The Experts below are selected from a list of 8349 Experts worldwide ranked by ideXlab platform
Alberto A. Guglielmone - One of the best experts on this subject based on the ideXlab platform.
-
using ground derived data to assess the environmental niche of the spinose ear tick otobius megnini
Entomologia Experimentalis Et Applicata, 2010Co-Authors: Agustin Estradapena, Ivan Gerard Horak, Santiago Nava, Alberto A. GuglielmoneAbstract:Four layers of environmental information, namely 1) monthly atmospheric temperature and rainfall, 2) annual ground and underground moisture, evaporation, surface adjacent specific humidity, and temperature, 3) monthly Normalized Derived Vegetation Index (NDVI), and 4) soil physical attributes, were used separately to define the expected geographical distribution and environmental niche of the spinose ear tick, Otobius megnini (Duges) (Acari: Ixodida: Argasidae), an endophilic argasid, in both tropical and neotropical Regions. The best predictive values were obtained from ground-derived climate. Air-derived features ranked second. The remaining environmental information had poor discriminatory abilities. The most informative variables in the distribution of neotropical populations are ground temperatures, with surface humidity ranking second. In the tropics, surface humidity is the most important factor delineating the distribution of O. megnini. Marginality scores are similar for tick populations in both Biogeographical Regions, but specialization factors are different, supporting the findings that both populations are regulated by different variables. Similarly, models trained with records of one Biogeographical Region and projected into the other one, resulted in poorer predictions than when trained with the homologous set of records. Populations of the tick in the tropics experience a different range of temperatures than their neotropical relatives, whereas marginality scores are similar. The conclusion is that each population uses particular portions of the environmental niche, probably because of different climate or competitor constraints on either Biogeographical Region.
-
Using ground‐derived data to assess the environmental niche of the spinose ear tick, Otobius megnini
Entomologia Experimentalis et Applicata, 2010Co-Authors: Agustín Estrada-peña, Ivan Gerard Horak, Santiago Nava, Alberto A. GuglielmoneAbstract:Four layers of environmental information, namely 1) monthly atmospheric temperature and rainfall, 2) annual ground and underground moisture, evaporation, surface adjacent specific humidity, and temperature, 3) monthly Normalized Derived Vegetation Index (NDVI), and 4) soil physical attributes, were used separately to define the expected geographical distribution and environmental niche of the spinose ear tick, Otobius megnini (Duges) (Acari: Ixodida: Argasidae), an endophilic argasid, in both tropical and neotropical Regions. The best predictive values were obtained from ground-derived climate. Air-derived features ranked second. The remaining environmental information had poor discriminatory abilities. The most informative variables in the distribution of neotropical populations are ground temperatures, with surface humidity ranking second. In the tropics, surface humidity is the most important factor delineating the distribution of O. megnini. Marginality scores are similar for tick populations in both Biogeographical Regions, but specialization factors are different, supporting the findings that both populations are regulated by different variables. Similarly, models trained with records of one Biogeographical Region and projected into the other one, resulted in poorer predictions than when trained with the homologous set of records. Populations of the tick in the tropics experience a different range of temperatures than their neotropical relatives, whereas marginality scores are similar. The conclusion is that each population uses particular portions of the environmental niche, probably because of different climate or competitor constraints on either Biogeographical Region.
-
argas persicargas keiransi n sp acari argasidae a parasite of the chimango milvago c chimango aves falconiformes in chile
Journal of Medical Entomology, 2003Co-Authors: Agustin Estradapena, Jose M Venzal, Daniel Gonzalezacuna, Alberto A. GuglielmoneAbstract:Abstract The larva of Argas (Persicargas) keiransi Estrada-Pena, Venzal & Gonzalez-Acuna n. sp. is described from specimens collected on the neck of a chimango, Milvago c. chimango (Aves: Falconiformes) in the Chillan, Chile, in the Sub-Antarctic Biogeographical Region. The larva of the new species shares the tarsus I setal formula with A. (P.) giganteus, these being the only two Persicargas species with three pairs of ventral setae plus both av4 and pv4 setae. However, it is unique in having a dorsal plate “V” or “U” shaped, with the anterior end open, without the typical reticulated pattern present in the remaining species of the genus.
Agustin Estradapena - One of the best experts on this subject based on the ideXlab platform.
-
using ground derived data to assess the environmental niche of the spinose ear tick otobius megnini
Entomologia Experimentalis Et Applicata, 2010Co-Authors: Agustin Estradapena, Ivan Gerard Horak, Santiago Nava, Alberto A. GuglielmoneAbstract:Four layers of environmental information, namely 1) monthly atmospheric temperature and rainfall, 2) annual ground and underground moisture, evaporation, surface adjacent specific humidity, and temperature, 3) monthly Normalized Derived Vegetation Index (NDVI), and 4) soil physical attributes, were used separately to define the expected geographical distribution and environmental niche of the spinose ear tick, Otobius megnini (Duges) (Acari: Ixodida: Argasidae), an endophilic argasid, in both tropical and neotropical Regions. The best predictive values were obtained from ground-derived climate. Air-derived features ranked second. The remaining environmental information had poor discriminatory abilities. The most informative variables in the distribution of neotropical populations are ground temperatures, with surface humidity ranking second. In the tropics, surface humidity is the most important factor delineating the distribution of O. megnini. Marginality scores are similar for tick populations in both Biogeographical Regions, but specialization factors are different, supporting the findings that both populations are regulated by different variables. Similarly, models trained with records of one Biogeographical Region and projected into the other one, resulted in poorer predictions than when trained with the homologous set of records. Populations of the tick in the tropics experience a different range of temperatures than their neotropical relatives, whereas marginality scores are similar. The conclusion is that each population uses particular portions of the environmental niche, probably because of different climate or competitor constraints on either Biogeographical Region.
-
argas persicargas keiransi n sp acari argasidae a parasite of the chimango milvago c chimango aves falconiformes in chile
Journal of Medical Entomology, 2003Co-Authors: Agustin Estradapena, Jose M Venzal, Daniel Gonzalezacuna, Alberto A. GuglielmoneAbstract:Abstract The larva of Argas (Persicargas) keiransi Estrada-Pena, Venzal & Gonzalez-Acuna n. sp. is described from specimens collected on the neck of a chimango, Milvago c. chimango (Aves: Falconiformes) in the Chillan, Chile, in the Sub-Antarctic Biogeographical Region. The larva of the new species shares the tarsus I setal formula with A. (P.) giganteus, these being the only two Persicargas species with three pairs of ventral setae plus both av4 and pv4 setae. However, it is unique in having a dorsal plate “V” or “U” shaped, with the anterior end open, without the typical reticulated pattern present in the remaining species of the genus.
Stefan Olin - One of the best experts on this subject based on the ideXlab platform.
-
Recent divergence in the contributions of tropical and boreal forests to the terrestrial carbon sink
Nature Ecology & Evolution, 2020Co-Authors: Torbern Tagesson, Guy Schurgers, Stéphanie Horion, Philippe Ciais, Feng Tian, Martin Brandt, Anders Ahlström, Jean-pierre Wigneron, Jonas Ardö, Stefan OlinAbstract:Anthropogenic land use and land cover changes (LULCC) have a large impact on the global terrestrial carbon sink, but this effect is not well characterized according to Biogeographical Region. Here, using state-of-the-art Earth observation data and a dynamic global vegetation model, we estimate the impact of LULCC on the contribution of biomes to the terrestrial carbon sink between 1992 and 2015. Tropical and boreal forests contributed equally, and with the largest share of the mean global terrestrial carbon sink. CO2 fertilization was found to be the main driver increasing the terrestrial carbon sink from 1992 to 2015, but the net effect of all drivers (CO2 fertilization and nitrogen deposition, LULCC and meteorological forcing) caused a reduction and an increase, respectively, in the terrestrial carbon sink for tropical and boreal forests. These diverging trends were not observed when applying a conventional LULCC dataset, but were also evident in satellite passive microwave estimates of aboveground biomass. These datasets thereby converge on the conclusion that LULCC have had a greater impact on tropical forests than previously estimated, causing an increase and decrease of the contributions of boreal and tropical forests, respectively, to the growing terrestrial carbon sink.
-
Recent divergence in the contributions of tropical and boreal forests to the terrestrial carbon sink
Nature Ecology & Evolution, 2020Co-Authors: Torbern Tagesson, Guy Schurgers, Stéphanie Horion, Philippe Ciais, Feng Tian, Martin Brandt, Anders Ahlström, Jean-pierre Wigneron, Jonas Ardö, Stefan OlinAbstract:Anthropogenic land use and land cover changes (LULCC) have a large impact on the global terrestrial carbon sink, but this effect is not well characterized according to Biogeographical Region. Here, using state-of-the-art Earth observation data and a dynamic global vegetation model, we estimate the impact of LULCC on the contribution of biomes to the terrestrial carbon sink between 1992 and 2015. Tropical and boreal forests contributed equally, and with the largest share of the mean global terrestrial carbon sink. CO2 fertilization was found to be the main driver increasing the terrestrial carbon sink from 1992 to 2015, but the net effect of all drivers (CO2 fertilization and nitrogen deposition, LULCC and meteorological forcing) caused a reduction and an increase, respectively, in the terrestrial carbon sink for tropical and boreal forests. These diverging trends were not observed when applying a conventional LULCC dataset, but were also evident in satellite passive microwave estimates of aboveground biomass. These datasets thereby converge on the conclusion that LULCC have had a greater impact on tropical forests than previously estimated, causing an increase and decrease of the contributions of boreal and tropical forests, respectively, to the growing terrestrial carbon sink. Combining Earth observation data and dynamic global vegetation models, the authors show that anthropogenic land use and land cover change has caused a reduction in the contribution to the terrestrial carbon sink for tropical forests but an increase for boreal forests between 1992 and 2015.
M De Heer - One of the best experts on this subject based on the ideXlab platform.
-
biodiversity trends in europe development and testing of a species trend indicator for evaluating progress towards the 2010 target
Philosophical Transactions of the Royal Society B, 2005Co-Authors: M De Heer, Valerie Kapos, Ten B BrinkAbstract:This paper presents a trial of a species population trend indicator for evaluating progress towards the 2010 biodiversity target in Europe, using existing data. The indicator integrates trends on different species (groups), and can be aggregated across habitats and countries. Thus, the indicator can deliver both headline messages for high-level decision-making and detailed information for in-depth analysis, using data from different sources, collected with different methods. International non-governmental organizations mobilized data on over 2800 historical trends in national populations of birds, butterflies and mammals, for a total of 273 species. These were combined by habitat and Biogeographical Region to generate a pilot pan-European scale indicator. The trial indicator suggests a decline of species populations in nearly all habitats, the largest being in farmland, where species populations declined by an average of 23% between 1970 and 2000. The indicator is potentially useful for monitoring progress towards 2010 biodiversity targets, but constraints include: the limited sensitivity of the historical data, which leads to conservative estimates of species decline; a potential danger of ambiguity because increases in opportunistic species can mask the loss of other species; and failure to account for pre-1970 population declines. We recommend mobilizing additional existing data, particularly for plants and fishes, and elaborating further the criteria for compiling representative sets of species. For a frequent, reliable update of the indicator, sound, sensitive and harmonized biodiversity monitoring programmes are needed in all pan-European countries.
Philippe J R Kok - One of the best experts on this subject based on the ideXlab platform.
-
historical biogeography of the palaeoendemic toad genus oreophrynella amphibia bufonidae sheds a new light on the origin of the pantepui endemic terrestrial biota
Journal of Biogeography, 2018Co-Authors: Philippe J R Kok, Sebastian Ratz, Ross D Macculloch, Amy Lathrop, Fabien Aubret, Raheleh Dezfoulian, Bruce D MeansAbstract:Aim Using the Pantepui palaeoendemic toad genus Oreophrynella, we explored (1) the origin of Pantepui endemism and the hypothesis of Pantepui being a source of diversity for the surrounding areas, including the geologically younger Andes; (2) whether early diversification of Oreophrynella conforms with that of Stefania (Hemiphractidae), another Pantepui endemic amphibian, which was recently shown to have vicariantly diverged from Pantepui highlands widespread Oligocene ancestors. Location The fractured island-like topography of the Pantepui Biogeographical Region in north-eastern South America. Methods We inferred the molecular phylogeny of Oreophrynella and other “basal” Bufonidae genera using three mitochondrial and two nuclear DNA sequences under Bayesian and maximum likelihood methods. We estimated divergence times using a relaxed-clock model and reconstructed ancestral areas through multiple models in a common likelihood framework. Results Phylogenetic analyses recovered a monophyletic Oreophrynella sister to Atelopus. Biogeographical analyses strongly suggested colonization of Pantepui via a pre-Miocene (Eocene/Oligocene) long-distance dispersal of a proto-Andean ancestor, followed by pre-Quaternary (lower Miocene) vicariant divergences of main lineages, and endemism of these main lineages to distinct Biogeographical subunits. Main conclusions Our results suggest that at least part of the Pantepui diversity stemmed from dispersals from the proto-Andes. Three hypotheses emerge for the origin and evolution of Pantepui endemism, the Distance Dispersal theory, the Plateau theory and the Disturbance–Vicariance theory. Our results indicate that the early diversification of Oreophrynella conforms to that of Stefania, but hint at different factors responsible for the survival or extinction of different tepui summit amphibians.
-
evolution in the south american lost world insights from multilocus phylogeography of stefanias anura hemiphractidae stefania
Journal of Biogeography, 2017Co-Authors: Philippe J R Kok, Valerio G Russo, Sebastian Ratz, Bruce D Means, Ross D Macculloch, Amy Lathrop, Fabien Aubret, Franky BossuytAbstract:Aim To investigate the influence of tepuian geomorphology on species diversification in the Pantepui Biogeographical Region based on the phylogenetic relationships and divergence times of tepui-endemic clades of stefania frogs (Stefania, Hemiphractidae). Location The ‘tepuis’ and uplands/lowlands of the Pantepui Biogeographical Region of northern South America, one of the least accessible and least studied areas in the world. Methods Two mitochondrial and two nuclear DNA sequences from 60 individuals of Stefania from 24 localities in Pantepui were employed to infer phylogenetic affinities and estimate divergence times within the genus using both concatenation and species tree analyses. Ancestral areas were inferred using multiple models in a common likelihood framework. Results Phylogenetic analyses revealed high diversity in the genus Stefania with 10 candidate species in the Eastern Pantepui District. Four strongly supported clades are recovered in the area, one being exclusively composed of microendemics on isolated tepui summits. Biogeographical analyses suggest episodes of fragmentation of widespread tepuian ancestors from the onset of diversification of the genus, estimated in the Oligocene (c. 26 Ma), therefore suggesting a neglected vicariant model of Pantepui evolution, the Plateau Theory. Main conclusions Although our results suggest that vicariance played an important role in the diversification of Stefania, speciation in Pantepui followed an intricate pattern implying multiple nonexclusive processes. Vicariance and dispersal likely influenced diversification patterns of the Pantepui fauna, possibly according to the following sequence: (1) Cenozoic vicariance; (2) reorganization of species diversity due to periods of climatic instability; (3) recent invasions (Pleistocene) of widespread upland taxa.