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The Atacama rocky coast in Northern Chile is a tectonically active region that displays a particular morphological assemblage along its extension. There is a major morphostructural element named the Great Coastal Cliff (GCC) that runs parallel to the coastline for almost 1000 km in hyper-arid conditions. This cliff reaches heights between 800 and 2000 m a.s.l. and its continuity is only interrupted by a few, great fluvial valleys that drain from the High Andes and by several, small creeks of the Coastal Cordillera. At the mouth of these creeks and valleys, it is possible to recognize sequences of staircased marine terraces formed and preserved by the interplay between the tectonic uplift, sea-level changes, and marine erosion action. The Pan de Azúcar National Park (~26°) is a segment of the Atacama rocky coast which exhibit a morphological segmentation along strike into three domains that shows how the GCC is limited by areas characterized by marine terraces: one domain with a high, steep scarp (>500 m) that sits on top a single shore platform, and two domains with a further inland, degraded cliff (heights 1.5 m2/yr (1.5 m3 for one meter of coast length) to develop the morphology of the GCC without stair-cased terraces. Instead, much lower erosion rates of 0.25-0.5 m2/yr or less are necessary to reproduce a shorter cliff with different terraces, i.e. low erosion rates to preserve terraces. This erosion variability is likely due to alongshore gradients in erosion efficiency by sediments-fed beaches that act as natural barriers against incoming waves, dissipating their energy. These sediments are provided by creeks with large catchment areas that discharge into the Pacific Ocean.

In the Western Cordillera of northern Chile, the Proterozoic-Paleozoic Belén Metamorphic Complex is covered by late Oligocene-early Miocene (25-18 Ma) rocks, and both units are involved in west-vergent contractional deformation, which results in exhumation. A Miocene age (18 to 6 Ma) for deformation has been previously constrained by stratigraphy and cross-cutting relationships. To understand the youngest exhumation event and reverse faulting, we obtained 21 (U-Th)/He ages from two samples of the metamorphic rocks and the associate inverse thermal modeling. Five zircon (U-Th)/He ages from one sample are 113 to 226 Ma, very scattered, while five zircon ages from the other, are 20 to 49 Ma. The high dispersion of zircon (U-Th)/He data prevents the geological interpretation of results. Apatite grains from both samples yielded 11 (U-Th)/He ages between 10.4 and 18.7 Ma, with 9 values from 12.0 to 15.5 Ma. A slight positive correlation between apatite single-grain dates and effective uranium for 4 crystals of one sample suggests relatively slow cooling. The T-t model including these 4 apatite ages shows continuous cooling from 15 to 0 Ma with a relatively more marked cooling period at 11-7 Ma. The middle-late Miocene thermal signal agrees with the geologic evolution of the region and would permit to date the last activity of the Chapiquiña-Belén reverse fault, which uplifted and exhumed the metamorphic rocks. This signal is relatively similar to that the eastern Altiplano, but differs considerably from that the forearc.

In the Pampas region of Argentina agriculture is dominated by intensive no-till (NT) soybean cropping which produce negative consequences on soil quality. A group of farmers started to use the Good Agricultural Practices (GAP) which include a higher crop rotation, use of winter cover crops and nutrient restoration. In this NT system earthworms have a significant role in soil functioning, particularly in organic matter cycling and soil structure formation. The aim of this paper was to examine the contribution of earthworm activity to the process of C incorporation and soil structure maintenance in soils with different NT variants of: NT with GAP for 30 years (NT + r30); NT with some of the GAP for 12 years (NT-r12) and NT with soybean monoculture (NTm). Also a natural grassland (NA) was sampled as a reference. Earthworm aggregates were obtained by gently separating them from surrounding soil. Fine (HOC) and coarse (POC) organic matter fractions, water-stable aggregates (WSA) and mean weight diameter (MWD) were calculated for earthworm aggregates and bulk soil. In all sites only one species (Aporrectodea caliginosa) was found, with higher density in the NA, followed by NT + r30, that had about 9 times more earthworms than NTm. The number of earthworm aggregates was higher in the NT + r30 followed by the NA, both showing differences with the other NT systems. The earthworm aggregates in NA and NT + r30 had significantly more POC than the surrounding soil (230% increase in NA and 100% NT + r30). Earthworm casts had higher values of MWD and WSA than physical soil aggregates in both NA and NT + r30 management treatments. Our results show the existence of a positive feedback loop we called earthworm-driven virtuous cycle. The increase in earthworm abundance promotes higher production of earthworm aggregates which are richer in organic matter and more water stable than the surrounding soil. This has favourable results in terms of soil quality but also increase crop yields (57% in maize and 18% in soybean), by means of biologically mediated soil processes, which is a highly desirable way to sustainability of agricultural production. Farmers, politicians and the whole society should pay more attention to soil as a key component supporting agricultural production by means of internal biological soil functioning.

Earthworms are drivers of important soil processes such as the nutrient cycle. Earthworms provide soil microbiota with mucus, temperature, and organic resources in their guts, enhancing organic matter decomposition. However, very little is known about the effect of different crop rotations on soil microbiota activation mediated by earthworm activity. We aimed to evaluate the effect of different crop rotations on enzymatic activity in A. caliginosa casts and on enzymatic stoichiometry patterns related to C, N, and P acquisition activities. We conducted a microcosm study using different crop residues as food supply: soybean (S), soybean plus maize (SM), vetch, maize, and soybean (VMS), and with no residue addition (NR). We measured α-glucosidase (AGLU), β-glucosidase (BGLU), cellobiohydrolase (CEL), acetylesterase (ACE), N-acetyl-glucosaminidase (NAG), and phosmonoesterase (PME) activities in A. caliginosa casts, immediately before starting the experiment for evaluating the initial condition (IC) and after the experiment in each residue treatment. SM and VMS residues enhanced BGLU, CEL, and NAG activity regarding S, NR, and IC treatments. S had similar or lower activity than NR and IC for all the analyzed enzymes. There was a positive, strong, and significant relationship among C, N, and P acquiring enzymes regardless of the treatment. We found lower ratios for C and N acquisition related to P acquisition than for C: N acquisition activity ratios. This result suggests P as the limiting nutrient for earthworm microbiomes. Our results indicate that soybean residue is unsuitable for A. caliginosa food requirements and that diversifying crop residues and the inclusion of maize as food enhance enzymatic activity mediated by earthworms and thus organic matter decomposition. We suggest differential activation and likely changes in microbiota composition as mechanisms responsible for higher enzymatic activation when earthworms are fed with different combination of crop residues.

New thermochronometric data provide evidence for an along-strike diachronous building of the Andes in north-central Chile (28.5-32 degrees S). Geochronological (U-Pb zircon) and thermochronological (apatite fission track and (U-Th)/He) analyses of rock units were obtained in west-to-east transects across the western topographic front. Thermal models indicate that the area west of the topographic front was little exhumed since approximately 45Ma. To the east of the western topographic front, the Main Cordillera shows both latitudinal and longitudinal differences in exhumation patterns. North of 31.5 degrees S, Cenozoic exhumation began before approximately 40-30Ma at the western and eastern limits of the Main Cordillera, building the Incaic Range. Later, accelerated exhumation focused on the core of the Main Cordillera and in the Frontal Cordillera at approximately 22-14Ma and approximately 7Ma, respectively. South of 31.5 degrees S, accelerated exhumation in the Main Cordillera occurred mainly around 22-14Ma, after an initial Eocene phase, and the locus of exhumation moved eastward by the late Miocene. Whereas accelerated exhumation in the early to mid-Miocene correlates with the breakup of the Farallon Plate, late Miocene accelerated exhumation correlates with the onset of flat subduction. Latitudinal differences on the exhumation timing along the western topographic front of the Main Cordillera may be due to the absence of the Paleozoic crystalline core south of 31.5 degrees S, which seems to have acted as a buttress for shortening during the Eocene.

Electricity tariffs convey information on internal system operation to the actors involved. Electricity pricing is, then, of major importance both in liberalised and regulated systems. Most electricity consumers interact with the industry only through the price they pay for the service. Consequently, good tariff design reflects industry regulation as a whole and is the instrument used to provide consumers with the right signals. The objective of this study is to define the theoretical principles that regulation should pursue in electric distribution tariff design and introduce the reader to the most relevant practical approaches that have been proposed or implemented. Although distribution costs are usually the largest part of the access tariff (or use of system charge), there is not a universally accepted methodology for distribution pricing. The earliest attempts at cost allocation conformed what is now known as the accounting approach, based on business accounting. In recent years, the proposals have focused on two approaches: the application of long-term marginal (or incremental) costs and the cost-causality principle. Although the former aims to achieve a better economic signal, because of the difficulties surrounding its implementation, the most usual solution applied in practice draws more heavily from the causality principle.

The effect of mean precipitation rate on erosion is debated. Three hypotheses may explain why the current erosion rate and runoff may be spatially uncorrelated: (1) the topography has reached a steady state for which the erosion rate pattern is determined by the uplift rate pattern; (2) the erosion rate only depends weakly on runoff; or (3) the studied catchments are experiencing different transient adjustments to uplift or to climate variations. In the Chilean Andes, between 278S and 398S, the mean annual runoff rates increase southwards from 0.01 to 2.6 m a but the catchment averaged rates of decadal erosion (suspended sediment) and millennial erosion (Be in river sand) peak at c. 0.25 mm a for runoff c. 0.5 m a and then decrease while runoff keeps increasing. Erosion rates increase non-linearly with the slope and weakly with the square root of the runoff. However, sediments trapped in the subduction trench suggest a correlation between the current runoff pattern and erosion over millions of years. The third hypothesis above may explain these different erosion rate patterns; the patterns seem consistent with, although not limited to, a model where the relief and erosion rate have first increased and then decreased in response to a period of uplift, at rates controlled by the mean precipitation rate. To what extent does the mean precipitation rate or tectonic uplift rate control the erosion rate in mountain ranges? Recent models suggest that climate, through its effect on erosion, plays a determinant role in localizing deformation, and in controlling mountain elevation and uplift rate (Whipple 2009). In addition, variations in palaeoerosion rates (Charreau et al. 2011) and in palaeosedimentation rates (e.g. Metivier et al. 1999; Clift 2006; Uba et al. 2007) potentially record variations in the mean precipitation rate (Castelltort & van den Driessche 2003). The role of climate in driving mountain erosion has become a central question in tectonics, geomorphology and sedimentology (Allen 2008). Because it is difficult to reconstruct the evolution of the erosion rate in mountains over 100 ka to Ma, the evolution of the sediment outflux from mountain ranges has been studied using numerical and physical modeling (e.g. Kooi & Beaumont 1994; Tucker & Slingerland 1996; Bonnet & Crave 2003; Whipple & Meade 2006; Stolar et al. 2007). A tectonic uplift is predicted to generate erosion, the amplitude of which varies according to a timescale called the response time (Kooi & Beaumont 1996; Whipple 2009). The response time is thought to be modulated by climatic conditions (Bonnet & Crave 2003; Stolar et al. 2006; Whipple & Meade 2006; Tucker & vanderBeek 2013). Consequently, the relationship between erosion and precipitation rates is predicted to depend on the timescale over which the erosion rate is analysed. In the simplest ideal case of non-glaciated mountain ranges where the uplift is held constant, the cumulative erosion at a given time (the time integral of the erosion rate since the onset of the uplift) is greater where the climate is wetter simply because the response time is less and the slopes are smaller in this case (Bonnet & Crave 2003). In some circumstances, decadal or millennial erosion rates can be greater where the climate is drier. This is predicted when the drainage network grows slowly, leading to steep hillslopes, deep valleys (high fluvial relief or From: Sepulveda, S. A., Giambiagi, L. B., Moreiras, S. M., Pinto, L., Tunik, M., Hoke, G. D. & Farias, M. (eds) Geodynamic Processes in the Andes of Central Chile and Argentina. Geological Society, London, Special Publications, 399, http://dx.doi.org/10.1144/SP399.16 # The Geological Society of London 2014. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics at Universidad de Chile on May 14, 2014 http://sp.lyellcollection.org/ Downloaded from

Paspalum notatum Flugge is a grass species organized as an agamic complex. The objective of the current research was to survey the frequencies and variation of cytosine methylation at CCGG sequences in diploid and tetraploid genotypes, and to determine the occurrence of methylation changes associated with tetraploidization by using methylation-sensitive amplification polymorphism (MSAP) markers. No differences were found in the average proportions of methylated CCGG sites between cytotypes, but methylation patterns were significantly more variable in tetraploids. In both groups of plants, epigenetic and non-epigenetic variation correlated significantly when compared by Mantel tests. The evaluation of 159 common MSAP markers showed that 18.86 % of them differed in their methylation status in the different ploidies. Dendrogram analysis, reflecting epigenetic distances, showed that the four diploids and one experimentally-obtained sexually-reproducing tetraploid, grouped together. MSAP analysis performed on a diploid plant and its autotetraploid derivative showed that new epialleles emerged after tetraploidization. Sequencing of several MASP markers showed homologies with low copy genes, non-coding sequences and transposon/retrotransposon elements.

Tetraploid (2n = 4x = 40) races of Paspalum notatum Flugge are important natural forage grasses for the tropical and subtropical areas of the Americas. Almost all natural accessions reproduce by obligate aposporous apomixis. Previous work on the species allowed the identification of several molecular markers completely linked to apospory, one component of apomictic reproduction. Moreover, after a fingerprinting characterization of a germplasm collection, 11 amplified fragment length polymorphism (AFLP) markers exclusive to apomictic accessions were detected. The objectives of this work were (1) to validate the presence of molecular markers linked to apospory in tetraploid races of different geographic origins, (2) to determine if markers specific to apomictic accessions were associated with the mode of reproduction, and (3) to develop single-locus markers of apospory that can be used for marker-assisted selection. Thirteen natural apomictic accessions were analyzed. Moreover, the parental plants Q4188 (non-aposporous) and Q4117 (aposporous) and 44 F1 progenies (36 non-aposporous, 8 aposporous) derived from them were used as a validation population. Nine markers [two random amplification of polymorphic DNA (RAPD) and seven AFLP] 100% linked to apospory in Q4117 were tested. Amplification reactions with the corresponding primers showed that all markers were present in the 13 aposporous (apomictic) accessions, but were absent in the non-aposporous controls. On the other hand, linkage analysis of the 11 AFLP markers specific to the apomictic accessions showed that all of them were linked in coupling to apospory (r = 0.00, LOD 13.245). Based on one AFLP (E36M37c), two sequence characterized amplification region (SCAR) markers (SPNA1 and SPNA2) co-segregating with the trait and present in the 13 apomictic accessions were developed. The presence of markers associated with apospory was conserved among tetraploid accessions of different geographic origins. Moreover, the single-locus markers SPNA1 and SPNA2 could be used for routine marker-assisted selection in hybrid populations segregating for apospory and to facilitate the isolation of apospory-related genes.

In north-central Chile, a wide shore platform is morphologically connected with a high fluvial terrace and a pediment. The eastward extension of Quaternary coastal uplift in the Southern Central Andes is poorly constrained since no age correlation between marine and continental landforms has been reported. We use Al-26 and Be-10 concentrations to constrain the geomorphic evolution of these marine and continental landforms near the Choapa valley (31.6 degrees S). Be-10 ages for the shore platform indicate that this surface was repeatedly reoccupied during sea-level highstands between similar to 800 and 500 ka and uplifted after 500 ka. While 'zero erosion' ages for the pediment between similar to 600 and 300 ka only partly overlap the shore platform age range, more realistic exposure ages calculated for an erosion rate of 1 m/Ma are between similar to 945 and 475 ka, fitting the age range of the correlated shore platform. Be-10 concentrations of the high fluvial terrace are highly scattered evidencing vertical mixing of clasts probably due to slow lowering of the surface. Although it is not possible to determine an age for this landform, the scattering among its Be-10 concentrations implies that this marker is several hundreds of thousands of years old and that the high fluvial terrace began to form at similar to 1200 ka or after. Finally, Be-10 concentrations of the high fluvial terrace, the pediment and the shore platform are of the same order of magnitude, which is consistent with the clear morphologic correlation between these three types of landforms. These data suggest that the marine and continental landforms studied formed synchronously, with some local differences, during a long period of relative tectonic stability between similar to(1200?) 800 and 500 ka and uplifted after 500 ka. Our results confirm recent studies showing a post-400 +/- 100 ka renewal of uplift along the Pacific coast after a Lower to Middle Pleistocene period of slow uplift. Moreover, the extension of the surfaces suggests that a broad region of similar to 40 km has been uplifted ca. 150 m during the Quaternary.

Fil: Podio, Maricel. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias; Argentina. Fil: Podio, Maricel. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias, Argentina. Fil. Rodríguez, María Pía. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias, Argentina. Fil: Felitti, Silvina Andrea. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias, Argentina. Fil: Stein, Juliana. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias, Argentina. Fil: Martínez, Eric J. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias; Argentina. Fil: Siena, Lorena Adelina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias, Argentina. Fil: Quarin, Camilo Luis. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias; Argentina. Fil: Pessino, Silvina Claudia. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias, Argentina. Fil: Ortíz, Juan Pablo Amelio. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias, Argentina. In previous studies we reported the identification of several AFLP, RAPD and RFLP molecular markers linked to apospory in Paspalum notatum. The objective of this work was to sequence these markers, obtain their flanking regions by chromosome walking and perform an in silico mapping analysis in rice and maize. The methylation status of two apospory-related sequences was also assessed using methylation-sensitive RFLP experiments. Fourteen molecular markers were analyzed and several protein-coding sequences were identified. Copy number estimates and RFLP linkage analysis showed that the sequence PnMAI3 displayed 2-4 copies per genome and linkage to apospory. Extension of this marker by chromosome walking revealed an additional protein-coding sequence mapping in silico in the apospory-syntenic regions of rice and maize. Approximately 5 kb corresponding to different markers were characterized through the global sequencing procedure. A more refined analysis based on sequence information indicated synteny with segments of chromosomes 2 and 12 of rice and chromosomes 3 and 5 of maize. Two loci associated with apomixis locus were tested in methylation-sensitive RFLP experiments using genomic DNA extracted from leaves. Although both target sequences were methylated no methylation polymorphisms associated with the mode of reproduction were detected.

Paspalum notatum Flugge is a warm-season forage grass with mainly diploid (2n =20) and autotetraploid (2n = 40) representa-tives.Diploid races reproduce sexually andrequire crosspollination due to a self-incom-patible mating system, while autotetraploids reproduce by aposporous apomixis. The objec-tives of this work were to develop a genetic linkage map of Paspalum notatum Flugge at the tetraploid level, identify the linkage/s group/s associated with apomixis and carry out a general characterization of its mode of inheritance. A pseudo test-cross F1 family of 113 individuals segregating for the mode of reproduction was obtained by crossinga syn-thetic completely sexual tetraploid plant (Q4188) as female parent with a naturalaposporous individual (Q4117) as pollen donor.Map construction was based on single-dose markers (SDAFs) segregating from both par-ents. Two linkage maps (female and male) were constructed. Within each map, homolo-gous groups were assembled by detectingrepulsion-phase linked SDAFs. Putative Q4188 and Q4117 homolog groups were identified by mapping shared single dose mark-ers (BSDF). The Q4188 map consisted of 263 markers distributed on 26 co-segregation groups over a total genetic distance of 1.590.6 cM, while the Q4117 map contained 216 loci dispersed on 39 co-segregation groups along 2.265.7 cM, giving an estimated genome cov-erage of 88% and 83%, respectively. Seven and 12 putative homologous chromosomes were detected within Q4188 and Q4117 maps,respectively. Afterward, ten female and male homologous chromosomes were identified by mapping BSDFs. In the Q4117 map, a single linkage group was associated with apospory. It was characterized by restriction in recombina-tion and preferential chromosome pairing. A BPSD marker mapping within this group allowed the detection of the female homolog and the putative four male groups of the set carrying apospory. Fil: Stein, Juliana. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Laboratorio de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pessino, Silvina Claudia. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Laboratorio de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Martínez, Eric Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina Fil: Rodriguez Romero, María Pía. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Laboratorio de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Siena, Lorena Adelina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Laboratorio de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Quarin, Camilo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina Fil: Ortiz, Juan Pablo Amelio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina