CEAZA
Heritability and genetic correlations of escape behaviours in juvenile scallop Argopecten purpuratus.
Brokordt, K., Farías, W., Lhorente, J., & Winkler, F.
Escape behaviours are generally considered adaptive because of their obvious effects on fitness. However, little is known about the genetic basis of escape responses. The estimation of the magnitude of hereditary factors affecting variation in escape responses indicates their potential to evolve by natural selection. Scallops are exceptional among bivalve molluscs because they possess an excellent swimming capacity, which helps them to escape predators. In this study we estimated the narrow-sense heritability (h2), phenotypic variance components and phenotypic and genetic correlations of several escape response traits (i.e. reaction time, number of claps (rapid valve closures and openings), and the duration and intensity of the clapping response) in juvenile Argopecten purpuratus scallops. We stimulated scallop escape responses using their natural predator, the sea star Meyenaster gelatinosus. Genetic estimates for escape response traits were determined by the animal model. Most studied traits showed substantial amounts of additive genetic variance controlling their phenotypic variation (CVA = 18.43–100.2), were repeatable (at least over a short period, R = 0.36–0.42), and had significant heritabilities (h2 = 0.36–0.57). Indeed, it can be inferred that most of the analysed escape response traits of A. purpuratus could evolve through natural selection. Moreover, significant genetic correlations between some escape response traits were observed, suggesting that selection acting on one escape trait will affect that of another, facilitating their coevolution.
Año: 2012
Palabras claves: Argopecten purpuratus; escape behaviour; genetic correlation; heritability; scallop
Referencia APA: Brokordt, K., Farías, W., Lhorente, J., & Winkler, F. (2012). Heritability and genetic correlations of escape behaviours in juvenile scallop Argopecten purpuratus. Animal Behaviour, 84(2), 479-484.
Effects of the toxic dinoflagellate Alexandrium catenella on histopathogical and escape responses of the Northern scallop Argopecten purpuratus.
Hégaret, H., Brokordt, K., Gaymer, C., Lohrmann, K., García, C., & Varela, D.
Juvenile Northern scallops Argopecten purpuratus were exposed to cultures of the paralytic shellfish toxin (PST) producing dinoflagellate, Alexandrium catenella, or a non-toxic microalga as a control, T-iso. After 3 and 6 days of exposure to either A. catenella or T-iso, scallops were stimulated to elicit an escape response by exposing them to the predatory sea star Meyenaster gelatinosus. We monitored the escape response of the scallops in terms of reaction time after first contact with the sea star, number of claps (burst of rapid valve closures) until exhaustion, clapping time, clapping rate, the time scallops spent closed when exhausted, and recovery from the initial number of claps, clapping time and clapping rate. Additionally, histopathological and stress responses (through heat-shock protein [hsp70] induction), as well as accumulation of Paralytic Shellfish Poisoning (PSP) toxins, were monitored on scallops after 3 and 6 days of exposure to A. catenella. After 6 days of exposure, scallops exposed to A. catenella accumulated PSTs and reacted more rapidly with a higher clapping rate, however the duration of their escape response was shorter than controls, when exposed to M. gelatinosus. Additionally, scallops exposed to A. catenella showed histopathological features, especially after 6 days of exposure, including increased melanization of the tissues and myopathy, with high levels of degeneration of the muscle fibers. A six-day exposure to A. catenella also caused an increase in prevalence of rickettsiales-like organisms within scallop tissues. This study suggests that PST accumulation can affect the interaction between the Northern scallop and both pathogens and predators, potentially increasing their susceptibility to either of them.
Año: 2012
Palabras claves: Scallop; Alexandrium; HAB; Escape response; Histopathology; PSP
Referencia APA: Hégaret, H., Brokordt, K., Gaymer, C., Lohrmann, K., García, C., & Varela, D. (2012). Effects of the toxic dinoflagellate Alexandrium catenella on histopathogical and escape responses of the Northern scallop Argopecten purpuratus. Harmful Algae, 18, 74-83.
Assessing the Influence of the MJO on Strong Precipitation Events in Subtropical, Semi-Arid North-Central Chile (30°S).
Juliá, C., Rahn, D., & Rutllant, J.
Annual precipitation in subtropical, semiarid north-central Chile (30°S) during rainy years comprises a few (3–5) strong events in the fall and winter, which are presumably modulated by the Madden–Julian oscillation (MJO). Precipitation from 1979–2009 was recorded daily at three stations along the Elqui Valley. The relationship between the MJO and precipitation is investigated from two perspectives: 1) examining a MJO index (MJOI) based on the actual precipitation events and 2) examining the likelihood of precipitation based on a favorable MJOI. About 80% of the strong precipitation events at the coast in La Serena are related to an active MJO near the central equatorial Pacific. These events are often typified by broad, slow moving synoptic systems in phase with the MJO propagation. Blocking in the far southeast Pacific is associated with precipitation 75% of the time, while deep troughs make up the rest.
A relationship between a MJOI and strong rainfall suggests that, though it could be used as a potential diagnostic, the number of cases where there is a favorable MJOI but no precipitation (i.e., false alarms) limits its utility. Additional criteria such as the Southern Oscillation (SO) and Antarctic Oscillation (AAO) phases were used to reject false alarms. Rejecting cases with positive values of the SO index reduced the number of false alarms from 70% to 58%, leaving about two false alarms for every correctly diagnosed event. The AAO index could not discriminate between false alarms and real cases. While a favorable MJOI increases the likelihood of precipitation in the Elqui Valley, false alarms remain problematic.
Año: 2012
Palabras claves: South America; Madden-Julian oscillation; Precipitation; Surface observations; Seasonal forecasting; Intraseasonal variability.
Referencia APA: Juliá, C., Rahn, D., & Rutllant, J. (2012). Assessing the Influence of the MJO on Strong Precipitation Events in Subtropical, Semi-Arid North-Central Chile (30°S). Journal Of Climate, 25(20), 7003-7013.
The conquest of the South Pole: Importance and lessons for the present.
Molina-Montenegro, M. & Corcuera, L.
On December 14, 1911, the Swedish Roald Amundsen, heading a group of explorers reached the South Pole. This date has become a symbol of all those great explorers that risking their lives in the most inhospitable continent in our planet, reached places that looked impossible to conquer. This date is also a symbol of the great difficulties that must be overcome to work in the Antarctic and of much that is yet to be known in the white continent. These are the reasons why Revista Chilena de Historia Natural is commemorating this important historic event with a Special Feature dedicated to Antarctic research.
The era of epic exploration in the Antarctic, such as those led by Roald Amundsen, Robert Scott, Ernest Shakleton, and many others has come to an end. This era had great unforgettable victories and defeats. The exciting race to conquer the South Pole among Amundsen and Scott left valuable lessons on the enormous difficulties to perform Antarctic exploration and the importance of planning and logistic design for any activity in the Antarctic. Perhaps, one of the best known expeditions for the magnitude of the encountered, adverse climatic conditions and importance of international cooperation is the Endurance Expedition, led by Ernest Shackleton in the period between 1914 and 1916. The loss of the Endurance, the courage of the explorers to reach Elephant Island, and the incredible determination of the leader of the expedition to achieve impress us even today. It was this determination that inspired the Chilean pilot Luis Pardo to risk the precarious ship Yelcho, performing one of the most celebrated rescue expeditions in Antarctic history. This era of great explorers, in addition to opening new routes, had the merit of drawing international attention on the great white continent and raised interest of many countries on the possible colonization, use of resources, and scientific research of Antarctic organisms, geological resources, climate, atmosphere, climatic change, and other aspects.
The difficulties and dangers of Antarctic research are still enormous in spite of the technology which is available today. Logistic costs to perform modern and safe Antarctic expeditions are very high. For this reason, the available budget is the main limitation for Antarctic research. However, in spite of the encountered difficulties, researchers have unveiled step by step the importance of Antarctic in the world's climate, ocean levels, availability of natural resources, and aspects of conservation and utilization of its flora and fauna.
Año: 2012
Palabras claves:
Referencia APA: Molina-Montenegro, M. & Corcuera, L. (2012). The conquest of the South Pole: Importance and lessons for the present. Rev. Chil. Hist. Nat., 85(4), 365-367.
Combining information from benthic community analysis and social studies to establish no-take zones within a multiple uses marine protected area
Rojas-Nazar, Ú., Gaymer, C., Squeo, F., Garay-Flühmann, R., & López, D.
A decision support tool was used to determine priority sites for marine conservation within the Isla Grande de Atacama multiple uses marine protected area (MUMPA) in northern Chile, based on both biological and social information. Scuba diving, and an unweighted paired-group method using arithmetic average (UPGMA) analyses were used to determine the main benthic communities found in the shallow rocky and soft-sediment subtidal.
Año: 2012
Palabras claves: Chile;coastal marine conservation;conservation costs;multiple uses marine protected area;benthic ecology;social ecology
Referencia APA: Rojas-Nazar, Ú., Gaymer, C., Squeo, F., Garay-Flühmann, R., & López, D. (2012). Combining information from benthic community analysis and social studies to establish no-take zones within a multiple uses marine protected area. Aquatic Conserv: Mar. Freshw. Ecosyst. 22(1), 74-86.
Isolation of microsatellite markers for two Chilean freshwater anomuran species (Aegla araucaniensis and Aegla pewenchae) using PCR-based methods.
Gouin, N., Bórquez, J., Samollow, P., Douglas, K., Jasti, M., & Bertin, A.
We developed ten polymorphic microsatellite markers for two species of freshwater anomura endemic to Chile, Aegla araucaniensis and Aegla pewenchae, using two PCR-based methods, PIMA and ISSR-PCR. Nine markers per species gave useful PCR products, revealing moderate to high levels of genetic variation. The number of alleles per locus ranged from 2 to 13 and the observed heterozygosity from 0.103 to 0.929. All the markers appeared to segregate independently. No departure from Hardy–Weinberg equilibrium was found in A. araucaniensis while three markers showed evidence for deficits of heterozygotes and presence of null alleles in A. pewenchae. These markers will be useful for population genetics analyses.
Año: 2012
Palabras claves: Aeglidae, Crustacean, Microsatellite, PIMA, ISSR-PCR, Population genetics.
Referencia APA: Gouin, N., Bórquez, J., Samollow, P., Douglas, K., Jasti, M., & Bertin, A. (2012). Isolation of microsatellite markers for two Chilean freshwater anomuran species (Aegla araucaniensis and Aegla pewenchae) using PCR-based methods. Conservation Genet Resour, 4(1), 93-96.
Male morphotypes in the Andean river shrimp Cryphiops caementarius (Decapoda: Caridea): morphology, coloration and injuries.
Rojas, R., Morales, M., Rivadeneira, M., & Thiel, M.
In many species, different male morphotypes usually employ different tactics to access resources. Males with highly developed weapons are expected to fight and possibly incur higher levels of injury than males with less developed weapons, which usually avoid agonistic encounters. Discrete male morphotypes, where some males are very large and feature powerful chelae, have been reported for several large shrimp species, where males show a lobster-like monopolization of resources. During competitive interactions, these large males fight more vigorously than small males and, consequently, it is expected that they accumulate more injuries. Herein, we identified different morphotypes in the river shrimp Cryphiops caementarius, and we compared the percentage of body damage between large and small shrimps. We measured 26 morphometric data and 6 intensities of color on the chelipeds. Multivariate analysis based on a combination of morphometric and color data confirmed that there are two morphotypes. The ‘dominant’ morph is characterized by stout teeth on the cutting edges and by dark blue color on the external surface of the major cheliped. The two morphotypes can be distinguished based on the differences in the allometric relationships between several morphologic traits and carapace length. Males from the large morphotype had a higher percentage of injuries on their chelipeds than other males. These results suggest that males from the large morphotype are dominant and compete aggressively for access to resources, a hypothesis to be tested in future, behavioral studies.
Año: 2012
Palabras claves: alternative reproductive tactics; male morphotypes; injury; weapon; large chela; shrimp
Referencia APA: Rojas, R., Morales, M., Rivadeneira, M., & Thiel, M. (2012). Male morphotypes in the Andean river shrimp Cryphiops caementarius (Decapoda: Caridea): morphology, coloration and injuries. J Zool, 288(1), 21-32.
Comparación del crecimiento de Argopecten purpuratus entre cohortes obtenidas de captacion de larvas en ambiente natural y de hatchery.
Perez, E., Azocar, C., Araya, A., Astudillo, O., & Ramos, M.
En Chile los cultivos del ostión del norte Argopecten purpuratus han sido desarrollados intensivamente a partir de la captación de semillas en ambiente natural y desde principios de 1980 con semillas obtenidas en hatchery. Para aportar información sobre el desempeño de semillas de ostión del norte en este estudio se comparó, mediante ANCOVA, el crecimiento en longitud entre cohortes producidas a partir de semillas de ambiente natural y de hatchery en Tongoy, Chile. Se evaluó la consistencia de esta comparación en distintos años y estaciones, comparándose parejas de cohortes producidas simultáneamente en los años 2003 (primavera), 2005 (invierno) y 2006 (verano). El análisis estadístico mostró que existen diferencias estadísticas significativas entre cohortes obtenidas en ambiente natural y aquellas obtenidas en hatchery. La prueba de Tukey evidenció diferencias significativas entre CN2003 y CH2003 como también entre CN2005 y CH2005, pero no así entre CN2006 y CH2006. Estas diferencias indican que las cohortes de semillas de ambiente natural crecieron más rápido que las de hatchery. La comparación interanual evidenció diferencias estadísticas significativas. Estos resultados son discutidos a la luz de dos factores: la temperatura de cultivo y la heterocigocidad de la población de cultivo.
Año: 2012
Palabras claves: ostión, semillas, ambiente natural, hatchery, crecimiento, norte de Chile.
Referencia APA: Perez, E., Azocar, C., Araya, A., Astudillo, O., & Ramos, M. (2012). Comparación del crecimiento de Argopecten purpuratus entre cohortes obtenidas de captacion de larvas en ambiente natural y de hatchery. Latin American Journal Of Aquatic Research, 40(4), 1026-1038.
Respuestas antioxidantes en dos ecotipos de Colobanthus quitensis (Caryophyllaceae) expuestos a alta radiación UV-B y baja temperatura.
Navarrete-Gallegos, A., Bravo, L., Molina-Montenegro, M., & Corcuera, L.
Colobanthus quitensis (Kunth) Bartl. (Caryophyllaceae) está distribuida desde México hasta la Antártida Marítima formando poblaciones adaptadas a distintas condiciones microambientales a lo largo de su distribución. La Antártica Marítima se caracteriza por una estación de crecimiento más fría y breve, con crecientes niveles de radiación UV-B. Los Andes de Chile Central, en cambio, tienen oscilaciones térmicas más amplias y una elevada tasa de radiación UV-B. El objetivo de este estudio es conocer las estrategias y mecanismos antioxidantes adoptadas por los ecotipos Antártico y Andino para tolerar los efectos dañinos de la radiación UV-B y el frío bajo condiciones controladas de laboratorio. Postulamos que los individuos de C. quitensis provenientes de la cordillera de Los Andes de Chile Central, donde los niveles de radiación UV-B son mayores que en la Antártica, tendrían un conjunto de mecanismos antioxidantes más eficaces para contrarrestar los efectos del UV-B y sufrirían menos daño que el ecotipo Antártico. Plantas cultivadas en laboratorio del ecotipo Antártico y Andino fueron sometidas a tres intensidades de radiación UV-B (70, 35 y 3 µW cm-2), a 4 y 15 °C, respectivamente. En cada tratamiento se evaluaron las respuestas de la actividad antioxidante total (TAS), actividad de la enzima superóxido dismutasa (SOD) y características anatómicas foliares con un posible rol protector frente a UV-B. Finalmente, se evaluaron los efectos dañinos del UV-B, como son: acumulación de malonaldialdehido (MDA), eficiencia fotoquímica máxima del PSII y fotoinactivación. Ambos ecotipos mostraron reducción de área foliar y engrosamiento del parénquima. El ecotipo andino presentó mayores niveles de TAS con radiación UV-B media y alta. La actividad SOD máxima se midió en el ecotipo andino, encontrándose un aumento de hasta ocho veces el nivel basal a las cuatro horas de irradiación. El ecotipo antártico expuesto a UV-B y frío presentó un mayor daño a membranas (MDA), al igual que un mayor grado de fotoinactivación. Adicionalmente, se detectó la acumulación de una nueva isoforma Cu-Zn/SOD, insensible a H2O2, en plantas tratadas con UV-B. En conclusión, el ecotipo andino presenta una respuesta antioxidante más efectiva contra el UV-B que el ecotipo antártico.
Año: 2012
Palabras claves: Antártica, antioxidantes, daño oxidativo, UV-B.
Referencia APA: Navarrete-Gallegos, A., Bravo, L., Molina-Montenegro, M., & Corcuera, L. (2012). Respuestas antioxidantes en dos ecotipos de Colobanthus quitensis (Caryophyllaceae) expuestos a alta radiación UV-B y baja temperatura. Rev. Chil. Hist. Nat., 85(4), 419-433.
Rodent middens reveal episodic, long-distance plant colonizations across the hyperarid Atacama Desert over the last 34,000 years.
Díaz, F., Latorre, C., Maldonado, A., Quade, J., & Betancourt, J.
Five middens span the last glacial period (34–21 ka) and three middens are from the last glacial–interglacial transition (19–11 ka). The remaining 13 middens span the last 7000 years. Coastal hyperarid sites exhibit low taxonomic richness in middens at 19.3, 1.1, 1.0, 0.9, 0.5 ka and a modern sample. Middens are also dominated by the same plants that occur today. In contrast, middens dated to 28.1, 21.3, 17.3, 3.7 and 0.5 ka contain more species, including Andean extralocals. Precordillera middens (c. 2700 m) show a prominent increase in plant macrofossil richness, along with the appearance of Andean extralocals and sedges at 34.5 and 18.9 ka. Six younger middens dated to 6.1–0.1 ka are similar to the modern local vegetation.
Año: 2012
Palabras claves: Abrocoma;aridland palaeoecology;Atacama Desert;fog oases;hyperarid environments;late Quaternary;Lomas vegetation;Phyllotis;rodent middens
Referencia APA: Díaz, F., Latorre, C., Maldonado, A., Quade, J., & Betancourt, J. (2012). Rodent middens reveal episodic, long-distance plant colonizations across the hyperarid Atacama Desert over the last 34,000 years. Journal Of Biogeography, 39(3), 510-525.
The role of spatial processes and environmental determinants in microgeographic shell variation of the freshwater snail Chilina dombeyana (Bruguière, 1789).
Bertin, A., Ruíz, V., Figueroa, R., & Gouin, N.
Wildlife data often show spatial organization, demonstrating positive correlations either as a result of processes occurring over the landscape or due to the influence of spatially structured environmental variables. It is, thus, essential to consider non-random spatial structure when evaluating the underlying causes of biological variation. In this study, we analyzed the population structure of Chilina dombeyana shell morphology of 14 populations that are close geographically and belong to the same hydrographic basin. We utilized a variation partitioning approach to evaluate the importance of spatial processes, such as migration, acting over the landscape, and environmental characteristics, including habitat and hydrologic characteristics, and the occurrence of aquatic predators in promoting between population variation. Our results demonstrate spatially structured variation in C. dombeyana shell morphology, with populations living near each other having more similar shell sizes than populations living farther apart. The shell size variation partition indicated that both spatially structured environmental factors and genetic relationships resulting from migration or shared common ancestry may explain this pattern. Shell shape variation, in contrast, was found to be essentially under the influence of non-spatially structured environmental factors, with habitat and water characteristics accounting for about half of the total variation among populations. The large proportion of the variation in shell size that is spatially structured demonstrates that spatial structure on morphological traits might be strong and highlights the need to consider such phenomenon in intraspecific studies of phenotypic evolution.
Año: 2012
Palabras claves: Shape, Size, Environmental factors, Spatial structure, Gastropod, Variation partition, Lotic environment
Referencia APA: Bertin, A., Ruíz, V., Figueroa, R., & Gouin, N. (2012). The role of spatial processes and environmental determinants in microgeographic shell variation of the freshwater snail Chilina dombeyana (Bruguière, 1789). Naturwissenschaften, 99(3), 225-232
Latin American plant sciences: from early naturalists to modern science.
Stoll, A. & Squeo, F.
Editorial
Año: 2012
Palabras claves:
Referencia APA: Stoll, A. & Squeo, F. (2012). Latin American plant sciences: from early naturalists to modern science. Plant Ecology & Diversity, 5(2), 147-151.