Small mammal distributional patterns in Northwestern Argentina / Patrones de endemicidad de pequeños mamíferos en el Noroeste de Argentina

Las evaluaciones cuantitativas de congruencia distribucional de las especies permiten comparar regionalizaciones biogeográficas propuestas previamente e incluso identificar áreas de endemismo que no han sido detectadas. El escenario geográfico del Noroeste Argentino ofrece condiciones ideales para el estudio de patrones de distribución de especies. En este artículo aplicamos un método explícito basado en cuadrículas con el objetivo de reconocer Patrones de Congruencia Distribucional (PDCs) y Áreas de Endemismo (AEs), así como las especies (nativas pero no endémicas y endémicas, respectivamente) que las determinan, para examinar las relaciones de las especies de micromamíferos con las principales unidades ambientales. Adicionalmente, relacionamos estos patrones distribucionales con las divisiones biogeográficas tradicionales de la región estudiada y con un estudio fitogeográfico muy reciente y reconsideramos lo que previamente rechazamos como 'áreas espurias'. Finalmente, evaluamos la generalidad de los patrones encontrados. El análisis resultó en 165 áreas consenso, caracterizadas por siete especies de marsupiales, 28 especies de murciélagos y 63 especies de roedores, lo que representa un gran porcentaje del total de especies (10, 41 y 73, respectivamente). Veinticinco por ciento de las especies que caracterizan las áreas consenso son endémicas a la región estudiada y definen seis AEs en sentido estricto, mientras que 12 PDCs están principalmente definidos por especies ampliamente distribuidas. Mientras que los análisis cuantitativos de la distribución de especies de plantas no resultan en unidades que coincidan con las divisiones fitogeográficas de Cabrera a esta escala espacial, los análisis de la distribución de especies animales muestran patrones que sí se corresponden con tales divisiones. Identificamos patrones de distribución de la fauna significativos y definimos más adecuadamente aquellos ya identificados. Identificamos PDCs y AEs que conforman los Patrones de las Pendientes Andinas del Este, los Patrones Andinos Altos del Oeste y los Patrones de las Pendientes Andinas Este y Oeste Fusionados, algunos de los cuales son re-interpretados a la luz de patrones conocidos de la flora vascular endémica. El endemismo no declina hacia el sur, pero sí hacia el oeste de la región estudiada. Los picos de endemismo se encuentran en las pendientes del este de los Andes en Jujuy y Tucumán/Catamarca, y en los biomas andinos del oeste en Tucumán/Catamarca. El tipo de hábitat principal para las especies endémicas de mamíferos pequeños está en las pendientes húmedas del este de los Andes. A pesar de esto, los biomas áridos y semiáridos y los paisajes húmedos están representados por el mismo número de AEs. Las especies de Rodentia definen 15 de los 18 Patrones Generales (GPs), y sólo en uno de ellas no participaron. Claramente, a esta escala espacial, los mamíferos no voladores, particularmente los roedores, son biogeográficamente más valiosos que los mamíferos voladores.

Quantitative evaluations of species distributional congruence allow evaluating previously proposed biogeographic regionalization and even identify undetected areas of endemism. The geographic scenery of Northwestern Argentina offers ideal conditions for the study of distributional patterns of species since the boundaries of a diverse group of biomes converge in a relatively small region, which also includes a diverse fauna of mammals. In this paper we applied a grid-based explicit method in order to recognize Patterns of Distributional Congruence (PDCs) and Areas of Endemism (AEs), and the species (native but non-endemic and endemic, respectively) that determine them. Also, we relate these distributional patterns to traditional biogeographic divisions of the study region and with a very recent phytogeographic study and we reconsider what previously rejected as 'spurious' areas. Finally, we assessed the generality of the patterns found. The analysis resulted in 165 consensus areas, characterized by seven species of marsupials, 28 species of bats, and 63 species of rodents, which represents a large percentage of the total species (10, 41, and 73, respectively). Twenty-five percent of the species that characterize consensus areas are endemic to the study region and define six AEs in strict sense while 12 PDCs are mainly defined by widely distributed species. While detailed quantitative analyses of plant species distribution data made by other authors does not result in units that correspond to Cabrera's phytogeographic divisions at this spatial scale, analyses of animal species distribution data does. We were able to identify previously unknown meaningful faunal patterns and more accurately define those already identified. We identify PDCs and AEs that conform Eastern Andean Slopes Patterns, Western High Andes Patterns, and Merged Eastern and Western Andean Slopes Patterns, some of which are re-interpreted at the light of known patterns of the endemic vascular flora. Endemism do not declines towards the south, but do declines towards the west of the study region. Peaks of endemism are found in the eastern Andean slopes in Jujuy and Tucumán/Catamarca, and in the western Andean biomes in Tucumán/Catamarca. The principal habitat types for endemic small mammal species are the eastern humid Andean slopes. Notwithstanding, arid/semi-arid biomes and humid landscapes are represented by the same number of AEs. Rodent species define 15 of the 18 General Patterns, and only in one they have no participation at all. Clearly, at this spatial scale, non-flying mammals, particularly rodents, are biogeographically more valuable species than flying mammals (bat species).

Small mammal distributional patterns in Northwestern Argentina / Patrones de endemicidad de pequeños mamíferos en el Noroeste de Argentina

Las evaluaciones cuantitativas de congruencia distribucional de las especies permiten comparar regionalizaciones biogeográficas propuestas previamente e incluso identificar áreas de endemismo que no han sido detectadas. El escenario geográfico del Noroeste Argentino ofrece condiciones ideales para el estudio de patrones de distribución de especies. En este artículo aplicamos un método explícito basado en cuadrículas con el objetivo de reconocer Patrones de Congruencia Distribucional (PDCs) y Áreas de Endemismo (AEs), así como las especies (nativas pero no endémicas y endémicas, respectivamente) que las determinan, para examinar las relaciones de las especies de micromamíferos con las principales unidades ambientales. Adicionalmente, relacionamos estos patrones distribucionales con las divisiones biogeográficas tradicionales de la región estudiada y con un estudio fitogeográfico muy reciente y reconsideramos lo que previamente rechazamos como 'áreas espurias'. Finalmente, evaluamos la generalidad de los patrones encontrados. El análisis resultó en 165 áreas consenso, caracterizadas por siete especies de marsupiales, 28 especies de murciélagos y 63 especies de roedores, lo que representa un gran porcentaje del total de especies (10, 41 y 73, respectivamente). Veinticinco por ciento de las especies que caracterizan las áreas consenso son endémicas a la región estudiada y definen seis AEs en sentido estricto, mientras que 12 PDCs están principalmente definidos por especies ampliamente distribuidas. Mientras que los análisis cuantitativos de la distribución de especies de plantas no resultan en unidades que coincidan con las divisiones fitogeográficas de Cabrera a esta escala espacial, los análisis de la distribución de especies animales muestran patrones que sí se corresponden con tales divisiones. Identificamos patrones de distribución de la fauna significativos y definimos más adecuadamente aquellos ya identificados. Identificamos PDCs y AEs que conforman los Patrones de las Pendientes Andinas del Este, los Patrones Andinos Altos del Oeste y los Patrones de las Pendientes Andinas Este y Oeste Fusionados, algunos de los cuales son re-interpretados a la luz de patrones conocidos de la flora vascular endémica. El endemismo no declina hacia el sur, pero sí hacia el oeste de la región estudiada. Los picos de endemismo se encuentran en las pendientes del este de los Andes en Jujuy y Tucumán/Catamarca, y en los biomas andinos del oeste en Tucumán/Catamarca. El tipo de hábitat principal para las especies endémicas de mamíferos pequeños está en las pendientes húmedas del este de los Andes. A pesar de esto, los biomas áridos y semiáridos y los paisajes húmedos están representados por el mismo número de AEs. Las especies de Rodentia definen 15 de los 18 Patrones Generales (GPs), y sólo en uno de ellas no participaron. Claramente, a esta escala espacial, los mamíferos no voladores, particularmente los roedores, son biogeográficamente más valiosos que los mamíferos voladores.(AU)

Quantitative evaluations of species distributional congruence allow evaluating previously proposed biogeographic regionalization and even identify undetected areas of endemism. The geographic scenery of Northwestern Argentina offers ideal conditions for the study of distributional patterns of species since the boundaries of a diverse group of biomes converge in a relatively small region, which also includes a diverse fauna of mammals. In this paper we applied a grid-based explicit method in order to recognize Patterns of Distributional Congruence (PDCs) and Areas of Endemism (AEs), and the species (native but non-endemic and endemic, respectively) that determine them. Also, we relate these distributional patterns to traditional biogeographic divisions of the study region and with a very recent phytogeographic study and we reconsider what previously rejected as 'spurious' areas. Finally, we assessed the generality of the patterns found. The analysis resulted in 165 consensus areas, characterized by seven species of marsupials, 28 species of bats, and 63 species of rodents, which represents a large percentage of the total species (10, 41, and 73, respectively). Twenty-five percent of the species that characterize consensus areas are endemic to the study region and define six AEs in strict sense while 12 PDCs are mainly defined by widely distributed species. While detailed quantitative analyses of plant species distribution data made by other authors does not result in units that correspond to Cabrera's phytogeographic divisions at this spatial scale, analyses of animal species distribution data does. We were able to identify previously unknown meaningful faunal patterns and more accurately define those already identified. We identify PDCs and AEs that conform Eastern Andean Slopes Patterns, Western High Andes Patterns, and Merged Eastern and Western Andean Slopes Patterns, some of which are re-interpreted at the light of known patterns of the endemic vascular flora. Endemism do not declines towards the south, but do declines towards the west of the study region. Peaks of endemism are found in the eastern Andean slopes in Jujuy and Tucumán/Catamarca, and in the western Andean biomes in Tucumán/Catamarca. The principal habitat types for endemic small mammal species are the eastern humid Andean slopes. Notwithstanding, arid/semi-arid biomes and humid landscapes are represented by the same number of AEs. Rodent species define 15 of the 18 General Patterns, and only in one they have no participation at all. Clearly, at this spatial scale, non-flying mammals, particularly rodents, are biogeographically more valuable species than flying mammals (bat species).(AU)

Afforestation or intense pasturing improve the ecological and economic value of abandoned tropical farmlands.

Increasing demands for livelihood resources in tropical rural areas have led to progressive clearing of biodiverse natural forests. Restoration of abandoned farmlands could counter this process. However, as aims and modes of restoration differ in their ecological and socio-economic value, the assessment of achievable ecosystem functions and benefits requires holistic investigation. Here we combine the results from multidisciplinary research for a unique assessment based on a normalization of 23 ecological, economic and social indicators for four restoration options in the tropical Andes of Ecuador. A comparison of the outcomes among afforestation with native alder or exotic pine, pasture restoration with either low-input or intense management and the abandoned status quo shows that both variants of afforestation and intense pasture use improve the ecological value, but low-input pasture does not. Economic indicators favour either afforestation or intense pasturing. Both Mestizo and indigenous Saraguro settlers are more inclined to opt for afforestation.

Bats and marsupials as indicators of endemism in the Yungas forest of Argentina.

Several studies have characterized the Yungas as a separate biogeographic unit, mainly based in floristic components. However, these characterizations were mainly qualitative and did not include faunal groups. The Yungas have been assumed as a region with rich floral and faunal diversity, but without testing how well they are described by animal distributions. Our study consists of a formal analysis of endemism based on distribution of small mammals in the southernmost portion of the Yungas. This area is biogeographically very interesting because the Yungas are comprised of discontinuous fragments of forests that extend into temperate arid and semiarid habitats. As a first approximation, we contrasted a group of volant species (bats) versus a group of non-volant species (marsupials). Our results show that small mammals are efficient indicators of endemism in Yungas. Eighty percent of the species of small marsupials included in the analysis supported the identified areas as being zones of endemism. Regarding bats, almost 55 percent of the species supported a designation of endemism. The results also show that the areas we considered are congruent with the botanical definition of the Yungas of northwestern Argentina and their subdivisions, an assumption that had not been previously tested with a formal quantitative method. We also found that non-volant species are better indicators of endemism than volant ones at regional scales, but volant species are better indicators than was previously thought.

Effect of anaerobic and stationary phase growth conditions on the heat shock and oxidative stress responses in Escherichia coli K-12.

The natural living style of Escherichia coli occurs in the gastrointestinal tract, where most of its existence is spent under anaerobic conditions and in stationary phase of growth. Here we report on the heat shock response of E. coli K-12 cells growing in the presence or absence of oxygen. An rpoH mutant (impaired in the synthesis of the sigma(32) transcriptional factor) exhibited an increased sensitivity to heat shock but only in the exponential phase of aerobic growth, suggesting that in anaerobic growth conditions, and in aerobic stationary phase, sigma(32)-independent mechanisms are playing a prime role in protecting cells from heat stress. Our results demonstrated that sigma(S) is not involved in this protection system. Studies on the kinetics of synthesis of Heat shock proteins (Hsp) after an abrupt rise in temperature demonstrated that in the absence of oxygen, the synthesis of Hsp is triggered faster and is sustained for a longer period of time compared to aerobic growth conditions. Finally, the heated cells in the exponential phase of aerobic growth displayed a high concentration of oxidatively damaged proteins in the presence of 4 mM H(2)O(2), in sharp contrast to cultures of stationary phase or anaerobic growth.