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Simple Summary It is known that species’ distributions are influenced by several ecological factors. Nonetheless, the geographical scale upon which the influence of these factors is perceived is largely undefined. We assessed the importance of competition in regulating the distributional limits of species at large geographical scales. We studied European Soricidae shrews, because their species have similar diets, and focused on how interspecific competition changes along climatic gradients. We used presence data for the seven most widespread terrestrial species of Soricidae in Europe, gathered from online repositories, European museums, and gridded climate data. Using two different methods, we analysed the correlations between species’ presences, aiming to understand the distinct roles of climate and competition in shaping species’ distributions. Our results support three key conclusions: (i) climate alone does not explain all species’ distributions at large scales; (ii) negative interactions, such as competition, seem to play a strong role in defining species’ range limits, even at large scales; and (iii) the impact of competition on a species’ distribution varies along a climatic gradient, becoming stronger at the climatic extremes. Our conclusions support previous research, highlighting the importance of considering biotic interactions when studying species’ distributions, regardless of geographical scale. Abstract It is known that species’ distributions are influenced by several ecological factors. Nonetheless, the geographical scale upon which the influence of these factors is perceived is largely undefined. We assessed the importance of competition in regulating the distributional limits of species at large geographical scales. We focus on species with similar diets, the European Soricidae shrews, and how interspecific competition changes along climatic gradients. We used presence data for the seven most widespread terrestrial species of Soricidae in Europe, gathered from GBIF, European museums, and climate data from WorldClim. We made use of two Joint Species Distribution Models to analyse the correlations between species’ presences, aiming to understand the distinct roles of climate and competition in shaping species’ distributions. Our results support three key conclusions: (i) climate alone does not explain all species’ distributions at large scales; (ii) negative interactions, such as competition, seem to play a strong role in defining species’ range limits, even at large scales; and (iii) the impact of competition on a species’ distribution varies along a climatic gradient, becoming stronger at the climatic extremes. Our conclusions support previous research, highlighting the importance of considering biotic interactions when studying species’ distributions, regardless of geographical scale.

The species–area relationship (SAR) has been described as one of the few general patterns in ecology. Although there are many types of SAR, here we are concerned solely with the so-called species accumulation curve (SAC). The theoretical basis of this relationship is not well established. Here, we suggest that extreme value theory, also known as the statistics of extremes, provides a theoretical foundation for, as well as functions to fit, empirical species accumulation curves. Among the several procedures in extreme value theory, the appropriate way to deal with the species accumulation curve is the so-called block minima procedure. We first provide a brief description of this approach and the relevant formulas. We then illustrate the application of the block minima approach using data on tree species from a 50 ha plot in Barro Colorado Island, Panama. We conclude by discussing the extent to which the assumptions under which the extreme types theorem occurs are confirmed by the data. Although we recognize limitations to the present application of extreme value theory, we predict that it will provide fertile ground for future work on the theory of SARs and its application in the fields of ecology, biogeography and conservation. info:eu-repo/semantics/publishedVersion

Ecology, biogeography and conservation biology, among other disciplines, often rely on species identity, distribution and abundance to perceive and explain patterns in space and time. Yet, species are not independent units in the way they interact with their environment. Species often perform similar roles in networks and their ecosystems, and at least partial redundancy or difference of roles might explain co-existence, competitive exclusion or other patterns reflected at the community level. Therefore, considering species traits, that is, the organisms’ functional properties that interact with the environment, might be of utmost importance in the study of species relative abundances. Several descriptive measures of diversity, such as the species-area relationship (SAR) and the species abundance distribution (SAD), have been used extensively to characterize the communities and as a possible window to gain insight into underlying processes shaping and maintaining biodiversity. However, if the role of species in a community is better assessed by their functional attributes, then one should also study the SAR and the SAD by using trait-based approaches, and not only taxonomic species. Here we merged species according to their similarity in a number of traits, creating functional units, and used these new units to study the equivalent patterns of the SAR and of the SAD (functional units abundance distributions - FUADs), with emphasis on their spatial scaling characteristics. This idea was tested using data on arthropods collected in Terceira island, in the Azorean archipelago. Our results showed that diversity scales differently depending on whether we use species or functional units. If what determines species communities’ dynamics is their functional diversity, then our results suggest that we may need to revaluate the commonly assumed patterns of species diversity and, concomitantly, the role of the underlying processes. SA was financed by the Fundacao para a Ciencia e a Tecnologia project PTDC/BIA-BIC/5558/2014. LB-A was financed by the Portuguese national funds through FCT-Fundacao para a Ciencia e a Tecnologia, I.P., under the Norma Transitoria-DL57/2016/CP1440/CT0022. info:eu-repo/semantics/publishedVersion

Infrastructures in natural areas are expanding rapidly worldwide. Consequently, roads, power-lines, and wind-farms cause millions of fatalities across several animal groups. Assessing the population impact of these infrastructures requires sound estimates of the total number of fatalities. These estimates can be heavily biased due to differences in searcher efficiency and carcass persistence rates, which may ultimately lead to the incorrect quantification of actual mortality, or to the inadequate prioritization of locations for mitigation. We reviewed 294 studies using carcass surveys conducted worldwide and performed analyses on the effects of variables potentially influencing searcher efficiency and carcass persistence rates. Our analytical review, including the largest number of studies to date, the use of multivariate approaches, and the study weighting by sample size, contradicts some previous findings. Whereas body mass is confirmed as the most important variable accounting for both biases, equally important was the use of dogs in searches, as they increased searcher efficiency for small carcasses, and the taxon of carcasses for persistence, as mammals persisted at higher rates than birds and the latter at higher rates than amphibians. Our results provide little support for previous ideas on the influence of the use of domestic or thawed carcasses on persistence rates. Our findings contribute to synthesizing knowledge on the main factors affecting the two main mortality biases across carcass field experiments, and suggest recommendations for improving survey designs in future studies to minimize the biases identified.

Aim Land-use change is a major threat to biodiversity globally. Roads cause direct mortality and limitation of individual movements, which may isolate populations and affect their viability in the long term. Here we provide the first comprehensive global assessment of the exposure of terrestrial mammalian carnivores to roads using an integrated modelling framework. Location Global. Methods We estimated critical road densities and critical patch sizes for each species based on a spatially explicit model and life-history traits. We calculated the distribution of landscape fragment sizes for each carnivore species by intersecting global road density with each species range. The proportion of a species’ geographical range with fragments below the critical patch size is used as an index of the vulnerability to roads. Results We found that the carnivores expected to be most exposed to roads belong to families Felidae, Ursidae, Mustelidae, Canidae and Procyonidae. Approximately one-third of the species most affected have not been identified by the IUCN as threatened by roads. Our model projects time to extinction that may be as low as one century for some species, such as the endangered Iberian lynx. Species are expected to be more exposed in areas with medium to high road density but, surprisingly, also in areas where road density is relatively low. Hotspots of the number of species locally endangered by roads occur in North America and Asia. Main conclusions Our results suggest the need to reassess the status and threats of those species that have not been previously recognized as strongly affected by roads. Our framework can be applied at different spatial scales, to assess the effects of the development of the road network and inform prioritization schemes for road building, and to identify areas for conservation, and species requiring particular mitigation and restoration measures.

Railway ecology is an emerging discipline. In this review, we focus on what is known today regarding the impacts of railways on wildlife, and on the methods to identify, monitor, and mitigate these impacts. Wildlife-train collisions are the most often reported impact, although railway lines can also represent barriers to animal movement, bisecting populations or reducing wildlife access to resources. Little is known on the impact of habitat loss and fragmentation due to railways alone, or on their disturbance effects, including pollution (noise, chemical, light), and on the potential to provide habitat connectivity or surrogate habitats for native species in degraded landscapes. Molecular techniques are one of the most promising methods to study the impacts of railways, as genetic analyses are useful to identify both population sub-structuring, and to assess the potential restoration of functional connectivity by mitigation measures like wildlife passes, or to estimate effective population sizes. Field work is necessary to provide credible mortality rates, which, combined with computer simulations, can allow for estimations of the impact of mortality on population viability. Studies should ideally have Before-After-Control-Impact designs and be long-term. We need to improve mortality estimates, and to understand how impacts threaten population dynamics. We need to go from local-scale studies (e.g., animals use the underpasses) to landscape-scale (i.e., where to place these underpasses to maximize the connectivity at regional/populational levels). Finally, we need to expand our knowledge on less studied, less charismatic species, and to explore the potential environmental benefits of green practices on railway corridors.

Our main tenet is that biodiversity should be studied as a function of scale. The epitome of a similar approach was that of Mandelbrot in his studies on fractals. Although biodiversity patterns may not necessarily follow the mathematical description of fractals, we argue that much can be learnt if we adopt the perspective of studying biodiversity across scales. A case where the concept of scaling is routinely applied in ecology is the species-area relationship, a relationship describing how the number of species (species richness) changes, i.e. scales, as a function of area. However, the importance of scaling is often neglected in ecology. For instance, it is seldomly applied to another component of diversity, the relative abundances of species, being the latter often described using the proportion of individuals of each species. We exemplify the application of scaling to the species relative abundance with our own work. One of the advantages of studying biodiversity under the framework of scaling is that patterns tend to emerge. These patterns emerge from a myriad of processes and their respective interactions. However, understanding the role of each process individually, or quantifying its role in the community functioning, may be empirically impossible. Thus, we argue from theoretical and practical perspectives, including approaches to conservation problems, that we should concentrate our endeavours on the quantitative description of known patterns, as it is often done in other basic and applied sciences, even if that implies temporarily relegating to a secondary position the detailed analyses of the underlying mechanisms.

Linear infrastructures (e.g. roads, railways or power lines) promote a myriad of negative impacts on wildlife around the world, of which direct mortality is the most visible one. When high mortality rates are found, mitigation measures are often discussed and applied. On the other hand, the lack of mortality is commonly interpreted as evidence of low impact on wildlife. We argue that the lack of mortality may actually mask two pervasive effects of linear infrastructures on animal populations: past massive mortality, causing local extinctions, or strong barrier effects due to the inability or reluctance of individuals to traverse the infrastructure corridor. In order to obtain a sound impact assessment of the linear infrastructures on wildlife, research is needed that integrates long-term mortality data with information on the abundance of the focal species, their genetic patterns and movement behavior. We discuss the implications of these impacts for both infrastructures and landscape management. Keywords: Barrier effect, Fences, Population depletion, Power lines, Railways, Roadkill, Roads, Transportation networks

Unbiased scientific reporting is crucial for data and research synthesis. Previous studies suggest that statistically significant results are more likely to be published and more likely to be submitted to high impact journals. However, the most recent research on statistical significance in relation to journal impact factors in ecological research was published more than two decades ago or addressed a small subset of the literature. Here, we extract p-values from all articles published in 11 journals in 2012 and 2014 across a wide range of impact factors with six journals sampled in both years. Our results indicate that the proportion of statistically significant results increases with rising impact factor. Such a trend can have important consequences for syntheses of ecological data and it highlights the importance of covering a wide range of impact factors when identifying published studies for data syntheses. This trend can also lead to a biased understanding of the probability of true effects in ecology and conservation. We caution against the possible downplaying of non-significant results by either journals or authors.

Linear infrastructures, one of several forms of land-use, are a major driver of biodiversity loss. Roads impact populations at many levels, with direct road mortality and barrier effect contributing to decreased population abundance, higher isolation and subdivision, and therefore to increased extinction risk. In this paper, we compared the effect of road mortality and of the barrier effect on population isolation, persistence and size, and assessed the interaction of these effects with dispersal. We used a spatially explicit, process-based model of population dynamics in landscapes fragmented by varying levels of road density. We modelled a barrier effect independently from road mortality by varying the probability with which individuals avoid crossing roads. Both road mortality and the barrier effect caused population isolation. While road mortality alone had stronger negative effects than the barrier effect without extra mortality, the latter also resulted in decreased population size. Yet, road avoidance could, in some cases, rescue populations from extinction. Populations with a large dispersal distance were more negatively affected as road mortality increased. However, when there was no road mortality they maintained larger sizes than populations with a short dispersal distance. Our results highlight the much higher relative importance of road mortality than the barrier effect for population size and persistence, and the importance of assessing relevant species traits for effective long-term transportation planning and conservation management. Our model can be used in species-specific situations and with real landscape configurations in applications such as conservation planning info:eu-repo/semantics/publishedVersion

Which distribution commonly used to fit a species abundance distribution gives the best fit across several area sizes? We approach this problem by looking at the moments of the distribution and compare these with those the distribution based on empirical data on tree species collected in Barro Colorado Island, Panama. We conclude that no single distribution gives the best fit at all scales.

One of the main tasks when dealing with the impacts of infrastructures on wildlife is to identify hotspots of high mortality so one can devise and implement mitigation measures. A common strategy to identify hotspots is to divide an infrastructure into several segments and determine when the number of collisions in a segment is above a given threshold, reflecting a desired significance level that is obtained assuming a probability distribution for the number of collisions, which is often the Poisson distribution. The problem with this approach, when applied to each segment individually, is that the probability of identifying false hotspots (Type I error) is potentially high. The way to solve this problem is to recognize that it requires multiple testing corrections or a Bayesian approach. Here, we apply three different methods that implement the required corrections to the identification of hotspots: (i) the familywise error rate correction, (ii) the false discovery rate, and (iii) a Bayesian hierarchical procedure. We illustrate the application of these methods with data on two bird species collected on a road in Brazil. The proposed methods provide practitioners with procedures that are reliable and simple to use in real situations and, in addition, can reflect a practitioner’s concerns towards identifying false positive or missing true hotspots. Although one may argue that an overly cautionary approach (reducing the probability of type I error) may be beneficial from a biological conservation perspective, it may lead to a waste of resources and, probably worse, it may raise doubts about the methodology adopted and the credibility of those suggesting it.

Understanding patterns of community structure and the causes for their variation can be furthered by comparative biogeographic analyses of island biotas. We used woody plant data at the local scale to investigate variations in species rarity, alpha, beta, and gamma diversity within and between three islands from the oceanic archipelagoes of Azores, Canaries and Mascarene. We used standardized protocols to sample ten 50 m × 50 m forest plots in each of the three islands with contrasting climate and regional species pools: Terceira (Azores), Tenerife (Canaries), and Reunion (Mascarene Islands). Occupancy frequency distributions and species abundance distributions were used to investigate rarity. The partitioning of beta diversity in a distance-decay framework was used to test for spatial patterns of community composition. Rarity was much more pronounced in the highly diverse islands of Tenerife and Reunion than in the regionally poorer island of Terceira. The number of species rose faster with increasing sample area in both Tenerife and Reunion. The slope of the species rank abundance curve was steeper in Terceira whereas the richer island assemblages approached a lognormal model. Compositional changes according to spatial distance were mostly due to replacement of species in Terceira and Reunion. Our results point to important differences in the community structure of Terceira, which is the less diverse and temperate region in comparison to Tenerife and Reunion which are highly diverse., This research was supported by the ERA-Net Net -Biome research framework, financed through the: Canary Islands Government ACIISI grants SE-12/02 (PO), SE-12/03 (JCC), SE-12/04 (BE), co-financed by FEDER; Portuguese FCT-NETBIOME grant 0003/2011 (PB); French ANR-NETBIOME grant n°11-EBIM-001-01 (CT); Région Reunion council for research activities (DS), Universitéde La Reunion contract DGADD/PE/20120585 (DS). CR, FR and IRA were supported by grants from Fundação da Ciência e Tecnologia - FCT-SFRH/BPD/91357/2012, FCT-PTDC/BIA-BIC/119255/2010, FCT-SFRH/BPD/102804/2014 respectively. MF has been funded by Direcção Regional da Ciência e Tecnologia, DRCT-M3.1.7/F/002/2011 and the Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq (401045/2014-5), Programa Ciência sem Fronteiras; the current MF’s contract is supported by the Universidad de Alcalá. The work of LBD in this manuscript was performed within the scope of the project MOMENTOS (PTDC/BIA-BIC/5558/2014).

Islands harbour evolutionary and ecologically unique biota, which are currently disproportionately threatened by a multitude of anthropogenic factors, including habitat loss, invasive species and climate change. Native forests on oceanic islands are important refugia for endemic species, many of which are rare and highly threatened. Long-term monitoring schemes for those biota and ecosystems are urgently needed: (i) to provide quantitative baselines for detecting changes within island ecosystems, (ii) to evaluate the effectiveness of conservation and management actions, and (iii) to identify general ecological patterns and processes using multiple island systems as repeated ‘natural experiments’. In this contribution, we call for a Global Island Monitoring Scheme (GIMS) for monitoring the remaining native island forests, using bryophytes, vascular plants, selected groups of arthropods and vertebrates as model taxa. As a basis for the GIMS, we also present new, optimized monitoring protocols for bryophytes and arthropods that were developed based on former standardized inventory protocols. Effective inventorying and monitoring of native island forests will require: (i) permanent plots covering diverse ecological gradients (e.g. elevation, age of terrain, anthropogenic disturbance); (ii) a multiple-taxa approach that is based on standardized and replicable protocols; (iii) a common set of indicator taxa and community properties that are indicative of native island forests’ welfare, building on, and harmonized with existing sampling and monitoring efforts; (iv) capacity building and training of local researchers, collaboration and continuous dialogue with local stakeholders; and (v) long-term commitment by funding agencies to maintain a global network of native island forest monitoring plots., We would like to thank all colleagues who supported this work for their inspiration in discussing the importance of island biodiversity monitoring within the project MACDIV (FCT-PTDC/BIABIC/0054/2014). Data were derived from previous projects NETBIOME-MOVECLIM (M2.1.2/F/04/2011/NET), NETBIOME-ISLANDBIODIV (NETBIOME/0003/2011). For the development of this paper the work of CR, MB, AG and IRA was partly supported respectively by grants FCT-SFRH/BPD/91357/2012, FCT-SFRH/BPD/86215/2012, FCT-SFRH/BPD/100017/2014 and FCT-SFRH/BPD/102804/2014. AMCS was supported by a Marie Curie Intra-European Fellowship (IEF 331623 ‘COMMSTRUCT’) and by a Juan de la Cierva Fellowship (IJCI-2014-19502) funded by the Spanish ‘Ministerio de Economía y Competitividad’. MF was funded by the Direcção Regional da Ciência, Tecnologia e Comunicações (DRCT) (M3.1.7/F/002/2011) and by the Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq (401045/2014-5), program Ciência sem Fronteiras funded by the University of Alcalá (Spain). SPR is supported by CNPq/Brazil. LBA’s worked on this manuscript within the project MOMENTOS (PTDC/BIA-BIC/5558/2014). GIMS will be implemented in La Réunion, with the DIVINES project (POE 2014-2020 FEDER) granted to DS and CAP at the University of La Réunion and to BL at the National Park of La Réunion.

© The Author(s) 2017., Species abundance distributions (SAD) are central to the description of diversity and have played a major role in the development of theories of biodiversity and biogeography. However, most work on species abundance distributions has focused on one single spatial scale. Here we used data on arthropods to test predictions obtained with computer simulations on whether dispersal ability influences the rate of change of SADs as a function of sample size. To characterize the change of the shape of the SADs we use the moments of the distributions: the skewness and the raw moments. In agreement with computer simulations, low dispersal ability species generate a hump for intermediate abundance classes earlier than the distributions of high dispersal ability species. Importantly, when plotted as function of sample size, the raw moments of the SADs of arthropods have a power law pattern similar to that observed for the SAD of tropical tree species, thus we conjecture that this might be a general pattern in ecology. The existence of this pattern allows us to extrapolate the moments and thus reconstruct the SAD for larger sample sizes using a procedure borrowed from the field of image analysis based on scaled discrete Tchebichef moments and polynomials., This work was funded by the FCT project MOMENTOS (PTDC/ BIA-BIC/5558/2014). AMCS was supported by a Marie Curie Intra-European Fellowship (IEF 331623 ‘COMMSTRUCT’) and by a Juan de la Cierva Fellowship (IJCI-2014-19502) funded by the Spanish ‘Ministerio de Economía y Competitividad’. IRA was supported by a FCT Fellowship (SFRH/BPD/102804/2014)

Road mortality affects natural populations worldwide. Although the effects of road mortality are often documented, studies assessing the impact of road mortality on the viability of the affected populations are not so common. In fact, road mortality data are often limited to a small number of years from which it is difficult to build statistical models to assess the impact of road mortality on population trends, including the probability of extinction. In the last decades several studies have reported a considerable decline in barn owl (Tyto alba) populations attributed mainly to land use change and to the expansion of the road network to accommodate traffic growth. For instance, road monitoring programs show high road mortality rates ranging from 0.07 owls/km/year to 2.61 owls/km/year. We developed a stochastic, age-structured model to evaluate the impact of road-kills on barn owl populations and their risk of extinction. Using this model we identified the range of parameters that are most likely to apply to a population in southern Portugal and assessed how road mortality has affected this population. Three important results are: the number of individuals of the barn owl population exhibits high intra and inter-annual variability, even an annual road mortality rate of 5% reduces barn owl populations to half of their original size, and probability of extinction increases dramatically when annual road mortality exceeds 30% and it is largely independent of the original population size. Although simulations seem to show that road mortality is still below the values for which there is risk of extinction, we recommend authorities to closely monitor the owls’ numbers temporal trends and to take the necessary measures to reduce road mortality.

In this chapter we provide practical suggestions, together with examples, to identify, monitor and mitigate railway barrier effects on wildlife, as this is considered one of the railways’ greatest impacts. Railways can be both physical and behavioral barriers to wildlife movement, as well as disturbance to populations living close to them. Also, mortality is recognized as an important contribution to the barrier effect. However, the consequences of habitat loss, and fragmentation due to railways alone remain largely unexplored. Barrier effects have mainly been mitigated with wildlife passes, with the effectiveness of this tool being one of the most-studied topics in Railway Ecology. Methods formerly employed to monitor pass usage, such as track beds or video-surveillance, are now being replaced by molecular ones. Among the latter methods, genetic fingerprinting allows individual-based approaches, opening the door to population-scale studies. In fact, genetic sampling allows for the assessment of functional connectivity, which is closely linked to successful reproduction and population viability, variables not necessarily coupled with crossing rates. There is strong evidence that railway verges offer new habitats for generalist species and for opportunistic individuals, a point that deserves to be experimentally explored in order to find wildlife-friendly policies. Preventing animals from crossing (e.g., by fencing), should be reserved for collision hotspots, as it increases barrier effects. Instead, it has been shown that warning signals or pole barriers effectively reduce collisions without increasing barrier effects. In this respect, we argue that computer simulations are a promising field to investigate potential impact scenarios. Finally, we present a protocol to guide planners and managers when assessing barrier effects, with emphasis on monitoring and mitigation strategies.

As societies realise the importance of maintaining biodiversity and, accordingly, acknowledge the need for monitoring, minimizing and compensating the impacts of socioeconomic activities, including transportation, more scientists will be called to address these societal challenges. Railway Ecology is emerging in this context as a relatively new field to identify and provide solutions to the specific environmental problems associated with the building and operation of railways, particularly their impacts on wildlife. This is an interdisciplinary field that uses and draws methods from other disciplines, ranging from ecology and genetics, to statistics and computer simulations. Here, we summarize the guidelines to address railway-related biodiversity conservation problems as they were identified in the several chapters of this book, and recommend lines for future research.

Numerous evolutionary studies have sought to explain the distribution of diversity across the limbs of the tree of life. At the same time, ecological studies have sought to explain differences in diversity and relative abundance within and among ecological communities. Traditionally, these patterns have been considered separately, but models that consider processes operating at the level of individuals, such as neutral biodiversity theory (NBT), can provide a link between them. Here, we compare evolutionary dynamics across a suite of NBT models. We show that NBT can yield phylogenetic tree topologies with imbalance closely resembling empirical observations. In general, metacommunities that exhibit greater disparity in abundance are characterized by more imbalanced phylogenetic trees. However, NBT fails to capture the tempo of diversification as represented by the distribution of branching events through time. We suggest that population-level processes might therefore help explain the asymmetry of phylogenetic trees, but that tree shape might mislead estimates of evolutionary rates unless the diversification process is modeled explicitly.

Roads can have drastic impacts on wildlife populations. Although there is wide recognition of the negative impacts caused by roads and a wealth of practical studies, there is a lack of theoretical work that can be used to predict the impact of road networks or to implement mitigation measures. Here, using Skellam’s diffusion model, we develop analytic and numerical approaches to analyze the impact of road networks on the survival of populations. Our models show that the viability of a population is determined not only by road density but also by the size and shape of patches. Accordingly, we studied the minimum size of a patch to sustain a population with given diffusion and growth parameters. We provide simple formulas to estimate the minimum patch size, and illustrate the importance of shape with square and rectangular patches. Our models also allow the estimation of time to extinction after road construction for a population in a patch smaller than that of the minimum size. Finally, using numerical computations we illustrate how the spatial arrangement of fences strongly affects both the equilibrium density and the spatial distribution of populations, and that not all fence layouts are equally effective. We anticipate that our methods provide a tool to assess the impact of geometrical features of road networks on wildlife and that they can be used to design mitigation measures to prevent the decline and extinction of populations in an anthropogenically disturbed landscape.

This article reviews existing models linking land-use change to biodiversity dynamics, both when native habitats are lost or when the landscape structure of countryside areas is modified. It covers both phenomenological models such as the species–area relationship and process-based models such as source-sink population models.

Copyright © 2012 The Authors. Ecography © 2012 Nordic Society Oikos. Species abundance distributions are an essential tool in describing the biodiversity of ecological communities. We now know that their shape changes as a function of the size of area sampled. Here we analyze the scaling properties of species abundance distributions by using the moments of the logarithmically transformed number of individuals. We find that the moments as a function of area size are well fitted by power laws and we use this pattern to estimate the species abundance distribution for areas larger than those sampled. To reconstruct the species abundance distribution from its moments, we use discrete Tchebichef polynomials. We exemplify the method with data on tree and shrub species from a 50 ha plot of tropical rain forest on Barro Colorado Island, Panama. We test the method within the 50 ha plot, and then we extrapolate the species abundance distribution for areas up to 5 km2. Our results project that for areas above 50 ha the species abundance distributions have a bimodal shape with a local maximum occurring for the singleton classes and that this maximum increases with sampled area size.

Feeley and Silman (1) call our extinction risk estimates (,2) “invalid.” They are not. They are approximations. Ranges of species with >106 individuals are sufficiently large to avoid extinction even under Laurance et al.'s (3) pessimistic scenario, irrespective of range shape. Range shapes of species with

Although fractals have been applied in ecology for some time, multifractals have, in contrast, received little attention. In this article, we apply multifractals to the species-area relationship and species abundance distributions. We highlight two results: first, species abundance distributions collected at different spatial scales may collapse into a single curve after appropriate renormalization, and second, the power-law form of the species-area relationship and the Shannon, Simpson, and Berger-Parker diversity indices belong to a family of equations relating the species number, species abundance, and area through the moments of the species abundance-probability density function. Explicit formulas for these diversity indices, as a function of area, are derived. Methods to obtain the multifractal spectra from a data set are discussed, and an example is shown with data on tree and shrub species collected in a 50-ha plot on Barro Colorado Island, Panama. Finally, we discuss the implications of the multifractal formalism to the relationship between species range and abundance and the relation between the shape of the species abundance distribution and area.

New roads, agricultural projects, logging, and mining are claiming an ever greater area of once-pristine Amazonian forest. The Mil- lennium Ecosystems Assessment (MA) forecasts the extinction of a large fraction of Amazonian tree species based on projected loss of forest cover over the next several decades. How accurate are these estimates of extinction rates? We use neutral theory to estimate the number, relative abundance, and range size of tree species in the Amazon metacommunity and estimate likely tree-species ex- tinctions under published optimistic and nonoptimistic Amazon scenarios. We estimate that the Brazilian portion of the Amazon Basin has (or had) 11,210 tree species that reach sizes >10 cm DBH (stem diameter at breast height). Of these, 3,248 species have population sizes >1 million individuals, and, ignoring possible climate-change effects, almost all of these common species persist under both optimistic and nonoptimistic scenarios. At the rare end of the abundance spectrum, however, neutral theory predicts the existence of 5,308 species with

Introduction To better understand biodiversity scaling, it may be useful to characterize the biodiversity scaling relationships that arise from the neutral perspective. This exercise will help in formulating quantitative null hypotheses for observed biodiversity scaling relationships. Here we use the term biodiversity to refer not only to species richness, but also to relative species abundance, and biodiversity scaling to refer to how patterns of biodiversity change on increasing sampling (spatial) scales. The study of biodiversity includes questions about the spatial dispersion and geographic range of species, relative species abundance, endemism, and beta diversity, the turnover of species across landscapes. A full discussion of all-taxa biodiversity scaling in the context of neutral theory is beyond the scope of the present theory because the theory currently applies only to communities of trophically similar species (a tree community, for example). It is also individual based rather than biomass based. Despite these limitations neutral theory is nevertheless a mechanistic, dynamical theory of community assembly based on fundamental demographic processes (birth, death, dispersal, speciation) – even though its postulated assembly rules are extremely simple. Under current neutral theory, speciation, ecological drift (demographic stochasticity in birth and deaths), and dispersal govern the presence or absence and the abundance of species in communities over local to global scales. Extinction is also critically important, but under neutrality, the extinction rate can be predicted once the other three processes are known. Neutral theory asserts that, to a first approximation, trophically similar species are identical (symmetric) in these vital rates on a per-capita basis. According to the theory, species develop differences in abundance due to demographic stochasticity and accidents of dispersal. Once species become differentiated in abundance, their expected fates diverge. Common species are expected to have longer life spans and to be more persistent members of local communities than rare species.

Arising from F. He & S. P. Hubbell , 368–371 (2011)10.1038/nature09985 . He and Hubbell developed a sampling theory for the species–area relationship (SAR) and the endemics–area relationship (EAR)1. They argued that the number of extinctions after habitat loss is described by the EAR and that extinction rates in previous studies are overestimates because the EAR is always lower than the SAR. Here we show that their conclusion is not general and depends on the geometry of habitat destruction and the scale of the SAR. We also question their critique of the Millennium Ecosystem Assessment estimates, as those estimates are not dependent on the SAR only, although important uncertainties remain due to other methodological issues.