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Asymmetric competitive effects during species range expansion: An experimental assessment of interaction strength between “equivalent” grazer species in their range overlap

Autores:

Aguilera, M., Valdivia, N., Jenkins, S., Navarrete, S., & Broitman, B.

Resumen:

Biotic interactions are central to the development of theory and concepts in community ecology; experimental evidence has shown their strong effects on patterns of population and community organization and dynamics over local spatial scales. The role of competition in determining range limits and preventing invasions at biogeographic scales is more controversial, partly because of the complexity of processes involved in species colonization of novel habitats and the difficulties in performing appropriate manipulations and controls.

We examined experimentally whether competition is likely to affect poleward range expansion hindering or facilitating the establishment of the limpet Scurria viridula along the south‐eastern Pacific rocky shore (30°S, Chile) in the region occupied by the congeneric S. zebrina. We also assessed whether competition with the “invader” or range‐expanding species could reduce individual performance of the “native” S. zebrina and depress local populations Geographic field surveys were conducted to characterize the abundance and identity of limpets along the south‐eastern Pacific coast from 18°S to 41°S, and the micro‐scale (few cm) spatial distribution across the range overlap of the two species. Field‐based competition experiments were conducted at the southern leading edge of the range of S. viridula (33°S) and at the northern limit of S. zebrina (30°S).

Field surveys showed poleward range expansion of S. viridula of ca. 210 km since year 2000, with an expansion rate of 13.1 km/year. No range shift was detected for S. zebrina. The resident S. zebrina had significant negative effects on the growth rate of the invading juvenile S. viridula, while no effect of the latter was found on S. zebrina. Spatial segregation between species was found at the scale of cms.
Our results provide novel evidence of an asymmetric competitive effect of a resident species on an invader, which may hamper further range expansion. No negative effect of the invader on the resident species was detected. This study highlights the complexities of evaluating the role of species interactions in setting range limits of species, but showed how interspecific competition might slow the advance of an invader by reducing individual performance and overall population size at the advancing front.

Año: 2018

Palabras claves: Field experiments, Grazers, Pacific Ocean, Range overlap, Range shift, Transitional zone

Referencia APA: Aguilera, M., Valdivia, N., Jenkins, S., Navarrete, S., & Broitman, B. (2018). Asymmetric competitive effects during species range expansion: An experimental assessment of interaction strength between “equivalent” grazer species in their range overlap. Journal Of Animal Ecology, 88(2), 277-289. doi: 10.1111/1365-2656.12917

The 2017 coastal El Niño

Autores:

Takahashi, K.; Aliaga-Nestares, V.; Avalos, G.; Bouchon, M.; Castro, A.; Cruzado, L.; Dewitte, B.; Gutiérrez, D.; Lavado-Casimiro, W.; Marengo, J.; Martínez, A. G.; Mosquera-Vásquez, K.; Quispe, N.

Resumen:

The original concept of El Niño consisted of anomalously high sea surface temperature and heavy rainfall along the arid northern coast of Peru (Carranza 1891; Carrillo 1893). The concept evolved into the El Niño–Southern Oscillation (ENSO; Bjerknes 1969), although the original El Niño and the Southern Oscillation do not necessarily have the same variability (Deser and Wallace 1987), and the strong El Niño episode in early 1925 coincided with cold-to-neutral ENSO conditions (Takahashi and Martínez 2017). To distinguish the near-coastal El Niño from the warm ENSO phase, Peru operationally defines the “coastal El Niño” based on the seasonal Niño 1+2 SST anomaly (ENFEN 2012; L’Heureux et al. 2017). While recent attention has been
brought to the concept of ENSO diversity (e.g., “central Pacific” vs “eastern Pacific” events; Capotondi et al. 2015), the coastal El Niño represents another facet of ENSO that requires further study in terms of its mechanisms and predictability.

Año: 2018

Palabras claves:

Referencia APA: Takahashi, K.; Aliaga-Nestares, V.; Avalos, G.; Bouchon, M.; Castro, A.; Cruzado, L.; Dewitte, B.; Gutiérrez, D.; Lavado-Casimiro, W.; Marengo, J.; Martínez, A. G.; Mosquera-Vásquez, K.; Quispe, N. (2018). The 2017 coastal El Niño. Bulletin of the American Meteorological Society. https://doi.org/10.1175/2018BAMSStateoftheClimate.1

Extreme El Niño Events

Autores:

Dewitte, B., & Takahashi, K.

Resumen:

Every few years the tropical Pacific warms abnormally in association with a relaxation of the trade winds, a phenomenon known as the El Niño–Southern Oscillation (ENSO) that represents the strongest fluctuation of the global climate system. Although the contemporary observational record indicates that all El Niño events are not alike, differing in amplitude, warming pattern, and teleconnection, there is a class of events that stands out in terms of the societal and economical impacts: the extreme El Niño events that have occurred every 15–20 years. In this chapter, we propose an overview of the state of knowledge and of some current lines of research dedicated to extreme El Niño events. Building on the recently proposed concept of ENSO diversity, we further synthesize our current understanding of the nonlinear dynamics of this class of events and their expected evolution in a warmer climate and highlight some challenges in ENSO research.

Año: 2018

Palabras claves: El Niño, ENSO diversity, External forcing, Global warming, Teleconnection.

Referencia APA: Dewitte, B., & Takahashi, K. (2019). Extreme El Niño Events. Tropical Extremes, 165-201. doi: 10.1016/b978-0-12-809248-4.00006-6

Is Precipitation a Good Metric for Model Performance?

Autores:

Tapiador, F., Roca, R., Del Genio, A., Dewitte, B., Petersen, W., & Zhang, F.

Resumen:

Precipitation has often been used to gauge the performances of numerical weather and climate models, sometimes together with other variables such as temperature, humidity, geopotential, and clouds. Precipitation, however, is singular in that it can present a high spatial variability and probably the sharpest gradients among all meteorological fields. Moreover, its quantitative measurement is plagued with difficulties, and there are even notable differences among different reference datasets. Several additional issues sometimes lead to questions about its usefulness in model validation. This essay discusses the use of precipitation for model verification and validation and the crucial role of highly precise and reliable satellite estimates, such as those from NASA’s Global Precipitation Mission Core Observatory.

Año: 2018

Palabras claves:

Referencia APA: Tapiador, F., Roca, R., Del Genio, A., Dewitte, B., Petersen, W., & Zhang, F. (2019). Is Precipitation a Good Metric for Model Performance?. Bulletin Of The American Meteorological Society, 100(2), 223-233. doi: 10.1175/bams-d-17-0218.1

Chapter 29 – Chile: Environmental Status and Future Perspectives

Autores:

Aguilera, M., Aburto, J., Bravo, L., Broitman, B., García, R., & Gaymer, C., Gelcich, S., López, B.A., Montecino, V., Pauchard, A., Ramos, M., Rutllant, J.A., Sáez, C.A., Valdivia, N., Thiel, M.

Resumen:

The coast of mainland Chile extends from 18°S to about 56°S, and is about 4200 km long. In the north, the coast is characterized by continuous, regular, and wave-exposed shores, while to south of 40°S it is highly fragmented, with extensive fjords and small archipelagos with many wave-protected zones. The Humboldt Current System (HCS) determines oceanographic and ecological processes in the northern part, with persistent upwelling fronts and episodic “El Niño” events. In the southern part the southward-flowing Magellan Current is important. Coastal upwelling along the HCS sustains a diverse pelagic and benthic food web structure. Rocky coastal habitats are dominated by large kelp forests and filter-feeding species like reef-forming mussels and tunicates.

The main coastal habitats along the coast of Chile are rocky shores, sandy beaches, coastal wetlands, and dunes. The main populated zones are concentrated between 33°S to 35°S in central Chile, with economically important trading ports. Sewage discharges from large cities have the potential to increase nutrients levels in nearshore habitats causing localized eutrophication. Mining activities in northern Chile contaminate coastal waters, while in the south intensive aquaculture affects the fjord ecosystem. Also, subsistence harvesting (of kelps, molluscs, fish) is dramatically reducing the abundance of top consumers or habitat-forming species.

The diverse and productive coastal marine ecosystems are used by different socioeconomic activities and exposed to interventions which are potentially harmful. Ecosystem services should be managed, and necessary interventions carefully planned. Achieving sustainable use of natural marine resources and coastal ecosystem integrity is challenging, and a basic understanding of ecosystem responses to direct human impacts and global climate change require better monitoring strategies. The establishment of a marine reserve “Humboldt Current System” would be a major step toward this goal.

Año: 2019

Palabras claves: Continental Chile, Climate, Coastal Ecology, Human interventions, Humboldt Current System, Oceanography, Southeastern Pacific.

Referencia APA: Aguilera, M., Aburto, J., Bravo, L., Broitman, B., García, R., & Gaymer, C., Gelcich, S., López, B.A., Montecino, V., Pauchard, A., Ramos, M., Rutllant, J.A., Sáez, C.A., Valdivia, N., Thiel, M. (2019). Chile: Environmental Status and Future Perspectives. World Seas: An Environmental Evaluation, 673-702. doi: 10.1016/b978-0-12-805068-2.00046-2

Cross-cultural invariances in the architecture of shame

Autores:

Sznycer, D., Xygalatas, D., Agey, E., Alami, S., An, X., & Ananyeva, K., Atkinson, Q.D., Broitman, B.R., Conte, T.J., Flores, C., Fukushima, S., Hitokoto, H., Kharitonov, A.N., Onyishi, C.N., Onyishi, I.E., Romero, P.P., Schrock, J.M., Snodgrass, J., Sugiyama, L.S., Takemura, K., Townsend, C., Zhuang, , J-Y., Athena Aktipis, C., Cronk, L., Cosmides, L., Tooby, J.

Resumen:

Human foragers are obligately group-living, and their high dependence on mutual aid is believed to have characterized our species’ social evolution. It was therefore a central adaptive problem for our ancestors to avoid damaging the willingness of other group members to render them assistance. Cognitively, this requires a predictive map of the degree to which others would devalue the individual based on each of various possible acts. With such a map, an individual can avoid socially costly behaviors by anticipating how much audience devaluation a potential action (e.g., stealing) would cause and weigh this against the action’s direct payoff (e.g., acquiring). The shame system manifests all of the functional properties required to solve this adaptive problem, with the aversive intensity of shame encoding the social cost. Previous data from three Western(ized) societies indicated that the shame evoked when the individual anticipates committing various acts closely tracks the magnitude of devaluation expressed by audiences in response to those acts. Here we report data supporting the broader claim that shame is a basic part of human biology. We conducted an experiment among 899 participants in 15 small-scale communities scattered around the world. Despite widely varying languages, cultures, and subsistence modes, shame in each community closely tracked the devaluation of local audiences (mean r = +0.84). The fact that the same pattern is encountered in such mutually remote communities suggests that shame’s match to audience devaluation is a design feature crafted by selection and not a product of cultural contact or convergent cultural evolution.

Año: 2018

Palabras claves: emotion, cognition, culture, cooperation, evolutionary psychology.

Referencia APA: Sznycer, D., Xygalatas, D., Agey, E., Alami, S., An, X., & Ananyeva, K., Atkinson, Q.D., Broitman, B.R., Conte, T.J., Flores, C., Fukushima, S., Hitokoto, H., Kharitonov, A.N., Onyishi, C.N., Onyishi, I.E., Romero, P.P., Schrock, J.M., Snodgrass, J., Sugiyama, L.S., Takemura, K., Townsend, C., Zhuang, , J-Y., Athena Aktipis, C., Cronk, L., Cosmides, L., Tooby, J. (2018). Cross-cultural invariances in the architecture of shame. Proceedings Of The National Academy Of Sciences, 115(39), 9702-9707. doi: 10.1073/pnas.1805016115

Pedogenic and microbial interrelations to regional climate and local topography: New insights from a climate gradient (arid to humid) along the Coastal Cordillera of Chile

Autores:

Bernhard, N., Moskwa, L., Schmidt, K., Oeser, R., Aburto, F., & Bader, M., Baumann, K., von Blanckenburg, F., Boy, J., van den Brink, L., Brucker, E., Büdel, B., Canessa, R., Dippold, M.A., Ehlers, T.A., Fuentes, J.P., Godoy, R., Jung, P., Karsten, U., Köster, M., Kuzyakov, Y., Leinweber, P., Neidhardt, H., Matus, F., Mueller, C.W., Oelmann, Y., Oses, R., Osses, P., Paulino, L., Samolov, E., Schaller, M., Schmid, M., Spielvogel, S., Spohn, M., Stock, S., Stroncik, N., Tielbörger, K., Übernickel, K., Scholten, T., Seguel, O., Wagner, D., Kühn, P.

Resumen:

The effects of climate and topography on soil physico-chemical and microbial parameters were studied along an extensive latitudinal climate gradient in the Coastal Cordillera of Chile (26°–38°S). The study sites encompass arid (Pan de Azúcar), semiarid (Santa Gracia), mediterranean (La Campana) and humid (Nahuelbuta) climates and vegetation, ranging from arid desert, dominated by biological soil crusts (biocrusts), semiarid shrubland and mediterranean sclerophyllous forest, where biocrusts are present but do have a seasonal pattern to temperate-mixed forest, where biocrusts only occur as an early pioneering development stage after disturbance. All soils originate from granitic parent materials and show very strong differences in pedogenesis intensity and soil depth.

Most of the investigated physical, chemical and microbiological soil properties showed distinct trends along the climate gradient. Further, abrupt changes between the arid northernmost study site and the other semi-arid to humid sites can be shown, which indicate non-linearity and thresholds along the climate gradient. Clay and total organic carbon contents (TOC) as well as Ah horizons and solum depths increased from arid to humid climates, whereas bulk density (BD), pH values and base saturation (BS) decreased. These properties demonstrate the accumulation of organic matter, clay formation and element leaching as key-pedogenic processes with increasing humidity. However, the soils in the northern arid climate do not follow this overall latitudinal trend, because texture and BD are largely controlled by aeolian input of dust and sea salts spray followed by the formation of secondary evaporate minerals. Total soil DNA concentrations and TOC increased from arid to humid sites, while areal coverage by biocrusts exhibited an opposite trend. Relative bacterial and archaeal abundances were lower in the arid site, but for the other sites the local variability exceeds the variability along the climate gradient. Differences in soil properties between topographic positions were most pronounced at the study sites with the mediterranean and humid climate, whereas microbial abundances were independent on topography across all study sites. In general, the regional climate is the strongest controlling factor for pedogenesis and microbial parameters in soils developed from the same parent material. Topographic position along individual slopes of limited length augmented this effect only under humid conditions, where water erosion likely relocated particles and elements downward. The change from alkaline to neutral soil pH between the arid and the semi-arid site coincided with qualitative differences in soil formation as well as microbial habitats. This also reflects non-linear relationships of pedogenic and microbial processes in soils depending on climate with a sharp threshold between arid and semi-arid conditions. Therefore, the soils on the transition between arid and semi-arid conditions are especially sensitive and may be well used as indicators of long and medium-term climate changes. Concluding, the unique latitudinal precipitation gradient in the Coastal Cordillera of Chile is predestined to investigate the effects of the main soil forming factor – climate – on pedogenic processes.

Año: 2018

Palabras claves: Climate, Topography, Soil texture, Total organic carbon, Carbon isotope ratio (δ13CTOC), Microbial abundance.

Referencia APA: Bernhard, N., Moskwa, L., Schmidt, K., Oeser, R., Aburto, F., & Bader, M., Baumann, K., von Blanckenburg, F., Boy, J., van den Brink, L., Brucker, E., Büdel, B., Canessa, R., Dippold, M.A., Ehlers, T.A., Fuentes, J.P., Godoy, R., Jung, P., Karsten, U., Köster, M., Kuzyakov, Y., Leinweber, P., Neidhardt, H., Matus, F., Mueller, C.W., Oelmann, Y., Oses, R., Osses, P., Paulino, L., Samolov, E., Schaller, M., Schmid, M., Spielvogel, S., Spohn, M., Stock, S., Stroncik, N., Tielbörger, K., Übernickel, K., Scholten, T., Seguel, O., Wagner, D., Kühn, P. (2018). Pedogenic and microbial interrelations to regional climate and local topography: New insights from a climate gradient (arid to humid) along the Coastal Cordillera of Chile. CATENA, 170, 335-355. doi: 10.1016/j.catena.2018.06.018

Crop pests and predators exhibit inconsistent responses to surrounding landscape composition

Autores:

Karp, D., Chaplin-Kramer, R., Meehan, T., Martin, E., DeClerck, F., & Grab, H., Gratton C., Hunt, L., Larsen, A.E., Martínez-Salinas, A., O’Rourke, M.E., Rusch, A., Poveda, K., Jonsson, M., Rosenheim, J.A., Schellhorn, N.A., Tscharntke, T., Wratten, S.D., Zhang, W., Iverson, A.L., Adler, L.S., Albrecht, M., Alignier, A., Angelella, G.M., Anjum, M.Z., Avelino, J., Batáry, P., Baveco, J.M., Bianchi, F.J.J.A., Birkhofer, K., Bohnenblust, E.W., Bommarco, R., Brewer, M.J., Caballero-López, B., Carrière, Y., Carvalheiro, L.G., Cayuela, L., Centrella, M., Ćetković, A., Henri, D.C., Chabert, A., Costamagna, A.C., De la Mora, A., de Kraker, J., Desneux, N., Diehl, E., Diekötter, T., Dormann, C.F., Eckberg, J.O., Entling, M.H., Fiedler, D., Franck, P., Frank van Veen, F.J., Frank, T., Gagic, V., Garratt, M.P.D., Getachew, A., Gonthier, D.J., Goodell, P.B., Graziosi, I., Groves, R.L., Gurr, G.M., Hajian-Forooshani, Z., Heimpel, G.E., Herrmann, J.D., Huseth, A.S., Inclán, D.J., Ingrao, A.J., Iv, P., Jacot, K., Johnson, G.A., Jones, L., Kaiser, M., Kaser, J.M., Keasar, T., Kim, T.N., Kishinevsky, M., Landis, D.A., Lavandero, B., Lavigne, C., Le Ralec, A., Lemessa, D., Letourneau, D.K., Liere, H., Lu, Y., Lubin, Y., Luttermoser, T., Maas, B., Mace, K., Madeira, F., Mader, V., Cortesero, A.M., Marini, L., Martinez, E., Martinson, H.M., Menozzi, P., Mitchell, M.G.E., Miyashita, T., Molina, G.A.R., Molina-Montenegro, M.A., O’Neal, M.E., Opatovsky, I., Ortiz-Martinez, S., Nash, M., Östman, Ö., Ouin, A., Pak, D., Paredes, D., Parsa, S., Parry, H., Perez-Alvarez, R., Perović, D.J., Peterson, J.A., Petit, S., Philpott, S.M., Plantegenest, M., Plećaš, M., Pluess, T., Pons, X., Potts, S.G., Pywell, R.F., Ragsdale, D.W., Rand, T.A., Raymond, L., Ricci, B., Sargent, C., Sarthou, J-P., Saulais, J., Schäckermann, J., Schmidt, N.P., Schneider, G., Schüepp, C., Sivakoff, F.S., Smith, H.G., Whitney, K.S., Stutz, S., Szendrei, Z., Takada, M.B., Taki, H., Tamburini, G., Thomson, L.J., Tricault, Y., Tsafack, N., Tschumi, M., Valantin-Morison, M., Van Trinh, M., van der Werf, W., Vierling, K.T., Werling, B.P., Wickens, J.B., Wickens, V.J., Woodcock, B.A., Wyckhuys, k., Xiao,, H., Yasuda, M., Yoshioka, A., Zou, Y.

Resumen:

The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies.

Año: 2018

Palabras claves: agroecology, biodiversity, biological control, ecosystem services, natural enemies

Referencia APA: Karp, D., Chaplin-Kramer, R., Meehan, T., Martin, E., DeClerck, F., & Grab, H., Gratton C., Hunt, L., Larsen, A.E., Martínez-Salinas, A., O’Rourke, M.E., Rusch, A., Poveda, K., Jonsson, M., Rosenheim, J.A., Schellhorn, N.A., Tscharntke, T., Wratten, S.D., Zhang, W., Iverson, A.L., Adler, L.S., Albrecht, M., Alignier, A., Angelella, G.M., Anjum, M.Z., Avelino, J., Batáry, P., Baveco, J.M., Bianchi, F.J.J.A., Birkhofer, K., Bohnenblust, E.W., Bommarco, R., Brewer, M.J., Caballero-López, B., Carrière, Y., Carvalheiro, L.G., Cayuela, L., Centrella, M., Ćetković, A., Henri, D.C., Chabert, A., Costamagna, A.C., De la Mora, A., de Kraker, J., Desneux, N., Diehl, E., Diekötter, T., Dormann, C.F., Eckberg, J.O., Entling, M.H., Fiedler, D., Franck, P., Frank van Veen, F.J., Frank, T., Gagic, V., Garratt, M.P.D., Getachew, A., Gonthier, D.J., Goodell, P.B., Graziosi, I., Groves, R.L., Gurr, G.M., Hajian-Forooshani, Z., Heimpel, G.E., Herrmann, J.D., Huseth, A.S., Inclán, D.J., Ingrao, A.J., Iv, P., Jacot, K., Johnson, G.A., Jones, L., Kaiser, M., Kaser, J.M., Keasar, T., Kim, T.N., Kishinevsky, M., Landis, D.A., Lavandero, B., Lavigne, C., Le Ralec, A., Lemessa, D., Letourneau, D.K., Liere, H., Lu, Y., Lubin, Y., Luttermoser, T., Maas, B., Mace, K., Madeira, F., Mader, V., Cortesero, A.M., Marini, L., Martinez, E., Martinson, H.M., Menozzi, P., Mitchell, M.G.E., Miyashita, T., Molina, G.A.R., Molina-Montenegro, M.A., O’Neal, M.E., Opatovsky, I., Ortiz-Martinez, S., Nash, M., Östman, Ö., Ouin, A., Pak, D., Paredes, D., Parsa, S., Parry, H., Perez-Alvarez, R., Perović, D.J., Peterson, J.A., Petit, S., Philpott, S.M., Plantegenest, M., Plećaš, M., Pluess, T., Pons, X., Potts, S.G., Pywell, R.F., Ragsdale, D.W., Rand, T.A., Raymond, L., Ricci, B., Sargent, C., Sarthou, J-P., Saulais, J., Schäckermann, J., Schmidt, N.P., Schneider, G., Schüepp, C., Sivakoff, F.S., Smith, H.G., Whitney, K.S., Stutz, S., Szendrei, Z., Takada, M.B., Taki, H., Tamburini, G., Thomson, L.J., Tricault, Y., Tsafack, N., Tschumi, M., Valantin-Morison, M., Van Trinh, M., van der Werf, W., Vierling, K.T., Werling, B.P., Wickens, J.B., Wickens, V.J., Woodcock, B.A., Wyckhuys, k., Xiao,, H., Yasuda, M., Yoshioka, A., Zou, Y. (2018). Crop pests and predators exhibit inconsistent responses to surrounding landscape composition. Proceedings Of The National Academy Of Sciences, 115(33), E7863-E7870. doi: 10.1073/pnas.1800042115

Chemistry and microbiology of the Critical Zone along a steep climate and vegetation gradient in the Chilean Coastal Cordillera

Autores:

Oeser, R., Stroncik, N., Moskwa, L., Bernhard, N., Schaller, M., Canessa, R., van den Brink, L., Köster, M., Brucker, E., Stock, S., Fuentes, J., Godoy, R., Matus, F., Oses Pedraza, R., Osses McIntyre, P., Paulino, L., Seguel, O., Bader, M., Boy, J., Dippold, M., Ehlers, T., Kühn, P., Kuzyakov, Y., Leinweber, P., Scholten, T., Spielvogel, S., Spohn, M., Übernickel, K., Tielbörger, K., Wagner, D. and von Blanckenburg, F.

Resumen:

The Chilean Coastal Cordillera features a spectacular climate and vegetation gradient, ranging from arid and unvegetated areas in the north to humid and forested areas in the south. The EarthShape project (“Earth Surface Shaping by Biota”) uses this natural gradient to investigate how climate and biological processes shape the Earth's surface. We explored the Critical Zone, the Earth's uppermost layer, in four key sites located in desert, semidesert, Mediterranean, and temperate climate zones of the Coastal Cordillera, with the focus on weathering of granitic rock. Here, we present first results from 16 approximately 2 m-deep regolith profiles to document: (1) architecture of weathering zone; (2) degree and rate of rock weathering, thus the release of mineral-derived nutrients to the terrestrial ecosystems; (3) denudation rates; and (4) microbial abundances of bacteria and archaea in the saprolite.

From north to south, denudation rates from cosmogenic nuclides are ~10 t km−2 yr−1 at the arid Pan de Azúcar site, ~20 t km−2 yr−1 at the semi-arid site of Santa Gracia, ~60 t km−2 yr−1 at the Mediterranean climate site of La Campana, and ~30 t km−2 yr−1 at the humid site of Nahuelbuta. A and B horizons increase in thickness and elemental depletion or enrichment increases from north (~26°S) to south (~38°S) in these horizons. Differences in the degree of chemical weathering, quantified by the chemical depletion fraction (CDF), are significant only between the arid and sparsely vegetated site and the other three sites. Differences in the CDF between the sites, and elemental depletion within the sites are sometimes smaller than the variations induced by the bedrock heterogeneity. Microbial abundances (bacteria and archaea) in saprolite substantially increase from the arid to the semi-arid sites.

Año: 2018

Palabras claves: Weathering, Denudation, Microbial abundance, Climate, Chile.

Referencia APA: Oeser, R., Stroncik, N., Moskwa, L., Bernhard, N., Schaller, M., Canessa, R., van den Brink, L., Köster, M., Brucker, E., Stock, S., Fuentes, J., Godoy, R., Matus, F., Oses Pedraza, R., Osses McIntyre, P., Paulino, L., Seguel, O., Bader, M., Boy, J., Dippold, M., Ehlers, T., Kühn, P., Kuzyakov, Y., Leinweber, P., Scholten, T., Spielvogel, S., Spohn, M., Übernickel, K., Tielbörger, K., Wagner, D. and von Blanckenburg, F. (2018). Chemistry and microbiology of the Critical Zone along a steep climate and vegetation gradient in the Chilean Coastal Cordillera. CATENA, 170, pp.183-203.

Hormonal and physiological changes driven by fungal endophytes increase Antarctic plant performance under UV-B radiation

Autores:

Ramos, P., Rivas, N., Pollmann, S., Casati, P. and Molina-Montenegro, M.

Resumen:

Antarctic environments are amongst the most stressful habitats for life on Earth, with high intensities of solar UV-B radiation reaching the land surface. In this study, we evaluated how the photochemical efficiency, cell damage and reproductive biomass of Antarctic pearlwort (Colobanthus quitensis) were affected by different intensities of UV-B radiation in the absence and presence of fungal endophytes. In addition, we evaluated the hormonal content of plants at different UV-B radiation intensities and how hormonal content was affected by endophytes. Overall, plants exposed to UV-B radiation showed higher numbers of flowers, higher total biomass and lower lipid peroxidation in the presence of endophytes compared with plants without endophytes. Photochemical efficiency was unaffected. Fungal endophytes affected the content of salicylic acid, jasmonate, indole-3-acetate and abscisic acid in shoot tissue of plants exposed to UV-B radiation. These results suggest that endophytes could modulate the hormonal content of C. quitensis to improve its ecophysiological performance under high UV-B radiation.

Año: 2018

Palabras claves: Antarctica, Climate change, Colobanthus quitensis, Ecophysiological performance, Fungal endophytes

Referencia APA: Ramos, P., Rivas, N., Pollmann, S., Casati, P. and Molina-Montenegro, M. (2018). Hormonal and physiological changes driven by fungal endophytes increase Antarctic plant performance under UV-B radiation. Fungal Ecology, 34, pp.76-82.

Scales of predator detection behavior and escape in Fissurella limbata: A field and laboratory assessment

Autores:

Manzur, T., Gonzalez-Mendez, A. and Broitman, B.

Resumen:

The consumptive effects of predators are widely acknowledged, but predation can also impact prey populations through non‐consumptive effects (NCEs) such as costly antipredator behavioral responses. The magnitude of antipredator behavioral responses by prey is determined by an assessment of risk using sensory cues, which in turn is modulated by the environmental context. We studied the detection behavior and escape response of the keyhole limpet Fissurella limbata from the predatory sea star Heliaster helianthus. Through laboratory and field experimental trials, we quantified the distance and time of predator detection behavior by the prey, and measured their active escape responses when elicited. We found that predator detection by the limpet was chiefly mediated by distance, with experimental individuals capable of detecting predator presence effectively up to distances of at least 50 cm in the field and 70 cm under laboratory conditions. Our results indicate that this prey species is able to evaluate the proximity of its predator and use it as an indication of predation risk; therefore, predator–prey distance appears to be a primary predictor of the magnitude of the antipredator response. Given the tight relationship between predator distance and prey movement and the important role herbivores can play, particularly in this ecosystem, we expect that NCEs will cascade to the patterns of abundance and composition of rocky shore communities through changes in prey foraging behavior under risk.

Año: 2018

Palabras claves: antipredator behavior, escape, non‐consumptive effects, predator detection behavior, predator–prey interactions, rocky inter‐tidal, spatial scale

Referencia APA: Manzur, T., Gonzalez-Mendez, A. and Broitman, B. (2018). Scales of predator detection behavior and escape in Fissurella limbata: A field and laboratory assessment. Marine Ecology, 39(2), p.e12492. https://doi.org/10.1111/maec.12492

Metagenomic exploration of soils microbial communities associated to Antarctic vascular plants

Autores:

Molina-Montenegro, M., Ballesteros, G., Castro-Nallar, E., Meneses, C., Torres-Díaz, C. and Gallardo-Cerda, J.

Resumen:

Antarctica is one of the most stressful ecosystems worldwide with few vascular plants,which are limited by abiotic conditions. Here, plants such as Deschampsia antarctica (Da)could generate more suitable micro-environmental conditions for the establishment ofother plants as Colobanthus quitensis (Cq). Although, plant-plant interaction is known todetermine the plant performance, little is known about how microorganisms mightmodulate the ability of plants to cope with stressful environmental conditions. Severalreports have focused on the possible ecological roles of microorganism with vascularplants, but if the rizospheric microorganisms can modulate the positive interactions amongvascular Antarctic plants has been seldom assessed. In this study, we compared therhizosphere microbiomes associated with Cq, either growing alone or associated with Da,using a shotgun metagenomic DNA sequencing approach and using eggNOG forcomparative and functional metagenomics. Overall, results show higher diversity oftaxonomic and functional groups in rhizospheric soil from Cq+Da than Cq. On the otherhand, functional annotation shows that microorganisms from rhizospheric soil from Cq+Dahave a significantly higher representation of genes associated to metabolic functionsrelated with environmental stress tolerance than Cq soils. Additional research is needed toexplore both the biological impact of these higher activities in terms of gene transfer onplant performance and in turn help to explain the still unsolved enigma about the strategydeployed by Cq to inhabit and cope with harsh conditions prevailing in Antarctic.

Año: 2018

Palabras claves:

Referencia APA: Molina-Montenegro, M., Ballesteros, G., Castro-Nallar, E., Meneses, C., Torres-Díaz, C. and Gallardo-Cerda, J. (2018). Metagenomic exploration of soils microbial communities associated to Antarctic vascular plants.