Home About us Contact
|
Home About us Contact | ||
|
|
||
Original Habitat (original + habitat)
Selected AbstractsRefining Biodiversity Conservation PrioritiesCONSERVATION BIOLOGY, Issue 6 2005GRANT M. HARRIS Bosque del Atlántico; percepción remota; priorización; SIG; sitios prioritarios para la conservación Abstract:,Although there is widespread agreement about conservation priorities at large scales (i.e., biodiversity hotspots), their boundaries remain too coarse for setting practical conservation goals. Refining hotspot conservation means identifying specific locations (individual habitat patches) of realistic size and scale for managers to protect and politicians to support. Because hotspots have lost most of their original habitat, species endemic to them rely on what remains. The issue now becomes identifying where this habitat is and these species are. We accomplished this by using straightforward remote sensing and GIS techniques, identifying specific locations in Brazil's Atlantic Forest hotspot important for bird conservation. Our method requires a regional map of current forest cover, so we explored six popular products for mapping and quantifying forest: MODIS continuous fields and a MODIS land cover (preclassified products), AVHRR, SPOT VGT, MODIS (satellite images), and a GeoCover Landsat thematic mapper mosaic (jpg). We compared subsets of these forest covers against a forest map based on a Landsat enhanced thematic mapper. The SPOT VGT forest cover predicted forest area and location well, so we combined it with elevation data to refine coarse distribution maps for forest endemic birds. Stacking these species distribution maps enabled identification of the subregion richest in threatened birds,the lowland forests of Rio de Janeiro State. We highlighted eight priority fragments, focusing on one with finer resolved imagery for detailed study. This method allows prioritization of areas for conservation from a region >1 million km2 to forest fragments of tens of square kilometers. To set priorities for biodiversity conservation, coarse biological information is sufficient. Hence, our method is attractive for tropical and biologically rich locations, where species location information is sparse. Resumen:,Aunque hay acuerdo generalizado sobre las prioridades de conservación a escalas mayores (i. e., sitios prioritarios para la conservación de la biodiversidad), los límites son muy gruesos como para definir metas de conservación prácticas. La refinación de la conservación de sitios prioritarios significa la identificación de localidades específicas (parches de hábitat individuales) de tamaño y escala realistas para ser protegidos por gestores y apoyados por políticos. Debido a que los sitios prioritarios han perdido la mayor parte de su hábitat original, las especies endémicas dependen del que permanece. Ahora el asunto es identificar donde están el hábitat y las especies. Logramos lo anterior mediante técnicas directas de percepción remota y de SIG para identificar localidades específicas importantes para la conservación de aves en el sitio prioritario Bosque del Atlántico en Brasil. Nuestro método requiere de un mapa regional de la cobertura forestal actual, así que exploramos seis productos populares para el mapeo y cuantificación de bosques: campos continuos MODIS y una cobertura de suelo MODIS (productos preclasificados), AVHRR, SPOT VGT, MODIS (imágenes de satélite) y un mosaico GeoCover Landsat thematic mapper (jpg). Comparamos subconjuntos de estas coberturas forestales con las de un mapa basado en un Landsat enhanced thematic mapper. La cobertura forestal SPOT VGT predijo bien la superficie y localización del bosque, así que lo combinamos con datos de altitud para refinar los mapas generales de distribución de aves endémicas de bosques. La sobreposición de estos mapas de distribución permitió la identificación de la subregión más rica en aves amenazadas,los bosques en bajíos del Estado de Río de Janeiro. Dimos relevancia a ocho fragmentos prioritarios, con atención en uno con imágenes de resolución fina para estudio en detalle. Este método permite la priorización de áreas para conservación de fragmentos de decenas de kilómetros cuadrados en una región >1 millón km2. La información biológica general es suficiente para definir prioridades de conservación de la biodiversidad. Por lo tanto, nuestro método es atractivo para localidades tropicales y biológicamente ricas, para las que la información sobre la ocalización de las especies es escasa. [source] Molecular mechanisms of pathogenicity: how do pathogenic microorganisms develop cross-kingdom host jumps?FEMS MICROBIOLOGY REVIEWS, Issue 3 2007Peter Van Baarlen Abstract It is common knowledge that pathogenic viruses can change hosts, with avian influenza, the HIV, and the causal agent of variant Creutzfeldt,Jacob encephalitis as well-known examples. Less well known, however, is that host jumps also occur with more complex pathogenic microorganisms such as bacteria and fungi. In extreme cases, these host jumps even cross kingdom of life barriers. A number of requirements need to be met to enable a microorganism to cross such kingdom barriers. Potential cross-kingdom pathogenic microorganisms must be able to come into close and frequent contact with potential hosts, and must be able to overcome or evade host defences. Reproduction on, in, or near the new host will ensure the transmission or release of successful genotypes. An unexpectedly high number of cross-kingdom host shifts of bacterial and fungal pathogens are described in the literature. Interestingly, the molecular mechanisms underlying these shifts show commonalities. The evolution of pathogenicity towards novel hosts may be based on traits that were originally developed to ensure survival in the microorganism's original habitat, including former hosts. [source] Reaction of Armillaria ostoyae to forest soil microfungiFOREST PATHOLOGY, Issue 3 2004H. Kwa Summary Fungi isolated from the oak (Quercus robur) rhizosphere were tested for their effects on rhizomorph formation and growth of 16 isolates of Armillaria ostoyae sampled in three localities in western Poland. The number of rhizomorphs, number of rhizomorph apices, and rhizomorph length and weight increased most in the presence of Penicillium lanosum, Penicillium notatum, Cylindrocarpon destructans, Penicillium spinulosum and Mycelium radicis atrovirens , and, to a lesser extent, in the presence of Nectria grammicospora. Inhibition of rhizomorph formation was caused by Trichoderma hamatum and Trichoderma viride in two A. ostoyae isolates and by M. radicis atrovirens , and P. spinulosum in one A. ostoyae isolate. It is suggested that variation in sensitivity to microbial stimulation within A. ostoyae is associated with the environmental and nutritional conditions of its original habitat. Isolates from nutrition-rich localities, with 20% of the land area covered by deciduous trees, were particularly susceptible to stimulation by rhizosphere fungi. Résumé Les champignons isolés de la rhizosphère de chêne (Quercus robur) ont été testés pour leurs effets sur la formation et la croissance des rhizomorphes de 16 isolats d'Armillaria ostoyae provenant de 3 localités de Pologne occidentale. L'augmentation du nombre de rhizomorphes et d'apex de rhizomorphes, de la longueur et du poids des rhizomorphes a été la plus importante en présence de Penicillium lanosum, Penicillium notatum, Cylindrocarpon destructans, Penicillium spinulosum et Mycelium radicis atrovirens, et, à un moindre degré, en présence de Nectria grammicospora. Trichoderma hamatum et Trichoderma viride ont inhibé la formation de rhizomorphes chez deux isolats d'A. ostoyae et M. radicis atrovirens, et P. spinulosum chez un isolat. Nos résultats suggèrent que la variation de sensibilitéà la stimulation microbienne entre isolats d'A. ostoyae est associée aux conditions environnementales et nutritionnelles de leurs habitats d'origine. Les isolats provenant de localités riches sur le plan nutritif, avec 20% de la surface couverte par des essences feuillues, sont particulièrement sensibles à la stimulation par des champignons de la rhizosphère. Zusammenfassung Verschiedene Rhizosphärenpilze von Quercus robur wurden auf ihre Wirkung auf die Bildung und das Wachstum der Rhizomorphen von 16 A. ostoyae -Isolaten getestet, die aus drei Gebieten in Westpolen stammten. Penicillium lanosum, P. notatum, Cylindrocarpon destructans, Penicillium spinulosum und Mycelium radicis atrovirens , erhöhten sowohl die Anzahl der Rhizomorphen und der Rhizomorphenspitzen als auch die Länge und das Gewicht der Rhizomorphen am deutlichsten. Nectria grammicospora war weniger wirksam. Trichoderma hamatum und T. viride hemmten die Rhizomorphenbildung bei zwei Isolaten von A. ostoyae, M. radicis atrovirens , und P. spinulosum hatten diesen Effekt bei einem Isolat. Aus den Daten ergibt sich, dass die unterschiedliche Empfindlichkeit der verschiedenen Isolate von A. ostoyae auf die mikrobielle Stimulation mit den Umweltbedingungen am Herkunftsort zusammenhängen könnte. Isolate von nährstoffreichen Standorten, wo 20% der Fläche mit Laubgehölzen bestockt waren, reagierten besonders deutlich auf die Präsenz von Rhizosphärenpilzen. [source] Nassella pulchra Survival and Water Relations Depend More on Site Productivity Than on Small-Scale DisturbanceRESTORATION ECOLOGY, Issue 2 2007Keith Lombardo Abstract We found no significant effect (p > 0.38) of clipping surrounding non-native annuals on the performance or survival of plantings of the native Nassella pulchra. However, the preplanting productivity of the three sites had a significant effect (p < 0.001) on the demography and water relations of Nassella. Survival was 85% on the lowest productivity site and it decreased by 6% for each additional 100 kg in average aboveground productivity between 2,400 and 3,600 kg/ha. Plants experienced greater water stress in higher productivity sites. Together, these results suggest that the original habitat of N. pulchra may have been in more marginal ecological sites rather than the more fertile soils of the Central Valley. [source] Spatial genetic analysis of the grass snake, Natrix natrix (Squamata: Colubridae), in an intensively used agricultural landscapeBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010BARBARA MEISTER Both the conversion of natural habitats to farmland and efforts at increasing the yield of existing crops contribute to a decline in biodiversity. As a consequence of land conversion, specialised species are restricted to remnants of original habitat patches, which are frequently isolated. This may lead to a genetic differentiation of the subpopulations. We used seven microsatellite markers to examine the genetic population structure of the grass snake, Natrix natrix (Linnaeus, 1758), sampled in remnants of pristine habitat embedded in an intensively used agricultural landscape in north-western Switzerland. The study area, a former wetland, has been drained and gradually converted into an agricultural plain in the last century, reducing the pristine habitat to approximately 1% of the entire area. The grass snake feeds almost entirely on amphibians, and is therefore associated with wetlands. In Central Europe, the species shows severe decline, most probably as a result of wetland drainage and decrease of amphibian populations. We found no genetically distinct grass snake populations in the study area covering 90 km2. This implies that there is an exchange of individuals between small remnants of original habitat. Thus, gene flow may prevent any genetic differentiation of subpopulations distributed over a relatively large area. Our results show that a specialized snake species can persist in an intensively used agricultural landscape, provided that suitable habitat patches are interconnected. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 51,58. [source] Interspecific Differences in Responses to Predation Risk May Confer Competitive Advantages to Invasive Freshwater Turtle SpeciesETHOLOGY, Issue 2 2008Nuria Polo-Cavia The nature of competitive interactions between native and introduced invasive species is unclear. In the Iberian Peninsula, the introduced red-eared slider (Trachemys scripta elegans) is an invasive species that is competing and displacing the endangered native Spanish terrapin (Mauremys leprosa). We hypothesized that interspecific differences in antipredatory behavior might confer competitive advantages to introduced T. scripta. We examined whether interspecific differences in responses to predation risk affect the time that turtles remained hidden in the shell before using an active escape to water. Both turtle species adjusted hiding times by balancing predation threat, microhabitat conditions and the costs of remaining hidden. However, introduced T. scripta showed longer hiding times before escaping than native M. Leprosa, which, in contrast, switched from waiting hidden in the shell to escape to deep water as soon as possible. These interspecific differences might result from the risk of facing different types of predators in different microhabitats (land vs. water) in their original habitats. However, in anthropogenically altered habitats where predators have been greatly reduced, T. scripta may avoid potential costs of unnecessary repeated escape responses to water (e.g. interruption of basking). These behavioral asymmetries could contribute to the greater competitive ability of introduced T. scripta within anthropogenically disturbed environments. [source] | ||||||||||