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Kinds of Andes Selected AbstractsBiological Sustainability of Live Shearing of Vicuña in PeruCONSERVATION BIOLOGY, Issue 1 2007CATHERINE TERESA SAHLEY Andes; conservación basada en comunidades; Vicugna vicugna Abstract:,The vicuña's (Vicugna vicugna) fiber is highly valued as an export product that is made into luxury fabric and clothing. The price of fiber in 2004 was $566/kg, which makes the fiber a potentially important source of income for Andean agropastoral communities and serves as an incentive to allow vicuña grazing on high-elevation Andean landscapes. It is presumed that a shorn vicuña has little value for poachers, so shearing vicuñas could serve as a disincentive to poaching. Thus, the supply of vicuña fiber may be sustainable if it is procured through live shearing, which should serve as a powerful conservation tool. We evaluated the effects of capture and shearing on the demography of vicuña in one site located in the Salinas Aguada Blanca Reserve, Arequipa, Peru, where vicuñas were captured and shorn in spring and then returned to the wild. We conducted fixed-width line-transect censuses from 1997 to 2003 of this population. We compared the proportion of young born to females that were shorn versus females that were unshorn for the 3 years in which shearing occurred. We evaluated the effect of capture and shearing on proportion of young born to shorn and unshorn females at a second site, Picotani, Puno. The wild population in Arequipa that underwent capture and shearing showed a steady increase in total population and average density between 1997 and 2003. No significant difference was found between the proportion of young per female for shorn and unshorn females at either site. We conclude that in spring, capture and live shearing of vicuñas can be biologically sustainable. Further research is needed to determine whether shearing during winter months is biologically sustainable. Resumen:,La fibra de vicuña (Vicugna vicugna) tiene gran valor como un producto de exportación que es transformado en tela y ropa de lujo. El precio de la fibra en 2004 era de $566/kg, lo que hace que la fibra sea una fuente de ingreso potencialmente importante para comunidades agropastoriles Andinas y servir como un incentivo para permitir el pastoreo de vicuñas en paisajes Andinos elevados. Se presume que una vicuña trasquilada tiene poco valor para cazadores furtivos, por lo que el trasquilado de vicuñas pudiera servir como un desincentivo para la caza furtiva. Por lo tanto, el abastecimiento de fibra de vicuña puede ser sustentable si se obtiene del trasquilado de animales vivos, y el trasquilado de animales vivos debería ser una poderosa herramienta de conservación. Evaluamos los efectos de la captura y trasquilado sobre la demografía de vicuñas en un sitio localizado en la Reserva Salinas Aguada Blanca, Arequipa, Perú, donde las vicuñas fueron capturadas y trasquiladas en primavera y liberadas. Realizamos censos de esta población en transectos lineales de ancho fijo de 1997 a 2003. Comparamos la proporción de crías de hembras trasquiladas con las de hembras no trasquiladas durante los 3 años en que ocurrió el trasquilado. Evaluamos el efecto de la captura y trasquilado sobre la proporción de crías de hembras trasquiladas y no trasquiladas en un segundo sitio, Picotani, Puno. La población silvestre en Arequipa que fue capturada y trasquilada mostró un incremento constante en la población total y la densidad promedio entre 1997 y 2003. No se encontró diferencia significativa entre la proporción de crías por hembra para hembras trasquiladas y no trasquiladas en ningún sitio. Concluimos que en la primavera, la captura y trasquilado de vicuñas vivas puede ser biológicamente sostenible. Se requiere más investigación para determinar si el trasquilado durante el invierno es biológicamente sostenible. [source] Extinction-Rate Estimates for a Modern Neotropical FloraCONSERVATION BIOLOGY, Issue 5 2002Nigel C. A. Pitman We present the first quantitative estimates of extinction rate in a complete Neotropical flora based on historical plant-collection records, quantitative measurements of forest loss and plant diversity, and the conservation status of endemic plant species in Ecuador. Our analyses suggest that 19,46 endemic plant species have gone extinct in Ecuador over the last 250 years, mostly because of habitat loss, and therefore are now globally extinct. An additional 282 species, nearly 7% of Ecuador's endemic flora, qualify as critically endangered. We found evidence of impending large-scale plant extinctions in the country's coastal and Andean forests, but little extinction and low potential for extinction in the Amazonian lowlands. Resumen: Las preocupaciones sobre las elevadas tasas de extinción en los trópicos son una característica común en la literatura sobre conservación, pero las mediciones directas son escasas. Presentamos las primeras estimaciones cuantitativas de la tasa de extinción en una flora neotropical completa basada en los expedientes históricos de colecciones de plantas, las mediciones cuantitativas de la pérdida de bosque y de diversidad y el estado de conservación de especies de plantas endémicas en Ecuador. Nuestro análisis sugiere que 19,46 especies de plantas se han extinguido en el Ecuador a lo largo de los últimos 250 años, debido principalmente a la pérdida de hábitat y por lo tanto son ahora extintas a nivel mundial. Además 282 especies, cerca del 7% de la flora endémica del Ecuador califica como críticamente amenazada. Encontramos indicaciones de inminentes extinciones de gran escala en el país, tanto en los bosques costeros como en los bosques de los Andes, pero poca extinción y bajo potencial de extinción en las tierras bajas del Amazonas. [source] Habitat Loss and Extinction in the Hotspots of BiodiversityCONSERVATION BIOLOGY, Issue 4 2002Thomas M. Brooks None of these hotspots have more than one-third of their pristine habitat remaining. Historically, they covered 12% of the land's surface, but today their intact habitat covers only 1.4% of the land. As a result of this habitat loss, we expect many of the hotspot endemics to have either become extinct or,because much of the habitat loss is recent,to be threatened with extinction. We used World Conservation Union [ IUCN ] Red Lists to test this expectation. Overall, between one-half and two-thirds of all threatened plants and 57% of all threatened terrestrial vertebrates are hotspot endemics. For birds and mammals, in general, predictions of extinction in the hotspots based on habitat loss match numbers of species independently judged extinct or threatened. In two classes of hotspots the match is not as close. On oceanic islands, habitat loss underestimates extinction because introduced species have driven extinctions beyond those caused by habitat loss on these islands. In large hotspots, conversely, habitat loss overestimates extinction, suggesting scale dependence (this effect is also apparent for plants). For reptiles, amphibians, and plants, many fewer hotspot endemics are considered threatened or extinct than we would expect based on habitat loss. This mismatch is small in temperate hotspots, however, suggesting that many threatened endemic species in the poorly known tropical hotspots have yet to be included on the IUCN Red Lists. We then asked in which hotspots the consequences of further habitat loss (either absolute or given current rates of deforestation) would be most serious. Our results suggest that the Eastern Arc and Coastal Forests of Tanzania-Kenya, Philippines, and Polynesia-Micronesia can least afford to lose more habitat and that, if current deforestation rates continue, the Caribbean, Tropical Andes, Philippines, Mesoamerica, Sundaland, Indo-Burma, Madagascar, and Chocó,Darién,Western Ecuador will lose the most species in the near future. Without urgent conservation intervention, we face mass extinctions in the hotspots. Resumen: Casi la mitad del total de plantas vasculares del mundo y un tercio de los vertebrados terrestres son endémicos en 25 "áreas críticas" para la biodiversidad, cada una de las cuales tiene por lo menos 1500 especies de plantas endémicas. En ninguno de estos sitios permanece más de un tercio de su hábitat prístino. Históricamente, cubrían 12% de la superficie terrestre, pero en la actualidad su hábitat intacto cubre solo 1.4% del terreno. Como resultado de esta pérdida de hábitat esperamos que muchas de las especies endémicas a estos sitios estén extintas o , porque la pérdida de hábitat es reciente , se encuentren amenazadas de extinción. Utilizamos Listas Rojas de UICN para comprobar esta predicción. En general, entre la mitad y dos tercios de las plantas amenazadas y el 57% de los vertebrados terrestres amenazados son endémicos de áreas críticas para la biodiversidad. Para aves y mamíferos en general, las predicciones de extinción en las áreas críticas para la biodiversidad, basadas en la pérdida de hábitat, coinciden con el número de especies consideradas extintas o amenazadas independientemente. En dos clases de áreas críticas para la biodiversidad la coincidencia no es muy grande. En islas oceánicas, la pérdida de hábitat subestima la extinción porque las especies introducidas han causado más extinciones que las producidas por la reducción del hábitat. Por lo contrario, la pérdida de hábitat sobrestima la extinción en áreas críticas para la biodiversidad extensas, lo que sugiere una dependencia de escala (este efecto también es aparente para plantas). Para reptiles, anfibios y plantas mucho menos especies endémicas son consideradas amenazadas o extintas por pérdida de hábitat. Sin embargo, esta discordancia es pequeña en áreas críticas para la biodiversidad en zonas templadas templadas, lo que sugiere que muchas especies endémicas amenazadas en las poco conocidas áreas críticas para la biodiversidad en zonas tropicales aun están por incluirse en las Listas Rojas. Posteriormente nos preguntamos en que áreas críticas para la biodiversidad serían más serias las consecuencias de una mayor pérdida de hábitat (absoluta o con las tasas actuales de deforestación). Nuestros resultados sugieren que el Arco Oriental y los Bosques Costeros de Tanzania/Kenia, Filipinas, Polinesia/Micronesia no pueden soportar mayores pérdidas y que, si continúan las tasas de deforestación actuales, el Caribe, Andes Tropicales, Filipinas, Mesoamérica, Sundaland, Indo-Burma, Madagascar y Chocó/Darién/Ecuador Occidental perderán más especies en el futuro. Sin acciones urgentes de conservación, habrá extinciones masivas en las áreas críticas para la biodiversidad. [source] Fixing the Hole in the Bucket: Household Poverty Dynamics in the Peruvian AndesDEVELOPMENT AND CHANGE, Issue 5 2006Anirudh Krishna ABSTRACT Achieving the Millennium Development Goal of halving poverty will require simultaneous action on two separate fronts: helping poor people escape from poverty, and stemming the flow of people into poverty. This article examines forty Peruvian communities, and finds that descents into poverty have occurred alongside escapes in every one of them. Escape and descent are asymmetric in terms of reasons: while one set of reasons is responsible for escapes from poverty, another and different set of reasons is associated with descent. Making progress in poverty reduction will require measures to accelerate escapes whilst at the same time slowing down descents. The article looks at the different policies which will be required to serve these two separate purposes. [source] Diversity and composition of Arctiidae moth ensembles along a successional gradient in the Ecuadorian AndesDIVERSITY AND DISTRIBUTIONS, Issue 5 2005Nadine Hilt ABSTRACT Andean montane rain forests are among the most species-rich terrestrial habitats. Little is known about their insect communities and how these respond to anthropogenic habitat alteration. We investigated exceptionally speciose ensembles of nocturnal tiger moths (Arctiidae) at 15 anthropogenically disturbed sites, which together depict a gradient of forest recovery and six closed-forest understorey sites in southern Ecuador. At weak light traps we sampled 9211 arctiids, representing 287 species. Arctiid abundance and diversity were highest at advanced succession sites, where secondary scrub or young forest had re-established, followed by early succession sites, and were lowest, but still high, in mature forest understorey. The proportion of rare species showed the reverse pattern. We ordinated moth samples by non-metric multidimensional scaling using the chord-normalized expected species shared index (CNESS) index at various levels of the sample size parameter m. A distinct segregation of arctiid ensembles at succession sites from those in mature forest consistently emerged only at high m -values. Segregation between ensembles of early vs. late succession stages was also clear at high m values only, and was rather weak. Rare species were responsible for much of the faunal difference along the succession gradient, whereas many common arctiid species occurred in all sites. Matrix correlation tests as well as exploration of relationships between ordination axes and environmental variables revealed the degree of habitat openness, and to a lesser extent, elevation, as best predictors of faunal dissimilarity. Faunal differences were not related to geographical distances between sampling sites. Our results suggest that many of the more common tiger moths of Neotropical montane forests have a substantial recolonization potential at the small spatial scale of our study and accordingly occur also in landscape mosaics surrounding nature reserves. These species contribute to the unexpectedly high diversity of arctiid ensembles at disturbed sites, whereas the proportion of rare species declines outside mature forest. [source] Vegetation and topographic controls on sediment deposition and storage on gully beds in a degraded mountain areaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2009Armando Molina Abstract Active gully systems developed on highly weathered or loose parent material are an important source of runoff and sediment production in degraded areas. However, a decrease of land pressure may lead to a return of a partial vegetation cover, whereby gully beds are preferred recolonization spots. Although the current knowledge on the role of vegetation on reducing sediment production on slopes is well developed, few studies exist on the significance of restoring sediment transport pathways on the total sediment budget of degraded mountainous catchments. This study in the Ecuadorian Andes evaluates the potential of vegetation to stabilize active gully systems by trapping and retaining eroded sediment in the gully bed, and analyses the significance of vegetation restoration in the gully bed in reducing sediment export from degraded catchments. Field measurements on 138 gully segments located in 13 ephemeral steep gullies with different ground vegetation cover indicate that gully bed vegetation is the most important factor in promoting short-term (1,15 years) sediment deposition and gully stabilization. In well-vegetated gully systems ( , 30% of ground vegetation cover), 0.035 m3 m,1 of sediment is deposited yearly in the gully bed. Almost 50 per cent of the observed variance in sediment deposition volumes can be explained by the mean ground vegetation cover of the gully bed. The presence of vegetation in gully beds gives rise to the formation of vegetated buffer zones, which enhance short-term sediment trapping even in active gully systems in mountainous environments. Vegetation buffer zones are shown to modify the connectivity of sediment fluxes, as they reduce the transport efficiency of gully systems. First calculations on data on sediment deposition patterns in our study area show that gully bed deposition in response to gully bed revegetation can represent more than 25 per cent of the volume of sediment generated within the catchment. Our findings indicate that relatively small changes in landscape connectivity have the potential to create strong (positive) feedback loops between erosion and vegetation dynamics. Copyright © 2009 John Wiley & Sons, Ltd. [source] Impact of a rock avalanche on a moraine-dammed proglacial lake: Laguna Safuna Alta, Cordillera Blanca, PeruEARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2005Bryn Hubbard Abstract Moraines that dam proglacial lakes pose an increasing hazard to communities in the Andes and other mountain ranges. The moraines are prone to failure through collapse, overtopping by lake waters or the effect of displacement waves resulting from ice and rock avalanches. Resulting floods have led to the loss of thousands of lives in the Cordillera Blanca mountains of Peru alone in the last 100 years. On 22 April 2002 a rock avalanche occurred immediately to the south-west of Laguna Safuna Alta, in the Cordillera Blanca. The geomorphic evidence for the nature, magnitude and consequences of this event was investigated in August 2002. Field mapping indicated that the avalanche deposited 8,20 × 106 m3 of rock into the lake and onto the surface of the frontal region of Glaciar Pucajirca, which flows into the lake. Repeated bathymetric surveying indicated that ,5 × 106 m3 of this material was deposited directly into the lake. The immediate effect of this event was to create a displacement wave that gained in height as it travelled along the lake basin, overtopping the impounding moraine at the lake's northern end. To achieve overtopping, the maximum wave height must have been greater than 100 m. This, and subsequent seiche waves, caused extensive erosion of both the proximal and distal faces of the impounding terminal moraine. Further deep gullying of the distal face of this moraine resulted from the supply of pressurized water to the face via a relief overflow tunnel constructed in 1978. Two-dimensional, steady-state analysis of the stability of the post-avalanche moraine rampart indicates that its proximal face remains susceptible to major large-scale rotational failure. Copyright © 2005 John Wiley & Sons, Ltd. [source] Antixenosis phloem-based resistance to aphids: is it the rule?ECOLOGICAL ENTOMOLOGY, Issue 4 2010VINCENT LE ROUX 1. The concept of plant defence syndrome states that plant species growing in similar biotic or abiotic constraints should have convergent defensive traits. This article is a first step to test the prediction of this concept, by conducting experiments on wild Solanum species (or accessions) that originated from the Andes. The nature and the tissue localisation of the resistance of five wild Solanum species known to be resistant against the aphids Myzus persicae and Macrosiphum euphorbiae were determined by olfactometry and electrical penetration graph experiments. 2. Volatile organic compounds may contribute to wild Solanum resistance, depending on Solanum accessions and aphid species. Volatiles of S. bukasovii and S. stoloniferum PI 275248 were not attractive to M. persicae, whereas S. bukasovii was repulsive to M. euphorbiae. In contrast, volatiles of S. stoloniferum PI 275248 were attractive for M. euphorbiae. 3. Some wild Solanum species presented a generalised resistance in all plant tissues, so as for S. bukasovii and S. stoloniferum PI 275248 against M. persicae. However, except for S. bukasovii which was susceptible to M. euphorbiae, all tested Solanum species presented a phloem-based antixenosis resistance against the two aphid species. 4. A review of articles focused on the nature of resistance of wild Solanum species against aphids corroborated with our results, i.e. a phloem-based antixenosis resistance against aphids is the rule concerning the system aphids,wild Solanum species. [source] PHYLOGEOGRAPHIC STRUCTURE AND CRYPTIC SPECIATION IN THE TRANS-ANTARCTIC MOSS PYRRHOBRYUM MNIOIDESEVOLUTION, Issue 2 2003Stuart F. McDaniel Abstract Many bryophyte species have distributions that span multiple continents. The hypotheses historically advanced to explain such distributions rely on either long-distance spore dispersal or slow rates of morphological evolution following ancient continental vicariance events. We use phylogenetic analyses of DNA sequence variation at three chloroplast loci (atpB-rbcL spacer, rps4 gene, and trnL intron and 3,spacer) to examine these two hypotheses in the trans-Antarctic moss Pyrrhobryum mnioides. We find: (1) reciprocal monophyly of Australasian and South American populations, indicating a lack of intercontinental dispersal; (2) shared haplotypes between Australia and New Zealand, suggesting recent or ongoing migration across the Tasman Sea; and (3) reciprocal monophyly among Patagonian and neotropical populations, suggesting no recent migration along the Andes. These results corroborate experimental work suggesting that spore features may be critical determinants of species range. We use the mid-Miocene development of the Atacama Desert, 14 million years ago, to calibrate a molecular clock for the tree. The age of the trans-Antarctic disjunction is estimated to be 80 million years ago, consistent with Gondwanan vicariance, making it among the most ancient documented cases of cryptic speciation. These data are in accord with niche conservatism, but whether the morphological stasis is a product of stabilizing selection or phylogenetic constraint is unknown. [source] Relationships in Taraxacum section Arctica s.l. (Asteraceae, Cichorieae) and allies based on nrITSFEDDES REPERTORIUM, Issue 1-2 2009I. Uhlemann nrITS sequences of 19 Taraxacum -species as well as four outgroups of Asteraceae-Cichorieae were analysed using Bayesian and parsimony analyses in order to establish their systematics. The Arctica s.l. clade together with T. bessarabicum is sister to all derived European and South American taxa. The division of Arctica s.l. into smaller units (sections: Antarctica, Arctica s. str., Australasica) is supported. Within the remaining taxa, Taraxacum farellonicum, a species from the Chilean Andes which is described as new, is supposed to be a hybrid of T. gilliesii and an introduced Ruderalia -species. Section Erythrosperma is well separated and supported. With the exception of T. patagonicum and T. bracteatum which are sister to the other representatives of the European taxa two groups are distinguished: first the Ruderalia/Hamata alliance (including T. tenebricans with some exceptional characters) of predominantly ruderal species and second an assemblage of the sections Celtica, Fontana, Macrodonta, Palustria and Taraxacum prefering a lesser ruderal habitate. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Molekulare Systematik der Gattung Taraxacum Sektion Arctica s.l. (Asteraceae, Cichorieae) und verwandter Arten auf der Basis von nuklearer ribosomaler DNA (nrITS) Die Verwandtschaftsverhältnisse von 19 Arten der Gattung Taraxacum und vier Außengruppen aus den Asteraceae-Cichorieae wurden mit Bayesischen und Parsimonieanalysen der nrITS Sequenzen rekonstruiert. Die Sektion Arctica s.l. bildet zusammen mit T. bessarabicum die Schwestergruppe zu den abgeleiteten europäischen und südamerikanischen Taxa. Die Klassifizierung der Arctica s.l. in die Sektionen Antarctica, Arctica s.str. und Australasica wird von den Analysen unterstützt. Die in dieser Studie neu beschriebene Art, Taraxacum farellonicum, aus den chilenischen Anden ist wahrscheinlich ein Hybrid aus T. gilliesii und einer neophytischen Art der Sektion Ruderalia. Die Sektion Erythrosperma erscheint als gut gestützte Gruppe. Mit Ausnahme von T. patagonicum und T. bracteatum, die Schwestergruppen zu den anderen Vertretern europäischer Taxa bilden, können zwei größere Komplexe unterschieden werden: erstens die Ruderalia/Hamata -Gruppe (einschließlich T. tenebricans mit einigen besonderen Merkmalen), welche vorwiegend Arten der ruderalen Standorte umfasst und zweitens ein Verwandtschaftskreis aus den Sektionen Celtica, Fontana, Macrodonta, Palustria und Taraxacum, die an weniger stark ruderalisierten Standorten vorkommen. [source] HUMBOLDT'S NODES AND MODES OF INTERDISCIPLINARY ENVIRONMENTAL SCIENCE IN THE ANDEAN WORLD,GEOGRAPHICAL REVIEW, Issue 3 2006Karl S. Zimmerer ABSTRACT. Alexander von Humboldt engaged in a staggering array of diverse experiences in the Andes and adjoining lowlands of northwestern South America between 1801 and 1803. Yet examination of Humboldt's diaries, letters, and published works shows how his principal activities in the Andes centered on three interests: mining and geological landscapes; communications and cartography; and use and distribution of the quinine-yielding cinchona trees. Each node represented a pragmatic concern dealing with environmental resources in the context of the Andes. To pursue these interests in his Andean field studies, Humboldt relied on varied cultural interactions and vast social networks for knowledge exchange, in addition to extensive textual comparisons. These modes of inquiry dovetailed with his pragmatic interests and his open-ended intellectual curiosity. Fertile combinations in his Andean studies provided the foundation and main testing ground for Humboldt's fused nature-culture approach as well as his contributions to early geography and interdisciplinary environmental science. [source] The tectonic regime along the Andes: Present-day and Mesozoic regimesGEOLOGICAL JOURNAL, Issue 1 2010Victor A. Ramos Abstract The analyses of the main parameters controlling the present Chile-type and Marianas-type tectonic settings developed along the eastern Pacific region show four different tectonic regimes: (1) a nearly neutral regime in the Oregon subduction zone; (2) major extensional regimes as the Nicaragua subduction zone developed in continental crust; (3) a Marianas setting in the Sandwich subduction zone with ocean floored back-arc basin with a unique west-dipping subduction zone and (4) the classic and dominant Chile-type under compression. The magmatic, structural and sedimentary behaviours of these four settings are discussed to understand the past tectonic regimes in the Mesozoic Andes based on their present geological and tectonic characteristics. The evaluation of the different parameters that governed the past and present tectonic regimes indicates that absolute motion of the upper plate relative to the hotspot frame and the consequent trench roll-back velocity are the first order parameters that control the deformation. Locally, the influences of the trench fill, linked to the dominant climate in the forearc, and the age of the subducted oceanic crust, have secondary roles. Ridge collisions of seismic and seismic oceanic ridges as well as fracture zone collisions have also a local outcome, and may produce an increase in coupling that reinforces compressional deformation. Local strain variations in the past and present Andes are not related with changes in the relative convergence rate, which is less important than the absolute motion relative to the Pacific hotspot frame, or changes in the thermal state of the upper plate. Changes in the slab dip, mainly those linked to steepening subduction zones, produce significant variations in the thermal state, that are important to generate extreme deformation in the foreland. Copyright © 2009 John Wiley & Sons, Ltd. [source] Geothermal prognoses for tunnels in the Andes / . Geothermische Prognose für AndentunnelGEOMECHANICS AND TUNNELLING, Issue 5 2010Mag. Giorgio Höfer-Öllinger Geothermal energy - Geothermie; Reconnaissance - Baugrunderkundung; Hydrology - Hydrologie; Geology - Geologie Abstract Geothermal prognoses were carried out for two tunnel projects in the Andes, each running between Argentina and Chile. Different methods were applied in accordance with the different project phases. For the feasibility study of a 52 km long railway tunnel, hydrogeological mapping and hydrochemical analyses were carried out as well as isotope analyses on a thermal spring. An attempt to use silica and ionic solute geothermometers produced different results. For the central section of the tunnel temperatures are assumed to reach 50 to 70 °C and further investigations are recommended. The second tunnel project is now in the design phase. Two investigation phases have been completed including geological/ hydrogeological mapping, water sampling and analysis and core drilling. The geothermal gradient is well known from borehole temperature measurements. The thermal conductivity of the rocks was determined from core samples in a laboratory, and an average heat flow of approximately 100 mW/m2 was calculated. During the driving of the tunnel, temperatures of just over 50 °C are expected. Für zwei Tunnelvorhaben in den Anden, jeweils zwischen Argentinien und Chile, wurden geothermische Prognosen durchgeführt. Für verschiedene Projektphasen kamen entsprechend unterschiedliche Methoden zur Anwendung: Für eine Machbarkeitsstudie eines 52 km langen Eisenbahntunnels wurde eine Quellkartierung mit Probennahme durchgeführt sowie Isotopenanalytik an einer Thermalquelle. Ein Versuch, Geothermometer anhand der Lösungsfracht des Quellwassers zu verwenden, scheiterte. Für den zentralen Bereich des Tunnels werden Temperaturen von 50 bis 70 °C vermutet, weitere Erkundungen wurden empfohlen. Das zweite Tunnelvorhaben ist in der Planungsphase deutlich weiter. Neben Kartierungen liegen zwei Erkundungsphasen mit Kernbohrungen vor. Aus Bohrlochmessungen ist der geothermische Gradient bekannt, die Wärmeleitfähigkeit der Gesteine wurde anhand von Bohrkernen im Labor ermittelt. Es konnte ein durchschnittlicher Wärmefluss von etwa 100 mW/m2 errechnet werden, für den Tunnelvortrieb werden Gebirgstemperaturen von maximal knapp über 50 °C erwartet. [source] P - and S -velocity images of the lithosphere,asthenosphere system in the Central Andes from local-source tomographic inversionGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2006Ivan Koulakov SUMMARY About 50 000 P and S arrival times and 25 000 values of t* recorded at seismic arrays operated in the Central Andes between 20°S and 25°S in the time period from 1994 to 1997 have been used for locating more than 1500 deep and crustal earthquakes and creating 3-D P, S velocity and Qp models. The study volume in the reference model is subdivided into three domains: slab, continental crust and mantle wedge. A starting velocity distribution in each domain is set from a priori information: in the crust it is based on the controlled sources seismic studies; in slab and mantle wedge it is defined using relations between P and S velocities, temperature and composition given by mineral physics. Each iteration of tomographic inversion consists of the following steps: (1) absolute location of sources in 3-D velocity model using P and S arrival times; (2) double-difference relocation of the sources and (3) simultaneous determination of P and S velocity anomalies, P and S station corrections and source parameters by inverting one matrix. Velocity parameters are computed in a mesh with the density of nodes proportional to the ray density with double-sided nodes at the domain boundaries. The next iteration is repeated with the updated velocity model and source parameters obtained at the previous step. Different tests aimed at checking the reliability of the obtained velocity models are presented. In addition, we present the results of inversion for Vp and Vp/Vs parameters, which appear to be practically equivalent to Vp and Vs inversion. A separate inversion for Qp has been performed using the ray paths and source locations in the final velocity model. The resulting Vp, Vs and Qp distributions show complicated, essentially 3-D structure in the lithosphere and asthenosphere. P and S velocities appear to be well correlated, suggesting the important role of variations of composition, temperature, water content and degree of partial melting. [source] Upward range extension of Andean anurans and chytridiomycosis to extreme elevations in response to tropical deglaciationGLOBAL CHANGE BIOLOGY, Issue 1 2007TRACIE A. SEIMON Abstract High-alpine life forms and ecosystems exist at the limits of habitable environments, and thus, are especially sensitive to environmental change. Here we report a recent increase in the elevational limit of anurans following glacial retreat in the tropical Peruvian Andes. Three species have colonized ponds in recently deglaciated terrain at new record elevations for amphibians worldwide (5244,5400 m). Two of these species were also found to be infected with Batrachochytrium dendrobatidis (Bd), an emerging fungal pathogen causally associated with global amphibian declines, including the disappearance of several Latin American species. The presence of this pathogen was associated with elevated mortality rates of at least one species. These results represent the first evidence of upward expansion of anurans to newly available habitat brought about by recent deglaciation. Furthermore, the large increase in the upper limit of known Bd infections, previously reported as 4112 m in Ecuador, to 5348 m in this study, also expands the spatial domain of potential Bd pathogenicity to encompass virtually all high elevation anuran habitats in the tropical Andes. [source] Bergmann's rule does not apply to geometrid moths along an elevational gradient in an Andean montane rain forestGLOBAL ECOLOGY, Issue 1 2004Gunnar Brehm ABSTRACT Aim, Bergmann's rule generally predicts larger animal body sizes with colder climates. We tested whether Bergmann's rule at the interspecific level applies to moths (Lepidoptera: Geometridae) along an extended elevational gradient in the Ecuadorian Andes. Location, Moths were sampled at 22 sites in the province Zamora-Chinchipe in southern Ecuador in forest habitats ranging from 1040 m to 2677 m above sea level. Methods, Wingspans of 2282 male geometrid moths representing 953 species were measured and analysed at the level of the family Geometridae, as well as for the subfamily Ennominae with the tribes Boarmiini and Ourapterygini, and the subfamily Larentiinae with the genera Eois, Eupithecia and Psaliodes. Results, Bergmann's rule was not supported since the average wingspan of geometrid moths was negatively correlated with altitude (r = ,0.59, P < 0.005). The relationship between body size and altitude in Geometridae appears to be spurious because species of the subfamily Larentiinae are significantly smaller than species of the subfamily Ennominae and simultaneously increase in their proportion along the gradient. A significant decrease of wingspan was also found in the ennomine tribe Ourapterygini, but no consistent body size patterns were found in the other six taxa studied. In most taxa, body size variation increases with altitude, suggesting that factors acting to constrain body size might be weaker at high elevations. Main conclusions, The results are in accordance with previous studies that could not detect consistent body size patterns in insects at the interspecific level along climatic gradients. [source] Agronomic performance and nutritive value of common and alternative grass and legume species in the Peruvian highlandsGRASS & FORAGE SCIENCE, Issue 2 2009K. Bartl Abstract The agronomic performance and nutritive value of twelve annual and perennial grasses and legumes were analysed in order to define alternatives to local forages for dry-season feeding of ruminants in the Peruvian Andes. There were twelve species and two fertilizer treatments (no fertilizer and a N;P;K fertilizer mainly applied at sowing) in an experiment with a randomized complete block design with three replicates at each of two sites. Plant height, soil cover by forage and weed species, frost damage, dry matter (DM) yield and nutritive value of herbage were evaluated in 2005 and 2006. Among the annual species, Hordeum vulgare L. cv. UNA 80 and ×Triticosecale Wittm. had the highest DM yields when fertilized (8226 and 6934 kg ha,1 respectively). Without fertilizer the alternative cultivars had similar DM yields to that of the local forages. Cultivars of Avena sativa L. had lower concentrations of neutral-detergent fibre (NDF) (557 g kg,1 DM) and higher concentrations of predicted net energy for lactation (5·86 MJ kg,1 DM) than the other annual grass species (625 g kg,1 DM and 5·01 MJ kg,1 DM respectively), while the legumes were superior in concentrations of crude protein (277 g kg,1 DM) and NDF (362 g kg,1 DM). Considering the low agronomic performance of the perennial forages, a mixture of fertilized annual grasses and legumes appears the most appropriate approach to meeting the demand for forage of high nutritive value in the Peruvian highlands. [source] Subsurface Transfer of Chloride After a Lake Retreat in the Central AndesGROUND WATER, Issue 5 2001Anne Coudrain The area under study covers 3500 km2 in the upstream part of the closed catchment basin of the salt crust of Uyuni. This crust is a remnant of the saline Lake Tauca, which covered the area about 15,000 years ago. In the downstream part of the aquifer, the Cl concentration of ground water and Cl content in the unsaturated zone exceed 20 meq/L and 18 kg/m2, respectively. With the present hydrological conditions under semiarid conditions, the ground water residence time in the study area exceeds 3000 years. Transient simulations over 11,000 years were made using initial conditions as the retreat of Lake Tauca and taking into account a low recharge during the arid mid-Holocene period. The modeling simulates ground water flow, Cl transport, and ground water residence time. It includes the evaporation from the aquifer that leads to the accumulation of chloride in the unsaturated zone. Results of the modeling are consistent with the observations if it is assumed that the Cl previously accumulated in the unsaturated zone was flushed back into the aquifer around 2000 years B.P., contemporaneously with the end of the arid period. [source] Tectonic control of erosion and sedimentation in the Amazon Basin of BoliviaHYDROLOGICAL PROCESSES, Issue 22 2009Patrice Baby Abstract The western Amazon drainage basin, which extends from southern Colombia to northern Bolivia, comprises the Cordillera Oriental of the Andes and its adjacent foreland basin system. In northern Bolivia, the orogenic wedge of the eastern Andes is very large, and its forward propagation controls the morphology of the Madeira drainage basin. We consider here the erosion and sedimentation mass balance in this part of the Amazon Basin, estimated on the basis of recent sediment yield data, within the current tectonic and geomorphic framework. The total suspended sediment (TSS) flux exported from the present orogenic wedge of northern Bolivia has been estimated at 500,600 million t year,1. More than 50% of the total sediment load crossing the Madeira foreland basin system is deposited. The rest of the sediments (less than 46%) reaches the eastern Amazon Basin, bypassing the Brazilian craton to the north. The average mass of sediment that has been deposited from the late Miocene to the present in the Madeira foreland basin sedimentation system is less than that intercepted today, by a factor of about 2·4. These results can be interpreted as an increase in Bolivian foreland basin flexural subsidence over time, associated with crust thickening and orogenic loading, and accentuated by the growing mass of retained sediments. They are consistent with the uplift rates of the Cordillera Oriental, obtained from fission-track dating, which began increasing significantly around 10,15 Ma. Copyright © 2009 John Wiley & Sons, Ltd. [source] Rainfall interception in a lower montane forest in Ecuador: effects of canopy propertiesHYDROLOGICAL PROCESSES, Issue 7 2005Katrin Fleischbein Abstract Rainfall interception in forests is influenced by properties of the canopy that tend to vary over small distances. Our objectives were: (i) to determine the variables needed to model the interception loss of the canopy of a lower montane forest in south Ecuador, i.e. the storage capacity of the leaves S and of the trunks and branches St, and the fractions of direct throughfall p and stemflow pt; (ii) to assess the influence of canopy density and epiphyte coverage of trees on the interception of rainfall and subsequent evaporation losses. The study site was located on the eastern slope of the eastern cordillera in the south Ecuadorian Andes at 1900,2000 m above sea level. We monitored incident rainfall, throughfall, and stemflow between April 1998 and April 2001. In 2001, the leaf area index (LAI), inferred from light transmission, and epiphyte coverage was determined. The mean annual incident rainfall at three gauging stations ranged between 2319 and 2561 mm. The mean annual interception loss at five study transects in the forest varied between 591 and 1321 mm, i.e. between 25 and 52% of the incident rainfall. Mean S was estimated at 1·91 mm for relatively dry weeks with a regression model and at 2·46 mm for all weeks with the analytical Gash model; the respective estimates of mean St were 0·04 mm and 0·09 mm, of mean p were 0·42 and 0·63, and of mean pt were 0·003 and 0·012. The LAI ranged from 5·19 to 9·32. Epiphytes, mostly bryophytes, covered up to 80% of the trunk and branch surfaces. The fraction of direct throughfall p and the LAI correlated significantly with interception loss (Pearson's correlation coefficient r = ,0·77 and 0·35 respectively, n = 40). Bryophyte and lichen coverage tended to decrease St and vascular epiphytes tended to increase it, although there was no significant correlation between epiphyte coverage and interception loss. Our results demonstrate that canopy density influences interception loss but only explains part of the total variation in interception loss. Copyright © 2004 John Wiley & Sons, Ltd. [source] Uranium and thorium isotopes in the rivers of the Amazonian basin: hydrology and weathering processesHYDROLOGICAL PROCESSES, Issue 1 2003Aguinaldo N. Marques Jr. Abstract Two expeditions (October 1989 and May 1992) were carried out to two points of the main Amazon River channel and four tributaries. The Solimões and Madeira rivers, taking their origin in the Andes, are whitewater rivers. The Negro River is a typical acid, blackwater river. The Trombetas River flows through bauxite-rich areas, and is characterized by low concentrations of dissolved humic substances. The 238U, 234U, 232Th and 230Th activities were recorded from dissolved, suspended particulate phases and river bank sediments. The latter were analysed for their 226Ra, 228Ra and 210Pb contents, and also subjected to leaching with 0·2 M hydroxylamine,hydrochloride solution to determine the concentrations of radionuclides bound to amorphous Fe hydroxides and Mn oxides and hydroxides. The dissolved U average concentration in the Amazon system is ten times lower than the mean world river concentration. The uranium concentration observed at Óbidos in the lower Amazon (0·095 µg L,1), where the U content in the river bank sediments and suspended matter is lowest, suggests U release from the solid phase during river transport. About 485 t of U are transported annually to the Amazon delta area in dissolved form, and 1943 t bound to suspended particulate matter. Total U and Th concentrations in the river bank sediments ranged from 1·59 to 7·14 µg g,1 and from 6·74 to 32 µg g,1, respectively. The highest concentrations were observed in the Trombetas River. The proportion extracted by means of the hydroxylamine solution (HL) was relatively high for U in the Trombetas river bank sediment (31%) and for Th in the Solimões sediment (30%). According to the alpha recoil effects, the 234U/238U activity ratios of the Andean river waters and downstream Amazon water (Óbidos) were >1, but were <1 in the Negro River (at Manaus). The activity ratios of dissolved U correlate with pH and also with the U activity ratios in the river bank sediment hydroxylamine extracts. As expected, the 234U/238U activity ratios in river bank sediments were <1 in the Andean rivers and in the downstream Amazon, but they were >1 in the Trombetas and Negro rivers. Such ratios probably result from the binding of dissolved uranium to solid sediment. The 228Th/232Th ratios of river bank sediments were close to unity (except for the Negro River, where it is lower), suggesting no significant Th exchanges between the river water and the sediment. The 226Ra/232Th activity ratios were <1, and the 226Ra/228Ra activity ratios generally were significantly higher than the activity ratios of their respective parents. This perhaps is the result of easier leaching of the 226Ra parent, 230Th, from solid material (owing to the alpha recoil effect) than of the 228Ra parent. Uranium and thorium isotopes were used as tools to evaluate the chemical weathering rate of rocks in the Amazon system, which was estimated to be 2·7 cm 1000 year,1 s,1. Copyright © 2002 John Wiley & Sons, Ltd. [source] A new species of piha (Cotingidae: Lipaugus) from the Cordillera Central of ColombiaIBIS, Issue 4 2001ANDRÉS M. CUERVO The Chestnut-capped Piha Lipaugus weberi sp. nov., is described from sub-Andean forest on the northern slope of the Central Cordillera of the Colombia Andes. The new species appears most closely related to Lipaugus fuscocinereus of the Northern Andes including the Central Cordillera, but is much smaller, with a distinctive chestnut-brown crown, yellow orbital ring, two modified primaries in the male, an overall darker grey coloration and unique vocalizations. It appears to be restricted to a narrow belt of premontane very humid forests (1500,1820 m asl) where it is fairly common. The restricted range and specific ecological requirements of Lipaugus weberi make the species of great conservation concern as the Central Cordillera has been severely deforested and remaining forests are highly fragmented. We present notes on the behaviour, ecology and conservation of this new species. Se describe Lipaugus weberi sp. nov, de bosque subandino de la vertiente norte de la Cordillera Central de los Andes de Colombia. La nueva especie parece estar bastante relacionada con Lipaugus fuscocinereus de los Andes septentrionales incluyendo la Cordillera Central, pero es mucho más pequeña, presenta una distintiva gorra castaño opaco, anillo ocular amarillo, dos remeras primarias modificadas, la coloración gris más oscura y vocalizaciones ünicas. Esta especie se restringe a una franja angosta de bosque muy hümedo premontano (1500,1820 msnm), donde es relativamente comün. El rango restringido y los requerimientos ecológicos especificos de Lipaugus weberi hacen que esta especie sea de gran relevancia para la conservación, más aün debido al estado de deforestación severa de la Cordillera Central, en la cual los bosques remanentes son muy fragmentados. Presentamos anotaciones sobre la ecologia, el comportamiento y la conservación de esta nueva especie. [source] On the interannual wintertime rainfall variability in the Southern AndesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2010M. H. González Abstract The paper concentrates on the analysis of the interannual variability of wintertime rainfall in the Southern Andes. Besides the socio-economic relevance of the region, mainly associated with hydroelectric energy production, the study of the climate variability in that area has not received as much attention as others along the Andes. The results show that winter rainfall explains the largest percentage of regional total annuals. A principal component analysis (PCA) of the winter rainfall anomalies showed that the regional year-to-year variability is mostly explained by three leading patterns. While one of them is significantly associated with both the El Niño Southern Oscillation (ENSO), and the Southern Annular Mode (SAM), the other two patterns are significantly related to interannual changes of the sea surface temperature (SST) anomalies in the tropical Indian Ocean. Specifically, changes in the ocean surface conditions at both tropical basins induce in the atmospheric circulation the generation of Rossby wave trains that extend along the South Pacific towards South America, and alter the circulation at the region under study. The relationship between variability in the Indian Ocean and the Andes climate variability has not been previously addressed. Therefore, this result makes a significant contribution to the identification of the sources of predictability in South America with relevant consequences for future applications in seasonal predictions. Copyright © 2009 Royal Meteorological Society [source] Distribution and temporal variability of 500 hPa cyclone characteristics in the Southern HemisphereINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2002Murray Keable Abstract A 40 year period (1958,97) of US National Centers for Environmental Prediction reanalysis data has been used to diagnose the behaviour and variability of 500 hPa extratropical cyclones for the Southern Hemisphere using a Lagrangian perspective. The ,finding' and ,tracking' of these systems were performed using a fully automated scheme. Seasonal distributions of system density, cyclone formation (cyclogenesis), decay (cyclolysis), cyclone centre velocity and intensity/strength are presented. System density is shown to exhibit a maximum in the surface circumpolar trough region and over the Antarctic continent. A broad band of enhanced cyclone system density was evident across the South Pacific from southeast Australia to South America in all seasons, most markedly in winter. As this feature appears also at the surface level, strong vertical consistency of these cyclones in the low and middle troposphere is indicated. Velocities of cyclone centres were found to peak in the latitudes 50,55 °S, and 500 hPa systems appeared to move on average in a much more zonal (easterly) direction than their sea-level counterparts. The mean number of midlatitude cyclones per analysis has exhibited a significant downward trend over the record, with particularly low values observed in the early 1980s. Offsetting this trend have been increases in three measures of mean cyclone vigour. Three orographic features, in particular, are seen to influence the behaviour of 500 hPa cyclones: the mountains of New Zealand, the Antarctic Peninsula and the southern Andes. Over most of Antarctica the rate of cyclogenesis exceeds that of cyclolysis, indicating that many of the cyclones being formed in the vortex are actually exported out (i.e. to the north) of the continent. In the subtropics, considerable numbers of systems are formed in the Mozambique Sea region, but these tend to be quasi-stationary features. Copyright © 2002 Royal Meteorological Society. [source] Subtropical cold surges: regional aspects and global distributionINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 10 2001René D. Garreaud Abstract Shallow surges of cold dry air are frequently observed to the east of the major mountain ranges, moving from mid-latitudes well into the Tropics in about 4 days. Because of their strong impact on weather, regional aspects of cold surges have received considerable attention, particularly over Southeast Asia, to the east of the Rockies and Mexican Sierras, and to the east of the subtropical Andes. Both observational and numerical studies reveal a similar structure and evolution of cold surges in different regions. These common aspects are reviewed in this work, as well as the mechanisms responsible for the development and subsequent advance of cold surges over the subtropics. Atmospheric reanalysis data are used to document the global distribution of cold surges on the basis of their continental-scale imprints on relevant fields, as well as to estimate their contribution on the regional and global energy balances. It is found that cold surges have a major cooling and drying effect over the regions where they are prevalent (e.g. subtropical South America) and represent a sizeable sink of energy for the Tropics. Copyright © 2001 Royal Meteorological Society [source] ,Amsterdam is Standing on Norway' Part I: The Alchemy of Capital, Empire and Nature in the Diaspora of Silver, 1545,1648JOURNAL OF AGRARIAN CHANGE, Issue 1 2010JASON W. MOORE In the first of two essays in this Journal, I seek to unify the historical geography of early modern ,European expansion' (Iberia and Latin America) with the environmental history of the ,transition to capitalism' (northwestern Europe). The expansion of Europe's overseas empires and the transitions to capitalism within Europe were differentiated moments within the geographical expansion of commodity production and exchange , what I call the commodity frontier. This essay is developed in two movements. Beginning with a conceptual and methodological recasting of the historical geography of the rise of capitalism, I offer an analytical narrative that follows the early modern diaspora of silver. This account follows the political ecology of silver production and trade from the Andes to Spain in Braudel's ,second' sixteenth century (c. 1545,1648). In highlighting the Ibero-American moment of this process in the present essay, I contend that the spectacular reorganization of Andean space and the progressive dilapidation of Spain's real economy not only signified the rise and demise of a trans-Atlantic, Iberian ecological regime, but also generated the historically necessary conditions for the unprecedented concentration of accumulation and commodity production in the capitalist North Atlantic in the centuries that followed. [source] From Agrarian Reform to Ethnodevelopment in the Highlands of EcuadorJOURNAL OF AGRARIAN CHANGE, Issue 4 2008VÍCTOR BRETÓN SOLO DE ZALDÍVAR Through an examination of interventions in the agrarian structures and rural society of the Ecuadorian Andes over the past 40 years, this article explores the gradual imposition of a particular line of action that separates rural development from the unresolved question of the concentration of land ownership and wealth among the very few. This imposition has been the consequence, it is argued, of the new development paradigms implemented in Andean peasant communities since the end of land reform in the 1970s. The new paradigms emphasize identity and organizational aspects of indigenous populations at the expense of anything connected with the class-based campesinista agenda, which was still operational in the indigenous movement in the early 1990s. The essay concludes with some thoughts on the remarkable parallels between the 1990s neoliberal and counter-reformist models of action, and the pre-reformist indigenist policies of the period that ended in the 1960s. [source] From ice age to modern: a record of landscape change in an Andean cloud forestJOURNAL OF BIOGEOGRAPHY, Issue 9 2010B. G. Valencia Abstract Aim, To investigate the palaeoecological changes associated with the last ice age, subsequent deglaciation and human occupation of the central Andes. Location, Lake Pacucha, Peruvian Andes (13°36,26, S, 73°19,42, W; 3095 m elevation). Methods, Vegetation assemblages were reconstructed for the last 24 cal. kyr bp (thousand calibrated 14C years before present), based on pollen analysis of sediments from Lake Pacucha. An age model was established using 14C accelerator mass spectrometry dates on bulk sediment. Fossil pollen and sedimentological analyses followed standard methodologies. Results, Puna brava replaced the Andean forest at the elevation of Lake Pacucha at the Last Glacial Maximum (LGM). Deglaciation proceeded rapidly after 16 cal. kyr bp, and near-modern vegetation was established by c. 14 cal. kyr bp. The deglacial was marked by the range expansion of forest taxa as grassland taxa receded in importance. The mid-Holocene was marked by a lowered lake level but relatively unchanged vegetation. Quinoa and maize pollen were found in the latter half of the Holocene. Main conclusions, Temperatures were about 7,8 °C colder than present at this site during the LGM. The pattern of vegetation change was suggestive of microrefugial expansion rather than simple upslope migration. The mid-Holocene droughts were interrupted by rainfall events sufficiently frequent to allow vegetation to survive largely unchanged, despite lowering of the lake level. Human activity at the lake included a 5500-year history of quinoa cultivation and 3000 years of maize cultivation. [source] Are the Northern Andes a species pump for Neotropical birds?JOURNAL OF BIOGEOGRAPHY, Issue 2 2010Phylogenetics, biogeography of a clade of Neotropical tanagers (Aves: Thraupini) Abstract Aim, We used mitochondrial DNA sequence data to reconstruct the phylogeny of a large clade of tanagers (Aves: Thraupini). We used the phylogeny of this Neotropical bird group to identify areas of vicariance, reconstruct ancestral zoogeographical areas and elevational distributions, and to investigate the correspondence of geological events to speciation events. Location, The species investigated are found in 18 of the 22 zoogeographical regions of South America, Central America and the Caribbean islands; therefore, we were able to use the phylogeny to address the biogeographical history of the entire region. Methods, Molecular sequence data were gathered from two mitochondrial markers (cytochrome b and ND2) and analysed using Bayesian and maximum-likelihood approaches. Dispersal,vicariance analysis (DIVA) was used to reconstruct zoogeographical areas and elevational distributions. A Bayesian framework was also used to address changes in elevation during the evolutionary history of the group. Results, Our phylogeny was similar to previous tanager phylogenies constructed using fewer species; however, we identified three genera that are not monophyletic and uncovered high levels of sequence divergence within some species. DIVA identified early diverging nodes as having a Northern Andean distribution, and the most recent common ancestor of the species included in this study occurred at high elevations. Most speciation events occurred either within highland areas or within lowland areas, with few exchanges occurring between the highlands and lowlands. The Northern Andes has been a source for lineages in other regions, with more dispersals out of this area relative to dispersals into this area. Most of the dispersals out of the Northern Andes were dispersals into the Central Andes; however, a few key dispersal events were identified out of the Andes and into other zoogeographical regions. Main conclusions, The timing of diversification of these tanagers correlates well with the main uplift of the Northern Andes, with the highest rate of speciation occurring during this timeframe. Central American tanagers included in this study originated from South American lineages, and the timing of their dispersal into Central America coincides with or post-dates the completion of the Panamanian isthmus. [source] Phytogeographical data and modern pollen rain of the puna belt in southern Peru (Nevado Coropuna, Western Cordillera)JOURNAL OF BIOGEOGRAPHY, Issue 10 2007Adèle Kuentz Abstract Aim, To improve knowledge of the distribution of species and modern pollen dispersal in the puna vegetation belt (central Andes) for palaeoenvironmental analysis and reconstructions. Location, Puna belt, Nevado Coropuna, Western Cordillera, Peru. Methods, The vegetation facies and belts of the area were mapped by remote sensing using a March 1998 SPOT4 image. This was complemented by the interpretation of aerial photographs, by field sampling, and by the identification of plants. Data from 1940 to 1994 from the Peruvian meteorological station network were modelled to characterize the relationship between climate and vegetation. Twenty-four soil-surface samples were collected in the various vegetation facies identified on the map, and standard palynological techniques were applied to analyse these samples. A principal components analysis was performed on the pollen data set. Results, The map shows three bioclimatic belts and seven facies in the puna sensu lato, and identifies the main plants that are characteristic of each bioclimatic area. The pollen results fit the vegetation facies and belts, including the plant species of the distinct facies that are well represented in the pollen assemblages. The mesotropical belt is characterized by the predominance of Asteraceae-type Ambrosia; the supratropical belt shows significant frequencies of Asteraceae-type Senecio; the orotropical belt is characterized by high frequencies of Apiaceae and includes Polylepis woodland and peat bogs; and the cryorotropical belt shows significant frequencies of Asteraceae-type Senecio and Apiaceae. Main conclusions, The pollen grains of the plants that grow on the puna sensu lato are generally entomophilous and are therefore not transported far from their plant source. The distinct bioclimatic facies and belts identified by the cartography can thus be well distinguished by their pollen production and deposition. We were therefore able to characterize the relationship between pollen, vegetation and climate that can be used for palaeoenvironmental reconstructions. An altitudinal pollen gradient on the western slopes of the central Andes was revealed by the pollen study, with the succession of Asteraceae-type Ambrosia (1800,2200 m), Malvaceae (2700,3300 m), Asteraceae-type Senecio (3500,4100 m) and Apiaceae (above 4600 m). [source] | ||||||||||||||||||||||||||||||||||