A global analysis of tree pests and emerging pest threats.

SignificanceThe introduction of trees outside their native ranges has greatly expanded the potential ranges of their pathogens and insect pests, which risk spilling over and impacting native flora. However, we often lack a strong understanding of the host, climatic, and geographic factors that allow pests to establish outside their hosts' native ranges. Using global datasets of pest occurrences and the native and nonnative ranges of tree hosts, we show there are strong generalizable trends controlling pest occurrences and can predict the occurrence of pests outside their hosts' native ranges with >75% accuracy. Our modeling framework offers a powerful tool to identify future invasive pest species and the ecological mechanisms controlling the accumulation of pests outside their hosts' native ranges.

The environmental conditions of endemism hotspots shape the functional traits of mammalian assemblages.

Endemic (small-ranged) species are distributed non-randomly across the globe. Regions of high topography and stable climates have higher endemism than flat, climatically unstable regions. However, it is unclear how these environmental conditions interact with and filter mammalian traits. Here, we characterize the functional traits of highly endemic mammalian assemblages in multiple ways, testing the hypothesis that these assemblages are trait-filtered (less functionally diverse) and dominated by species with traits associated with small range sizes. Compiling trait data for more than 5000 mammal species, we calculated assemblage means and multidimensional functional metrics to evaluate the distribution of traits across each assemblage. We then related these metrics to the endemism of global World Wildlife Fund ecoregions using linear models and phylogenetic fourth-corner regression. Highly endemic mammalian assemblages had small average body masses, low fecundity, short lifespans and specialized habitats. These traits relate to the stable climate and rough topography of endemism hotspots and to mammals' ability to expand their ranges, suggesting that the environmental conditions of endemism hotspots allowed their survival. Furthermore, species living in endemism hotspots clustered near the edges of their communities' functional spaces, indicating that abiotic trait filtering and biotic interactions act in tandem to shape these communities.

Disentangling the drivers of continental mammalian endemism.

Endemic species and species with small ranges are ecologically and evolutionarily distinct and are vulnerable to extinction. Determining which abiotic and biotic factors structure patterns of endemism on continents can advance our understanding of global biogeographic processes, but spatial patterns of mammalian endemism have not yet been effectively predicted and reconstructed. Using novel null model techniques, we reconstruct trends in mammalian endemism and describe the isolated and combined effects of physiographic, ecological, and evolutionary factors on endemism. We calculated weighted endemism for global continental ecoregions and compared the spatial distribution of endemism to niche-based, geographic null models of endemism. These null models distribute species randomly across continents, simulating their range sizes from their degree of climatic specialization. They isolate the effects of physiography (topography and climate) and species richness on endemism. We then ran linear and structural models to determine how topography and historical climate stability influence endemism. The highest rates of mammalian endemism were found in topographically rough, climatically stable ecoregions with many species. The null model that isolated physiography did not closely approximate the observed distribution of endemism (r2  = .09), whereas the null model that incorporated both physiography and species richness did (r2  = .59). The linear models demonstrate that topography and climatic stability both influenced endemism values, but that average climatic niche breadth was not highly correlated with endemism. Climate stability and topography both influence weighted endemism in mammals, but the spatial distribution of mammalian endemism is driven by a combination of physiography and species richness. Despite its relationship to individual range size, average climate niche breadth has only a weak influence on endemism. The results highlight the importance of historical biogeographic processes (e.g. centers of speciation) and geography in driving endemism patterns, and disentangle the mechanisms structuring species ranges worldwide.

Temperature-Dependent Competitive Outcomes between the Fruit Flies Drosophila santomea and Drosophila yakuba.

AbstractChanges in temperature associated with climate change can alter species' distributions, drive adaptive evolution, and in some cases cause extinction. Research has tended to focus on the direct effects of temperature, but changes in temperature can also have indirect effects on populations and species. Here, we test whether temperature can indirectly affect the fitness of Drosophila santomea and Drosophila yakuba by altering the nature of interspecific competition. We show that when raised in isolation, both D. santomea and D. yakuba display similar variation in relative fitness across temperatures of 18°, 22°, and 25°C. However, D. santomea has higher fitness than D. yakuba when experiencing interspecific competition at 18°C, while the inverse is true at 25°C. Patterns of fitness across thermal and competitive environments therefore indicate that the outcome of interspecific competition varies with temperature. We then use a coexistence experiment to show that D. santomea is rapidly (within eight generations) extirpated when maintained with D. yakuba at 25°C. By contrast, D. santomea remains as (or more) abundant than D. yakuba over the course of ∼10 generations when maintained at 18°C. Our results provide an example of how the thermal environment can affect interspecific competition and suggest that some species may become more prone to extinction under scenarios of climate change through indirect effects of the thermal environment on competitive advantages between species.

ΔTraitSDMs: species distribution models that account for local adaptation and phenotypic plasticity.

Improving our understanding of species ranges under rapid climate change requires application of our knowledge of the tolerance and adaptive capacity of populations to changing environmental conditions. Here, we describe an emerging modelling approach, ΔTraitSDM, which attempts to achieve this by explaining species distribution ranges based on phenotypic plasticity and local adaptation of fitness-related traits measured across large geographical gradients. The collection of intraspecific trait data measured in common gardens spanning broad environmental clines has promoted the development of these new models - first in trees but now rapidly expanding to other organisms. We review, explain and harmonize the main findings from this new generation of models that, by including trait variation over geographical scales, are able to provide new insights into future species ranges. Overall, ΔTraitSDM predictions generally deliver a less alarming message than previous models of species distribution under new climates, indicating that phenotypic plasticity should help, to a considerable degree, some plant populations to persist under climate change. The development of ΔTraitSDMs offers a new perspective to analyse intraspecific variation in single and multiple traits, with the rationale that trait (co)variation and consequently fitness can significantly change across geographical gradients and new climates.

A global risk assessment of primates under climate and land use/cover scenarios.

Primates are facing an impending extinction crisis, driven by extensive habitat loss, land use change and hunting. Climate change is an additional threat, which alone or in combination with other drivers, may severely impact those taxa unable to track suitable environmental conditions. Here, we investigate the extent of climate and land use/cover (LUC) change-related risks for primates. We employed an analytical approach to objectively select a subset of climate scenarios, for which we then calculated changes in climatic and LUC conditions for 2050 across primate ranges (N = 426 species) under a best-case scenario and a worst-case scenario. Generalized linear models were used to examine whether these changes varied according to region, conservation status, range extent and dominant habitat. Finally, we reclassified primate ranges based on different magnitudes of maximum temperature change, and quantified the proportion of ranges overall and of primate hotspots in particular that are likely to be exposed to extreme temperature increases. We found that, under the worst-case scenario, 74% of Neotropical forest-dwelling primates are likely to be exposed to maximum temperature increases up to 7°C. In contrast, 38% of Malagasy savanna primates will experience less pronounced warming of up to 3.5°C. About one quarter of Asian and African primates will face up to 50% crop expansion within their range. Primary land (undisturbed habitat) is expected to disappear across species' ranges, whereas secondary land (disturbed habitat) will increase by up to 98%. With 86% of primate ranges likely to be exposed to maximum temperature increases >3°C, primate hotspots in the Neotropics are expected to be particularly vulnerable. Our study highlights the fundamental exposure risk of a large percentage of primate ranges to predicted climate and LUC changes. Importantly, our findings underscore the urgency with which climate change mitigation measures need to be implemented to avert primate extinctions on an unprecedented scale.

Physical effects of habitat-forming species override latitudinal trends in temperature.

Latitudinal and elevational temperature gradients (LTG and ETG) play central roles in biogeographical theory, underpinning predictions of large-scale patterns in organismal thermal stress, species' ranges and distributional responses to climate change. Yet an enormous fraction of Earth's taxa live exclusively in habitats where foundation species modify temperatures. We examine little-explored implications of this widespread trend using a classic model system for understanding heat stresses - rocky intertidal shores. Through integrated field measurements and laboratory trials, we demonstrate that thermal buffering by centimetre-thick mussel and seaweed beds eliminates differences in stress-inducing high temperatures and associated mortality risk that would otherwise arise over 14° of latitude and ~ 1 m of shore elevation. These results reveal the extent to which physical effects of habitat-formers can overwhelm broad-scale thermal trends, suggesting a need to re-evaluate climate change predictions for many species. Notably, inhabitant populations may exhibit deceptive resilience to warming until refuge-forming taxa become imperiled.

New patterns in human biogeography revealed by networks of contacts between linguistic groups.

Human languages differ broadly in abundance and are distributed highly unevenly on the Earth. In many qualitative and quantitative aspects, they strongly resemble biodiversity distributions. An intriguing and previously unexplored issue is the architecture of the neighbouring relationships between human linguistic groups. Here we construct and characterize these networks of contacts and show that they represent a new kind of spatial network with uncommon structural properties. Remarkably, language networks share a meaningful property with food webs: both are quasi-interval graphs. In food webs, intervality is linked to the existence of a niche space of low dimensionality; in language networks, we show that the unique relevant variable is the area occupied by the speakers of a language. By means of a range model analogous to niche models in ecology, we show that a geometric restriction of perimeter covering by neighbouring linguistic domains explains the structural patterns observed. Our findings may be of interest in the development of models for language dynamics or regarding the propagation of cultural innovations. In relation to species distribution, they pose the question of whether the spatial features of species ranges share architecture, and eventually generating mechanism, with the distribution of human linguistic groups.

Giant panda-focused conservation has limited value in maintaining biodiversity and carbon sequestration.

Biodiversity and climate are interconnected through carbon. Drivers of climate change and biodiversity loss interact in complex ways to produce outcomes that may be synergistic, and biodiversity loss and climate change reinforce each other. Prioritizing the conservation of flagship and umbrella species is often used as a surrogate strategy for broader conservation goals, but it is unclear whether these efforts truly benefit biodiversity and carbon stocks. Conservation of the giant panda offers a paradigm to test these assumptions. Here, using the benchmark estimates of ecosystem carbon stocks and species richness, we investigated the relationships among the giant panda, biodiversity, and carbon stocks and assessed the implications of giant panda conservation for biodiversity and carbon-focused conservation efforts. We found that giant panda density and species richness were significantly positively correlated, while no correlation was found between giant panda density and soil carbon or total carbon density. The established nature reserves protect 26 % of the giant panda conservation region, but these areas contain <21 % of the ranges of other species and <21 % of total carbon stocks. More seriously, giant panda habitats are still facing high risks of habitat fragmentation. Habitat fragmentation is negatively correlated with giant panda density, species richness, and total carbon density. The ongoing giant panda habitat fragmentation is likely to cause an additional 12.24 Tg C of carbon emissions over 30 years. Thus, giant panda-focused conservation efforts have effectively prevented giant panda extinction but have been less effective in maintaining biodiversity and high­carbon ecosystems. It is urgent for China to contribute to the development of an effective and representative national park system that integrates climate change issues into national biodiversity strategies and vice versa in dealing with the dual environmental challenges of biodiversity loss and climate change under a post-2020 framework.

Introduction to the theme issue 'Species' ranges in the face of changing environments'.

Understanding where, when and how species' ranges will be modified is both a fundamental problem and essential to predicting how spatio-temporal environmental changes in abiotic and biotic factors impact biodiversity. Notably, different species may respond disparately to similar environmental changes: some species may overcome an environmental change only with difficulty or not at all, while other species may readily overcome the same change. Ranges may contract, expand or move. The drivers and consequences of this variability in species' responses remain puzzling. Importantly, changes in a species' range creates feedbacks to the environmental conditions, populations and communities in its previous and current range, rendering population genetic, population dynamic and community processes inextricably linked. Understanding these links is critical in guiding biodiversity management and conservation efforts. This theme issue presents current thinking about the factors and mechanisms that limit and/or modify species' ranges. It also outlines different approaches to detect changes in species' distributions, and illustrates cases of range modifications in several taxa. Overall, this theme issue highlights the urgency of understanding species' ranges but shows that we are only just beginning to disentangle the processes involved. One way forward is to unite ecology with evolutionary biology and empirical with modelling approaches. This article is part of the theme issue 'Species' ranges in the face of changing environments (Part II)'.

Systematic revision of Calligrapha s. str/. Chevrolat (Coleoptera: Chrysomelidae, Chrysomelinae).

In this work, the Chrysomelinae leaf beetle subgenus Calligrapha s. str. Chevrolat, 1836 is revised, offering redescriptions and keys for identification of twelve species currently considered in this group, allied to the South American species Calligrapha polyspila (Germar, 1821), the generic type of Calligrapha. The current species count results from important taxonomic changes. These include reversing a long-held synonymy, resurrecting the name Calligrapha mexicana Stål, 1859 stat. rev. for a species that is different from Chrysomela serpentina Rogers, 1856; upgrading the status of Polyspila serpentina var. discrepans Achard, 1923 to Calligrapha discrepans (Achard) stat. rev.; and formally proposing a number of new synonymies for several species, including: (1) Calligrapha discrepans (Achard) (= Calligrapha serpentina ssp. temaxensis Bechyné, 1952 syn. nov.); (2) Calligrapha fulvipes (Gistel, 1848) (= Calligrapha bajula Stål, 1860 syn. nov.; = Calligrapha nupta Stål, 1859 syn. nov.; = C. sponsa Stål, 1859 syn. nov.); and (3) Calligrapha polyspila (Germar) (= Polyspila polyspila var. bilineolata Achard, 1923 syn. nov.; = Polyspila polyspila var. plagata Achard, 1923 syn. nov.).

First insights into the feeding habits of the Critically Endangered black snub-nosed monkey, Rhinopithecus strykeri (Colobinae, Primates).

Since its initial discovery in 2010 in the Gaoligong Mountains on the Sino-Myanmar border, there remains no direct information on the feeding habits of the black snub-nosed monkey (Rhinopithecus strykeri). This species is on the verge of extinction, with an estimated remaining population of < 400 individuals. Due to difficulties in following these monkeys across steep mountainous terrain, during 203 observation days (September 2015-January 2017) we recorded 80 h of behavioral records of a wild population (Luoma group). Our preliminary results identified 14 plant species and four lichen species consumed by the monkeys. In addition, we provided the only two captive individuals of this species with a cafeteria diet composed of > 600 wild-collected plant species that were gathered from known R. strykeri habitats to determine which plant species and food items were considered palatable. Our results indicate that the captive monkeys freely consumed young and mature leaves, fruits/seeds, buds, flowers, twigs, and bark from 170 different species of trees, bushes, and herbs representing 76 genera and 41 plant families, as well as 15 species of lichen. All foods consumed by the wild monkeys were also consumed by the captive individuals. Food plants consumed by R. strykeri were found principally in intact subtropical evergreen broadleaf forests and hemlock-broadleaf mixed forests at an altitude of 2200-3000 m. Strict enforcement of habitat protection and access to resources across this elevation zone appear to be essential for the conservation and survivorship of this critically endangered primate.

Extent of biodiversity surveys and ranges for endemic species in the Albertine Rift.

This article contains data on the estimated ranges of endemic species in the Albertine Rift both currently and under future climate change related to the research article entitled "Conservation of the endemic species of the Albertine Rift under future climate change" (Ayebare et al., 2018) [1]. Biodiversity surveys focused mainly on 5 taxa: birds, mammals, reptiles, amphibians and plants. A combination of line transects, point counts, recce walks, camera traps, visual encounter surveys, qualitative surveys and appropriate capture methods (mist nets, Sherman traps, pitfall traps) were used to survey the different taxa and provide point location data for each species. The biodiversity surveys were conducted by the Wildlife Conservation Society starting in the late 1990s. Additional species data were sourced from individual researchers and institutions. The current and future species ranges were estimated using the Maximum Entropy '(Maxent)' species distribution modeling algorithm. The areas of suitable habitat (current and future) of 162 endemic species for 5 taxa (birds (40), mammals (33), plants (49), reptiles (11), amphibians (29), the extent of occurrence (EOO), area of occupancy (AOO), percentage range contraction due to climate change and to agriculture conversion of suitable habitat for each species are given in Table S1. Threshold geotiffs are also provided for each species modeled and made available at www.albertinerift.org.