Search

Question What are the interacting effects of stress and disturbance on both competition and facilitation, and ultimately their impact on diversity and species ranges? Location Simulated data. Method We extended the spatially explicit model of Xiao et al. ( Oikos, 118, 2009, 1343) to consider how stress and disturbance - operating alone or together - affect species distributions through varying biotic interactions. Results In the absence of facilitation, species ranges only occurred within the limits of a triangular zone, which can be considered equivalent to Grime's C-S-R triangle. Competitive species were distributed in low stress and disturbance conditions. Stress- and disturbance-tolerant species occurred in more stressed and disturbed environments. Species richness followed a hump-shaped relationship with a hotspot of diversity occurring close to the centre of the C-S-R triangle. In contrast, facilitation was able to dampen the negative impacts of stress and disturbance acting either solely or simultaneously, but this influence was not simply the sum of the effects of the processes operating independently on the two environmental gradients. Facilitation extended species distributions along both the stress and disturbance gradients and displaced the hotspot of diversity into the centre of the response surface. Conclusions Facilitation was able to promote the occurrence and persistence of communities in highly stressed and disturbed conditions, i.e. allowing a stable community to exist beyond the limits of the C-S-R triangle. We also showed that facilitation can be an important mechanism driving the displacement of hotspots of diversity from benign toward intermediate stressed and disturbed environments. [ABSTRACT FROM AUTHOR]

Abstract: Sandy beach ecology has progressed rapidly with the emergence of several theories developed on the basis of understanding of hydrodynamic and morphodynamic processes on sandy beach habitats. However, the possible role of dynamic geophysical processes in the sediments remains poorly understood. The present study aims to explore the role of such geophysical processes in the sediments in forming the habitat environment and how they influence the species distributions. We conducted sets of integrated observations and surveys on intertidal and supratidal geophysical environments and the distributions of three amphipod and isopod species at four exposed sandy beaches located on the Japan Sea coast of Niigata Prefecture, Japan. The field results combined with a series of laboratory soil tests demonstrate that suction governed the variability of habitat environments observed, involving the degree of saturation, density, and hardness of the cross-shore intertidal and supratidal sediments, depending on the severity of the suction-dynamics-induced sediment compaction. While the observed species abundances were consistent with existing theories relating to intertidal and supratidal species, the observed magnitudes of suction were responsible for the distribution limits of the amphipods Haustorioides japonicus and Talorchestia brito and the isopod Excirolana chiltoni manifested consistently throughout the different beaches. The results of controlled laboratory experiments and field tests further revealed three distinctive suction-induced mechanisms, associated with their burrowing and physiology and the stability of the burrows. The novel role of such suction-induced geophysical processes in forming the habitat environment and influencing the species distributions may advance our understanding of sandy beach ecology in intertidal and supratidal zones. [Copyright &y& Elsevier]

The remote tropical Kimberley region of Western Australia is introduced, its physical marine environment, habitats and classification into bioregions are described, and its marine science history is summarised. An introduction to the ongoing Western Australian Museum marine biological survey program and its objectives are also provided. The geology, metocean conditions and climate of the region are summarised. A primary division of the Kimberley coastline is noted with a northern section dominated by Proterozoic meta-sedimentary and igneous rocks (Kimberley and Bonaparte Gulf Bioregions) and a southern section dominated by Mesozoic and Cainozoic sedimentary rocks (King Sound and Canning Bioregions). In the former section inner shelf seabed sediments overlying the inundated Yampi Plateau are principally of terrestrial origin while in the Canning Bioregion they are principally marine carbonates. On the middle and outer shelf (Oceanic Shoals and North West Shelf Bioregions) sediments are primarily marine carbonates. Along the shelf margin the water is clear and oligotrophic and subject to the Indonesian Through Flow current that originates in the western Pacific. The coastal zone is macrotidal, currents are predominantly tide driven and the coastal water is turbid and probably nutrient rich. These environmental differences and the different connectivity regimes account for distinctive offshore and coastal reef communities. [ABSTRACT FROM AUTHOR]

As a consequence of anthropogenic climate change, marine species on continental shelves around the world are rapidly shifting deeper and poleward. However, whether these shifts deeper and poleward will allow species to access more, less, or equivalent amounts of continental shelf area and associated critical habitats remains unclear. By examining the proportion of seabed area at a range of depths for each large marine ecosystem (LME), we found that shelf area declined monotonically for 19% of LMEs examined. However, the majority exhibited a greater proportion of shelf area in mid-depths or across several depth ranges. By comparing continental shelf area across 2° latitudinal bands, we found that all coastlines exhibit multiple instances of shelf area expansion and contraction, which have the potential to promote or restrict poleward movement of marine species. Along most coastlines, overall shelf habitat increases or exhibits no significant change moving towards the poles. The exception is the Southern West Pacific, which experiences an overall loss of area with increasing latitude. Changes in continental shelf area availability across latitudes and depths are likely to affect the number of species local ecosystems can support. These geometric analyses help identify regions of conservation priority and ecological communities most likely to face attrition or expansion due to variations in available area., (© 2022 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)

Critical thermal limits (CTLs) constrain the performance of organisms, shaping their abundance, current distributions, and future distributions. Consequently, CTLs may also determine the quality of ecosystem services as well as organismal and ecosystem vulnerability to climate change. As some of the most ubiquitous animals in terrestrial ecosystems, ants are important members of ecological communities. In recent years, an increasing body of research has explored ant physiological thermal limits. However, these CTL data tend to centre on a few species and biogeographical regions. To encourage an expansion of perspectives, we herein review the factors that determine ant CTLs and examine their effects on present and future species distributions and ecosystem processes. Special emphasis is placed on the implications of CTLs for safeguarding ant diversity and ant-mediated ecosystem services in the future. First, we compile, quantify, and categorise studies on ant CTLs based on study taxon, biogeographical region, methodology, and study question. Second, we use this comprehensive database to analyse the abiotic and biotic factors shaping ant CTLs. Our results highlight how CTLs may affect future distribution patterns and ecological performance in ants. Additionally, we identify the greatest remaining gaps in knowledge and create a research roadmap to promote rapid advances in this field of study., (© 2022 Cambridge Philosophical Society.)

The Indo-Malay-Philippine ( IMP) biodiversity hotspot, bounded by the Philippines, the Malay Peninsula and New Guinea, is the epicentre of marine biodiversity. Hypotheses to explain the source of the incredible number of species found there include the centre of overlap hypothesis, which proposes that in this region the distinct faunas of the Pacific and Indian Oceans overlap. Here we review the biogeographical evidence in support of this hypothesis. We examined tropical reef fish distributions, paying particular attention to sister species pairs that overlap in the IMP hotspot. We also review phylogeographical studies of wide-ranging species for evidence of lineage divergence and overlap in the IMP region. Our synthesis shows that a pattern of isolation between the Pacific and the Indian Ocean faunas is evident across a wide range of taxa. The occurrence of sister species, with one member in each ocean, indicates that the mechanism(s) of isolation has been in effect since at least the Miocene, while phylogeographical studies indicate more recent divergences in the Pleistocene. Divergence in isolation followed by population expansion has led to an overlap of closely related taxa or genetic lineages in the hotspot, contributing to diversity and species richness in the region. These findings are consistent with the centre of overlap hypothesis and highlight the importance of this process in generating biodiversity within the IMP. [ABSTRACT FROM AUTHOR]

Climate change is altering phenology and distributions of many species and further changes are projected. Can species physiologically adapt to climate warming? We analyse thermal tolerances of a large number of terrestrial ectotherm ( n = 697), endotherm ( n = 227) and plant ( n = 1816) species worldwide, and show that tolerance to heat is largely conserved across lineages, while tolerance to cold varies between and within species. This pattern, previously documented for ectotherms, is apparent for this group and for endotherms and plants, challenging the longstanding view that physiological tolerances of species change continuously across climatic gradients. An alternative view is proposed in which the thermal component of climatic niches would overlap across species more than expected. We argue that hard physiological boundaries exist that constrain evolution of tolerances of terrestrial organisms to high temperatures. In contrast, evolution of tolerances to cold should be more frequent. One consequence of conservatism of upper thermal tolerances is that estimated niches for cold-adapted species will tend to underestimate their upper thermal limits, thereby potentially inflating assessments of risk from climate change. In contrast, species whose climatic preferences are close to their upper thermal limits will unlikely evolve physiological tolerances to increased heat, thereby being predictably more affected by warming. [ABSTRACT FROM AUTHOR]

Rapid climate change may prompt species distribution shifts upward and poleward, but species movement in itself is not sufficient to establish climate causation. Other dynamics, such as disturbance history, may prompt species distribution shifts resembling those expected from rapid climate change. Links between species distributions, regional climate trends and physiological mechanism are needed to convincingly establish climate-induced species shifts. We examine a 38-year shift (1974-2012) in an elevation ecotone between two closely related ant species, Aphaenogaster picea and A. rudis. Even though A. picea and A. rudis are closely related with North American distributions that sometimes overlap, they also exhibit local- and regional-scale differences in temperature requirements so that A. rudis is more southerly and inhabits lower elevations whereas A. picea is more northerly and inhabits high elevations. We find considerable movement by the warm-habitat species upward in elevation between 1974 and 2012 with A. rudis, replacing the cold-habitat species, A. picea, along the southern edge of the Appalachian Mountain chain in north Georgia, USA. Concomitant with the distribution shifts, regional mean and maximum temperatures remain steady (1974-2012), but minimum temperatures increase. We collect individuals from the study sites and subject them to thermal tolerance testing in a controlled setting and find that maximum and minimum temperature acclimatization occurs along the elevation gradient in both species, but A. rudis consistently becomes physiologically incapacitated at minimum and maximum temperatures 2 °C higher than A. picea. These results indicate that rising minimum temperatures allow A. rudis to move upward in elevation and displace A. picea. Given that Aphaenogaster ants are the dominant woodland seed dispersers in eastern deciduous forests, and that their thermal tolerances drive distinct differences in temperature-cued synchrony with early blooming plants, these climate responses not only impact ant-ant interactions, but might have wide implications for ant-plant interactions. [ABSTRACT FROM AUTHOR]

Aim We hypothesized that mechanisms underlying beta diversity in rivers would differ between gradients where (1) natural stressors result in progressive species turnover with high specificity and (2) anthropogenic stressors result in the loss of specialist taxa thus giving rise to nestedness. Location Great Britain, the Iberian Peninsula and the Himalayan Mountains. Methods We analysed five datasets describing benthic macroinvertebrates sampled along natural (elevation, salinity) and anthropogenic (acidity, metals, land use) stress gradients. Predictions were tested by fitting models relating species richness and beta-diversity components (total, turnover and nestedness dissimilarities) to putative stress intensity (i.e. the degree to which a particular environmental constraint filters species occurrence). Results Stress intensity accounted for most of the variability in species richness ( r2 = 0.64-0.93), which declined with increasing stress. Dissimilarity in community composition between locations increased with the difference in stress intensity for all datasets. For natural stressors, beta-diversity patterns mainly reflected species turnover, whilst for anthropogenic stressors beta diversity mainly reflected nesting of subsets of species as stress intensity increased. Main conclusions Our results support the hypothesis that natural and anthropogenic stressors generate contrasting patterns in beta diversity that arise through different mechanisms. [ABSTRACT FROM AUTHOR]

A controversial issue in ecology and conservation is whether community composition is controlled by niche or dispersal assembly. We assessed the importance of climatic factors and geographic gradients on the distribution of orchid bees in a severely-fragmented and species-rich tropical forest region in Brazil. Orchid-bee males were attracted to 17 different scent baits and collected in 15 forest sites. In total we captured 11,081 bees from 40 species. Climatic variables explained twice as much of the observed variation in the bee species data set as did pure spatial variation. However, most of the climatic explained variation was spatially structured, indicating that the species and the climatic data have a similar spatial arrangement. In fact, part of the observed latitudinal changes in community composition appears to be explained by a concomitant gradient in precipitation seasonality. Similarly, reduced temperatures and a more seasonal precipitation may help to explain the relative distinctiveness of the fauna from some of the westernmost sites. The level of similarity among the sampled sites, although highly variable, decayed both as function of the climatic and geographic distances among these sites. The greatest pairwise dissimilarities in the composition of the orchid-bee fauna were observed among sites 200-300 km from each other, since in many case those sites were more dissimilar in terms of climate than those further apart. It is suggested that global warming and consequent altered climatic regimes will influence the distribution patterns of orchid bees in a region already threatened by deforestation and forest fragmentation. [ABSTRACT FROM AUTHOR]

In 1999, the edited volume Primate Communities presented several studies that examined broad-scale patterns of primate diversity.1 Similar studies were being conducted on nonprimate taxa; advances in data availability and statistical approaches were allowing scientists to investigate a variety of new questions and to reexamine classical questions in novel ways. While such studies on nonprimate taxa have continued at a steady pace, they have only crept forward for primate species (Fig. ). In the intervening time, the field of macroecology (Box 1) rapidly developed and has resulted in several books and the establishment of new research institutes. We suggest that examining primate communities, especially in a macroecological context, is an important line of research for our field to embrace and an area where biological anthropologists can provide major contributions. We review the current state of research, describe new datasets and research tools, and suggest future research directions. [ABSTRACT FROM AUTHOR]

We estimated the latitudinal velocity (km/decade) of northern and southern boundaries of core distributions for 30 woody taxa over the last 16 000 years (biotic velocities) using networks of fossil pollen records, and compared these with climate velocities estimated from CCSM3 simulations. Biotic velocities were faster during periods of rapid temperature change (i.e. 16 to 7 ka) than times of relative stability (i.e. 7 to 1 ka), with a consistent northward movement of northern and southern boundaries. For most taxa, biotic velocities were faster for northern than for southern boundaries between 12 and 7 ka, resulting in expanding distributions. For individual time periods, biotic velocities were as fast or faster than climate velocities calculated using multivariate approaches. These results indicate that climate change paced the rate of distribution shifts in both northern and southern populations while suggesting that northern populations were more sensitive. A similar sensitivity and pacing is expected under 21st century climate change. [ABSTRACT FROM AUTHOR]

Aim Species' distributional responses to cool periods in the Pleistocene appear to have been diverse, but patterns of response are poorly known globally, and the nature of distributional responses to interglacial conditions remains largely unknown. The aim of this contribution is to assess distributional responses of forest bird species to Last Interglacial ( LIG) and Last Glacial Maximum ( LGM) conditions within nine forest regions world-wide, to test whether different regions experienced consistently different types of distributional responses. Location Global. Methods We use ecological niche modelling approaches under an assumption of ecological niche conservatism to assess degrees of fragmentation of species distributions through the LIG-LGM-present transitions. Models trained under present-day conditions were transferred to Pleistocene conditions, and fragmentation of potential distributional areas was assessed using Frag Stats. Results Our results showed four regions to have greater fragmentation at LGM than at LIG or at present; three showed greater connectivity at LGM; and two were equivocal. Main conclusions Our results suggest that the world is a patchwork of regions in which forest species experienced either consistently greater or consistently lesser population subdivision during the alternating cool and warm periods that characterized the Pleistocene. Speciation timing and dynamics should differ dramatically among major regions and biomes if these periods of connection and disjunction translate into speciation opportunity. [ABSTRACT FROM AUTHOR]

Abstract: Concerns about the impacts of climate change loom large among biodiversity scientists. A pressing issue is the role of Protected Area networks under future climate change, because of the shifting of species distributions polewards due to climate warming. In this study we use two techniques in conservation science, first, to estimate the likely impacts on the distributions of mammals and butterflies in Egypt (MaxEnt), and second, to measure the effectiveness of Egypt’s Protected Area network (Zonation). We predict that future climate will have significant effects on species richness and the relative value for conservation of sites in Egypt: some areas will increase in species richness, whilst others will decrease significantly. Currently, the sites of highest relative conservation value are found in the Nile Delta, south-eastern and Sinai regions of Egypt and along the Mediterranean and Red Sea coastlines, with Protected Areas having a higher conservation value than unprotected areas. Under future climate scenarios the relative conservation value of Protected Areas are predicted initially to decline and then gradually increase by the 2080s. It is predicted that many areas, especially the Nile Delta and the southeast, will require extra protection in the future; areas that are currently not protected, but have high species richness and conservation value, may need to be protected to prevent loss of biodiversity. [Copyright &y& Elsevier]

Plant species distributions and transitions between vegetation types are determined by numerous factors, including disturbances such as fire. Documentation of past changes in the distribution and structure of fire-dependent ecosystems is necessary to assess the success of land management in maintaining historic vegetation types. In our study system--longleaf pine (Pinus palustris)-wiregrass (Aristida stricta) savannas and embedded wetlands (i.e., pocosins)--wiregrass is dependent on frequent burning. We used soil carbon (C) isotopes to test for past changes in the abundance of wiregrass and for shifts in the ecotone between savanna and pocosin in four sites at Fort Bragg, North Carolina. Wiregrass has a C4 photosynthetic pathway and therefore produces organic matter enriched in 13C compared to other dominant species in the community that have a C3 photosynthetic pathway. At each of the four sites, we measured profiles of soil δ13C to a depth of 1 m at four locations along the vegetation gradient from upland savannas to lowland pocosins. Surface soil δ13C, which reflects C inputs from current vegetation, did not differ along the gradient despite a decrease in wiregrass cover from savanna, where it is abundant, to pocosin, where it is absent. Enrichment of soil δ13C with depth was indistinguishable from effects of decomposition, indicating that past variation in the abundance and distribution of wiregrass was not detectable in our study sites. Our results suggest that wiregrass currently does not produce, and historically has not produced, enough biomass to influence soil δ13C values along the savanna-pocosin gradient. [ABSTRACT FROM AUTHOR]

The intent of this paper is to facilitate future research of the Solomon Islands ant fauna by providing the first comprehensively researched species inventory in over 75 years. The species list presented here includes the names of all ant species recorded from the islands that are available in the literature together with specimen records from several museum collections and new records from our 2008 Makira field expedition. All the names of described species presented are valid in accordance with the most recent Formicidae classification. In total, the checklist is composed of 237 species and subspecies (including 30 morphospecies) in 59 genera representing nine subfamilies. We report that the recent field expedition added 67 new species records to Makira and 28 new species records to the Solomon Islands. Our research recovered species occurrence records for 32 individual islands and five island groups. The five islands with the highest number of recorded species are: Makira (142 spp.), Guadalcanal (107 spp.), Malaita (70 spp.), Santa Isabel (68 spp.), and Rennell (66 spp.). Based on our results, we discuss the taxonomic composition of the archipelago's ant fauna, which islands are most in need of additional sampling, and the importance of establishing biodiversity baselines before environmental threats such as the invasive ant Wasmannia auropunctata cause irrevocable harm to the native biodiversity. [ABSTRACT FROM AUTHOR]

Background: Understanding the factors that influence microbes' environmental distributions is important for determining drivers of microbial community composition. These include environmental variables like temperature and pH, and higher-dimensional variables like geographic distance and host species phylogeny. In microbial ecology, "specificity" is often described in the context of symbiotic or host parasitic interactions, but specificity can be more broadly used to describe the extent to which a species occupies a narrower range of an environmental variable than expected by chance. Using a standardization we describe here, Rao's (Theor Popul Biol, 1982. https://doi.org/10.1016/0040-5809(82)90004-1, Sankhya A, 2010. https://doi.org/10.1007/s13171-010-0016-3 ) Quadratic Entropy can be conveniently applied to calculate specificity of a feature, such as a species, to many different environmental variables., Results: We present our R package specificity for performing the above analyses, and apply it to four real-life microbial data sets to demonstrate its application. We found that many fungi within the leaves of native Hawaiian plants had strong specificity to rainfall and elevation, even though these variables showed minimal importance in a previous analysis of fungal beta-diversity. In Antarctic cryoconite holes, our tool revealed that many bacteria have specificity to co-occurring algal community composition. Similarly, in the human gut microbiome, many bacteria showed specificity to the composition of bile acids. Finally, our analysis of the Earth Microbiome Project data set showed that most bacteria show strong ontological specificity to sample type. Our software performed as expected on synthetic data as well., Conclusions: specificity is well-suited to analysis of microbiome data, both in synthetic test cases, and across multiple environment types and experimental designs. The analysis and software we present here can reveal patterns in microbial taxa that may not be evident from a community-level perspective. These insights can also be visualized and interactively shared among researchers using specificity's companion package, specificity.shiny., (© 2022. The Author(s).)

The climatic changes of the next decades will modify human and livestock interactions with venomous animals; Some venomous species will disappear in the coming decades; Other venomous species will shift their distributions or increase their geographic ranges invading new countries that may not have specific antivenoms., (© 2022 John Wiley & Sons Ltd.)

Aim: Comprehensive, global information on species' occurrences is an essential biodiversity variable and central to a range of applications in ecology, evolution, biogeography and conservation. Expert range maps often represent a species' only available distributional information and play an increasing role in conservation assessments and macroecology. We provide global range maps for the native ranges of all extant mammal species harmonised to the taxonomy of the Mammal Diversity Database (MDD) mobilised from two sources, the Handbook of the Mammals of the World (HMW) and the Illustrated Checklist of the Mammals of the World (CMW)., Location: Global., Taxon: All extant mammal species., Methods: Range maps were digitally interpreted, georeferenced, error-checked and subsequently taxonomically aligned between the HMW (6253 species), the CMW (6431 species) and the MDD taxonomies (6362 species)., Results: Range maps can be evaluated and visualised in an online map browser at Map of Life (mol.org) and accessed for individual or batch download for non-commercial use., Main Conclusion: Expert maps of species' global distributions are limited in their spatial detail and temporal specificity, but form a useful basis for broad-scale characterizations and model-based integration with other data. We provide georeferenced range maps for the native ranges of all extant mammal species as shapefiles, with species-level metadata and source information packaged together in geodatabase format. Across the three taxonomic sources our maps entail, there are 1784 taxonomic name differences compared to the maps currently available on the IUCN Red List website. The expert maps provided here are harmonised to the MDD taxonomic authority and linked to a community of online tools that will enable transparent future updates and version control., Competing Interests: CONFLICT OF INTEREST The authors declare no competing interests.

Why species are found where they are is a central question in biogeography. The most widely used tool for understanding the controls on distribution is species distribution modelling. Species distribution modelling is now a well-established method in both the theoretical and applied ecological literature. In this special issue we examine the current state of the art in species distribution modelling and explore avenues for including more biological processes in such models. In particular we focus on physiological, demographic, dispersal, competitive and ecological-modulation processes. This overview highlights opportunities for new species distribution model concepts and developments, as well as a statistical agenda for implementing such models. [ABSTRACT FROM AUTHOR]

Diversity assessments are widely used in various fields of knowledge and rely on good estimates of species distribution. There are several methods available to estimate species distribution and the effect of using them is not clearly understood. In this research, we assess the effect of species distributions derived from four geographical distribution estimation methods on derived species richness and phylogenetic diversity (PD). We used the following four most common approaches to determine species geographical distributions: (1) range-wide occurrences are records of presence from databases and museum collections; (2) marginal occurrences are generally expert drawn distributional maps; (3) species distribution modeling (SDM) combines geographic records and environmental data to predict species occurrence; and (4) a combined approach that constrains the statistical modeling predictions by the marginal occurrence distributions. Using these approaches, we estimated richness and PD and their correspondent geographic hotspots for three different analysis resolutions using non-overlapping square windows of 2°, 4°, and 6° across Australia. We also assessed the differences of the resultant geographical distributions for three different spatial resolutions. We found markedly different hotspots when using range-wide occurrences and statistical modeling approaches. Range-wide occurrences resulted in low values of species richness and PD and statistical modeling resulted in high values. The combined and marginal occurrences approaches both had intermediate values, with the combined approach showing a finer level of detail than the marginal occurrences. There is a tendency for species range sizes between methods to converge with decreasing spatial resolution. Even for a relatively well-sampled group such as the Australian marsupials, the range-wide occurrences approach is likely to underestimate the presence of species. Conversely, because SDMs usually do not account for dispersal abilities or biotic interactions, it is likely that species geographical distributions using this approach are overestimated. Depending on the method used, the resultant estimates of diversity may be completely different. Caution is needed when choosing the method to estimate species distribution. [ABSTRACT FROM PUBLISHER]

To further our understanding of invasive species' novel distributions, knowledge of invasive species' relationships with environmental variables at multiple spatial scales is paramount. Here, we investigate which environmental variables and which spatial scales best explain the invasive mute swan's ( Cygnus olor) distribution in southern Ontario (Canada). Specifically we model mute swan distribution changes according to ecologically-relevant spatial scales: average territory size radius, 140 m; median dispersal distance of cygnets, 3,000 m; and average activity distance of males, 8,000 m. For individual spatial scales, global models using variables measured at each particular scale result in the highest Akaike weights, AUC, and Cohen's Kappa values. Yet composite models (models combining variables measured at different scales) elicit the best models, as determined by higher Akaike weights and high AUC and Cohen's Kappa values. Overall, percent water, waterbody perimeter density, temperature, precipitation, and road density are positively correlated with mute swan distribution, while percent forest and elevation are negatively correlated at all scales of analysis. Only percent water and annual precipitation are more influential in determining mute swan distribution at the 3,000 and 8,000 m zone scales than the territory scale. While most species distribution models are performed at a single scale, the results of our study suggest that composite models reflecting a species' ecological needs provide models of better fit with similar, if not better, predictive accuracy. When analyzing species distributions, we also recommend that ecologists consider the scale of the underlying landscape processes and the effect that this may have on their modelling outcomes. [ABSTRACT FROM AUTHOR]

Diatom species distributions on remote islands are influenced by both habitat quality and location. In this study diatom distributions and water quality were explored in the Falkland Islands archipelago with reference to island floras elsewhere, using 28 freshwater sites (small ponds, shallow lowland lakes, upland tarns and several streams). Site water chemistries varied from strongly acid to circum-neutral and from low to high conductivity and water-colour. Dissolved ions co-varied with conductivity and varied strongly between sites and ion ratios indicated a strong influence of sea-salt deposition. Canonical Correspondence Analysis of the diatom and environmental data revealed three groups of sites, (1) high water-colour and low pH, (2) low conductivity and low water-colour, and (3) high conductivity and higher pH. Diatom species frequency abundances were most strongly influenced by water conductivity and pH. Diatom assemblages were composed of both cosmopolitan and regionally endemic Subantarctic species. Water chemistry was a weak predictor of diatom diversity but sites with more regionally endemic species tended also to have more cosmopolitan species. Taxonomic harmonization allowed species comparisons to be made with diatom assemblages on two islands elsewhere, Signy Island (Antarctica) and South Uist (Scottish Outer Hebrides). Detrended Correspondence Analysis of the species data from these three locations strongly discriminated the Signy Island sites and Subantarctic species characterized the Falkland Islands samples. Regionally endemic species groups within the Subantarctic zone were configured by biogeographical controls on dispersal, as well as by habitat selection and water quality. Variance partitioning showed that water chemistry and spatial (location) variables were both highly significant in accounting for similar proportions of unique variance in the combined island-species dataset. Despite overall low diversity, Subantarctic species are an important floral component and need to be incorporated into global freshwater diatom diversity patterns by using species-sensitive and carefully harmonized datasets. [ABSTRACT FROM AUTHOR]

Aim It is a central issue in ecology and biogeography to understand what governs community assembly and the maintenance of biodiversity in tropical rain forest ecosystems. A key question is the relative importance of environmental species sorting (niche assembly) and dispersal limitation (dispersal assembly), which we investigate using a large dataset from diverse palm communities. Location Lowland rain forest, western Amazon River Basin, Peru. Methods We inventoried palm communities, registering all palm individuals and recording environmental conditions in 149 transects of 5 m × 500 m. We used ordination, Mantel tests and indicator species analysis (ISA) to assess compositional patterns, species responses to geographical location and environmental factors. Mantel tests were used to assess the relative importance of geographical distance (as a proxy for dispersal limitation) and environmental differences as possible drivers of dissimilarity in palm species composition. We repeated the Mantel tests for subsets of species that differ in traits of likely importance for habitat specialization and dispersal (height and range size). Results We found a strong relationship between compositional dissimilarity and environmental distance and a weaker but also significant relationship between compositional dissimilarity and geographical distance. Consistent with expectations, relationships with environmental and geographical distance were stronger for understorey species than for canopy species. Geographical distance had a higher correlation with compositional dissimilarity for small-ranged species compared with large-ranged species, whereas the opposite was true for environmental distance. The main environmental correlates were inundation and soil nutrient levels. Main conclusions The assembly of palm communities in the western Amazon appears to be driven primarily by species sorting according to hydrology and soil, but with dispersal limitation also playing an important role. The importance of environmental characteristics and geographical distance varies depending on plant height and geographical range size in agreement with functional predictions, increasing our confidence in the inferred assembly mechanisms. [ABSTRACT FROM AUTHOR]

Bioclimatic envelope models use associations between aspects of climate and species' occurrences to estimate the conditions that are suitable to maintain viable populations. Once bioclimatic envelopes are characterized, they can be applied to a variety of questions in ecology, evolution, and conservation. However, some have questioned the usefulness of these models, because they may be based on implausible assumptions or may be contradicted by empirical evidence. We review these areas of contention, and suggest that criticism has often been misplaced, resulting from confusion between what the models actually deliver and what users wish that they would express. Although improvements in data and methods will have some effect, the usefulness of these models is contingent on their appropriate use, and they will improve mainly via better awareness of their conceptual basis, strengths, and limitations. [ABSTRACT FROM AUTHOR]

Random Forests is frequently used to model species distributions over large geographic areas. Complications arise when data used to train the models have been collected in stratified designs that involve different sampling intensity per stratum. The modeling process is further complicated if some of the target species are relatively rare on the landscape leading to an unbalanced number of presences and absences in the training data. We explored means to accommodate unequal sampling intensity across strata as well as the unbalanced species prevalence in Random Forest models for tree and shrub species distributions in the state of Nevada. For the unequal sampling intensity issue, we tested three modeling strategies: fitting models using all the data, down-sampling the intensified stratum; and building separate models for each stratum. We explored unbalanced species prevalence by investigating the effects of down-sampling the more prevalent response (presence or absence), and by optimizing the cutoff thresholds for declaring a species present. When modeling species presence with stratified data that was collected with different sampling intensities per stratum, we found that neither down-sampling the intensified stratum, nor fitting individual strata models, improved model performance. We also found that balancing the number of presences and absences in a training data set by down-sampling did not improve predictive models of species distributions, and did not eliminate the need to optimize thresholds. We then apply our final choice of model to the full raster layers for Nevada to produce statewide species distribution maps. [Copyright &y& Elsevier]

Abstract: This short paper is centered on hierarchical modeling for problems in spatial and spatio-temporal statistics. It draws its motivation from the interdisciplinary research work of the author in terms of applications in the environmental sciences—ecological processes, environmental exposure, and weather modeling. The paper briefly reviews hierarchical modeling specification, adopting a Bayesian perspective with full inference and associated uncertainty within the specification, while achieving exact inference to avoid what may be uncomfortable asymptotics. It focuses on point-referenced (geo-statistical) and point pattern spatial settings. It looks in some detail at problems involving data fusion, species distributions, and large spatial datasets. It also briefly describes four further examples arising from the author’s recent research projects. [Copyright &y& Elsevier]

The article presents a study which investigates the distribution of understory birds along gradients of distance from soil clay content, streams, and slope in a central Amazonian forest. It says that the dimensionality of species qualitative and quantitative composition to one multivariate axis was reduced using nonmetric multidimensional scaling (NMDS). The result of the study shows that there was a consistency in the distribution patterns of birds in relation to distance from streams.