A procedure to assess the spatial variability in the importance of abiotic factors affecting distributions: the case of world freshwater fishes.

Understanding the factors shaping species' distributions is a key longstanding topic in ecology with unresolved issues. The aims were to test whether the relative contribution of abiotic factors that set the geographical range of freshwater fish species may vary spatially and/or may depend on the geographical extent that is being considered. The relative contribution of factors, to discriminate between the conditions prevailing in the area where the species is present and those existing in the considered extent, was estimated with the instability index included in the R package SPEDInstabR. We used 3 different extent sizes: 1) each river basin where the species is present (local); 2) all river basins where the species is present (regional); and 3) the whole Earth (global). We used a data set of 16,543 freshwater fish species with a total of 845,764 geographical records, together with bioclimatic and topographic variables. Factors associated with temperature and altitude show the highest relative contribution to explain the distribution of freshwater fishes at the smaller considered extent. Altitude and a mix of factors associated with temperature and precipitation were more important when using the regional extent. Factors associated with precipitation show the highest contribution when using the global extent. There was also spatial variability in the importance of factors, both between species and within species and from region to region. Factors associated with precipitation show a clear latitudinal trend of decreasing in importance toward the equator.

Distribution of Canthon rutilans rutilans and Canthon rutilans cyanescens Along Spatio-Temporal and Temperature Gradients.

Subspecies is a debated taxonomic rank that, in some cases, could indicate that a speciation process is taking place. Studying the degree of co-occurrence among subspecies along environmental gradients may help to determine its taxonomic status. In this study, we explore the distribution of two subspecies of Canthon rutilans along spatio-temporal and temperature gradients in the Atlantic Forest of southern Brazil in order to reinforce their current subspecies status or to support their consideration as two different species. A yearly survey conducted along an elevational transect (from 250 m to 1630 m) shows that there is no spatio-temporal overlap between the two taxa. We collected 899 individuals of Canthon rutilans cyanescens and 29 individuals of Canthon rutilans rutilans. C. rutilans cyanescens can be found at 250 m (all year except in June), 430 m (August to April), and 840 m (September to April) in elevation, and when the air temperature oscillates from 15.3 °C to 24.0 °C. C. rutilans rutilans can be found at 1360 m (October to February), 1630 m (January) in elevation, and when the air temperature oscillates from 14.4 °C to 18.6 °C. Furthermore, local temperature data taken during the survey indicates that both subspecies also have a limited overlap in their thermal response curves. All these results suggest that these two taxa could be considered as two different species with dissimilar physiological and ecological requirements probably as a consequence of temperature-mediated divergent adaptation. Further molecular data can confirm or reject this supposition in the near future.

Elytra Absorb Ultraviolet Radiation but Transmit Infrared Radiation in Neotropical Canthon Species (Coleoptera, Scarabaeinae).

Strategies to deal with global radiation may be related to important aspects of species biology and ecology by reflecting, transmitting or absorbing the radiation of varying wavelengths differently. The elytra capacity to manage infrared, visible and ultraviolet radiations (from 185 to 1400 nm) was assessed with a spectrophotometric analysis in five Canthon species of dung beetles; we calculated the reflectance, transmittance and absorbance capacity of the elytra of these species. These species have different ecologies: two species preferentially inhabit forest areas (Canthon angularis and Canthon lividus lividus), two species preferentially inhabit open areas (Canthon chalybaeus and Canthon tetraodon) including agricultural crops, and one species does not present a clear habitat preference and can be found in both habitats (Canthon quinquemaculatus). All the species show a similar pattern in which the light from shorter wavelengths and higher frequencies is almost entirely absorbed by the elytra, while radiation from longer wavelengths and lower frequencies can mostly pass through the elytra. However, C. quinquemaculatus seems to have significantly higher rates of reflectance and transmittance in the visible- and near-infrared spectrum. This different pattern found in C. quinquemaculatus may be associated with its capacity to establish populations both in agricultural and forest areas.

Exoskeleton may influence the internal body temperatures of Neotropical dung beetles (Col. Scarabaeinae).

The insect exoskeleton is a multifunctional coat with a continuum of mechanical and structural properties constituting the barrier between electromagnetic waves and the internal body parts. This paper examines the ability of beetle exoskeleton to regulate internal body temperature considering its thermal permeability or isolation to simulated solar irradiance and infrared radiation. Seven Neotropical species of dung beetles (Coleoptera, Scarabaeinae) differing in colour, surface sculptures, size, sexual dimorphism, period of activity, guild category and altitudinal distribution were studied. Specimens were repeatedly subjected to heating trials under simulated solar irradiance and infrared radiation using a halogen neodymium bulb light with a balanced daylight spectrum and a ceramic infrared heat emitter. The volume of exoskeleton and its weight per volume unit were significantly more important for the heating rate at the beginning of the heating process than for the asymptotic maximum temperature reached at the end of the trials: larger beetles with relatively thicker exoskeletons heated more slowly. The source of radiation greatly influences the asymptotic temperature reached, but has a negligible effect in determining the rate of heat gain by beetles: they reached higher temperatures under artificial sunlight than under infrared radiation. Interspecific differences were negligible in the heating rate but had a large magnitude effect on the asymptotic temperature, only detectable under simulated sun irradiance. The fact that sun irradiance is differentially absorbed dorsally and transformed into heat among species opens the possibility that differences in dorsal exoskeleton would facilitate the heat gain under restrictive environmental temperatures below the preferred ones. The findings provided by this study support the important role played by the exoskeleton in the heating process of beetles, a cuticle able to act passively in the thermal control of body temperature without implying energetic costs and metabolic changes.

Using indigenous knowledge to link hyper-temporal land cover mapping with land use in the Venezuelan Amazon: "The Forest Pulse" / Utilización de conocimiento indígena para relacionar el mapeado hiper-temporal de coberturas de suelo con el uso del territorio en el Amazonas venezolano: "El Pulso del Bosque"

Abstract:Remote sensing and traditional ecological knowledge (TEK) can be combined to advance conservation of remote tropical regions, e.g. Amazonia, where intensive in situ surveys are often not possible. Integrating TEK into monitoring and management of these areas allows for community participation, as well as for offering novel insights into sustainable resource use. In this study, we developed a 250 m resolution land-cover map of the Western Guyana Shield (Venezuela) based on remote sensing, and used TEK to validate its relevance for indigenous livelihoods and land uses. We first employed a hyper-temporal remotely sensed vegetation index to derive a land classification system. During a 1 300 km, eight day fluvial expedition in roadless areas in the Amazonas State (Venezuela), we visited six indigenous communities who provided geo-referenced data on hunting, fishing and farming activities. We overlaid these TEK data onto the land classification map, to link land classes with indigenous use. We characterized land classes using patterns of greenness temporal change and topo-hydrological information, and proposed 12 land-cover types, grouped into five main landscapes: 1) water bodies; 2) open lands/forest edges; 3) evergreen forests; 4) submontane semideciduous forests, and 5) cloud forests. Each land cover class was identified with a pulsating profile describing temporal changes in greenness, hence we labelled our map as "The Forest Pulse". These greenness profiles showed a slightly increasing trend, for the period 2000 to 2009, in the land classes representing grassland and scrubland, and a slightly decreasing trend in the classes representing forests. This finding is consistent with a gain in carbon in grassland as a consequence of climate warming, and also with some loss of vegetation in the forests. Thus, our classification shows potential to assess future effects of climate change on landscape. Several classes were significantly connected with agriculture, fishing, overall hunting, and more specifically the hunting of primates, Mazama americana, Dasyprocta fuliginosa, and Tayassu pecari. Our results showed that TEK-based approaches can serve as a basis for validating the livelihood relevance of landscapes in high-value conservation areas, which can form the basis for furthering the management of natural resources in these regions. Rev. Biol. Trop. 64 (4): 1661-1682. Epub 2016 December 01.

Resumen:La teledetección y el conocimiento ecológico tradicional (CET) se pueden combinar para avanzar en la conservación de regiones tropicales remotas como la Amazonía, donde la toma de datos intensiva in situ a menudo es imposible. Integrar el CET en el seguimiento y el manejo de estas áreas permite la participación de la comunidad, y ofrece nuevos puntos de vista sobre el uso sostenible de los recursos naturales. En este estudio se desarrolla un mapa de cobertura del suelo del Escudo Guayanés (Venezuela), con una resolución espacial de 250 m, basado en datos de teledetección, y se utiliza el CET para validar su relevancia en relación con la subsistencia de los pueblos indígenas y el uso que éstos hacen del territorio. En primer lugar se ha empleado un índice de vegetación basado en teledetección hiper-temporal para realizar una clasificación del territorio. Durante una expedición fluvial de 8 días, a lo largo de 1 300 km por áreas sin carreteras en el Estado Amazonas (Venezuela), se han visitado seis comunidades que han proporcionado datos geo-referenciados sobre sus actividades cinegéticas, pesqueras y agrícolas. Estos datos de CET se han superpuesto al mapa de clasificación, con el fin de relacionar las clases de coberturas con los usos indígenas. Se han caracterizado las clases de cobertura en función de patrones de cambio temporal del verdor y la topo-hidrografía, y se han propuesto 12 tipos de cobertura del suelo, agrupadas en cinco tipos principales de paisaje: 1) masas de agua; 2) campo abierto/ márgenes del bosque; 3) bosques siempre-verdes; 4) bosques semi-caducifolios submontanos; y 5) bosques nublados. Cada clase de cobertura del suelo se ha identificado con un perfil pulsátil que describe cambios temporales en el verdor, de ahí que el mapa haya sido titulado "El Pulso del Bosque". Estos perfiles de verdor han mostrado una tendencia ligeramente ascendente, durante el periodo 2000 a 2009, en las clases que representan pastizales y zonas de matorral, así como una tendencia ligeramente decreciente en las clases que representan bosques. Este hallazgo es compatible con la ganancia de carbono en los pastizales como consecuencia del calentamiento del clima, y también con una cierta pérdida de vegetación en los bosques. De este modo, nuestra clasificación muestra potencial para la evaluación de efectos futuros del cambio climático sobre el paisaje. Algunas clases han resultado estar significativamente relacionadas con la agricultura, la pesca, la caza como práctica general, y más concretamente con la caza de primates, de Mazama Americana, Dasyprocta fuliginosa, y Tayassu pecari. Los resultados demuestran la utilidad de las aproximaciones basadas en CET como base para validar la importancia del paisaje, en áreas con alto valor de conservación, para la supervivencia de las personas, lo que proporciona una base para avanzar en el manejo de los recursos naturales en estas regiones.

Using indigenous knowledge to link hyper-temporal land cover mapping with land use in the Venezuelan Amazon: "The Forest Pulse".

Remote sensing and traditional ecological knowledge (TEK) can be combined to advance conservation of remote tropical regions, e.g. Amazonia, where intensive in situ surveys are often not possible. Integrating TEK into monitoring and management of these areas allows for community participation, as well as for offering novel insights into sustainable resource use. In this study, we developed a 250 m resolution land-cover map of the Western Guyana Shield (Venezuela) based on remote sensing, and used TEK to validate its relevance for indigenous livelihoods and land uses. We first employed a hyper-temporal remotely sensed vegetation index to derive a land classification system. During a 1 300 km, eight day fluvial expedition in roadless areas in the Amazonas State (Venezuela), we visited six indigenous communities who provided geo-referenced data on hunting, fishing and farming activities. We overlaid these TEK data onto the land classification map, to link land classes with indigenous use. We characterized land classes using patterns of greenness temporal change and topo-hydrological information, and proposed 12 land-cover types, grouped into five main landscapes: 1) water bodies; 2) open lands/forest edges; 3) evergreen forests; 4) submontane semideciduous forests, and 5) cloud forests. Each land cover class was identified with a pulsating profile describing temporal changes in greenness, hence we labelled our map as "The Forest Pulse". These greenness profiles showed a slightly increasing trend, for the period 2000 to 2009, in the land classes representing grassland and scrubland, and a slightly decreasing trend in the classes representing forests. This finding is consistent with a gain in carbon in grassland as a consequence of climate warming, and also with some loss of vegetation in the forests. Thus, our classification shows potential to assess future effects of climate change on landscape. Several classes were significantly connected with agriculture, fishing, overall hunting, and more specifically the hunting of primates, Mazama americana, Dasyprocta fuliginosa, and Tayassu pecari. Our results showed that TEK-based approaches can serve as a basis for validating the livelihood relevance of landscapes in high-value conservation areas, which can form the basis for furthering the management of natural resources in these regions.

Deriving the species richness distribution of Geotrupinae (Coleoptera: Scarabaeoidea) in Mexico from the overlap of individual model predictions.

Predictions from individual distribution models for Mexican Geotrupinae species were overlaid to obtain a total species richness map for this group. A database (GEOMEX) that compiles available information from the literature and from several entomological collections was used. A Maximum Entropy method (MaxEnt) was applied to estimate the distribution of each species, taking into account 19 climatic variables as predictors. For each species, suitability values ranging from 0 to 100 were calculated for each grid cell on the map, and 21 different thresholds were used to convert these continuous suitability values into binary ones (presence-absence). By summing all of the individual binary maps, we generated a species richness prediction for each of the considered thresholds. The number of species and faunal composition thus predicted for each Mexican state were subsequently compared with those observed in a preselected set of well-surveyed states. Our results indicate that the sum of individual predictions tends to overestimate species richness but that the selection of an appropriate threshold can reduce this bias. Even under the most optimistic prediction threshold, the mean species richness error is 61% of the observed species richness, with commission errors being significantly more common than omission errors (71 +/- 29 versus 18 +/- 10%). The estimated distribution of Geotrupinae species richness in Mexico in discussed, although our conclusions are preliminary and contingent on the scarce and probably biased available data.

Assessing the accuracy of species distribution models to predict amphibian species richness patterns.

1. Evaluating the distribution of species richness where biodiversity is high but has been insufficiently sampled is not an easy task. Species distribution modelling has become a useful approach for predicting their ranges, based on the relationships between species records and environmental variables. Overlapping predictions of individual distributions could be a useful strategy for obtaining estimates of species richness and composition in a region, but these estimates should be evaluated using a proper validation process, which compares the predicted richness values and composition with accurate data from independent sources. 2. In this study, we propose a simple approach to estimate model performance for several distributional predictions generated simultaneously. This approach is particularly suitable when species distribution modelling techniques that require only presence data are used. 3. The individual distributions for the 370 known amphibian species of Mexico were predicted using maxent to model data on their known presence (66,113 presence-only records). Distributions were subsequently overlapped to obtain a prediction of species richness. Accuracy was assessed by comparing the overall species richness values predicted for the region with observed and predicted values from 118 well-surveyed sites, each with an area of c. 100 km(2), which were identified using species accumulation curves and nonparametric estimators. 4. The derived models revealed a remarkable heterogeneity of species richness across the country, provided information about species composition per site and allowed us to obtain a measure of the spatial distribution of prediction errors. Examining the magnitude and location of model inaccuracies, as well as separately assessing errors of both commission and omission, highlights the inaccuracy of the predictions of species distribution models and the need to provide measures of uncertainty along with the model results. 5. The combination of a species distribution modelling method like maxent and species richness estimators offers a useful tool for identifying when the overall pattern provided by all model predictions might be representing the geographical patterns of species richness and composition, regardless of the particular quality or accuracy of the predictions for each individual species.