RESUMENLa tribu de roedores Oryzomyini es la más diversa dentro de la subfamilia Sigmodontinae. Está constituida por 120 especies y 31 géneros, de las cuales 83 son endémicas del continente sudamericano. Este grupo exhibe una extensa distribución que abarca toda la región Neotropical, caracterizada por la presencia de una mayor riqueza en la Amazonia con una disminución monotónica hacia el sur y norte de Sudamérica. Este es un patrón bastante conocido en la mayoría de los taxones, por lo que se han propuesto varios mecanismos causales. Sin embargo, se desconocen los mecanismos que dan cuenta de este gradiente latitudinal en la riqueza de especies de Oryzomyini. Debido a que estas especies son originarias de la Amazonia, y que a través de su historia colonizaron ambientes nuevos y más variables (sur y norte), se evaluó la hipótesis fuente-sumidero, mediada por procesos de colonización y extinción, como potencial explicación al patrón de riqueza observado. Para evaluar esta hipótesis se reunió una base de datos de distribución y riqueza de especies por grado de latitud para todo el continente sudamericano. Posteriormente se evaluó el grado de anidamiento mediante los índices de T (temperatura), BR (discrepancia) y NODF. Nuestros resultados evidenciaron un grado de anidamiento signifi cativo en la distribución de Oryzomyini, y un anidamiento signifi cativo separadamente en fi las y columnas de la matriz. Por lo tanto, se concluye que la dinámica fuente-sumidero afecta el patrón de distribución de la riqueza de roedores Oryzominos, a través de un proceso de colonización durante su expansión en Sudamérica que fue mediado por los rangos de tolerancia de las especies. Finalmente, las especies menos tolerantes se habrían extinguido, lo que determinaría un menor número de especies hacia el sur y norte de la Amazonia.Palabras clave: anidamiento, biodiversidad, gradiente latitudinal, hipótesis fuente-sumidero, macroecología. ABSTRACTThe Oryzomyini rodent tribe is the most diverse taxon within the Sigmodontinae subfamily. This tribe includes 120 species and 31 genera, of which 83 are endemic to the South American continent. This tribe presents a wide distribution, covering the entire Neotropical biogeographic province, and is characterized by the presence of greater richness in the Amazonian area, with a monotonic decrease towards the south and north of South America. This pattern is wellknown in many taxa, for which various causal mechanisms have been proposed. However, the mechanisms that explain this pattern of species richness along the latitudinal gradient in the Oryzomyini tribe are unknown. Given that these species are native to Amazonia, and that throughout their history they colonized new and more variable environments (towards the south and north), we evaluated the source-sink hypothesis, mediated by processes of colonization and extinction, as a potential explanation for the observed pattern of richness. To test this hypothesis we built a database of species' distribution and richness every one degree of latitude...
The renewable energy sector is growing at a rapid pace in northern Chile and the solar energy potential is one of the best worldwide. Therefore, many types of solar power plant facilities are being built to take advantage of this renewable energy resource. Solar energy is considered a clean source of energy, but there are potential environmental effects of solar technology, such as landscape fragmentation, extinction of local biota, microclimate changes, among others. To be able to minimize environmental impacts of solar power plants, it is important to know what kind of environmental conditions solar power plants create. This study provides information about abiotic and biotic conditions in the vicinity of photovoltaic solar power plants. Herein, the influence of these power plants as drivers of new microclimate conditions and arthropods diversity composition in the Atacama Desert was evaluated. Microclimatic conditions between panel mounts was found to be more extreme than in the surrounding desert yet beneath the panels temperature is lower and relative humidity higher than outside the panel area. Arthropod species composition was altered in fixed-mount panel installations. In contrast, solar tracking technology showed less influence on microclimate and species composition between Sun and Shade in the power plant. Shady conditions provided a refuge for arthropod species in both installation types. For example, Dipterans were more abundant in the shade whereas Solifugaes were seldom present in the shade. The presented findings have relevance for the sustainable planning and construction of solar power plants.
Magellanic Sphagnum peatlands are characterized by their ability to maintain biodiversity and water cycle of subantarctic ecosystems, together withits contribution to the global carbon storage through the slow production and accumulation of peat. Through industrial peat extraction, these wetlands have become an economic resource for the past 30 years, generating impacts on the landscape, hydrology and flora of these ecosystems. To evaluate the effects of peat extraction on peatland vegetation, we studied a Sphagnum peatland exploited 20 years ago in the locality of Río Rubens, Province of Última Esperanza, Magallanes, Chile. 42 plots of 1 m 2 were studied in order to determine differences in species composition and plant coverage. In total 24 taxa were identified, 8 of these were alien to the study area, all classified as invasive. Significant differences where found in floristic composition between the exploited and non exploitedares. The mechanical modification of the area, as a result of peat extraction and construction of drainage channels, favors the arrival of exotic flora specimens such as Rumex acetosella, Carex canescens, Holcus lanatus and Hieracium pilosella.
The southern South America presents a complex history of geomorphological and climatic events, which have modulated and fragmented the southwestern part of the Andes mostly. Given the complexity of the southern landscape, the analysis of the hierarchical components alpha-α, beta-β and gamma-γ on carabid diversity allows exploring the responses of species to spatial changes patterns according to the scales of the landscape. In order to understand how spatial scales infl uence the carabid diversity in southern South America, we used an approach at multiple spatial scales of multiplicative diversity partitioning. We included four spatial scales in our analysis: among 0.25° quadrats, 0.5° quadrats, provinces and biogeographic sub-regions. The results showed that the pattern of carabid distribution is not random, and varies according to the spatial scale. At larger scales β-diversities are observed to be higher than expected, but lower than expected at smaller scales. This suggests that carabid ensembles are more homogenous than expected, particularly at the scale of 0.5° quadrats. As explanatory factors, glacial/post-glacial events and historical processes may have had an impact on the present species patterns. Furthermore, due to the importance of beta-β diversity on local and regional scales, a promising approach for future studies is to investigate which biogeographic mechanisms seem to determine the species distribution in different provinces. KEYWORDS:Beta diversity, Multiplicative partitioning, Island Systems, Chile. RESUMENLa compleja historia geomorfológica y climática de Sudamérica austral ha modulado y fragmentado particularmente el sector sur de los Andes. Dada la complejidad del paisaje austral, un análisis de los componentes de diversidad alfa-α, beta-β and gamma-γ de carábidos, permite explorar los cambios de los patrones espaciales considerando las escalas de paisaje. Para analizar el efecto de la escala espacial sobre la diversidad de carábidos en Sudamérica austral, realizamos un particionamiento multiplicativo de diversidad. Para nuestro análisis incluimos cuatro escalas espaciales, cuadrículas de 0,25°, cuadrículas 0,5°, provincias biogeográfi cas y subregiones biogeográfi cas. Nuestros resultados muestran que el patrón de distribución de carábidos no es aleatorio. A gran escala se observa que las diversidades beta son mayores a lo esperado, mientras a baja escala son menores a lo esperado. Lo anterior sugiere que los ensambles de carábidos son más homogéneos, principalmente entre cuadrículas de 0,5°. Discutimos el efecto de procesos históricos en el patrón actual de especies. Debido a la importancia de la diversidad beta-β a escala local y regional, es que se da pie a una interesante línea de investigación para entender que mecanismos biogeográfi cos parecen determinar la distribución de especies en diferentes provincias.
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