Navegando por Palavras-chave "Amazonia"
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- ItemSomente MetadadadosAge of depositional and weathering events in Central Amazonia(Pergamon-Elsevier Science Ltd, 2017) Sant'Anna, Lucy Gomes; Soares, Emilio Alberto do Amaral; Riccomini, Claudio; Tatumi, Sonia Hatsue [UNIFESP]; Yee, Márcio [UNIFESP]In the last three decades, several studies have been devoted to understanding the role of Late Pleistocene Holocene climate changes in the Amazonia lowlands environment. However, most of these studies used data obtained from sedimentary deposits (lakes, swamps, and colluvium) located away from the central plain or on the edges of the Amazonia region. This article integrates optically stimulated luminescence and accelerated mass spectrometry C-14 ages with sedimentological and geomorphological data obtained during this study or compiled from the literature for fluvial and lacustrine deposits of the central alluvial plain of the Solimoes-Amazon River. The age data allow us to present a chronological framework for the Late Pleistocene Holocene deposits and conclude that (i) the dryness of the LGM in central Amazonia lowlands is recorded by the formation of fluvial terraces and their weathering to pedogenic hematite between 25.3 ka and 17.7 ka
- ItemAcesso aberto (Open Access)Delimitação de espécies no complexo Physalaemus ephippifer (Anura: Leptodactylidae)(Universidade Federal de São Paulo, 2021-12-17) Silva, Izadora Emanuelle [UNIFESP]; Sturaro, Marcelo José [UNIFESP]; http://lattes.cnpq.br/2776090230754156; http://lattes.cnpq.br/7512323633571570Embora ameaçada, a região Neotropical abriga uma riqueza ainda subestimada, pois diversas espécies novas vêm sendo descritas para a região. Nesta região é muito comum a ocorrência de espécies morfologicamente crípticas e nestes casos, o uso de várias fontes de evidências e análises de delimitação têm sido recomendados para investigar a diversidade de táxons, concedendo estabilidade taxonômica aos grupos estudados. Physalaemus ephippifer está amplamente distribuída na região norte do Neotrópico (Amazônia e nordeste brasileiro) e recentemente foi indicada como um possível complexo de espécies. Portanto, empregando uma abordagem integrativa utilizando dados morfológicos e moleculares em análises de delimitação baseadas em locus único (ABGD, mPTP e GMYC) e nos modelos coalescente multiespécies (BPP e iBPP), busquei inferir as possíveis linhagens e suas relações dentro do complexo P. ephippifer e testar hipóteses de delimitação de espécies. A análise filogenética recuperou cinco linhagens distintas dentro do complexo P. ephippifer, estruturadas geograficamente por rios e/ou biomas. Os métodos de delimitação baseados num locus único divergiram em relação ao número e configuração das espécies candidatas (1–3 possíveis espécies). Entretanto, através de testes de hipóteses de delimitação com métodos coalescentes de multiespécies (dados moleculares e/ou morfológicos) foram recuperadas cinco possíveis espécies candidatas em P. ephippifer.
- ItemSomente MetadadadosFire and deforestation dynamics in Amazonia (1973-2014)(Amer Geophysical Union, 2017) van Marle, Margreet J. E.; Field, Robert D.; van der Werf, Guido R.; de Wagt, Ivan A. Estrada; Houghton, Richard A.; Rizzo, Luciana Varanda [UNIFESP]; Artaxo, Paulo; Tsigaridis, KostasConsistent long-term estimates of fire emissions are important to understand the changing role of fire in the global carbon cycle and to assess the relative importance of humans and climate in shaping fire regimes. However, there is limited information on fire emissions from before the satellite era. We show that in the Amazon region, including the Arc of Deforestation and Bolivia, visibility observations derived from weather stations could explain 61% of the variability in satellite-based estimates of bottom-up fire emissions since 1997 and 42% of the variability in satellite-based estimates of total column carbon monoxide concentrations since 2001. This enabled us to reconstruct the fire history of this region since 1973 when visibility information became available. Our estimates indicate that until 1987 relatively few fires occurred in this region and that fire emissions increased rapidly over the 1990s. We found that this pattern agreed reasonably well with forest loss data sets, indicating that although natural fires may occur here, deforestation and degradation were the main cause of fires. Compared to fire emissions estimates based on Food and Agricultural Organization's Global Forest and Resources Assessment data, our estimates were substantially lower up to the 1990s, after which they were more in line. These visibility-based fire emissions data set can help constrain dynamic global vegetation models and atmospheric models with a better representation of the complex fire regime in this region.
- ItemSomente MetadadadosMolecular phylogeny, biogeography and insights into the origin of parthenogenesis in the Neotropical genus Leposoma (Squamata: Gymnophthalmidae): Ancient links between the Atlantic Forest and Amazonia(Elsevier B.V., 2011-11-01) Pellegrino, Katia C. M. [UNIFESP]; Rodrigues, Miguel T.; James Harris, D.; Yonenaga-Yassuda, Yatiyo; Sites, Jack W.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); UP; Brigham Young UnivLeposoma is a conspicuous component of leaf litter herpetofauna of South and Central American rainforests. the 15 bisexual and one parthenogenetic species are allocated to the parietale and scincoides groups based on morphology. Phylogenetic analyses of 1830 bp (mtDNA + nuclear) were performed on 63 specimens of four species from Amazonian and Panamanian rainforests, and six species and one undescribed form from the Atlantic Forest. Different methods of tree reconstruction were explored, with Anotosaura vanzolinia and Colobosauroides cearensis as outgroups. the monophyly of the parietale and scincoides groups is strongly supported. Contrary to previous hypotheses suggesting a recent contact between Atlantic and Amazon forests, our estimates point to an initial split in Miocene. the position of Leposoma baturitensis, endemic to relictual forests in the semiarid Caatingas northeastern Brazil, and its divergence from the remaining species of the Atlantic Forest, suggests an ancient isolation with no indication of a secondary contact with forests of the eastern coast. Our data do not permit unambiguous assignment of parental species of the unisexual Leposoma percarinatum or the mechanism involved in the origin of parthenogenesis, but revealed two highly divergent diploid and triploid lineages within L percarinatum, indicating that the unisexuals represent a species complex. (C) 2011 Elsevier Inc. All rights reserved.
- ItemSomente MetadadadosMolecular phylogeny, species limits, and biogeography of the Brazilian endemic lizard genus Enyalius (Squamata: Leiosauridae): An example of the historical relationship between Atlantic Forests and Amazonia(Elsevier B.V., 2014-12-01) Rodrigues, Miguel Trefaut; Vina Bertolotto, Carolina Elena; Amaro, Renata Cecilia; Yonenaga-Yassuda, Yatiyo; Xavier Freire, Eliza Maria; Machado Pellegrino, Katia Cristina [UNIFESP]; Universidade de São Paulo (USP); Univ Santo Amaro; Univ Fed Rio Grande do Norte; Universidade Federal de São Paulo (UNIFESP)The endemic Brazilian Enyalius encompasses a diverse group of forest lizards with most species restricted to the Atlantic Forest (AF). Their taxonomy is problematic due to extensive variation in color pattern and external morphology. We present the first phylogenetic hypothesis for the genus based on 2102 bp of the mtDNA (cyt-b, ND4, and 16S) and nuclear (c-mos) regions, uncovering all previously admitted taxa (9 spp). Different methods of tree reconstruction were explored with Urostrophus vautieri, Anisolepis grilli and A. longicauda as outgroups. the monophyly of Enyalius and its split into two deeply divergent clades (late Oligocene and early Miocene) is strongly supported. Cade A assembles most lineages restricted to south and southeastern Brazil, and within it Enyalius brasiliensis is polyphyletic; herein full species status of E. brasiliensis and E. boulengeri is resurrected. Cade B unites the Amazonian E. leechii as sister-group to a major clade containing E. bilineatus as sister-group to all remaining species from northeastern Brazil. We detected unrecognized diversity in several populations suggesting putative species. Biogeographical analyses indicate that Enyalius keeps fidelity to shadowed forests, with few cases of dispersal into open regions. Ancient dispersal into the Amazon from an AF ancestor may have occurred through northeastern Brazil. (C) 2014 Elsevier Inc. All rights reserved.
- ItemSomente MetadadadosMotility, morphology and phylogeny of the plasmodial worm, Ceratomyxa vermiformis n. sp (Cnidaria: Myxozoa: Myxosporea)(Cambridge Univ Press, 2017) Adriano, E. A. [UNIFESP]; Okamura, B.The Myxozoa demonstrate extensive morphological simplification and miniaturization relative to their free-living cnidarian ancestors. This is particularly pronounced in the highly derived myxosporeans, which develop as plasmodia and pseudoplasmodia. To date, motility in these stages has been linked with membrane deformation (e.g. as pseudopodia and mobile folds). Here we illustrate a motile, elongate plasmodium that undergoes coordinated undulatory locomotion, revealing remarkable convergence to a functional worm at the cellular level. Ultrastructural and confocal analyses of these plasmodia identify a highly differentiated external layer containing an actin-rich network, long tubular mitochondria, abundant microtubules, a secreted glycocalyx layer, and an internal region where sporogony occurs and which contains homogeneously distributed granular/fibrillar material. We consider how some of these features may support motility. We also describe the species based on spore morphology and SSU rDNA sequence data, undertake molecular phylogenetic analysis to place it within an early-diverging clade of the ceratomyxids, and evaluate the resultant implications for classification (validity of the genus Meglitschia) and for inferring early host environments (freshwater) of ceratomyxids.