5x103, A2 5x104, A3 5x106 cells / mL) and also
different densities of zooplankton (initial density C1 5, C2 15 and C3 30 organisms), in
the production of resistance forms in Moina micrura. The estimated density was 1.18
effipios/g in sediment. The mean hatching rate was 20.8 individuals m-2 day-1. The
production’s average rate was 164.5 resting eggs m-2 day-1. The resting eggs present
in the sediments are determinant for the success in zooplankton production. The
density of phytoplankton was preponderant for asexual reproduction prevailing in the
population during the period of study. We didn’t find relation between the increase in
population density and the production of resting eggs in this study.No que diz respeito à produção de alimento vivo, o cultivo em grande escala do
zooplâncton sempre foi um fator limitante nas práticas da aquicultura. Os locais
designados para a produção do zooplâncton normalmente são tanques, que são
fertilizados com nutrientes orgânicos ou inorgânicos, para proporcionar o
desenvolvimento de microalgas e assim suportar o crescimento do zooplâncton. A
composição e densidade das microalgas no ambiente tem sido relatado como um dos
principais fatores controladores do crescimento populacional do zooplâncton durante
o cultivo, uma vez que a baixa disponibilidade desse recurso diminui o número de
progênies produzidas, além de mudar o modo reprodutivo dos cladóceros de
reprodução assexuada para sexuada, na qual as fêmeas produzem no máximo duas
progênies, que entram em dormência. A produção das formas de resistência tem uma
série de implicações envolvendo tanto a produção do próprio zooplâncton como o
zooplâncton como alimento vivo para o sucesso da larvicultura. Portanto,
compreender o papel dessas formas para a produção do zooplâncton como alimento
vivo, além de entender em quais condições o zooplâncton passa a produzir as formas
dormentes foi o objetivo desse estudo. Para entender o papel das formas dormentes
no processo de cultivo, foi utilizado um tanque (9,6x4,8x0,9m) do INPA. No tanque,
foram realizadas coletas para estimativa da densidade do fitoplâncton, coletas do
sedimento tanto para estimativa da densidade quanto para eclosão diária das formas
de resistência, além da coleta das formas dormentes produzidas pela comunidade
ativa no tanque. Para entender em quais condições o zooplâncton passa a produzir
as formas dormentes, nós testamos o efeito de diferentes densidades de fitoplâncton
(A1 5x103, A2 5x104, A3 5x106 cells/mL) e diferentes densidades (densidade inicial
C1 5, C2 15 e C3 30 organismos) na produção de formas de resistência em Moina
micrura. Foi estimado uma densidade de 1,18 de efípios/g de sedimento. A taxa média
de eclosão foi de 20,8 indivíduos m-2 dia-1. A taxa média de produção foi de 164,5
formas de resistência m-2 dia-1. As formas de resistência presentes nos sedimentos
são determinantes para o sucesso na produção do zooplâncton. A densidade do
fitoplâncton foi preponderante para a reprodução assexuada prevalecer na população
durante o período de estudo. Não encontramos relação entre o aumento da densidade
populacional e a produção de formas de resistência neste estudo
An HpaII/MspI-PCR assay to measure methylation of DNA in Hoplosternum littorale (Callichthyidae, Siluriformes) from a polluted environment in the central Amazon basin
No full textThe HpaII/MspI-PCR is a method based on the sensitivity of restriction enzymes to methylation at their cleavage sites, which permits the comparison of the DNA methylation status of different organisms, based on the differential patterns of digestion. Prior to the present study, nothing was known of the methylation profile of specific DNA sequences in Amazonian fish based on enzymes sensitive to methylation. Given this, the present study investigated the methylation profile of the 18S rRNA gene of the armored catfish, Hoplosternum littorale, which inhabits relatively inhospitable environments in the Amazon basin. A differential methylation profile was found in the 18S rRNA sites, indicating that polluted environments may influence the methylation of DNA, and would have evolved in the species, initially, as a defense mechanism against the expression of transposable elements. © 201
Major range extension for Orange-fronted Plushcrown Metopothrix aurantiaca in the central Amazon of Brazil
Get PDFOrange-fronted Plushcrown Metopothrix aurantiaca is a unique, but easily overlooked, small furnariid found in the midstorey and canopy of riverine areas in the Amazon. The species' previously published distribution includes parts of southernmost Colombia, eastern Ecuador, eastern Peru, northern Bolivia and western Brazil. In the easternmost part of its distribution (Brazil), M. aurantiaca occurs in the states of Acre, Amazonas and Rondônia, east to 64°W. We present nine new records of the species in Brazil, all of them east of its previously known distribution and together extending the range by c.750 km. These new records derive from sampling that includes collecting expeditions, exhaustive várzea surveys, and incidental observations. We propose a new continuous distribution for this species restricted to white-water river floodplains with known occurrences. © 2019 The Authors
Distance to large rivers affects fish diversity patterns in highly dynamic streams of Central Amazonia
Get PDFLongitudinal-zonation hypotheses generally predict gradual changes in fish composition from upstream to downstream due to changes in habitat conditions, but largely disregard downstream effects on upstream segments. Floodplains of large rivers represent areas of high connectivity during flood periods and can act as stable refuges in dry seasons, which may attenuate deterministic constraints imposed by local conditions on fish assemblages in surrounding habitats. In this study, we investigated the effects of proximity to large rivers on taxonomic- and functional-diversity patterns of stream-fish assemblages in an extensive region of Central Amazonia. We sampled 31 headwater-stream reaches in nine catchments in the Purus and Madeira Rivers interfluve between December 2014 and March 2015. Ninety seven fish species from seven orders and 19 families were captured. The results indicate that distance to large rivers is more important than distance among sites and local conditions in explaining functional and taxonomic diversity of stream-fish assemblages at large spatial scales. We also found a decrease in taxonomic and functional richness towards headwaters, mainly related to the loss of benthic and sedentary species along the distance gradient. These species may be favored by the proximity to refuge areas and high resource availability near the floodplain. In contrast, upstream assemblages were mainly occupied by small-sized, nektonic species with higher dispersal capacity, highly dependent of allochthonous resources. Downstream effects could be detected for many kilometers upstream in hydrographic catchments and this reinforces the crucial role of connectivity between fluvial habitats in maintenance of stream-fish diversity patterns in the region. © 2019 Stegmann et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited