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Research Highlights: This paper integrates disparate research results pertaining to climate change impacts to 12 co-occurring forest tree species and their climatypes such that management options for the ecosystem as a whole become discernible. Background and Objectives: The ecosystem under analysis is the Thuja-Tsuga forest ecosystem, occupying ca. 121,500 km2 in a largely mountainous setting in the interior northwest, USA. Our goal is to present land management options tied directly to climate-change in a straightforward framework for both the current and future generations. Materials and Methods: By merging synecological and genecological concepts in a climatic framework, we simplify complex interactions in a manner that relates directly to climate change impacts. Species and climatype distributions are redefined in terms of mean annual temperature and elevation of forested landscapes. Results: For each 2 °C increase in temperature, plant associations should shift upwards ca. 400 m, provided precipitation remains at or near contemporary levels, which, for this ecosystem, vary between 300 mm and 1450 mm. Management guidelines are developed for (a) selecting climatypes of the species suited to the climate at the leading edge of the migration front, (b) anticipating decline at the trailing edge, and (c) converting climatypes in areas where species should persist. Conclusions: Our results can provide robust strategies for adapting forest management to the effects of climate change, but their effectiveness is dependent on the implementation of global warming mitigation actions.

Despite the global implementation of rock-rubble groyne structures, there is limited research investigating their ecology, much less than for other artificial coastal structures. Here we compare the intertidal ecology of urban (or semi-urban) rock-rubble groynes and more rural natural rocky shores for three areas of the UK coastline. We collected richness and abundance data for 771 quadrats across three counties, finding a total of 81 species, with 48 species on the groynes and 71 species on the natural rocky shores. We performed three-way analysis of variance (ANOVA) on both richness and abundance data, running parallel analysis for rock and rock-pool habitats. We also performed detrended correspondence analysis on all species to identify patterns in community structure. On rock surfaces, we found similar richness and abundance across structures for algae, higher diversity and abundance for lichen and mobile animals on natural shores, and higher numbers of sessile animals on groynes. Rock-pool habitats were depauperate on groynes for all species groups except for sessile animals, relative to natural shores. Only a slight differentiation between groyne and natural shore communities was observed, while groynes supported higher abundances of some ‘at risk’ species than natural shores. Furthermore, groynes did not differ substantially from natural shores in terms of their presence and abundance of species not native to the area. We conclude that groynes host similar ecological communities to those found on natural shores, but differences do exist, particularly with respect to rock-pool habitats.

Plants growing at the edges of their range limits are expected to be particularly sensitive to changes in precipitation and temperature regimes associated with climatic change. However, non-climatic factors are increasingly recognized as important constraints to species’ range expansions. Therefore, we assessed the effects of soil provenance with respect to the alpine treeline on the germination, growth, and survival of Engelmann spruce (Picea engelmannii) seedlings. Seedlings were grown under controlled conditions in a growth chamber and greenhouse for ninety days in soils collected from four treeline ecotones in the Canadian Rocky Mountains. By controlling seed source and climatic conditions, and eliminating competition and predation, we attribute differences in seedling viability to soil properties that differed across elevation zones and individual treeline sites. Overall, alpine soils originating from beyond the species’ current elevational range were least amenable to growth, and there was some indication of reduced germination and survival in high-elevation soils. Forest soils, which were coarser and more nutrient rich, hosted seedlings with greater above- and below-ground biomass. Thus, the physical and chemical characteristics of alpine soils in our study region may constrain future treeline expansion, underscoring the importance of incorporating soil properties when considering species’ distributions under climate change.

Background and Aims: How well plants reproduce near their geographic range edge can determine whether distributions will shift in response to changing climate. Reproduction at the range edge can be limiting if pollinator scarcity leads to pollen limitation, or if abiotic stressors affect allocation to reproduction. For many animal-pollinated plants with expanding ranges, the mechanisms by which they have overcome these barriers are poorly understood., Methods: In this study, we examined plant-pollinator interactions hypothesized to impact reproduction of the black mangrove, Avicennia germinans, which is expanding northward in coastal Florida, USA. We monitored insects visiting A. germinans populations varying in proximity to the geographic range edge, measured the pollen loads of the most common insect taxa and pollen receipt by A. germinans stigmas, and quantified flower and propagule production., Key Results: We found that despite an 84 % decline in median floral visits by insects at northernmost versus southernmost sites, range-edge pollen receipt remained high. Notably, local floral visitor assemblages exhibited substantial turnover along the study's latitudinal gradient, with large-bodied bees and hover flies increasingly common at northern sites. We also observed elevated flower production in northern populations and higher per capita reproductive output at the range edge. Furthermore, mean propagule mass in northern populations was 18 % larger than that from the southernmost populations., Conclusions: These findings reveal no erosion of fecundity in A. germinans populations at range limits, allowing rapid expansion of mangrove cover in the region. These results also illustrate that substantial turnover in the assemblage of flower-visiting insects can occur at an expanding range edge without altering pollen receipt., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Policy makers require high-level summaries of biodiversity change. However, deriving such summaries from raw biodiversity data is a complex process involving several intermediary stages. In this paper, we describe an operational workflow for generating annual estimates of species occupancy at national scales from raw species occurrence data, which can be used to construct a range of policy-relevant biodiversity indicators. We describe the workflow in detail: from data acquisition, data assessment and data manipulation, through modelling, model evaluation, application and dissemination. At each stage, we draw on our experience developing and applying the workflow for almost a decade to outline the challenges that analysts might face. These challenges span many areas of ecology, taxonomy, data science, computing and statistics. In our case, the principal output of the workflow is annual estimates of occupancy, with measures of uncertainty, for over 5000 species in each of several defined 'regions' (e.g. countries, protected areas, etc.) of the UK from 1970 to 2019. This data product corresponds closely to the notion of a species distribution Essential Biodiversity Variable (EBV). Throughout the paper, we highlight methodologies that might not be applicable outside of the UK and suggest alternatives. We also highlight areas where the workflow can be improved; in particular, methods are needed to mitigate and communicate the risk of bias arising from the lack of representativeness that is typical of biodiversity data. Finally, we revisit the 'ideal' and 'minimal' criteria for species distribution EBVs laid out in previous contributions and pose some outstanding questions that should be addressed as a matter of priority. Going forward, we hope that this paper acts as a template for research groups around the world seeking to develop similar data products., (© 2023 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.)

Functional traits offer a promising avenue to improve predictions of species range shifts under climate change, which will entail warmer and often drier conditions. Although the conceptual foundation linking traits with plant performance and range shifts appears solid, the predictive ability of individual traits remains generally low. In this review, we address this apparent paradox, emphasizing examples of woody plants and traits associated with drought responses at the species' rear edge. Low predictive ability reflects the fact not only that range dynamics tend to be complex and multifactorial, as well as uncertainty in the identification of relevant traits and limited data availability, but also that trait effects are scale- and context-dependent. The latter results from the complex interactions among traits (e.g. compensatory effects) and between them and the environment (e.g. exposure), which ultimately determine persistence and colonization capacity. To confront this complexity, a more balanced coverage of the main functional dimensions involved (stress tolerance, resource use, regeneration and dispersal) is needed, and modelling approaches must be developed that explicitly account for: trait coordination in a hierarchical context; trait variability in space and time and its relationship with exposure; and the effect of biotic interactions in an ecological community context., (© 2023 The Authors New Phytologist © 2023 New Phytologist Foundation.)

Abstract: Treeline advance has occurred throughout the twentieth century in mountainous regions around the world; however, local variation and temporal lags in responses to climate warming indicate that the upper limits of some treelines are not necessarily in climatic equilibrium. These observations suggest that factors other than climate are constraining tree establishment beyond existing treelines. Using a seed addition experiment, we tested the effects of seed availability, predation and microsite limitation on the establishment of two subalpine tree species (Picea engelmannii and Abies lasiocarpa) across four treelines in the Canadian Rocky Mountains. The effect of vegetation removal on seedling growth was also determined, and microclimate conditions were monitored. Establishment limitations observed in the field were placed in context with the effects of soil properties observed in a parallel experiment. The seed addition experiment revealed reduced establishment with increasing elevation, suggesting that although establishment within the treeline ecotone is at least partially seed limited, other constraints are more important beyond the current treeline. The effects of herbivory and microsite availability significantly reduced seedling establishment but were less influential beyond the treeline. Microclimate monitoring revealed that establishment was negatively related to growing season temperatures and positively related to the duration of winter snow cover, counter to the conventional expectation that establishment is limited by low temperatures. Overall, it appears that seedling establishment beyond treeline is predominantly constrained by a combination of high soil surface temperatures during the growing season, reduced winter snowpack and unfavourable soil properties. Our study supports the assertion that seedling establishment in alpine treeline ecotones is simultaneously limited by various climatic and nonclimatic drivers. Together, these factors may limit future treeline advance in the Canadian Rocky Mountains and should be considered when assessing the potential for treeline advance in alpine systems elsewhere [ABSTRACT FROM AUTHOR]

SUMMARY: In many developing countries, high rates of deforestation and biodiversity loss make conservation efforts urgent. Improving existing land-use plans can be an option for enhancing biodiversity conservation. We showcase an approach to enhancing an existing forest land-use plan using widely available data and spatial tools, focusing on Argentina's Southern Yungas ecoregion. We mapped the distribution of wilderness areas and species and habitats of conservation concern, assessed their representation in the land-use plan and quantified potential changes in habitat availability and forest connectivity. Wilderness comprised 48% of the study area, and the highest concentrations of elements of conservation concern were in the north. In the current land-use plan, wilderness areas often occur in regions where logging and grazing are allowed, and a large proportion of the forest with the highest conservation value (43%) is under some level of human influence. Furthermore, we found that deforestation being legally allowed in the land-use plan could reduce forest connectivity and habitat availability substantially. We recommend updating the current land-use plan by considering human influence and elements of conservation concern. More broadly, we demonstrate that widely available spatial datasets and straightforward approaches can improve the usefulness of existing land-use plans so that they more fully incorporate conservation goals. [ABSTRACT FROM AUTHOR]

Climate warming has been proposed as the main cause of the recent range shifts seen in many species. Although species' thermal tolerances are thought to play a key role in determining responses to climate change, especially in ectotherms, empirical evidence is still limited. We investigate the connection between species' thermal tolerances, elevational range and shifts in the lower elevational limit of dung beetle species (Coleoptera, Aphodiidea) in an upland region in the northwest of England. We measured thermal tolerances in the laboratory, and used current and historical distribution data to test specific hypotheses about the area's three dominant species, particularly the species most likely to suffer from warming: Agollinus lapponum. We found marked differences between species in their minimum and maximum thermal tolerance and in their elevational range and patterns of abundance. Overall, differences in thermal limits among species matched the abundance patterns along the elevation gradient expected if distributions were constrained by climate. Agollinus lapponum abundance increased with elevation and this species showed lower maximum and minimum thermal limits than Acrossus depressus, for which abundance declined with elevation. Consistent with lower tolerance to high temperature, we recorded an uphill retreat of the low elevation limit of A. lapponum (177 m over 57 yr) in line with the increase in summer temperature observed in the region over the same period. Moreover, this species has been replaced at low and mid‐elevations by the other two warm‐tolerant species (A. depressus and Agrilinus ater). Our results provide empirical evidence that species' thermal tolerance constrains elevational ranges and contributes to explain the observed responses to climate warming. A mechanistic understanding of how climate change directly affects species, such as the one presented here, will provide a robust base to inform predictions of how individual species and whole assemblages may change in the future. [ABSTRACT FROM AUTHOR]

Distributions of taxa across time and space are central to understanding biodiversity and biotic change, yet currently available occurrence data, drawn from biodiversity specimen records and observational datasets, are often insufficient to answer many driving questions. Records of “associated taxa,” taxa co-occurring with a specimen at the time and place of collection, have the potential to fill data gaps and expand the spatiotemporal scope of current occurrence records. I developed a method to extract associated taxon records from 84,328 digitized specimen records and examined the potential of these data to improve the quantity and quality of existing species occurrence data. Adding associated taxon records increased the size of the test dataset by 18.5%, spanned multiple decades (1937-2016), and potentially extended the known range of 217 taxa in Florida and up to 1500 taxa in the United States, demonstrating the capacity of these records to deepen our understanding of changes in the distributions of taxa on Earth. These results suggest that increased attention to documenting associated taxa could be a promising way to maximize the impact of every collecting event. [ABSTRACT FROM AUTHOR]

The use of species distribution as a climate proxy for ecological forecasting is thought to be acceptable for invasive species. Kudzu (Pueraria montana var. lobata) is an important invasive whose northern distribution appears to be limited by winter survival; however, kudzu’s cold tolerance thresholds are uncertain. Here, we used biogeographic evidence to hypothesize that exposure to − 20 °C is lethal for kudzu and thus determines its northern distribution limit. We evaluated this hypothesis using survival tests and electrolyte leakage to determine relative conductivity, a measure of cell damage, on 14 populations from eastern North America. Relative conductivity above 36% was lethal. Temperatures causing this damage averaged − 19.6 °C for northern and − 14.4 °C for southern populations, indicating kudzu acclimates to winter cold. To assess this, we measured relative conductivity of above- and belowground stems, and roots collected throughout the winter at a kudzu population in southern Ontario, Canada. Consistent with acclimation, the cold tolerance threshold of aboveground stems at the coldest time of year was − 26 °C, while stems insulated from cold extremes survived to − 17 °C—colder than the survival limits indicated by kudzu’s biogeographic distribution. While these results do not rule out alternative cold limitations, they indicate kudzu can survive winters north of its current distribution. For kudzu, biogeography is not a proxy for climatic tolerance and continued northward migration is possible. Efforts to limit its spread are therefore prudent. These results demonstrate that physiological constraints inform predictions of climate-related changes in species distribution and should be considered where possible. [ABSTRACT FROM AUTHOR]

Efforts to understand population dynamics and identify high-quality habitat require information about spatial variation in demographic parameters. However, estimating demographic parameters typically requires labor-intensive capturerecapture methods that are difficult to implement over large spatial extents. Spatially explicit integrated population models (IPMs) provide a solution by accommodating spatial capture-recapture (SCR) data collected at a small number of sites with survey data that may be collected over a much larger extent. We extended the spatial IPM framework to include a spatio-temporal point process model for recruitment, and we applied the model to 4 yr of SCR and distancesampling data on Canada Warblers (Cardellina canadensis) near the southern extent of the species' breeding range in North Carolina, USA, where climate change is predicted to cause population declines and distributional shifts toward higher elevations. To characterize spatial variation in demographic parameters over the climate gradient in our study area, we modeled density, survival, and per capita recruitment as functions of elevation. We used a male-only model because males comprised >90% of our point-count detections. Apparent survival was low but increased with elevation, from 0.040 (95% credible interval [CI]: 0.0032-0.12) at 900 m to 0.29 (95% CI: 0.16-0.42) at 1,500 m. Recruitment was not strongly associated with elevation, yet density varied greatly, from <0.03 males ha-1 below 1,000 m to >0.2 males ha-1 above 1,400 m. Point estimates of population growth rate were <1 at all elevations, but 95% CIs included 1. Additional research is needed to assess the possibility of a long-term decline and to examine the effects of abiotic variables and biotic interactions on the demographic parameters influencing the species' distribution. The modeling framework developed here provides a platform for addressing these issues and advancing knowledge about spatial demography and population dynamics. [ABSTRACT FROM AUTHOR]

Movement is considered an essential process in shaping the distributions of species. Nevertheless, most species distribution models (SDMs) still focus solely on environment-species relationships to predict the occurrence of species. Furthermore, the currently used indirect estimates of movement allow to assess habitat accessibility, but do not provide an accurate description of movement. Better proxies of movement are needed to assess the dispersal potential of individual species and to gain a more practical insight in the interconnectivity of communities. Telemetry techniques are rapidly evolving and highly capable to provide explicit descriptions of movement, but their usefulness for SDMs will mainly depend on the ability of these models to deal with hitherto unconsidered ecological processes. More specifically, the integration of movement is likely to affect the environmental data requirements as the connection between environmental and biological data is crucial to provide reliable results. Mobility implies the occupancy of a continuum of space, hence an adequate representation of both geographical and environmental space is paramount to study mobile species distributions. In this context, environmental models, remote sensing techniques and animal-borne environmental sensors are discussed as potential techniques to obtain suitable environmental data. In order to provide an in-depth review of the aforementioned methods, we have chosen to use the modelling of fish distributions as a case study. The high mobility of fish and the often highly variable nature of the aquatic environment generally complicate model development, making it an adequate subject for research. Furthermore, insight into the distribution of fish is of great interest for fish stock assessments and water management worldwide, underlining its practical relevance. [ABSTRACT FROM AUTHOR]

Plant geography seeks to describe the patterns of species distributions and understand the underlying mechanisms. The foundation of the field is attributed to Alexander von Humboldt following the broad-scale insights he gained on his explorations of the New World two centuries ago. Today, in the age of "Big Data," advances in methods and data availability allow us to better assess the complex drivers of species distributions. In this essay, we give an overview of the relevant legacy of Humboldt in the field of plant geography. Comparing the foremost insights and approaches of Humboldt's time and of today, we highlight areas in which major changes have taken place and areas in which Humboldt's approach is still relevant. We present advances in the description and understanding of plant geography, which have changed our entire worldview to a much more dynamic one. Further, we present some of the outstanding challenges of the field, and how solving them requires going back to the "Humboldtian" approach to science, i.e., combining precise, quantitative empirical studies with a holistic approach. Finally, we discuss how our recognition of the planetary impact of humans in the Anthropocene means that much of our research is no longer exclusively driven by curiosity, but also by the societal need to make predictions of ecosystem responses to environmental change. There is thus a strong need for combining quantitative empiricism with a holistic perspective to address the complex challenges of the current epoch. [ABSTRACT FROM AUTHOR]

Abiotic conditions have long been considered essential in structuring freshwater macroinvertebrate communities. Ecological drift, dispersal and biotic interactions also structure communities, and although these mechanisms are more difficult to detect, they may be of equal importance in natural communities. Here, we hypothesized that in 10 naturally replicated headwater streams in eastern Switzerland, locally dominant amphipod species would be associated with differences in environmental conditions. We conducted repeated surveys of amphipods and used a hierarchical joint species distribution model to assess the influence of different drivers on species co-occurrences. The species had unique environmental requirements, but a distinct spatial structure in their distributions was unrelated to habitat. Species co-occurred much less frequently than predicted by the model, which was surprising because laboratory and field evidence suggests they are capable of coexisting in equal densities. We suggest that niche preemption may limit their distribution and that a blocking effect related to the specific linear configuration of streams determines which species colonizes and dominates a given stream catchment, thus suggesting a new solution a long-standing conundrum in freshwater ecology. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To evaluate how biogeographical and ecological processes influenced species distributions and community assembly in a continental rain forest flora with mixed biogeographical origins. Location: Continental Australia. Methods: We identified 795 species with Sahul ancestry (Australian rain forest flora of Gondwanan origin) and 604 species with Sunda ancestry (rain forest plant lineages of Indo‐Malaysian origin) from a total of 1,872 free‐standing Australian woody rain forest taxa. We then compared the distribution of Sunda to Sahul species in relation to variation in species richness and phylogenetic endemism at continental scale, and local species distributions in available plot data from the Tropics (Cape York and the Australian Wet Tropics in northern Queensland) and subtropics (Nightcap‐Border Ranges, Washpool and Dorrigo, in northern New South Wales). We compared the dispersal and persistence characteristics, and key functional traits (leaf size, fruit size, wood density and maximum height at maturity) of the Sunda and Sahul components of the continental rain forest flora. The influence of climate (temperature) and local environmental (altitude) factors in driving fine‐scale distributional patterns was evaluated. Results: Sunda rain forest species richness decreased with increasing latitude but maintained high levels of endemism, including in the south. Sunda species traits suggest more efficient dispersal and faster growth than Sahul lineages. Resprouting (persistence) was less evident in species with Sunda than Sahul ancestry. We show that Sunda lineage distributions were influenced by interacting environmental and climatic factors, as well as historical contingencies. Main conclusions: Efficient dispersal and relatively fast growth likely facilitated the establishment and spread of Sunda lineages in Australia. However, the Sunda invasion was resisted in stable, saturated communities of Sahul lineages, and in the temperate south where climate acted as a strong filter. The results highlight the importance of integrating historical biogeography and contemporary ecological processes to study continental‐scale rain forest distribution and assembly. [ABSTRACT FROM AUTHOR]

Abstract: Aim: Recognition that statistical models do not always reliably predict habitat suitability under future climate scenarios is leading increasingly to explicit incorporation of the physiological constraints that underlie species’ distributions into spatially explicit predictions. However, computational intensity constrains the use of high‐resolution, process‐explicit models. We examined whether geostatistical analysis can effectively interpolate a biophysical model, reducing the computational investment typically required for using mechanistic methods to inform physiological predictions. Location: New Zealand [40°40′00″ S 174°00′00″ E]. Methods: We used a spatially explicit, mechanistic microclimate model to predict hourly temperatures at five soil depths under two scenarios of climate warming. Using the predicted soil temperatures as input to a biophysical model of temperature‐dependent embryonic development, we estimated incubation temperatures and corresponding hatchling sex ratios for tuatara, a reptile with temperature‐dependent sex determination, at a submetre horizontal spatial resolution. We then applied ordinary kriging, a robust method of geostatistical interpolation, to estimate predictions throughout the full extent of our study location, an additional 480,000+ microsites, and validated the interpolation against an independent set of predictions. Results: Ordinary kriging accurately predicted spatial variability in incubation temperatures. Mean predictions were similar between methods, and error in the geospatial model generally decreased with increasing soil depth. Error was higher for the geospatial model of the ‘maximum warming’, compared with the ‘minimum warming’, scenario of climate change. Main conclusions: Our results show that ordinary kriging can be a reliable method for interpolating variability in high‐resolution predictions. However, the effects of error on the accuracy of interpolated predictions will become more severe as values approach a physiological threshold, such as the minimum and maximum incubation temperatures that result in extreme sex ratio bias. For distribution models, the widths of geographic areas predicted to be suitable for, in this case, maintaining balanced sex ratios, compared to those predicted to be unsuitable, may be narrower than in reality. [ABSTRACT FROM AUTHOR]

Abstract: Charismatic invertebrates are popular subjects for citizen science but it is harder to engage the public in research on animals that are perceived as dangerous. Many successful citizen science projects exist in North America and Europe, but with the increased use of new technologies and social media, there is a greater capacity to expand citizen science to less developed regions. Baboon spiders are African members of the tarantula family. They are threatened by habitat loss and illegal harvesting for the pet trade, and conservation efforts are hampered by a lack of knowledge on their ecology. Here, we describe the Baboon Spider Atlas, a project combining traditional research with citizen science to map the diversity and distributions of baboon spiders (Araneae: Theraphosidae) in Southern Africa. Our project embraces the ‘fear factor’ associated with spiders to obtain photographic records from the public. The Baboon Spider Atlas has assembled the largest database of information on baboon spiders in Southern Africa and is providing novel insights into their biology. Distribution ranges have been extended and potential new species discovered. Preliminary results suggest that their distribution may be limited more by cold, wet climatic conditions than hot, dry conditions. Records for wandering adult females and immatures highlight a previously undocumented behaviour and challenges the notion that baboon spiders are sedentary animals. Ultimately, the project is generating the data needed for effective conservation and motivating further research that will provide a better understanding of baboon spider biology. [ABSTRACT FROM AUTHOR]

Abstract: A key challenge to understanding microbiomes and their role in ecological processes is contextualizing their effects on host organisms, particularly when faced with environmental stress. One influential theory, the Stress Gradient Hypothesis, might predict that the frequency of positive interactions increases with stressful conditions such that microbial taxa would mitigate harmful effects on host performance. Yet, equally plausible is that microbial taxa could exacerbate these effects. Here, we introduce the Mitigation–Exacerbation Continuum as a novel framework to conceptualize microbial mediation of stress. We (1) use this continuum to quantify microbial mediation of stress for six plant species and (2) test the association between these continuum values and natural species' abundance. We factorially manipulated a common stress (allelopathy) and the presence of soil microbes to quantify microbial effects in benign and stressed environments for two critical early life‐history metrics, seed germination and seedling biomass. Although we found evidence of both mitigation and exacerbation among the six species, exacerbation was more common. Across species, the degree of microbial‐mediated effects on germination explained >80% of the variation of natural field abundances. Our results suggest a critical role of soil microbes in mediating plant stress responses, and a potential microbial mechanism underlying species abundance. [ABSTRACT FROM AUTHOR]

Spatial genetic structure in plants can be affected by continuity of geographical distribution, cultivation history, pollination and seed dispersal mechanisms. Here, we examined the relative effects of these factors on the genetic structure of Agave palmeri and A. parryi, which share similar pollination syndromes and seed dispersal mechanisms but differ in the continuity of their distributions and cultivation history. Agave parryi has a patchy distribution and was cultivated by Native Americans, whereas A. palmeri has a more continuous distribution and no documented history of cultivation. We sampled populations of each species in their North American ranges, genotyped individuals with microsatellite loci and analysed patterns of genetic structure. No genetic structuring was detected in A. palmeri, but A. parryi formed three distinct genetic clusters, corresponding to geographical locations. One genetic cluster of A. parryi contained populations from lower elevations and had lower levels of genetic diversity, probably indicating anthropogenic origins. We conclude that continuity of distribution, pollinators and cultivation history all may affect patterns of genetic connectivity. [ABSTRACT FROM AUTHOR]

Butternut trees dying from a canker disease were first reported in southwestern Wisconsin in 1967. Since then, the disease has caused extensive mortality of butternut throughout its North American range. The objectives of this study were to quantify changes in butternut populations and density across its range and identify habitat characteristics of sites where butternut is surviving in order to locate regions for potential butternut restoration. The natural range of butternut ( Juglans cinerea L.) extends over a large region of eastern N. America encompassing New Brunswick south to North Carolina, north to Minnesota, and southwest to Missouri. Despite the species' large range, it is typically not a common tree, comprising a relatively minor component of several different forest types. We evaluated change in butternut abundance and volume from current and historic data from 21 states in the eastern United States. We related abundance and volume at two time periods to a suite of ecological and site factors in order to characterize site conditions where butternut survived. We also assessed the current level of butternut mortality across its range. Since the 1980s, the number of butternut trees and butternut volume have decreased by 58% and 44%, respectively, across its US range. Substantial relative decreases in tree numbers and volume occurred in most ecoregion sections. Five environmental variables were found to be significant predictors of butternut presence. The potential impacts of butternut canker are particularly acute as the canker pathogen invasion pushes a rare tree species toward extinction, at least at a local scale. Based on the results presented here, large-diameter maple/beech/birch stands in dry, upland sites in eastern Minnesota, western Wisconsin, and upstate New York appear to offer the most favorable conditions for butternut growth and survival and thus may be the best stands for planting resistant butternut trees. [ABSTRACT FROM AUTHOR]

Taxonomic relationships in genus Berylmys (B. bowersi, B. mackenziei, B. manipulus, B. berdmorei) have traditionally been ambiguous and made difficult by their geographically disjunct and scattered populations. Several specimens held in museum collections are still of unknown or disputed species assignations. Nor have cranial characters in this genus been tested for significance in variance or for usefulness in separating species. Appropriate species identifications are important for any museum-based study of phylogeny, phylogeography, population biology, functional morphology, or conservation. This study tested diagnostic characters and species assignments on one-hundred two specimens of Berylmys housed in American Museum of Natural History (AMNH), Smithsonian Museum of Natural History (NMNH), and Field Museum of Natural History (FMNH) collections. Discriminant function (DFA), principal components (PCA), and linear regression were used to analyze sixteen morphometric measurements. DFA correctly assigned >90% of specimens to their predefined species group. Length of palate (PL) and auditory bulla (LAB), length (RL) and depth of rostrum (RD), and breadth of incisive foramina (BIF) were the best discriminators among species. Six specimens of B. bowersi were re-classified as B. mackenziei, and two B. mackenziei were re-classifed as B. bowersi. One specimen of B. bowersi, of unknown locality, is indicative of Malaysian affinity under DFA. [ABSTRACT FROM AUTHOR]

Microclimatic conditions have a strong influence on the distribution of vascular epiphytes, among which orchids often occur in sunnier and more drought-prone situations than ferns. However, very few studies have looked at the distribution of ferns and orchids in Australian tropical rainforests. By using transmitted light measurements at the locations of individual epiphytes and vapour pressure deficit from the canopy and base of host trees, we were able to determine the patterns of light and humidity in the rainforest environment, and the responses of ferns and orchids to variation in the physical environments. We surveyed five sites, ranging from 800 to 1180 m in elevation in the lower montane rainforests of north-east Australia. Data loggers recorded the vapour pressure deficit ( VPD) at the forest floor and canopy of each site. Light was correlated with height within the host tree and VPD differed significantly over position in the host tree and elevation. There was a strong partitioning of taxonomic groups over the light and VPD gradients. Orchids occurred in environments that had higher mean light levels and mean daily maximum VPD (27% and 0.43 kPa, respectively) than ferns (21% and 0.28 kPa). There was also strong microclimatic partitioning of species within taxonomic groups, suggesting that microclimatic factors play an important role in the realized niche spaces of epiphytes within the tropical Australian rainforest. Thus, the tested ecological generalizations made on tropical rainforest epiphytes apply in Australia. [ABSTRACT FROM AUTHOR]

Atlas data provide biodiversity information at a relatively fine spatial grain over a broad spatial extent and, increasingly, at multiple points in time, which make them invaluable for understanding processes that affect species distributions over time. The effect of survey effort on species detection has long been appreciated and Atlases typically include survey standards and records of effort, but challenges remain in analysing Atlas data that have not been collected using a repeated sampling protocol designed to correct for imperfect detection., We developed a single-visit dynamic occupancy model to quantify the effects of climatic and land-use drivers on local species extinction and colonization while accounting for imperfect detection using repeat Atlas data. We evaluated model stability using data simulated under alternative scenarios and, ultimately, applied the model to empirical data for Canada warbler Cardellina canadensis, a wide-spread species exhibiting a long-term population decline., At sample sizes that are realistic for many Atlases ( n = 1000-10 000 independent survey blocks), our models produced unbiased estimates of detection, occupancy, colonization and extinction parameters. Slope estimates for explanatory covariates were somewhat less stable than overall occupancy, colonization and extinction rates, with covariate effects being sensitive to the total number of, and relationships among, explanatory variables., In comparison to other analyses of Canada warbler distributions that indicated minor changes over time, our approach identified a widespread decline in occupancy probability across New York, consistent with the broader population trend, particularly in the areas where it was initially more likely to occur., Synthesis and applications. A single-visit dynamic occupancy model is a novel method for analysing common, ecologically valuable datasets, such as Atlases, that lack repeated sampling necessary to correct for imperfect detection using alternative multi-season occupancy modelling approaches. As a result, using this method can improve understanding of species distributions and factors that shape them over time, thereby providing more accurate information to guide conservation and management. [ABSTRACT FROM AUTHOR]

Understanding the drivers of stream macroinvertebrate distribution patterns-the most diverse animal group in freshwater ecosystems-is a major goal in freshwater biogeography. Climate and topography have been shown to explain species' distributions at continental scales, but the contribution of natural and anthropogenically altered streamflow is often omitted in large-scale analyses due to the lack of appropriate data. We test how macroinvertebrate occurrences can be linked to streamflow observations and evaluate the relative importance of streamflow regimes and water use for macroinvertebrate occurrences from 19 orders across Europe. We first paired species sampling locations with hydrological gauging stations considering 5 combinations of the geographic distance and difference in flow accumulation (upstream contributing area). We then used Generalized Linear Models to assess the influence of the streamflow regime, simulated water use, and climate and topography on the occurrence of macroinvertebrates. The pairing method that assigned species records to the closest gauging station in terms of both distance and flow accumulation performed best. Most of the species studied occurred preferentially in river habitats with low mean annual streamflow and streamflow variability, high winter streamflow, and low levels of water withdrawals for irrigation or manufacturing. We conclude that flow accumulation is a useful proxy to evaluate the proximity of species records to gauging stations, omitting species records that do not belong to a given stream reach. The strong contribution of streamflow and water use indicators on macroinvertebrate occurrences underline their importance for yielding robust occurrence estimates. [ABSTRACT FROM AUTHOR]

It is commonly assumed that the geographical distributions of plants are governed mainly by abiotic variables. However, interactions with other organisms, such as pollinators, also have the potential to influence plant distributions. To investigate this, we developed niche models for 32 plant taxa that have specialized pollination systems and which are native to a biodiversity hotspot (South Africa). We found that the distributions of these taxa are best explained by a combination of biotic (pollinators) and abiotic factors, rather than by abiotic factors alone. For approximately 66% of these plant taxa, pollinator distributions were the factor that provided the best predictor of their niches. Furthermore, co-occurrence of these plants and their pollinators was generally not explained solely by shared abiotic niches, and thus probably reflects broad-scale positive ecological interactions. These results are consistent with the proposal that pollinator distributions may constrain plant distributions and highlight the general potential for species distributions to be shaped by positive interactions with other species. This has important consequences for predicting howdistributions of species might change in the face of loss of their key mutualists. [ABSTRACT FROM AUTHOR]

Ongoing increases in air temperature and changing precipitation patterns are altering water temperatures and flow regimes in lotic freshwater systems, and these changes are expected to continue in the coming century. Freshwater taxa are responding to these changes at all levels of biological organization. The generation of appropriate hydrologic and water temperature projections is critical to accurately predict the impacts of climate change on freshwater systems in the coming decade. The goal of this review is to provide an overview of how changes in climate affect hydrologic processes and how climate-induced changes in freshwater habitat can impact the life histories and traits of individuals, and the distributions of freshwater populations and biodiversity. Projections of biological responses during the coming century will depend on accurately representing the spatially varying sensitivity of physical systems to changes in climate, as well as acknowledging the spatially varying sensitivity of freshwater taxa to changes in environmental conditions. [ABSTRACT FROM AUTHOR]

Communities of free-floating aquatic plants dominated by Lemnaceae (duckweeds) are common in ponds and wetlands globally with important ecological functions. In addition to the cosmopolitan common duckweed (Lemna minor) , other species of Lemnaceae , liverworts (Ricciaceae), hornworts (Ceratophyllum), and water ferns (Salviniaceae) often coexist over broad geographic areas. Despite these species all sharing a similar mode of life and resource requirements, they have important morphological and physiological differences such as variation in body size, degree of morphological reduction, presence/number of roots, and position in the water column. The degree to which these differences play a role in shaping their distributions is, however, unclear. We report a field survey of floating aquatic plants in southern Quebec, Canada. We find that species distributions are influenced by habitat specialization to water phosphorus levels. High nutrient specialization followed a continual reduction in body size and morphological complexity, with smaller, simpler species found in higher nutrient sites. We also found a latitudinal gradient in species richness with more northerly sites supporting less diversity. Rare species did not show clustering suggesting that dispersal limitation was not an important factor in determining local abundance. Our results suggest that the distribution of these plants is in part driven by competitive sorting of suitable species from a regional species pool. • Species distributions are driven by specialization to water phosphorus. • High nutrient specialization followed a continual reduction in body size. • Species richness showed a latitudinal gradient with fewer species further north. [ABSTRACT FROM AUTHOR]

Ecological studies often are subjected to unintentional biases, suggesting that improved research designs for hypothesis testing should be used. Double-blind ecological studies are rare but necessary to minimize sampling biases and omission errors, and improve the reliability of research. We used a double-blind design to evaluate associations between nests of red wood ants (Formica rufa, RWA) and the distribution of tectonic faults. We randomly sampled two regions in western Denmark to map the spatial distribution of RWA nests. We then calculated nest proximity to the nearest active tectonic faults. Red wood ant nests were eight times more likely to be found within 60 m of known tectonic faults than were random points in the same region but without nests. This pattern paralleled the directionality of the fault system, with NNE–SSW faults having the strongest associations with RWA nests. The nest locations were collected without knowledge of the spatial distribution of active faults thus we are confident that the results are neither biased nor artefactual. This example highlights the benefits of double-blind designs in reducing sampling biases, testing controversial hypotheses, and increasing the reliability of the conclusions of research.

Most experimental studies on adaptation to stressful environments are performed under conditions that are rather constant and rarely ecologically relevant. Fluctuations in natural environmental conditions are ubiquitous and include for example variation in intensity and duration of temperature, droughts, parasite loads, and availability of nutrients, predators and competitors. The frequency and amplitude of many of these fluctuations are expected to increase with climate change. Tolerance curves are often used to describe fitness components across environmental gradients. Such curves can be obtained by assessing performance in a range of constant environmental conditions. In this perspective we briefly list theoretical and experimental evidence why results obtained under constant environmental conditions might be misleading for processes in nature and therefore may not be suitable for predicting fitness and future species distribution and abundance. We further suggest experimental avenues that can provide a better foundation for forecasts of the distribution of biota.

I surveyed more than 1,700 Western Hemisphere mammal species ranges to identify, quantify, and examine patterns of disjunction at multiple taxonomic levels. Species that had disjunct populations (isolated by at least 500 km from other parts of the species range) were further analyzed using novel measures of disjunction by determining the distance to the disjunction and the relative area of disjunctions compared to the primary range area. Disjunction at this scale is rare (6.4 percent) in all terrestrial mammals but more common in bats (14.6 percent) than nonvolant mammals. Disjunctions are concentrated in six families, specifically Molossidae (31.5 percent disjunct), Didelphidae (24.7 percent disjunct), Felidae (28.6 percent disjunct), Vespertilionidae (15.3 percent disjunct), Emballonuridae (10.5 percent disjunct), and Phyllostomidae (10.4 percent disjunct). Geographically, 85 percent of disjunct mammal species have ranges that occur entirely or partially in South America. Geographic information systems analysis of species range maps is capable of identifying disjunct species and evaluating the severity of disjunctions. When compiled at the family level, these data suggest that species in certain families are more susceptible to disjunction. In some cases (e.g., species ranges separated by the Amazon rainforest), species-level data offer insight into the causes of disjunction. Study of species identified as disjunct in this study can inform conservation efforts by providing an opportunity to determine the characteristics that enable them to survive as isolated populations. [ABSTRACT FROM AUTHOR]