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TTER Evidence of climatic niche shift during biological invasion
"... Niche-based models calibrated in the native range by relating species observations to climatic variables are commonly used to predict the potential spatial extent of speciesÕ invasion. This climate matching approach relies on the assumption that invasive species conserve their climatic niche in the ..."
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Niche-based models calibrated in the native range by relating species observations to climatic variables are commonly used to predict the potential spatial extent of speciesÕ invasion. This climate matching approach relies on the assumption that invasive species conserve their climatic niche in the invaded ranges. We test this assumption by analysing the climatic niche spaces of Spotted Knapweed in western North America and Europe. We show with robust cross-continental data that a shift of the observed climatic niche occurred between native and non-native ranges, providing the first empirical evidence that an invasive species can occupy climatically distinct niche spaces following its introduction into a new area. The models fail to predict the current invaded distribution, but correctly predict areas of introduction. Climate matching is thus a useful approach to identify areas at risk of introduction and establishment of newly or not-yet-introduced neophytes, but may not predict the full extent of invasions
2007. Applications of ecological niche modeling for species delimitation: A review and empirical evaluation using day geckos (Phelsuma) from Madagascar. Syst. Biol. 56:This issue
"... Abstract.—Although the systematic utility of ecological niche modeling is generally well known (e.g., concerning the recog-nition and discovery of areas of endemism for biogeographic analyses), there has been little discussion of applications concerning species delimitation, and to date, no empirica ..."
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Cited by 20 (1 self)
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Abstract.—Although the systematic utility of ecological niche modeling is generally well known (e.g., concerning the recog-nition and discovery of areas of endemism for biogeographic analyses), there has been little discussion of applications concerning species delimitation, and to date, no empirical evaluation has been conducted. However, ecological niche mod-eling can provide compelling evidence for allopatry between populations, and can also detect divergent ecological niches between candidate species. Here we present results for two taxonomically problematic groups of Phelsuma day geckos from Madagascar, where we integrate ecological niche modeling with mitochondrial DNA and morphological data to evaluate species limits. Despite relatively modest levels of genetic and morphological divergence, for both species groups we find divergent ecological niches between closely related species and parapatric ecological niche models. Niche models based on the new species limits provide a better fit to the known distribution than models based upon the combined (lumped) species limits. Based on these results, we elevate three subspecies of Phelsuma madagascariensis to species rank and describe a new species of Phelsuma from the P. dubia species group. Our phylogeny continues to support a major endemic radiation of Phelsuma in Madagascar, with dispersals to Pemba Island and the Mascarene Islands. We conclude that ecological niche modeling offers great potential for species delimitation, especially for taxonomic groups exhibiting low vagility and local-ized endemism and for groups with more poorly known distributions. In particular, niche modeling should be especially
Estimating daily Land Surface Temperatures in mountainous environments by reconstructed MODIS LST data
- REMOTE SENSING
, 2010
"... Abstract: Continuous monitoring of extreme environments, such as the European Alps, is hampered by the sparse and/or irregular distribution of meteorological stations, the difficulties in performing ground surveys and the complexity of interpolating existing station data. Remotely sensed Land Surfac ..."
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Cited by 20 (4 self)
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Abstract: Continuous monitoring of extreme environments, such as the European Alps, is hampered by the sparse and/or irregular distribution of meteorological stations, the difficulties in performing ground surveys and the complexity of interpolating existing station data. Remotely sensed Land Surface Temperature (LST) is therefore of major interest for a variety of environmental and ecological applications. But while MODIS LST data from the Terra and Aqua satellites are aimed at closing the gap between data demand and availability, clouds and other atmospheric disturbances often obscure parts or even the entirety of these satellite images. A novel algorithm is presented in this paper, which is able to reconstruct incomplete MODIS LST maps. All nine years of the available daily LST data (2000–2008) have been processed, allowing the original LST map resolution of 1,000 m to be improved to 200 m, which means the resulting LST maps can be applied at a regional level. Extracted time series and aggregated data are shown as examples and are compared to meteorological station time series as an indication of the quality obtained.
Global patterns in plant height
- Journal of Ecology
, 2009
"... 1. Plant height is a central part of plant ecological strategy. It is strongly correlated with life span, seedmass and time tomaturity, and is a major determinant of a species ’ ability to compete for light. Plant height is also related to critical ecosystem variables such as animal diversity and ca ..."
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Cited by 18 (5 self)
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1. Plant height is a central part of plant ecological strategy. It is strongly correlated with life span, seedmass and time tomaturity, and is a major determinant of a species ’ ability to compete for light. Plant height is also related to critical ecosystem variables such as animal diversity and carbon storage capacity. However, remarkably little is known about global patterns in plant height. Here, we use maximum height data for 7084 plant Species · Site combinations to provide the first global, cross-species quantification of the latitudinal gradient in plant height. 2. The mean maximum height of species growing within 15 of the equator (7.8 m) was 29 times greater than the height of species between 60 and 75 N (27 cm), and 31 times greater than the height of species between 45 and 60 S (25 cm). There was no evidence that the latitudinal gradient in plant height was different in the northern hemisphere than in the southern hemisphere (P = 0.29). A 2.4-fold drop in plant height at the edge of the tropics (P = 0.006) supports the idea that there might be a switch in plant strategy between temperate and tropical zones. 3. We investigated 22 environmental variables to determine which factors underlie the latitudinal gradient in plant height.We found that species with a wide range of height strategies were present in
Changes in climate will modify the geography of crop suitability: Agricultural biodiversity can help with adaptation
- Journal of Semi-arid Tropical Agricultural Research
, 2007
"... Climate change will cause shifts in areas suitable for cultivation of a wide range of crops. We used current and projected future climate data for ~2055, and the Ecocrop model to predict the impact of climate change on areas suitable for all crops listed in Table 1 of the International Treaty on Pla ..."
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Cited by 12 (1 self)
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Climate change will cause shifts in areas suitable for cultivation of a wide range of crops. We used current and projected future climate data for ~2055, and the Ecocrop model to predict the impact of climate change on areas suitable for all crops listed in Table 1 of the International Treaty on Plant Genetic Resources for Food and Agriculture and other major staple and cash crops. Most detrimentally affected in terms of reduction of suitable areas for a range of crops will be sub-Saharan Africa and the Caribbean, areas with the least capacity to cope. Conversely, Europe and North America will see an increase in area suitable for cultivation. These regions have the greatest capacity to manage climate change impacts. To minimize the impacts of these climate and other environmental changes, it will be crucial to breed new varieties for improved resistance to abiotic and biotic stresses is. Plant breeders need to increase their attention to breeding varieties that have greater tolerance to local abiotic stresses such as drought, flooding and extreme temperatures as well as continuing to breed for resistance to pests and diseases. Priorities for breeding should consider the magnitude of the predicted impacts on productivity of the crop, the number of people who depend on the crop and their level of poverty, and the opportunities for
Insights into the area under the receiver operating characteristic curve (AUC) as a discrimination measure in species. Ecology 5:498–507
"... ABSTRACT Aim The area under the receiver operating characteristic (ROC) curve (AUC) is a widely used statistic for assessing the discriminatory capacity of species distribution models. Here, I used simulated data to examine the interdependence of the AUC and classical discrimination measures (sensi ..."
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ABSTRACT Aim The area under the receiver operating characteristic (ROC) curve (AUC) is a widely used statistic for assessing the discriminatory capacity of species distribution models. Here, I used simulated data to examine the interdependence of the AUC and classical discrimination measures (sensitivity and specificity) derived for the application of a threshold. I shall further exemplify with simulated data the implications of using the AUC to evaluate potential versus realized distribution models. Innovation After applying the threshold that makes sensitivity and specificity equal, a strong relationship between the AUC and these two measures was found. This result is corroborated with real data. On the other hand, the AUC penalizes the models that estimate potential distributions (the regions where the species could survive and reproduce due to the existence of suitable environmental conditions), and favours those that estimate realized distributions (the regions where the species actually lives). Main conclusions Firstly, the independence of the AUC from the threshold selection may be irrelevant in practice. This result also emphasizes the fact that the AUC assumes nothing about the relative costs of errors of omission and commission. However, in most real situations this premise may not be optimal. Measures derived from a contingency table for different cost ratio scenarios, together with the ROC curve, may be more informative than reporting just a single AUC value. Secondly, the AUC is only truly informative when there are true instances of absence available and the objective is the estimation of the realized distribution. When the potential distribution is the goal of the research, the AUC is not an appropriate performance measure because the weight of commission errors is much lower than that of omission errors.
Large trees drive forest aboveground biomass variation in moist lowland forests across the tropics, Global
- Ecol. Biogeogr
"... ABSTRACT Aim Large trees (d.b.h. Ն 70 cm) store large amounts of biomass. Several studies suggest that large trees may be vulnerable to changing climate, potentially leading to declining forest biomass storage. Here we determine the importance of large trees for tropical forest biomass storage and ..."
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Cited by 11 (0 self)
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ABSTRACT Aim Large trees (d.b.h. Ն 70 cm) store large amounts of biomass. Several studies suggest that large trees may be vulnerable to changing climate, potentially leading to declining forest biomass storage. Here we determine the importance of large trees for tropical forest biomass storage and explore which intrinsic (species trait) and extrinsic (environment) variables are associated with the density of large trees and forest biomass at continental and pan-tropical scales. Location Pan-tropical. Methods Aboveground biomass (AGB) was calculated for 120 intact lowland moist forest locations. Linear regression was used to calculate variation in AGB explained by the density of large trees. Akaike information criterion weights (AICcwi) were used to calculate averaged correlation coefficients for all possible multiple regression models between AGB/density of large trees and environmental and species trait variables correcting for spatial autocorrelation. Results Density of large trees explained c. 70% of the variation in pan-tropical AGB and was also responsible for significantly lower AGB in Neotropical [287.8 (mean) Ϯ 105.0 (SD) Mg ha ). Pan-tropical variation in density of large trees and AGB was associated with soil coarseness (negative), soil fertility (positive), community wood density (positive) and dominance of wind dispersed species (positive), temperature in the coldest month (negative), temperature in the warmest month (negative) and rainfall in the wettest month (positive), but results were not always consistent among continents. Main conclusions Density of large trees and AGB were significantly associated with climatic variables, indicating that climate change will affect tropical forest biomass storage. Species trait composition will interact with these future biomass changes as they are also affected by a warmer climate. Given the importance of large trees for variation in AGB across the tropics, and their sensitivity to climate change, we emphasize the need for in-depth analyses of the community dynamics of large trees. bs_bs_banner Global Ecology and Biogeography, (Global Ecol. Biogeogr.)
A method for quantifying biodiversity loss and its application to a 50-year record of deforestation across Madagascar
- Conservation Letters
, 2008
"... Abstract Madagascar is a top global conservation priority for high rates of deforestation and endemism. Deforestation has been extensive, but impacts of forest loss on biodiversity have not been well quantified, especially for nonvertebrates. We use generalized dissimilarity modeling (GDM) as a bas ..."
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Cited by 10 (0 self)
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Abstract Madagascar is a top global conservation priority for high rates of deforestation and endemism. Deforestation has been extensive, but impacts of forest loss on biodiversity have not been well quantified, especially for nonvertebrates. We use generalized dissimilarity modeling (GDM) as a basis for estimating forest biodiversity remaining at different points in time. We predict that 9.1% of species in Madagascar have been committed to extinction from deforestation between 1950 and 2000. This quantity is higher than losses expected from random deforestation of the same total area, indicating that deforestation has been biased towards environmentally and biologically distinct areas. In contrast to traditional area-based methods, these techniques allow one to estimate biodiversity loss based on the location of deforestation and thus can inform land-use policies that aim to minimize biodiversity impacts of deforestation or development.
Multivariate forecasts of potential distributions of invasive plant species.
- Ecol. Appl.
, 2009
"... Abstract. The fact that plant invasions are an ongoing process makes generalizations of invasive spread extraordinarily challenging. This is particularly true given the idiosyncratic nature of invasions, in which both historical and local conditions affect establishment success and hinder our abili ..."
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Cited by 10 (1 self)
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Abstract. The fact that plant invasions are an ongoing process makes generalizations of invasive spread extraordinarily challenging. This is particularly true given the idiosyncratic nature of invasions, in which both historical and local conditions affect establishment success and hinder our ability to generate guidelines for early detection and eradication of invasive species. To overcome these limitations we have implemented a comprehensive approach that examines plant invasions at three spatial scales: regional, landscape, and local levels. At each scale, in combination with the others, we have evaluated the role of key environmental variables such as climate, landscape structure, habitat type, and canopy closure in the spread of three commonly found invasive woody plant species in New England, Berberis thunbergii, Celastrus orbiculatus, and Euonymus alatus. We developed a spatially explicit hierarchical Bayesian model that allowed us to take into account the ongoing nature of the spread of invasive species and to incorporate presence/absence data from the species' native ranges as well as from the invaded regions. Comparisons between predictions from climate-only models with those from the multiscale forecasts emphasize the importance of including landscape structure in our models of invasive species' potential distributions. In addition, predictions generated using only native range data performed substantially worse than those that incorporated data from the target range. This points out important limitations in extrapolating distributional ranges from one region to another.
Indexing large-scale raster geospatial data using massively parallel GPGPU computing
- In Proc. ACM-GIS
, 2010
"... Advances in geospatial technologies have generated large amounts of raster geospatial data. Massively parallel General Purpose Graph-ics Processing Unit (GPGPU) computing technologies have pro-vided personal computers with tremendous computing capabilities. In this paper, we report our work on fast ..."
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Cited by 9 (8 self)
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Advances in geospatial technologies have generated large amounts of raster geospatial data. Massively parallel General Purpose Graph-ics Processing Unit (GPGPU) computing technologies have pro-vided personal computers with tremendous computing capabilities. In this paper, we report our work on fast indexing of large-scale raster geospatial data using GPGPU computing. We have designed a cache conscious, pointerless quadtree data structure (CCQ-Tree) that has low memory footprint, is suitable for GPU indexing and al-lows fast mapping between main memory and hard drives. A set of algorithms have been developed and integrated to construct CCQ-Trees on GPU devices by utilizing multiple pyramid data structures and Z-order based prefix sum. Experiments on multiple 4096*4096 blocks of a global precipitation raster data have shown that CCQ-Tree indexing using an Nvidia Quadro FX3700 GPU device re-duces construction times from around 9.83 seconds to 0.42 seconds (23X speedup). The experiment results have led us to project the possibility of real time indexing of global 30 arc-seconds (approx-imately 1km) resolution data (43200*21600) in 1-5 seconds on a personal workstation with 1-4 Nvidia next generation Fermi GPU devices. 1.
