Subtidal macrozoobenthos communities from northern Chile during and post El Niño 1997–1998

Despite a large amount of climatic and oceanographic information dealing with the recurring climate phenomenon El Niño (EN) and its well known impact on diversity of marine benthic communities, most published data are rather descriptive and consequently our understanding of the underlying mechanisms and processes that drive community structure during EN are still very scarce. In this study, we address two questions on the effects of EN on macrozoobenthic communities: (1) how does EN affect species diversity of the communities in northern Chile? and (2) is EN a phenomenon that restarts community assembling processes by affecting species interactions in northern Chile? To answer these questions, we compared species diversity and co-occurrence patterns of soft-bottoms macrozoobenthos communities from the continental shelf off northern Chile during (March 1998) and after (September 1998) the strong EN event 1997–1998. The methods used varied from species diversity and species co-occurrence analyses to multivariate ordination methods. Our results indicate that EN positively affects diversity of macrozoobenthos communities in the study area, increasing the species richness and diversity and decreasing the species dominance. EN represents a strong disturbance that affects species interactions that rule the species assembling processes in shallow-water, sea-bottom environments

Context Matters: Promises and Concerns Regarding Nanotechnologies for Water and Food Applications

Expectations in the form of promises and concerns contribute to the sense-making and valuation of emerging nanotechnologies. They add up to what we call ‘de facto assessments’ of novel socio-technical options. We explore how de facto assessments of nanotechnologies differ in the application domains of water and food by examining promises and concerns, and their relations in scientific discourse. We suggest that domain characteristics such as prior experiences with emerging technologies, specific discursive repertoires and user-producer relationships, play a key role in framing expectations of nanotechnology-enabled options. The article concludes by suggesting that domain-specific discourses may lead to undesirable lock-ins into specific de facto assessments pre-structuring anticipatory strategies of actor

Isolation on a remote island: genetic and morphological differentiation of a cosmopolitan odonate

Although low levels of genetic structure are expected in highly widespread species, geographical and/or ecological factors can limit species distributions and promote population structure and morphological differentiation. In order to determine the effects of geographical isolation on population genetic structure and wing morphology, 281 individuals of the cosmopolitan odonate Pantala flavescens were collected from four continental (Central and South America) and five insular sites (Polynesian islands and the Maldives). COI sequences and eight microsatellite loci were used to characterize genetic diversity and genetic structure between and within locations. Linear and geometric morphometry were used to evaluate differences in the size and shape of wings. Genetic analysis showed a global genetic difference between the continental and insular sites. American locations did not show genetic structure, even in locations separated by a distance of 5000 km. Easter Island showed the lowest values of genetic diversity (mainly mitochondrial diversity) and the highest values of genetic differences compared to other insular and continental sites. Individuals from Easter Island showed smaller forewings, a different abdomen length to thorax length ratio, and a different configuration of anal loop in the hindwings. Thus, the greater isolation, smaller area, and young geological age seem to have determined the genetic and morphological differences in P. flavescens of Easter Island, where selection could promote a loss of migratory behavior and may improve other life history traits, such as reproduction. This work provides new insight into how microevolutionary processes operate in isolated populations of cosmopolitan speciesAunque se esperan niveles bajos de estructura genética en especies muy extendidas, los factores geográficos y / o ecológicos pueden limitar la distribución de especies y promover la estructura de la población y la diferenciación morfológica. Para determinar los efectos del aislamiento geográfico sobre la estructura genética de la población y la morfología de las alas, se recolectaron 281 individuos del odonato cosmopolita Pantala flavescens de cuatro sitios continentales (América Central y del Sur) y cinco sitios insulares (islas Polinesias y Maldivas). Se utilizaron secuencias COI y ocho loci de microsatélites para caracterizar la diversidad genética y la estructura genética entre ubicaciones y dentro de ellas. Se utilizó morfometría lineal y geométrica para evaluar las diferencias en el tamaño y la forma de las alas. El análisis genético mostró una diferencia genética global entre los sitios continentales e insulares. Las ubicaciones americanas no mostraron estructura genética, incluso en ubicaciones separadas por una distancia de 5000 km. Isla de Pascua mostró los valores más bajos de diversidad genética (principalmente diversidad mitocondrial) y los valores más altos de diferencias genéticas en comparación con otros sitios insulares y continentales. Los individuos de la Isla de Pascua mostraron alas anteriores más pequeñas, una relación entre la longitud del abdomen y la longitud del tórax diferente y una configuración diferente del asa anal en las alas posteriores. Así, el mayor aislamiento, menor área y edad geológica joven parecen haber determinado las diferencias genéticas y morfológicas en P. flavescens de Isla de Pascua, donde la selección podría promover una pérdida del comportamiento migratorio y mejorar otros rasgos del ciclo de vida, como la reproducción. . Este trabajo proporciona una nueva perspectiva sobre cómo operan los procesos microevolutivos en poblaciones aisladas de especies cosmopolitas.Universidad de Chile, ChileUniversidad Católica del Norte, ChileUniversidad de Tarapacá, ChileUniversidad Nacional, Costa RicaEscuela de Ciencias Biológica