Atlas palinológico de la amazonia colombiana IV. familia arecaceae

Se describen los granos de polen pertenecientes a géneros representativos de la familia Arecaceae con área de distribución en la región Amazónica. De acuerdo con el arreglo sistemático de la familia, se analizaron representantes de las tribus Lepidocaryeae (tres géneros, tres especies), Hyphorbeae (un género, una  especie), Iriarteae (cuatro géneros, cuatro especies y siete subespecies), Areceae (cinco géneros, cinco especies y seis subespecies), Cocoeae (cinco géneros, trece especies y dieciséis subespecies) y Geonomeae (dos géneros, dos especies). En general en Arecaceae, los granos son heteropolares, de forma oblado a pro lado esferoidal, intectados, tectados, tectados perforados o semitectados y con procesos supratectales. Los tipos de estructura más frecuentes son espinado, liso, fosulado y foveolado.Pollen grains belonging to the most representative genera of Arecaceae family at the Amazonian region are described. According to the systematic arrangement of the family, taxa of the following tribes were analyzed: Lepidocaryeae (three genera and three species), Hyphorbeae (one genera, one species), Iriarteae (four genera, four species and seven subspecies), Areceae (five genera, five species and six subspecies), Cocoeae (five genera, thirteen species and sixteen subspecies) and Geonomeae (two genera and two species). In general those grains are heteropolar, oblato to prolate spheroidal, intectate, tectate or perforated tectate or semitectate. The most frequent structure types are echinate, psilate, fossulate and foveolate

The evolutionary history of the Central Asian steppe-desert taxon Nitraria (Nitrariaceae) as revealed by integration of fossil pollen morphology and molecular data

The transition from a greenhouse to an icehouse world at the Eocene-Oligocene Transition (EOT) coincided with a large decrease of pollen from the steppe-adapted genus Nitraria. This genus, now common along the Mediterranean coast, Asia and Australia, has a proposed coastal origin and a geographically widespread fossil record. Here we investigated the evolution, taxonomic diversity and morphological disparity of Nitraria throughout the Cenozoic by integrating extant taxa and fossil palynological morphotypes into a unified phylogenetic framework based on both DNA sequences and pollen morphological data. We present the oldest fossil pollen grain of Nitraria, at least 53 Myr old. This fossil was found in Central Asian deposits, providing new evidence for its origin in this area. We found that the EOT is an evolutionary bottleneck for Nitraria, coinciding with retreat of the proto-Paratethys Sea, a major global cooling event and a turnover in Central Asian steppe vegetation. We infer the crown age of modern Nitraria spp. to be significantly younger (Miocene) than previously estimated (Palaeocene). The diversity trajectory of Nitraria inferred from extant-only taxa differs markedly from one that also considers extinct taxa. Our study demonstrates it is therefore critical to apply an integrative approach to fully understand the plant evolutionary history of Nitrariaceae.publishedVersio

Análisis palinológico de mieles de tres localidades de la Sabana de Bogotá

En 48 muestras de mieles producidas por Apis mellifera provenientes de apiarios de las localidades de Cogua, Tabio y Zipaquirá (Cundinamarca), se diferenciaron 167 tipos polínicos, que se agruparon en 69 familias. La identificación de palinomorfos se realizó en un 10% a nivel de especie, 39% a género y 28% a familia. Los tipos que no se lograron determinar representan eI23%. Los espectros polínicos permitieron caracterizar mieles uniflorales y multiflorales; en Cogua se encontraron 13 muestras uniflorales (polen dominante Eucalyptus cf. globulus) y 3 multiflorales (polen dominante Eucalyptus cf. globulus y Trifolium sp.). En Tabio 10 de las mieles eran uniflorales, de Eucalyptus cf. globulus (9) y de Prunus serotina (1) Yseis multiflorales de Val/ea stipularis y Eucalyptus cf. globulus (1), Ugni sp., Asteraceae tubiflorae y Eucalyptus cf. globulus (3); Prunus serotina y Eucalyptus cf. globulus (1) y Eucalyptus cf. globulus y Oreopanax cf. mutisianus (1). En la zona de Zipaquirá todas las mieles fueron uniflorales y estaban dominadas por Eucalyptus cf. Globulus (4) o por Weinmannia sp. (12).In forty-eight samples of honey coming from Cogua, Tabio, and Zipaquirá (Cundinamarca) 167 pollen-types of sixty-nine plant families were differentiated. The identification was made to species level in 10% ofthe cases, at 39 % to genera, 28% at family level. 23% of the palinomorphes remained unindentified. Thirteen samples from Cogua were classified as unifloral (dominant pollen of Eucaliptus globulus) and three like multifloral (dominant pollen of Eucaliptus cf. globulus and Trifolium sp.). Ten samples from Tabio were classified as unifloral (nine ofthese with dominant pollen of Eucaliptus globulus and one with Prunus serotinai and six like multifloral (dominant pollen of Vallea stipularis y Eucafyptus cf. globufus (1), Ugni sp., Asteraceae tubiliflora and Eucalyptus cf. globulus (3); Prunus serafina and Eucalyptus cf. globulus (l) y Eucafyptus cf. gfobulus and Oreopanax cf. mutisianus (1). All samples from Zipaquirá were classified like unifloral, pollen dominant  Eucafyptus cf. globulus (4) or by Weinmannia sp. (12).</p

Análisis palinológico de mieles de tres localidades de la Sabana de Bogotá

En 48 muestras de mieles producidas por Apis mellifera provenientes de apiarios de las localidades de Cogua, Tabio y Zipaquirá (Cundinamarca), se diferenciaron 167 tipos polínicos, que se agruparon en 69 familias. La identificación de palinomorfos se realizó en un 10% a nivel de especie, 39% a género y 28% a familia. Los tipos que no se lograron determinar representan eI23%. Los espectros polínicos permitieron caracterizar mieles uniflorales y multiflorales; en Cogua se encontraron 13 muestras uniflorales (polen dominante Eucalyptus cf. globulus) y 3 multiflorales (polen dominante Eucalyptus cf. globulus y Trifolium sp.). En Tabio 10 de las mieles eran uniflorales, de Eucalyptus cf. globulus (9) y de Prunus serotina (1) Yseis multiflorales de Val/ea stipularis y Eucalyptus cf. globulus (1), Ugni sp., Asteraceae tubiflorae y Eucalyptus cf. globulus (3); Prunus serotina y Eucalyptus cf. globulus (1) y Eucalyptus cf. globulus y Oreopanax cf. mutisianus (1). En la zona de Zipaquirá todas las mieles fueron uniflorales y estaban dominadas por Eucalyptus cf. Globulus (4) o por Weinmannia sp. (12).In forty-eight samples of honey coming from Cogua, Tabio, and Zipaquirá (Cundinamarca) 167 pollen-types of sixty-nine plant families were differentiated. The identification was made to species level in 10% ofthe cases, at 39 % to genera, 28% at family level. 23% of the palinomorphes remained unindentified. Thirteen samples from Cogua were classified as unifloral (dominant pollen of Eucaliptus globulus) and three like multifloral (dominant pollen of Eucaliptus cf. globulus and Trifolium sp.). Ten samples from Tabio were classified as unifloral (nine ofthese with dominant pollen of Eucaliptus globulus and one with Prunus serotinai and six like multifloral (dominant pollen of Vallea stipularis y Eucafyptus cf. globufus (1), Ugni sp., Asteraceae tubiliflora and Eucalyptus cf. globulus (3); Prunus serafina and Eucalyptus cf. globulus (l) y Eucafyptus cf. gfobulus and Oreopanax cf. mutisianus (1). All samples from Zipaquirá were classified like unifloral, pollen dominant  Eucafyptus cf. globulus (4) or by Weinmannia sp. (12)

Cyclic sediment deposition by orbital forcing in the Miocene wetland of western Amazonia? New insights from a multidisciplinary approach

International audienceIn the Miocene, a large wetland system extended from the Andean foothills into western Amazonia. This system has no modern analogue and the driving mechanisms are not yet fully understood. Dynamic topography and Andean uplift are thought to have controlled deposition, with allocyclic base level changes driven by eustasy and orbital forcing also playing a role. In this study we investigate the presumed orbital cyclicity that controlled sediment deposition, while also assessing sediment source and biomes in the Miocene wetland. We do this by integrating lithological, palynological, malacological and geochemical data from the Los Chorros site (Amazon River, Colombia), and by placing our data in a sequence stratigraphic framework. In this sequence biostratigraphic evaluation, the Los Chorros succession is visualized to be composed of a series of flood-fill packages, with a rapid initial flood, marine-influenced conditions at the time of maximum flood, followed by a longer regressive infill phase. Based on the palynology we could differentiate local vegetation, such as palm swamps, from regional origin such as terra firme vegetation (non-flooded Amazonian forest) and Andean montane forest, while from sediment geochemistry we could separate local and regional sediment sources. At the times of flooding, oligotrophic and eutrophic aquatic conditions alternatively characterized the wetland, as is shown by the presence of algae, floating ferns, and mollusc assemblages, while intervening subaquatic debris points to proximal submerged lowlands. In the lower 20 m of the section, marine influences are intermittently evident and shown by short-lived maxima of mangrove pollen, foraminiferal test linings, dinoflagellate cysts, coastal mollusc species, and an episodic decline in terrestrial biomarkers. The upper 5 m of the section is characterized by floodplain forest taxa with a diversity in tropical rain forest taxa and relatively few lacustrine indicators. These marine, mangrove, and lacustrine indicators suggest that the outcrops at Los Chorros represent predominant marine-influenced lacustrine conditions during periods of sea level highstand. The sequence biostratigraphic evaluation further points to eight 41 kyr obliquity-driven depositional cycles, with rapid phases of transgression. Mangrove elements would have colonised within the timeframe of each sea level rise. Based on this relative age constraint and comparison to regional records, deposition likely took place prior to the 13.8 Myr global sea level fall, and most likely during the period just after 14.5 Ma, between Middle Miocene Climatic Optimum (MMCO; 17-14 Ma) and Middle Miocene Climate Transition (MMCT; 14.7-13.8 Ma). Palynological evidence further suggests that to the west, surface elevation ranged from ~1000 up to ~3500 m and hosted protoparamo vegetation, the oldest yet reported and in agreement with predictions from molecular studies. In contrast, contemporaneous sites to the northeast of the wetland consisted of fluvial and cratonic formations, as shown by their Nd and Sr isotopic sediment signature. In summary, our data lead to an improved understanding of how geological and astronomical mechanisms controlled the floral and faunal distribution and controlled sediment deposition in western Amazonia during the middle Miocene. As Miocene conditions strongly contrast with modern western Amazonia, our data provide an important context for the deep time history and evolution of the modern western Amazon rainforest