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opencc-zeroDec 2016View details →

Data from: Incorporating interspecific competition into species-distribution mapping by upward scaling of small-scale model projections to the landscape

There are a number of overarching questions and debate in the scientific community concerning the importance of biotic interactions in species distribution models at large spatial scales. In this paper, we present a framework for revising the potential distribution of tree species native to the Western Ecoregion of Nova Scotia, Canada, by integrating the long-term effects of interspecific competition into an existing abiotic-factor-based definition of potential species distribution (PSD). The PSD model is developed by combining spatially explicit data of individualistic species' response to normalized incident photosynthetically active radiation, soil water content, and growing degree days. A revised PSD model adds biomass output simulated over a 100-year timeframe with a robust forest gap model and scaled up to the landscape using a forestland classification technique. To demonstrate the method, we applied the calculation to the natural range of 16 target tree species as found in 1,240 provincial forest-inventory plots. The revised PSD model, with the long-term effects of interspecific competition accounted for, predicted that eastern hemlock (Tsuga canadensis), American beech (Fagus grandifolia), white birch (Betula papyrifera), red oak (Quercus rubra), sugar maple (Acer saccharum), and trembling aspen (Populus tremuloides) would experience a significant decline in their original distribution compared with balsam fir (Abies balsamea), black spruce (Picea mariana), red spruce (Picea rubens), red maple (Acer rubrum L.), and yellow birch (Betula alleghaniensis). True model accuracy improved from 64.2% with original PSD evaluations to 81.7% with revised PSD. Kappa statistics slightly increased from 0.26 (fair) to 0.41 (moderate) for original and revised PSDs, respectively.

opencc-zeroDec 2014View details →

Data from: From ratites to rats: the size of fleshy fruits shapes species' distributions and continental rainforest assembly

Seed dispersal is a key process in plant spatial dynamics. However, consistently applicable generalisations about dispersal across scales are mostly absent because of the constraints on measuring propagule dispersal distances for many species. Here, we focus on fleshy-fruited taxa, specifically taxa with large fleshy fruits and their dispersers across an entire continental rainforest biome. We compare species-level results of whole-chloroplast DNA analyses in sister taxa with large and small fruits, to regional plot-based samples (310 plots), and whole of continent patterns for the distribution of woody species with either large (>30mm) or smaller fleshy fruits (1093 taxa). The pairwise genomic comparison found higher genetic distances between populations and between regions in the large-fruited species (Endiandra globosa), but higher overall diversity within the small-fruited species (Endiandra discolor). Floristic comparisons among plots confirmed lower numbers of large-fruited species in areas where more extreme rainforest contraction occurred, and re-colonisation by small-fruited species readily dispersed by the available fauna. Species distribution patterns showed that larger-fruited species had smaller geographic ranges than smaller-fruited species and locations with stable refugia (and high endemism) aligned with concentrations of large fleshy-fruited taxa, making them a potentially valuable conservation-planning indicator.

Data from: Genomic comparisons reveal biogeographic and anthropogenic impacts in the koala (Phascolarctos cinereus); a dietary-specialist species distributed across heterogeneous environments

The Australian koala is an iconic marsupial with specific dietary requirements distributed across heterogeneous environments, over a large geographic range. The distribution and genetic structure of koala populations has been heavily influenced by human actions, specifically habitat modification, hunting and translocation of koalas. There is currently limited information on population diversity and gene-flow at a species-wide scale, or with consideration to the potential impacts of local adaptation. Using species-wide sampling across heterogeneous environments, and high-density genome-wide markers (SNPs and PAVs), we show that most koala populations display levels of diversity comparable to other outbred species, except for those populations impacted by population reductions. Genetic clustering analysis and phylogenetic reconstruction reveals a lack of support for taxonomic classification of three koala sub-species, with only a single evolutionary significant unit supported. Furthermore, ~70% of genetic variance is accounted for at the individual level. The Sydney Basin region is highlighted as a unique reservoir of genetic diversity, having higher diversity levels (ie. Blue Mountains region; AvHecorr=0.20, PL%=68.6). Broad-scale population differentiation is primarily driven by an Isolation by Distance genetic structure model (49% of genetic variance), with clinal local adaptation corresponding to habitat bioregions. Signatures of selection were detected between bioregions, with no single region returning evidence of strong selection. The results of this study show that although the koala is widely considered to be a dietary-specialist species, this apparent specialisation has not limited the koala's ability to maintain gene-flow and adapt across divergent environments as long as the required food source is available.

Data from: Negative biotic interactions drive predictions of distributions for species from a grassland community

Understanding the factors that determine species' geographic distributions is important for addressing a wide range of biological questions, including where species will be able to maintain populations following environmental change. New methods for modelling species distributions include the effects of biotic interactions alongside more commonly used abiotic variables such as temperature and precipitation; however, it is not clear which types of interspecific relationship contribute to shaping species distributions and should therefore be prioritised in models. Even if some interactions are known to be influential at local spatial scales, there is no guarantee they will have similar impacts at macroecological scales. Here we apply a novel method based on information theory to determine which types of interspecific relationship drive species distributions. Our results show that negative biotic interactions such as competition have the greatest effect on model predictions for species from a California grassland community. This knowledge will help focus data collection and improve model predictions for identifying at-risk species. Furthermore, our methodological approach is applicable to any kind of species distribution model that can be specified with and without interspecific relationships.

opencc-zeroAug 2019View details →

Data from: Distributions of mammals in Southeast Asia: the role of the legacy of climate and species body mass

Aim: Current species distributions are shaped by present and past biotic and abiotic factors. Here we assessed whether abiotic factors (habitat availability) in combination with past connectivity and a biotic factor (body mass) can explain the unique distribution pattern of Southeast Asian mammals, which are separated by the enigmatic biogeographic transition zone, the Isthmus of Kra (IoK), for which no strong geophysical barrier exists. Location: Southeast Asia Taxon: Mammals Methods: We projected habitat suitability for 125 mammal species using climate data for the present period and for two historic periods: mid-Holocene (6 kya) and last glacial maximum (LGM 21 kya). Next, we employed a phylogenetic linear model to assess how present species distributions were affected by the suitability of areas in these different periods, habitat connectivity during LGM and species body mass. Results: Our results show that cooler climate during LGM provided suitable habitat south of IoK for species presently distributed north of IoK (in mainland Indochina). However, the potentially suitable habitat for these Indochinese species did not stretch very far southwards onto the exposed Sunda Shelf. Instead, we found that the emerged landmasses connecting Borneo and Sumatra provided suitable habitat for forest dependent Sundaic species. We show that for species whose current distribution ranges are mainly located in Indochina, the area of the distribution range that is located south of IoK is explained by the suitability of habitat in the past and present in combination with the species body mass. Main conclusions: We demonstrate that a strong geophysical barrier may not be necessary for maintaining a biogeographic transition zone for mammals, but that instead a combination of abiotic and biotic factors may suffice.

opencc-zeroDec 2016View details →

Data from: Importance of antecedent environmental conditions in modeling species distributions

Although species distributions can change in an unexpectedly short period of time, most species distribution models (SDMs) use only long-term averaged environmental conditions to explain species distributions. We aimed to demonstrate the importance of incorporating antecedent environmental conditions into SDMs in comparison to long-term averaged environmental conditions. We modeled the presence/absence of 18 fish species captured across 108 sampling events along a 50-km length of the Sagami River in Japan throughout the 1990s (one to four times per site at 45 sites). We constructed and compared the two types of SDMs: (1) a conventional model that uses only long-term averaged (10-year) environmental conditions; and (2) a proposed model that incorporates environmental conditions 2 years prior to a sampling event (antecedent conditions) together with long-term averages linked to life-history stages. These models both included geomorphological, hydrological, and sampling conditions as predictors. A random forest algorithm was applied for modeling and quantifying the relative importance of the predictors. For seven species, antecedent hydrological conditions were more important than the long-term averaged hydrological conditions. Furthermore, the distributions of two species with low prevalence could not be predicted using long-term averaged hydrological conditions but only using antecedent hydrological conditions. In conclusion, incorporating antecedent environmental factors linked with life-history stages at appropriate time scales can better explain changes in species distribution through time.

opencc-zeroDec 2012View details →

Data from: Correction of location errors for presence-only species distribution models

1. Species distribution models (SDMs) for presence-only data depend on accurate and precise measurements of geographic and environmental covariates that influence presence and abundance of the species. Some data sets, however, may contain both systematic and random errors in the recorded location of the species. Environmental covariates at the recorded location may differ from those at the true location and result in biased parameter estimates and predictions from SDMs. 2. Regression calibration is a well-developed statistical method that can be used to correct the bias in estimated coefficients and predictions from SDMs when the recorded geographic location differ from the true location for some, but not all locations. We expand the application of regression calibration methods to SDMs and provide illustrative examples using simulated data and opportunistic records of whooping cranes (Grus americana). 3. We found we were able to successfully correct the bias in our SDM parameters estimated from simulated data and opportunistic records of whooping cranes using regression calibration. 4. When modeling species distributions with data that have geographic location errors, we recommend researchers consider the effect of location errors. Correcting for location errors requires that at least a portion of the data have locations recorded without error. Bias correction can result in an increase in variance; this increase in variance should be considered when evaluating the utility of bias correction.

Data from: Growth responses to soil water potential indirectly shape local species distributions of tropical forest seedlings

1. Local tree species distributions in tropical forests correlate strongly with soil water availability. However, it is unclear how species distributions are shaped by demographic responses to soil water availability. Specifically, it remains unknown how growth affects species distributions along water availability gradients relative to mortality. 2. We quantified spatial variation in dry season soil water potential (SWP) in the moist tropical forest on Barro Colorado Island, Panama, and used a hierarchical Bayesian approach to evaluate relationships between demographic responses of naturally regenerating seedlings to SWP (relative growth rates and first-year mortality) and species distributions along the SWP gradient for 62 species. We also tested whether species that were more abundant at the wet or dry end of the gradient performed better (1) at their 'home end' of the gradient ('best at home' hypothesis) and (2) 'at home' compared to co-occurring species ('home advantage' hypothesis). 3. Four and five species responded significantly to SWP in terms of growth or mortality, respectively. Growth (but not mortality) responses were positively related to species distributions along the SWP gradient; species with a more positive (negative) growth response to SWP were more abundant at higher (lower) SWP, i.e. at wetter (drier) sites. In addition, wet distributed species grew faster on the wet end of the SWP gradient than on the dry end ('best at home') and grew faster on the wet end than dry distributed species ('home advantage'). Mortality rates declined with seedling size for all species. Thus, seedling growth responses to SWP indirectly shaped local species distributions by influencing seedling size and thereby mortality risk. 4. Synthesis. By demonstrating how growth responses to spatial variation in soil water availability affect species distributions, we identified a demographic process underlying niche differentiation on hydrological gradients in tropical forests. Recognizing the role of these growth responses in shaping species distributions should improve understanding of tropical forest composition and diversity along rainfall gradients and with climate change.

Data from: Using public surveys to reliably and rapidly estimate the distributions of multiple invasive species on the Andaman archipelago

To effectively manage multiple biological invasions, information on their distributions must be generated rapidly and over large spatial scales. Using public surveys in a false-positive occupancy framework, we reliably estimate the distributions of three synanthropic invasive species on the Andaman Islands.

opencc-zeroJun 2019View details →

Data from: Bunching up the background betters bias in species distribution models

Sets of presence records used to model species' distributions typically consist of observations collected opportunistically rather than systematically. As a result, sampling probability is geographically uneven, which may confound the model's characterization of the species' distribution. Modelers frequently address sampling bias by manipulating training data: either subsampling presence data or creating a similar spatial bias in non-presence background data. We tested a new method, which we call "background thickening," in the latter category. Background thickening entails concentrating background locations around presence locations in proportion to presence location density. We compared background thickening to two established sampling bias correction methods — target group background selection and presence thinning — using simulated data and data from a case study. In the case study, background thickening and presence thinning performed similarly well, both producing better model discrimination than target group background selection, and better model calibration than models without correction. In the simulation, background thickening performed better than presence thinning when the number of simulated presence locations was low, and vice versa. We discuss drawbacks to target group background selection, why background thickening and presence thinning are conservative but robust sampling bias correction methods, and why background thickening is better than presence thinning for small sample sizes. Particularly, background thickening is advantageous for treating sampling bias when data are scarce because it avoids discarding presence records.

opencc-zeroDec 2013View details →

Data from: Modelling plant species distribution in alpine grasslands using airborne imaging spectroscopy

Remote sensing using airborne imaging spectroscopy (AIS) is known to retrieve fundamental optical properties of ecosystems. However, the value of these properties for predicting plant species distribution remains unclear. Here, we assess whether such data can add value to topographic variables for predicting plant distributions in French and Swiss alpine grasslands. We fitted statistical models with high spectral and spatial resolution reflectance data and tested four optical indices sensitive to leaf chlorophyll content, leaf water content and leaf area index. We found moderate added-value of AIS data for predicting alpine plant species distribution. Contrary to expectations, differences between species distribution models (SDMs) were not linked to their local abundance or phylogenetic/functional similarity. Moreover, spectral signatures of species were found to be partly site-specific. We discuss current limits of AIS-based SDMs, highlighting issues of scale and informational content of AIS data.

opencc-zeroDec 2016View details →

Data from: Using citizen science monitoring data in species distribution models to inform isotopic assignment of migratory connectivity in wetland birds

Stable isotopes have been used to estimate migratory connectivity in many species. Estimates are often greatly improved when coupled with species distribution models (SDMs), which temper estimates in relation to occurrence. SDMs can be constructed using from point locality data from a variety of sources including extensive monitoring data typically collected by citizen scientists. However, one potential issue with SDM is that these data oven have sampling bias. To avoid this potential bias, an approach using SDMs based on marsh bird monitoring program data collected by citizen scientists and other participants following protocols specifically designed to maximize detections of species of interest at locations representative of the species range. We then used the SDMs to refine isotopic assignments of breeding areas of autumn-migrating and wintering Sora (Porzana carolina), Virginia Rails (Rallus limicola), and Yellow Rails (Coturnicops noveboracensis) based on feathers collected from individuals caught at various locations in the United States from Minnesota south to Louisiana and South Carolina. Sora were assigned to an area that included much of the western U.S. and prairie Canada, covering parts of the Pacific, Central, and Mississippi Flyways. Yellow Rails were assigned to a broad area along Hudson and James Bay in northern Manitoba and Ontario, as well as smaller parts of Quebec, Minnesota, Wisconsin, and Michigan, including parts of the Mississippi and Atlantic Flyways. Virginia Rails were from several discrete areas, including parts of Colorado, New Mexico, the central valley of California, and southern Saskatchewan and Manitoba in the Pacific and Central Flyways. Our study demonstrates extensive data from organized citizen science monitoring programs are especially useful for improving isotopic assignments of migratory connectivity in birds, which can ultimately lead to better informed management decisions and conservation actions.

FIGURES 11–13 in Comparative study of mouthparts of three species of horse flies of the tribe Pangoniini of Chilean distribution (Diptera: Tabanidae)

FIGURES 11–13. Protodasyapha (P.) hirtuosa, female. 11, dorsal view of laciniae; 12, dorsal view of labra; 13, ventral view of hypopharynx. Scale bars 11, 12: 10 µm; 13: 100 µm.

FIGURES 1719. Veprius presbiter, female. 17 in Comparative study of mouthparts of three species of horse flies of the tribe Pangoniini of Chilean distribution (Diptera: Tabanidae)

FIGURES 1719. Veprius presbiter, female. 17, dorsal view of laciniae; 18, dorsal view of labra; 19, ventral view of hypopharynx. Scale bars: 10 µm.

FIGURES 1416. Veprius presbiter, male. 14 in Comparative study of mouthparts of three species of horse flies of the tribe Pangoniini of Chilean distribution (Diptera: Tabanidae)

FIGURES 1416. Veprius presbiter, male. 14, dorsal view of laciniae; 15, dorsal view of labra; 16, ventral view of hypopharynx. Scale bars 14, 15: 10 µm; 16: 100 µm.

FIGURES 4–7 in Comparative study of mouthparts of three species of horse flies of the tribe Pangoniini of Chilean distribution (Diptera: Tabanidae)

FIGURES 4–7. Esenbeckia (P.) fascipennis, female. 4, mandible; 5, dorsal view of laciniae; 6, dorsal view of labra; 7, ventral view of hypopharynx. Scale bars 4, 6: 10 µm; 5, 7: 100 µm

FIGURES 8–10 in Comparative study of mouthparts of three species of horse flies of the tribe Pangoniini of Chilean distribution (Diptera: Tabanidae)

FIGURES 8–10. Protodasyapha (P.) hirtuosa, male. 8, dorsal view of laciniae; 9, dorsal view of labra; 10, ventral view of hypopharynx. Scale bars: 10 µm.

FIGURES 1–3 in Comparative study of mouthparts of three species of horse flies of the tribe Pangoniini of Chilean distribution (Diptera: Tabanidae)

FIGURES 1–3. Esenbeckia (P.) fascipennis, male. 1, dorsal view of laciniae; 2, dorsal view of labra; 3, ventral view of hypopharynx. Scale bars 1, 2: 10 µm; 3: 100 µm

opennotspecifiedDec 2003View details →

FIGURES 7–9 in New data on the distribution of species of Gastroserica Brenske, 1897, with descriptions of five new taxa from China and Laos (Coleoptera: Scarabaeidae: Sericini)

FIGURES 7–9: Gastroserica huaphanensis sp. n. (Holotype: Laos, Hua Phan prov., Ban Saluei, Phu Phan Mt.); 7, 9 Aedeagus lateral view, 8 Parameres dorsal view. Scale: 0.5 mm.