The macro-eco-evolutionary interplay between dispersal, competition and landscape structure in generating biodiversity

Theory links dispersal and diversity, predicting the highest diversity at intermediate dispersal levels. However, the modulation of this relationship by macro-eco-evolutionary mechanisms and competition within a landscape is still elusive. We examine the interplay between dispersal, competition and landscape structure in shaping biodiversity over 5 million years in a dynamic archipelago landscape. We model allopatric speciation, temperature niche, dispersal, competition, trait evolution and trade-offs between competitive and dispersal traits. Depending on dispersal abilities and their interaction with landscape structure, our archipelago exhibits two 'connectivity regimes', that foster speciation events among the same group of islands. Peaks of diversity (i.e. alpha, gamma and phylogenetic), occurred at intermediate dispersal; while competition shifted diversity peaks towards higher dispersal values for each connectivity regime. This shift demonstrates how competition can boost allopatric speciation events through the evolution of thermal specialists, ultimately limiting geographical ranges. Even in a simple landscape, multiple intermediate dispersal diversity relationships emerged, all shaped similarly and according to dispersal and competition strength. Our findings remain valid as dispersal- and competitive-related traits evolve and trade-off; potentially leaving identifiable biodiversity signatures, particularly when trade-offs are imposed. Overall, we scrutinize the convoluted relationships between dispersal, species interactions and landscape structure on macro-eco-evolutionary processes, with lasting imprints on biodiversity.This article is part of the theme issue 'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics'.

Systematics and evolutionary dynamics of insect-fern interactions in the specialized fern-spore feeding Cuprininae (Lepidoptera, Stathmopodidae)

Fern-spore-feeding (FSF) is rare and found in only four families of Lepidoptera. Stathmopodidae is the most speciose family that contains FSF species, and its subfamily Cuprininae exclusively specializes on FSF. However, three species of Stathmopodinae also specialize on FSF. To better understand the evolutionary history of FSF and, more generally, the significance of specialization on a peculiar host, a phylogenetic and taxonomic revision for this group is necessary. We reconstructed the most comprehensive molecular phylogeny, including one mitochondrial and four nuclear genes, of Stathmopodidae to date, including 137 samples representing 62 species, with a particular focus on the FSF subfamily, Cuprininae, including 33 species (41% of named species) from 6 of the 7 Cuprininae genera. Species from two other subfamilies, Stathmopodinae and Atkinsoniinae, were also included. We found that FSF evolved only once in Stathmopodidae and that the previous hypothesis of multiple origins of FSF was misled by inadequate taxonomy. Moreover, we showed that (1) speciation/extinction rates do not differ significantly between FSF and non-FSF groups and that (2) oligophage is the ancestral character state in Cuprininae. We further revealed that a faster rate of accumulating specialists over time, and thus a higher number of specialists, was achieved by a higher transition rate from oligophagages to specialists compared to the transition rate in the opposite direction. We finish by describing three new genera, Trigonodagen. nov., Petalagen. nov., and Pediformisgen. nov., and revalidating five genera: Cuprina, Calicotis, Thylacosceles, Actinoscelis, Thylacosceloides in Cuprininae, and we provide an updated taxonomic key to genera and a revised global checklist of Cuprininae.

The Geography of Metacommunities: Landscape Characteristics Drive Geographic Variation in the Assembly Process through Selecting Species Pool Attributes

AbstractThe nonrandom association between landscape characteristics and the dominant life history strategies observed in species pools is a typical pattern in nature. Here, we argue that these associations determine predictable changes in the relative importance of assembly mechanisms along broadscale geographic gradients (i.e., the geographic context of metacommunity dynamics). To demonstrate that, we employed simulation models in which groups of species with the same initial distribution of niche breadths and dispersal abilities interacted across a wide range of landscapes with contrasting characteristics. By assessing the traits of dominant species in the species pool in each landscape type, we determined how different landscape characteristics select for different life history strategies at the metacommunity level. We analyzed the simulated data using the same analytical approaches used in the study of empirical metacommunities to derive predictions about the causal relationships between landscape characteristics and dominant life histories in species pools, as well as their reciprocal influence on empirical inferences regarding the assembly process. We provide empirical support for these predictions by contrasting the assembly of moth metacommunities in a tropical versus a temperate mountainous landscape. Together, our model framework and empirical analyses demonstrate how the geographic context of metacommunities influences our understanding of community assembly across broadscale ecological gradients.

Genomic factors shape carbon and nitrogen metabolic niche breadth across Saccharomycotina yeasts

Organisms exhibit extensive variation in ecological niche breadth, from very narrow (specialists) to very broad (generalists). Two general paradigms have been proposed to explain this variation: (i) trade-offs between performance efficiency and breadth and (ii) the joint influence of extrinsic (environmental) and intrinsic (genomic) factors. We assembled genomic, metabolic, and ecological data from nearly all known species of the ancient fungal subphylum Saccharomycotina (1154 yeast strains from 1051 species), grown in 24 different environmental conditions, to examine niche breadth evolution. We found that large differences in the breadth of carbon utilization traits between yeasts stem from intrinsic differences in genes encoding specific metabolic pathways, but we found limited evidence for trade-offs. These comprehensive data argue that intrinsic factors shape niche breadth variation in microbes.

Population status and genetic assessment of mugger (Crocodylus palustris) in a tropical regulated river system in North India

For rewilding the depleted crocodylian populations in India, a targeted 'one-species one area' based conservation approach was adopted in the early-1970s. Suitable habitats were identified and designated as protected areas, specifically targeted to recover a particular crocodylian species. A ~ 610 km stretch of Chambal River in the Ganga River Basin was declared as National Chambal Sanctuary to restore the 'Critically Endangered' gharial (Gavialis gangeticus), where active management of mugger (Crocodylus palustris) was discouraged. In the present study, we examined the population trends, occupancy, and genetic status of mugger by conducting population monitoring and genetic assessment to understand the status of potentially competitive mugger in the Sanctuary. Our finding suggests that the mugger population has notably increased and colonised the Sanctuary. We observed a moderate level of genetic diversity in the mugger, which was relatively higher compared to the gharial in the Sanctuary. The rapid colonization of ecological generalist mugger raises concerns about potential competition with ecological specialist gharial threatening its long-term sustainability. Considering the coexistence dynamics between the species, it is essential to extend adaptive management strategies for mugger to ensure successful recovery of gharial population in the Sanctuary.

Rhizosphere assembly alters along a chronosequence in the Hallstätter glacier forefield (Dachstein, Austria)

Rhizosphere microbiome assembly is essential for plant health, but the temporal dimension of this process remains unexplored. We used a chronosequence of 150 years of the retreating Hallstätter glacier (Dachstein, Austria) to disentangle this exemplarily for the rhizosphere of three pioneer alpine plants. Time of deglaciation was an important factor shaping the rhizosphere microbiome. Microbiome functions, i.e. nutrient uptake and stress protection, were carried out by ubiquitous and cosmopolitan bacteria. The rhizosphere succession along the chronosequence was characterized by decreasing microbial richness but increasing specificity of the plant-associated bacterial community. Environmental selection is a critical factor in shaping the ecosystem, particularly in terms of plant-driven recruitment from the available edaphic pool. A higher rhizosphere microbial richness during early succession compared to late succession can be explained by the occurrence of cold-acclimated bacteria recruited from the surrounding soils. These taxa might be sensitive to changing habitat conditions that occurred at the later stages. A stronger influence of the plant host on the rhizosphere microbiome assembly was observed with increased time since deglaciation. Overall, this study indicated that well-adapted, ubiquitous microbes potentially support pioneer plants to colonize new ecosystems, while plant-specific microbes may be associated with the long-term establishment of their hosts.

Evolution of realized niche breadth diversity driven by community dynamics

Why many herbivorous insects are host plant specialists, with non-negligible exceptions, is a conundrum of evolutionary biology, especially because the host plants are not necessarily optimal larval diets. Here, I present a novel model of host plant preference evolution of two insect species. Because habitat preference evolution is contingent upon demographic dynamics, I integrate the evolutionary framework with the modern coexistence theory. The results show that the two insect species can evolve into a habitat specialist and generalist, when they experience both negative and positive frequency-dependent community dynamics. This happens because the joint action of positive and negative frequency dependence creates multiple (up to nine) eco-evolutionary equilibria. Furthermore, initial condition dependence due to positive frequency dependence allows specialization to poor habitats. Thus, evolved habitat preferences do not necessarily correlate with the performances. The model provides explanations for counterintuitive empirical patterns and mechanistic interpretations for phenomenological models of niche breadth evolution.

Contrasting patterns of genetic and phenotypic divergence of two sympatric congeners, Phragmites australis and P. hirsuta, in heterogeneous habitats

Habitat heterogeneity leads to genome-wide differentiation and morphological and ecological differentiation, which will progress along the speciation continuum, eventually leading to speciation. Phragmites hirsuta and Phragmites australis are sympatric congeners that coexist in saline-alkaline meadow soil (SAS) and sandy soil (SS) habitats of the Songnen Meadow. The results provided genetic evidence for two separate species of reeds. Genetic diversity and spatial genetic structure supported the specialist-generalist variation hypothesis (SGVH) in these two sympatric reed species, suggesting that P. australis is a generalist and P. hirsuta is a habitat specialist. When we compared these different species with respect to phenotypic and genetic variation patterns in different habitats, we found that the phenotypic differentiation of P. australis between the two habitats was higher than that of P. hirsuta. Multiple subtle differences in morphology, genetic background, and habitat use collectively contribute to ecological success for similar congeners. This study provided evidence of the two reed congeners, which should contribute to their success in harsh environments.

Local niches explain coexistence in environmentally-distinct contact zones between Western Mediterranean vipers

Species' ecological niches are frequently analysed to gain insights into how anthropogenic changes affect biodiversity. Coping with these changes often involves shifts in niche expression, which can disrupt local biotic interactions. Secondary contact zones, where competition and ecological segregation commonly occur, are ideal for studying the ecological factors influencing species' niches. In this study, we investigated the effect of climate and landscape factors on the ecological niches of two viper species, Vipera aspis and Vipera latastei, across three contact zones in northern Iberia, characterized by varying levels of landscape alteration. Using niche overlap tests, ecological niche models and spatial analyses we observed local variation in the expression of the species' niches across the three contact zones, resulting from the different abiotic and biotic conditions of each area. Rather than spatial niche segregation, we observed high niche overlap, suggesting niche convergence. A pattern of asymmetrical niche variation was identified in all contact zones, driven by species' climatic tolerances and the environmental conditions of each area. V. aspis generally exhibited a wider niche, except in the southernmost zone where the pure Mediterranean climate favored V. latastei. Human-induced landscape changes intensified niche asymmetry, by favoring the most generalist V. aspis over the specialist V. latastei, increasing habitat overlap, and likely competition. This study presents a comprehensive analysis of niche expression at range margins, anticipating a heightened impact of landscape changes in V. latastei. The methodological framework implemented here, and our findings, hold significant relevance for biodiversity management and conservation in human-impacted areas.

Phenotypic plasticity of a generalist fish species resident to lotic environments: Insights from the Great Lakes region

Fish morphology is incredibly plastic and local/resident morphology can be influenced by factors including habitat, predation, resource availability, and water velocity. Through analysis of body shape using geometric morphometrics, we describe the degree of phenotypic plasticity within a generalist fish species resident to low-order tributaries of Green Bay and Lake Michigan. We predicted that isolated populations of creek chub (Semotilus atromaculatus) would display plastic responses in body shape due to differences in selective pressures imposed by stream environments. We show that body shape of creek chub was significantly different between streams which are considered to be isolated populations, and while we expected body shape variation to remain constant between study years, we found that shape was not fixed and changed over time in the same manner among focal streams. The diversity of creek chub diet and degree of agricultural land use in the watershed were significant predictors of body morphology. The effect of resource availability and land use within the watershed demonstrates how selective pressures influence phenotypes at the population level. Our study provides insight into morphological changes of stream fish populations, which may be important in the context of changing ecosystems and novel conditions.

Uncovering the processes of microbial community assembly in the near-surface sediments of a climate-sensitive glacier-fed lake

Glacier-fed lakes are characterized by cold temperatures, high altitudes, and nutrient-poor conditions. Despite these challenging conditions, near-surface sediments of glacier-fed lakes harbor rich microbial communities that are critical for ecosystem functioning and serve as a bridge between aquatic ecology and the deep subsurface biosphere. However, there is limited knowledge regarding the microbial communities and their assembly processes in these sediments, which are highly vulnerable to climate change. To fill this knowledge gap, this study systematically analyzed environmental variables, microbial communities, diversity, co-occurrence relationships, and community assembly processes in the near-surface sediments of a glacier-fed lake in the Tibetan Plateau. The results revealed distinct vertical gradients in microbial diversity and subcommunities, highlighting the significant influence of selection processes and adaptive abilities on microbial communities. Specifically, specialists played a crucial role within the overall microbial communities. Microbial assembly was primarily driven by homogeneous selection, but its influence declined with increasing depth. In contrast, homogenizing dispersal showed an opposite pattern, and the bottom layer exhibited heterogeneous selection and undominated processes. These patterns of microbial assembly were primarily driven by environmental gradients, with significant contributions from processes associated to ammonium and organic matter deposition, as well as chemical precipitation in response to a warming climate. This study enhances our understanding of the microbial communities and assembly processes in the near-surface sediments of glacier-fed lakes and sheds light on geo-microbiological processes in climate-sensitive lacustrine sediments.

Genomic and ecological factors shaping specialism and generalism across an entire subphylum

Organisms exhibit extensive variation in ecological niche breadth, from very narrow (specialists) to very broad (generalists). Paradigms proposed to explain this variation either invoke trade-offs between performance efficiency and breadth or underlying intrinsic or extrinsic factors. We assembled genomic (1,154 yeast strains from 1,049 species), metabolic (quantitative measures of growth of 843 species in 24 conditions), and ecological (environmental ontology of 1,088 species) data from nearly all known species of the ancient fungal subphylum Saccharomycotina to examine niche breadth evolution. We found large interspecific differences in carbon breadth stem from intrinsic differences in genes encoding specific metabolic pathways but no evidence of trade-offs and a limited role of extrinsic ecological factors. These comprehensive data argue that intrinsic factors driving microbial niche breadth variation.

Host specificity and adaptive evolution in settlement behaviour of coral-associated barnacle larvae (Cirripedia: Pyrgomatidae)

Coral-associated organisms often exhibit a continuum of host specificities. We do not know whether the variation in host specificity is related to the settlement organs or preferential settlement behaviours of the larvae. We examined the morphology of attachment discs, the settlement and metamorphosis of coral barnacles-Pyrgoma cancellatum (lives in a single coral species), Nobia grandis (two families of corals), and Armatobalanus allium (six families of corals). Our results revealed that the attachment organ of all three species are spear-shaped with sparse villi, indicating that the morphology of the attachment organs does not vary among species with different host specificities. Larvae of P. cancellatum and N. grandis only settle on their specific hosts, suggesting that chemical cues are involved in the settlement. Cyprids of N. grandis display close searching behaviour before settlement. Cyprids of P. cancellatum settle immediately on their specific host corals, without any exploratory behaviour. The host specificity and exploratory behaviours of coral barnacle cyprids are results of adaptive evolution. We argue that there is a trade-off between exploration and energy conservation for metamorphosis processes. Coral barnacle metamorphosis is longer when compared to free-living species, likely because it involves the development of a tube-shaped base on the coral surface.

Resistance but not recovery is related to the role of specialist taxa in river communities submitted to hydric stress

One of the main effects of global change is the human interference in the global water cycle, which alters river hydrological dynamics and submits their biological communities to hydric stress. Hydric stress is a pulse disturbance with potential multiple effects on biodiversity and functions in river ecosystems. The presence of habitat specialists may support the response of biological communities to pulse disturbances, maintaining ecological functions more consistently than other communities only having generalists. We tested this general hypothesis in stream communities submitted to increasing hydric stress (normal conditions vs humidity vs desiccation). We used communities with variable proportion of specialist algal and cyanobacterial taxa and tested their resistance to hydric stress by analyzing potential changes on their number of species, biovolume, proportion of intact cells, and photosynthetic variables (basal fluorescence, photosynthetic yield). We also evaluated the recovery of ecological functions (net community primary production, community respiration, phosphorus uptake) once hydric stress conditions ended. Hydric stress caused a slight decrease in the number of species and biovolume of assemblages, but the proportion of intact cells did not significantly change because of the disturbance. Basal fluorescence and photosynthetic yield under hydric stress decreased more markedly in communities without specialist taxa, while communities with habitat specialists resisted better. Metabolism did not remarkably decrease under moderate hydric stress, but dropped by half under desiccation in all communities, having or not specialist taxa. Overall, specialist taxa did provide higher resistance to stress but did not support a distinct recovery of ecological functions. We suggest that this characteristic response is related to the high plasticity of biofilm structures.

A Comparison of Small Rodent Assemblages after a 20 Year Interval in the Alps

Human-induced environmental alterations in the Alps may importantly affect small mammal species, but evidence in this sense is limited. We live-trapped small rodents in the Central-Eastern Italian Alps in three close-by habitat types (rocky scree, alpine grassland, and heath) at 2100 m a.s.l. during summer-fall, in 1997 and 2016. We compared small rodent assemblages through a Redundancy Detrended Analysis (RDA). In both surveys, we detected two specialist species, i.e., the common vole (Microtus arvalis) and the snow vole (Chionomys nivalis), and, unexpectedly, the forest generalist bank vole (Myodes glareolus). In 1997, grassland was mainly occupied by the common vole, while the bank vole and the snow vole were sympatric in the other habitats. In 2016, the snow vole was detected only in the scree, while other species did not show distribution changes. We discuss a series of hypotheses that might have driven the differences observed across decades, among which is a species-specific response to abiotic and biotic environmental alterations, with the alpine habitat specialist moving out of sub-optimal habitats. We encourage further research on this topic, e.g., via long-term longitudinal studies.

The ephemeral resource patch concept

Ephemeral resource patches (ERPs) - short lived resources including dung, carrion, temporary pools, rotting vegetation, decaying wood, and fungi - are found throughout every ecosystem. Their short-lived dynamics greatly enhance ecosystem heterogeneity and have shaped the evolutionary trajectories of a wide range of organisms - from bacteria to insects and amphibians. Despite this, there has been no attempt to distinguish ERPs clearly from other resource types, to identify their shared spatiotemporal characteristics, or to articulate their broad ecological and evolutionary influences on biotic communities. Here, we define ERPs as any distinct consumable resources which (i) are homogeneous (genetically, chemically, or structurally) relative to the surrounding matrix, (ii) host a discrete multitrophic community consisting of species that cannot replicate solely in any of the surrounding matrix, and (iii) cannot maintain a balance between depletion and renewal, which in turn, prevents multiple generations of consumers/users or reaching a community equilibrium. We outline the wide range of ERPs that fit these criteria, propose 12 spatiotemporal characteristics along which ERPs can vary, and synthesise a large body of literature that relates ERP dynamics to ecological and evolutionary theory. We draw this knowledge together and present a new unifying conceptual framework that incorporates how ERPs have shaped the adaptive trajectories of organisms, the structure of ecosystems, and how they can be integrated into biodiversity management and conservation. Future research should focus on how inter- and intra-resource variation occurs in nature - with a particular focus on resource × environment × genotype interactions. This will likely reveal novel adaptive strategies, aid the development of new eco-evolutionary theory, and greatly improve our understanding of the form and function of organisms and ecosystems.

Unraveling global impacts of climate change on amphibians distributions: A life-history and biogeographic-based approach

Climate change can affect species distribution patterns in three different ways: pushing them to disperse to new suitable areas, forcing them to adapt to novel climatic conditions, or driving them to extinction. However, the biological and geographical traits that lead to these different responses remain poorly explored. Here, we evaluated how ecological and biogeographic traits influence amphibians’ response to climate change. We performed a systematic review searching for studies that evaluated the effects of future climate change on amphibian’s distribution. Our research returned 31 articles that projected the distribution of 331 amphibians. Our results demonstrate that species inhabiting an elevation above 515 m will lose a significant portion of their climatically suitable area. We also found that as isothermality increases, the amount of area suitable in response to climate change also increases. Another important discovery was that as the size of the baseline area increases, the greater must be the loss of climatically suitable areas. On the other hand, species with very small areas tend to keep their current climatically suitable area in the future. Furthermore, our results indicate that species that inhabit dry habitats tend to expand their suitable area in response to climate change. This result can be explained by the environmental characteristics of these habitats, which tend to present extreme seasonal climates with well-defined periods of drought and rain. We also found that anurans that inhabit exclusively forests are projected to lose a greater portion of their suitable areas, when compared to species that inhabit both forest and open areas, wetlands, and dry and rupestrian environments. The biogeographical realm also influenced anuran’s range shifts, with Afrotropic and Nearctic species projected to expand their geographical ranges. The assessment of climate change effects on amphibian distribution has been the focus of a growing number of studies. Despite this, some regions and species remain underrepresented. Current literature evaluates about 4% of the 7,477 species of Anura and 8% of the 773 species of Caudata and some regions rich in amphibian species remain severely underrepresented, such as Madagascar. Thus, future studies should focus on regions and taxas that remain underrepresented.

Bird Communities in a Changing World: The Role of Interspecific Competition

Significant changes in the environment have the potential to affect bird species abundance and distribution, both directly, through a modification of the landscape, habitats, and climate, and indirectly, through a modification of biotic interactions such as competitive interactions. Predicting and mitigating the consequences of global change thus requires not only a sound understanding of the role played by biotic interactions in current ecosystems, but also the recognition and study of the complex and intricate effects that result from the perturbation of these ecosystems. In this review, we emphasize the role of interspecific competition in bird communities by focusing on three main predictions derived from theoretical and empirical considerations. We provide numerous examples of population decline and displacement that appeared to be, at least in part, driven by competition, and were amplified by environmental changes associated with human activities. Beyond a shift in relative species abundance, we show that interspecific competition may have a negative impact on species richness, ecosystem services, and endangered species. Despite these findings, we argue that, in general, the role played by interspecific competition in current communities remains poorly understood due to methodological issues and the complexity of natural communities. Predicting the consequences of global change in these communities is further complicated by uncertainty regarding future environmental conditions and the speed and efficacy of plastic and evolutionary responses to fast-changing environments. Possible directions of future research are highlighted.

Sod translocation to restore habitats of the myrmecophilous butterfly Phengaris (Maculinea) teleius on former agricultural fields

In Europe, 50%–70% of former natural grassland area has been destroyed during the past 30 years due to land use changes, losses are expected to increase in the future. Restoration is thought to reverse this situation by creating suitable abiotic conditions. In this paper, we investigate the effects of sod translocation with specific vegetation to facilitate the restoration of a former intensive agricultural field into a wet meadow. First, starting conditions were optimized including modification of the local hydrology, removal of the fertilized topsoil, application of liming, and translocation of fresh clippings as a seed source. The second part aimed at restoring the habitat for the butterfly species Phengaris (Maculinea) teleius, one of the species that was especially affected by the loss of wet meadows. This species engages in a complex myrmecophilous relationship with one host plant, Sanguisorba officinalis, and one obligate host ant, Myrmica scabrinodis. We used sod translocation to create islands of habitat to promote host plant and host ant colonization. After 4 years following the restoration, we observed that plants spread from the transplanted sods to the surroundings. The vegetation composition and structure of the transplanted sods attracted colonization of Myrmica ants into the restored areas. Following the increase in vegetation cover and height, Myrmica ant colonies further spread into the restored areas. Therefore, sod translocations can be considered an effective restoration method following topsoil removal in the process of restoring wet meadows to provide a starting point for ant colonization and plant dispersion. With these findings, this paper contributes to the evidence‐based restoration of wet meadows on former agricultural fields, including complex interactions between invertebrates and their required ecological relationships.

Soil seed bank responses to edge effects in temperate European forests

AIM

The amount of forest edges is increasing globally due to forest fragmentation and land-use changes. However, edge effects on the soil seed bank of temperate forests are still poorly understood. Here, we assessed edge effects at contrasting spatial scales across Europe and quantified the extent to which edges can preserve the seeds of forest specialist plants.

LOCATION

Temperate European deciduous forests along a 2,300-km latitudinal gradient.

TIME PERIOD

2018-2021.

MAJOR TAXA STUDIED

Vascular plants.

METHODS

Through a greenhouse germination experiment, we studied how edge effects alter the density, diversity, composition and functionality of forest soil seed banks in 90 plots along different latitudes, elevations and forest management types. We also assessed which environmental conditions drive the seed bank responses at the forest edge versus interior and looked at the relationship between the seed bank and the herb layer species richness.

RESULTS

Overall, 10,108 seedlings of 250 species emerged from the soil seed bank. Seed density and species richness of generalists (species not only associated with forests) were higher at edges compared to interiors, with a negative influence of C : N ratio and litter quality. Conversely, forest specialist species richness did not decline from the interior to the edge. Also, edges were compositionally, but not functionally, different from interiors. The correlation between the seed bank and the herb layer species richness was positive and affected by microclimate.

MAIN CONCLUSIONS

Our results underpin how edge effects shape species diversity and composition of soil seed banks in ancient forests, especially increasing the proportion of generalist species and thus potentially favouring a shift in community composition. However, the presence of many forest specialists suggests that soil seed banks still play a key role in understorey species persistence and could support the resilience of our fragmented forests.

Factors contributing to the range expansion and population increase of a native generalist species

Ecological communities are becoming more typified by generalist species in conjunction with anthropogenic activities. Using a long-term dataset (1968-2019), we documented the expansion of a native generalist species, the red-eared slider (Trachemys scripta elegans), into a river community, and studied the subsequent population changes that occurred in conjunction with short- and long-term changes within the ecosystem. Trachemys scripta elegans was able to expand into a new geographic area following a harvesting-induced population decline of a native competitor, the northern map turtle (Graptemys geographica). The population of T. s. elegans remained small for approximately 2.5 decades, then significantly increased in conjunction with habitat degradation in the form of increased silt/sediment deposits and nuisance aquatic vegetation growth. Our results demonstrate how a generalist species can expand and establish a population in an area impacted by multiple anthropogenic stressors. This research reveals how ecological communities become characterized by more generalist species following anthropogenically-induced competitive release caused by harvesting of native competitors, habitat degradation, and extreme flooding associated with land cover and climate change.

What affects the desiccation tolerance threshold of Brazilian Eugenia (Myrtaceae) seeds?

Desiccation sensitive (DS) seeds are shed at high water contents (WC) and metabolically active, but WC thresholds vary broadly among species even in the same genus. Eugenia is an important ecological genus that has high occurrence in several Brazilian morphoclimatic domains. In this study, we assessed seed desiccation tolerance of five Eugenia species collected in specific meteorological conditions. We reported the species geographical ranges and verified the rainfall and temperature of species sites in the year prior to seed collection. We also assessed initial WC, seed germination and vigor and seedling growth upon desiccation. Eugenia uniflora was the widest spread among the five species, while E. astringens was the most restricted. In this specific study, widespread species showed a higher WC threshold than restricted species. In the same way, the WC of fresh seeds was not correlated to the desiccation tolerance threshold. Seed desiccation tolerance was species dependent and correlated with the environmental status of seed collection sites. Wetter and warmer conditions were correlated to the E. uniflora higher DS threshold. Low rainfall and temperature corresponded to a lower desiccation sensitivity of E. astringens seeds. Seeds of the five species lost half viability between 0.44 and 0.25 g H₂O g DW^- 1 and after 65-270 h of desiccation. Our results indicate that abiotic factors impact plant populations during the seed production season and can drive seed desiccation tolerance threshold and physiological behavior. These results should be taken into account in ex-situ plant conservation programs and tropical species management.

Ride the dust: Linking dust dispersal and spatial distribution of microorganisms across an arid landscape

In arid ecosystems, where the soil is directly exposed to the action of the wind due to sparse vegetation, dust aerosolization is a consequence of soil degradation and concomitantly, a major vector of microbial dispersal. Disturbances such as livestock grazing or fire can exacerbate wind erosion and dust production. Here, we sampled surface soils in 29 locations across an arid landscape in southwestern USA and characterized their prokaryotic and fungal communities. At four of these locations, we also sampled potential fugitive dust. By comparing the composition of soil and dust samples, we determined the role of dust dispersal in structuring the biogeography of soil microorganisms across the landscape. For Bacteria/Archaea, we found dust associated taxa to have on average, higher regional occupancies compared to soil associated taxa. Complementarily, we found dust samples to harbor a higher amount of widely distributed taxa compared to soil samples. Overall, our study shows how dust dispersal plays a role in the spatial distribution of soil Bacteria/Archaea, but not soil Fungi, and might inform indicators of soil health and stability in arid ecosystems. This article is protected by copyright. All rights reserved.

Effective specialist or jack of all trades? Experimental evolution of a crop pest in fluctuating and stable environments

Understanding pest evolution in agricultural systems is crucial for developing effective and innovative pest control strategies. Types of cultivation, such as crop monocultures versus polycultures or crop rotation, may act as a selective pressure on pests’ capability to exploit the host’s resources. In this study, we examined the herbivorous mite Aceria tosichella (commonly known as wheat curl mite), a widespread wheat pest, to understand how fluctuating versus stable environments influence its niche breadth and ability to utilize different host plant species. We subjected a wheat‐bred mite population to replicated experimental evolution in a single‐host environment (either wheat or barley), or in an alternation between these two plant species every three mite generations. Next, we tested the fitness of these evolving populations on wheat, barley, and on two other plant species not encountered during experimental evolution, namely rye and smooth brome. Our results revealed that the niche breadth of A. tosichella evolved in response to the level of environmental variability. The fluctuating environment expanded the niche breadth by increasing the mite’s ability to utilize different plant species, including novel ones. Such an environment may thus promote flexible host‐use generalist phenotypes. However, the niche expansion resulted in some costs expressed as reduced performances on both wheat and barley as compared to specialists. Stable host environments led to specialized phenotypes. The population that evolved in a constant environment consisting of barley increased its fitness on barley without the cost of utilizing wheat. However, the population evolving on wheat did not significantly increase its fitness on wheat, but decreased its performance on barley. Altogether, our results indicated that, depending on the degree of environmental heterogeneity, agricultural systems create different conditions that influence pests’ niche breadth evolution, which may in turn affect the ability of pests to persist in such systems.

Wildlife at the crossroads: wild animal road kills due to vehicular collision on a mountainous highway in northwestern Himalayan region

Wildlife mortality due to vehicular collision is well known across the world and the number of such incidences is steadily rising in Himalaya as well. To assess the quantum of wildlife road kills, we conducted an intensive survey spanning 33 months along a mountainous National Highway 244 in the Union Territory of Jammu & Kashmir. Forty-nine wild animal carcasses of 13 species of higher vertebrates were observed lying on the road, shoulders, edges, and valley slopes. These included seven mammals, four birds, and two reptiles. This survey, first of its kind in this part of the Himalaya would be helpful in understanding the underlying reasons of the rising wildlife fatalities on the hill roads, identifying susceptible hotspots, and developing measures to address this new threat to Himalayan wildlife. We recommend creating wildlife passages, raising speed halters, and placing warning signages in vulnerable sections to reduce the road-related wildlife mortality in such mountainous highways.

Winter coexistence in herbivorous waterbirds: Niche differentiation in a floodplain, Poyang Lake, China

The classical niche theory supports the idea that stable coexistence requires ecological differences between closely related species. However, information on waterbirds coexistence in the entirely landlocked freshwater system of Poyang Lake is not well understood, especially when the available biomass of their food in the area decreases. In this study, we tested the ecological segregation mechanisms in the 2015/2016 and 2016/2017 wintering periods among eight herbivorous waterbirds (including the Siberian crane Grus leucogeranus, hooded crane Grus monacha, white-naped crane Grus vipio, common crane Grus grus, greater white-fronted goose Anser albifrons, bean goose Anser fabalis, swan goose Anser cygnoides, and tundra swan Cygnus columbianus) at Poyang Lake. Using field observations and species niche and foraging habitat selection models, we investigated the abundance, distribution, and food sources of these eight waterbird species to quantify and compare their habitat use and ecological niches. Our results showed that niche segregation among the waterbirds, with respect to food types, time, and spatial location, allow them to coexist and use similar resources. The water level gradually receded in the sub-lakes of the Poyang Lake, which could provide food sources and various habitats for wintering herbivorous waterbirds to coexist. We demonstrated that the differences in habitat use could mitigate interspecific competition, which may explain the mechanism whereby waterbirds of Poyang Lake coexist during the wintering period, despite considerable overlap in the dietary niches of herbivorous waterbirds.

Edge effects on the realised soil seed bank along microclimatic gradients in temperate European forests

Despite the crucial role of the seed bank in forest conservation and dynamics, the effects of forest edge microclimate and climate warming on germination responses from the forest seed bank are still almost unknown. Here, we investigated edge effects on the realised seed bank and seedling community in two types of European temperate deciduous forest, one in the Oceanic and one in the Mediterranean climatic region. Responses in terms of seedling density, diversity, species composition and functional type of the seed bank at the forest edge and interior were examined along latitudinal, elevational and stand structural gradients by means of soil translocation experiments. Moreover, we translocated soil samples from high to low elevation forests in the two regions, thus performing a warming simulation. Density, species diversity and mortality of the seedlings varied with region and elevation. Seedling density also differed between forest edge and interior position, while seedling cover mainly depended on forest structure. Both the edge and interior forest seed bank contained a high proportion of generalist species. In Belgium, a more homogeneous seed bank was found at the forest edge and interior, while in Italy compositional and ecological differences were larger: at the forest edge, more light and less moisture demanding seedling communities developed, with a higher proportion of generalists compared to the interior. In both regions, the upland-to-lowland translocation experiment revealed effects of warming on forest seed banks with thermophilization of the realised communities. Moreover, edge conditions shifted the seedling composition towards more light-demanding communities. The establishment of more light and warm-adapted species from the seed bank could in the long term alter the aboveground vegetation composition, with communities becoming progressively richer in light-demanding generalists and poorer in forest specialists.

Seasonal food preferences and group activity pattern of Blackbuck Antilope cervicapra (L., 1758) (Mammalia: Cetartiodactyla: Bovidae) in a semi-arid region of western Haryana, India

To evaluate food preferences and group activity patterns, a fragmented population of Blackbuck Antilope cervicapra was selected for observation in a semi-arid ecosystem of western Haryana. A field survey was conducted fortnightly, from dawn to dusk, between September 2019 and August 2020, covering every season. Scan sampling and quadrat methods were used to record data on group size and vegetation. Group sizes ranged from 3 to 72 individuals. Based on visual observation, blackbuck seasonally consumed 26 species belonging to 25 families with varied preferences, out of a total of 53 plant species documented from the study site. Some plant species with high medicinal and therapeutic values were preferred, including Artemisia scoparia, Cucumis callous, Ziziphus jujuba, and Ziziphus nummularia. Unlike most herbivores, Blackbuck also consumed the toxic and medicinally rich Calotropis procera. We suggest that zoos which house blackbuck include these preferred wild plant species in their diet. Observations on group activity were analyzed on hourly, monthly and seasonal bases, and converted into time percentages. Group foraging activity was at a maximum in the monsoon (62%) and minimum in winter (50%), followed by resting: maximum in winter (21%) and minimum (12%) in monsoon, largely influenced by food availability. Foraging/walking ratio was at a maximum (5.2) in monsoon and minimum (3.1) in winter, and was correlated with the number of group sightings (maximum in winter and minimum in monsoon) in nearby farmland, when the animals faced food scarcity in their natural habitat and fed on crops. 

A plant-pollinator metanetwork along a habitat fragmentation gradient

To understand how plant-pollinator interactions respond to habitat fragmentation, we need novel approaches that can capture properties that emerge at broad scales, where multiple communities engage in metanetworks. Here we studied plant-pollinator interactions over 2 years on 29 calcareous grassland fragments selected along independent gradients of habitat size and surrounding landscape diversity of cover types. We associated network centrality of plant-pollinator interactions and grassland fragments with their ecological and landscape traits, respectively. Interactions involving habitat specialist plants and large-bodied pollinators were the most central, implying that species with these traits form the metanetwork core. Large fragments embedded in landscapes with high land cover diversity exhibited the highest centrality; however, small fragments harboured many unique interactions not found on larger fragments. Intensively managed landscapes have reached a point in which all remaining fragments matter, meaning that losing any further areas may vanish unique interactions with unknown consequences for ecosystem functioning.

Metabolic flexibility allows bacterial habitat generalists to become dominant in a frequently disturbed ecosystem

Ecological theory suggests that habitat disturbance differentially influences distributions of habitat generalist and specialist species. While well-established for macroorganisms, this theory has rarely been explored for microorganisms. Here we tested these principles in permeable (sandy) sediments, ecosystems with much spatiotemporal variation in resource availability and physicochemical conditions. Microbial community composition and function were profiled in intertidal and subtidal sediments using 16S rRNA gene amplicon sequencing and metagenomics, yielding 135 metagenome-assembled genomes. Community composition and metabolic traits modestly varied with sediment depth and sampling date. Several taxa were highly abundant and prevalent in all samples, including within the orders Woeseiales and Flavobacteriales, and classified as habitat generalists; genome reconstructions indicate these taxa are highly metabolically flexible facultative anaerobes and adapt to resource variability by using different electron donors and acceptors. In contrast, obligately anaerobic taxa such as sulfate reducers and candidate lineage MBNT15 were less abundant overall and only thrived in more stable deeper sediments. We substantiated these findings by measuring three metabolic processes in these sediments; whereas the habitat generalist-associated processes of sulfide oxidation and fermentation occurred rapidly at all depths, the specialist-associated process of sulfate reduction was restricted to deeper sediments. A manipulative experiment also confirmed habitat generalists outcompete specialist taxa during simulated habitat disturbance. Together, these findings show metabolically flexible habitat generalists become dominant in highly dynamic environments, whereas metabolically constrained specialists are restricted to narrower niches. Thus, an ecological theory describing distribution patterns for macroorganisms likely extends to microorganisms. Such findings have broad ecological and biogeochemical ramifications.

Non-protected areas demanding equitable conservation strategies as of protected areas in the Central Himalayan region

The present study aims to explore the mammalian diversity of Darjeeling district using camera traps along with questionnaire survey in protected area (PA) and non- protected area (Non-PA). We also attempted to understand the influence of habitat variables on mammalian species richness using the generalized linear mixed models (GLMM). A total of 30 mammal species were recorded of which 21 species were detected through camera trapping with the most abundant records of barking deer (Muntiacus muntjak) and least of the elusive Chinese pangolin (Manis pentadactyla) and red panda (Ailurus fulgens). Additionally, melanistic forms of four mammals were also recorded. The mammalian species richness, their capture rate and naïve occupancy did not differ significantly among the PA and Non-PA. The GLMM revealed that the proportions of oak and bamboo in the forest, percentage canopy cover and camera trap operational days (wAICc = 0.145, wBIC = 0.603) were significant predictors of species richness in the study. We suggest Non-PA forest of Darjeeling should be given equal conservation importance as to the PA. Landscape based conservation planning will be imperative for achieving long term conservation goals in the study area.

Differential habitat use by sympatric species of mouse lemurs across a mangrove–dry forest habitat gradient

Understanding the mechanisms by which similar species coexist in sympatry is a major driver of ecological research. Niche partitioning and ecological plasticity can facilitate spatial and habitat use overlap between generalist and specialist species. Mouse lemurs (Microcebus spp.) are a highly speciose group of small primates that are endemic to the forests of Madagascar. In northwestern Madagascar, the relatively widespread M. murinus occurs sympatrically with the microendemic M. ravelobensis. We investigated spatial distributions and densities of these two species across a mangrove–dry forest habitat gradient in Mariarano commune. We used capture-mark-recapture techniques and nocturnal line transect surveys along six transects during June and July 2017. Spatial capture-recapture and distance sampling models were used to estimate lemur densities across habitat types. The congeners displayed differential patterns of spatial distribution and densities. Microcebus murinus was found in similar densities across all habitat types, while M. ravelobensis was found at much higher densities in dry forests compared with mangroves. This suggests that the generalist M. murinus uses a wider array of habitats more evenly than the specialist M. ravelobensis. Our study provides empirical evidence of how cryptic lemur species differ in their habitat use and distribution across an environmental gradient and provides new insights into their ecology in an understudied habitat. Lemurs are one of the most threatened groups of mammals in the world, and understanding how these species are distributed across different forest types is crucial for planning and implementing conservation measures to protect lemur habitat.

Evolution of the "world's only alpine parrot": Genomic adaptation or phenotypic plasticity, behaviour and ecology?

Climate warming, in particular in island environments, where opportunities for species to disperse are limited, may become a serious threat to cold adapted alpine species. In order to understand how alpine species may respond to a warming world, we need to understand the drivers that have shaped their habitat specialisation and the evolutionary adaptations that allow them to utilize alpine habitats. The endemic, endangered New Zealand kea (Nestor notabilis) is considered the only alpine parrot in the world. As a species commonly found in the alpine zone it may be highly susceptible to climate warming. But is it a true alpine specialist? Is its evolution driven by adaptation to the alpine zone, or is the kea an open habitat generalist that simply uses the alpine zone to, for example, avoid lower lying anthropogenic landscapes? We use whole genome data of the kea and its close, forest adapted sister species, the kākā (Nestor meridionalis) to reconstruct the evolutionary history of both species and identify the functional genomic differences that underlie their habitat specialisations. Our analyses do not identify major functional genomic differences between kea and kākā in pathways associated with high-altitude. Rather, we found evidence that selective pressures on adaptations commonly found in alpine species are present in both Nestor species, suggesting that selection for alpine adaptations has not driven their divergence. Strongly divergent demographic responses to past climate warming between the species nevertheless highlight potential future threats to kea survival in a warming world.

Many roads to bacterial generalism

The fundamental niches of bacteria can be defined along many environmental axes, including temperature tolerance and resources consumed, while interactions with other organisms can constrain (e.g. competition) or enlarge (e.g. cross-feeding) realized niches. Organisms are often categorized as generalists or specialists, corresponding to broad or narrow niche requirements, which can then be linked to their functional role in an ecosystem. We show how these terms are applied to bacteria, make predictions about how the type and extent of generalism displayed by an organism relates to its functional potential and discuss the value of collecting different types of generalist bacteria. We believe that new approaches that take advantage of both high-throughput sequencing and environmental manipulation can allow us to understand the many types of generalism found within both cultivated and yet-to-be-cultivated bacteria.

Interactions between the introduced European honey bee and native bees in urban areas varies by year, habitat type and native bee guild

European honey bees have been introduced across the globe and may compete with native bees for floral resources. Compounding effects of urbanization and introduced species on native bees are, however, unclear. Here, we investigated how honey bee abundance and foraging patterns related to those of native bee abundance and diversity in residential gardens and native vegetation remnants for 2 years in urbanized areas of the Southwest Australian biodiversity hotspot and assessed how niche overlap influenced these relationships. Honey bees did not overtly suppress native bee abundance; however, complex relationships emerged when analysing these relationships according to body size, time of day and floral resource levels. Native bee richness was positively correlated with overall honeybee abundance in the first year, but negatively correlated in the second year, and varied with body size. Native bees that had higher resource overlap with honey bees were negatively associated with honey bee abundance, and resource overlap between honey bees and native bees was higher in residential gardens. Relationships with honey bees varied between native bee taxa, reflecting adaptations to different flora, plus specialization. Thus, competition with introduced bees varies by species and location, mediated by dietary breadth and overlap and by other life-history traits of individual bee species.

Current Condition of Pannonic Salt Steppes at Their Distribution Limit: What Do Indicator Species Reveal about Habitat Quality?

Little is known about the suite of ecological conditions under which characteristic species may continue to develop under the pressure of recent habitat deterioration. We aimed to determine the niche of three indicator species of the priority habitat Pannonic salt steppes and to find out how their vegetation composition, land use, and soil chemistry mirror the current condition of their typical habitat. A plot-based vegetation survey was conducted in degraded and in pristine (reference) inland salt steppes in East-Central Europe. We confirmed decreased habitat quality at their northern geographical limit. Most of the sites there showed a strong prevalence of generalists (e.g., Elytrigia repens) and lack of specialists, both resulting from lowered habitat extremity and inappropriate land use (abandonment). A small proportion of plots (19%) were in the same good condition as the reference vegetation in the central area. Soil analyses revealed that the studied halophytes are able to persist on desalinized soils if the land use is suitable. The occurrence of the annual Camphorosma annua (Amaranthaceae) was driven largely by abiotic stress; grazing alone is insufficient for its long-term persistence, while the perennial Artemisia santonicum (Asteraceae) and Tripolium pannonicum (Asteraceae) have higher survival chances as they are able to coexist with generalists. Overall habitat quality can be reliably determined from the analyzed ecological conditions of indicator species. The outcomes of the presented work are relevant for conservation practice and can serve as a quick tool for assessing the current stage of other grassland habitats.

Cryopreservation and Resuscitation of Natural Aquatic Prokaryotic Communities

Experimental reproducibility in aquatic microbial ecology is critical to predict the dynamics of microbial communities. However, controlling the initial composition of naturally occurring microbial communities that will be used as the inoculum in experimental setups is challenging, because a proper method for the preservation of those communities is lacking. To provide a feasible method for preservation and resuscitation of natural aquatic prokaryote assemblages, we developed a cryopreservation procedure applied to natural aquatic prokaryotic communities. We studied the impact of inoculum size, processing time, and storage time on the success of resuscitation. We further assessed the effect of different growth media supplemented with dissolved organic matter (DOM) prepared from naturally occurring microorganisms on the recovery of the initially cryopreserved communities obtained from two sites that have contrasting trophic status and environmental heterogeneity. Our results demonstrated that the variability of the resuscitation process among replicates decreased with increasing inoculum size. The degree of similarity between initial and resuscitated communities was influenced by both the growth medium and origin of the community. We further demonstrated that depending on the inoculum source, 45-72% of the abundant species in the initially natural microbial communities could be detected as viable cells after cryopreservation. Processing time and long-term storage up to 12 months did not significantly influence the community composition after resuscitation. However, based on our results, we recommend keeping handling time to a minimum and ensure identical incubation conditions for repeated resuscitations from cryo-preserved aliquots at different time points. Given our results, we recommend cryopreservation as a promising tool to advance experimental research in the field of microbial ecology.

Impact of Past and Future Climate Change on the Potential Distribution of an Endangered Montane Shrub Lonicera oblata and Its Conservation Implications

Climate change is an important driver of biodiversity patterns and species distributions, understanding how organisms respond to climate change will shed light on the conservation of endangered species. In this study, we modeled the distributional dynamics of a critically endangered montane shrub Lonicera oblata in response to climate change under different periods by building a comprehensive habitat suitability model considering the effects of soil and vegetation conditions. Our results indicated that the current suitable habitats for L. oblata are located scarcely in North China. Historical modeling indicated that L. oblata achieved its maximum potential distribution in the last interglacial period which covered southwest China, while its distribution area decreased for almost 50% during the last glacial maximum. It further contracted during the middle Holocene to a distribution resembling the current pattern. Future modeling showed that the suitable habitats of L. oblata contracted dramatically, and populations were fragmentedly distributed in these areas. As a whole, the distribution of L. oblata showed significant migration northward in latitude but no altitudinal shift. Several mountains in North China may provide future stable climatic areas for L. oblata, particularly, the intersections between the Taihang and Yan mountains. Our study strongly suggested that the endangered montane shrub L. oblata are sensitive to climate change, and the results provide new insights into the conservation of it and other endangered species.

Rethinking Biological Invasions as a Metacommunity Problem

Perhaps more than any other ecological discipline, invasion biology has married the practices of basic science and the application of that science. The conceptual frameworks of population regulation, metapopulations, supply-side ecology, and community assembly have all to some degree informed the regulation, management, and prevention of biological invasions. Invasion biology needs to continue to adopt emerging frameworks and paradigms to progress as both a basic and applied science. This need is urgent as the biological invasion problem continues to worsen. The development of metacommunity theory in the last two decades represents a paradigm-shifting approach to community ecology that emphasizes the multi-scale nature of community assembly and biodiversity regulation. Work on metacommunities has demonstrated that even relatively simple processes at local scales are often heavily influenced by regional-scale processes driven primarily by the dispersal of organisms. Often the influence of dispersal interacts with, or even swamps, the influence of local-scale drivers like environmental conditions and species interactions. An emphasis on dispersal and a focus on multi-scale processes enable metacommunity theory to contribute strongly to the advancement of invasion biology. Propagule pressure of invaders has been identified as one of the most important drivers facilitating invasion, so the metacommunity concept, designed to address how dispersal-driven dynamics affect community structure, can directly address many of the central questions of invasion biology. Here we revisit many of the important concepts and paradigms of biological invasions—propagule pressure, biotic resistance, enemy release, functional traits, neonative species, human-assisted transport,—and view those concepts through the lens of metacommunity theory. In doing so, we accomplish several goals. First, we show that work on metacommunities has generated multiple predictions, models, and the tools that can be directly applied to invasion scenarios. Among these predictions is that invasibility of a community should decrease with both local controls on community assembly, and the dispersal rates of native species. Second, we demonstrate that framing biological invasions in metacommunity terms actually unifies several seemingly disparate concepts central to invasion biology. Finally, we recommend several courses of action for the control and management of invasive species that emerge from applying the concepts of metacommunity theory.

Nested Species Distribution Models of Chlamydiales in Ixodes ricinus (Tick) Hosts in Switzerland

The tick Ixodes ricinus is the vector of various pathogens, including Chlamydiales bacteria, which potentially cause respiratory infections. In this study, we modeled the spatial distribution of I. ricinus and associated Chlamydiales over Switzerland from 2009 to 2019. We used a total of 2,293 ticks and 186 Chlamydiales occurrences provided by a Swiss Army field campaign, a collaborative smartphone application, and a prospective campaign. For each tick location, we retrieved from Swiss federal data sets the environmental factors reflecting the topography, climate, and land cover. We then used the Maxent modeling technique to estimate the suitability of particular areas for I. ricinus and to subsequently build the nested niche of Chlamydiales bacteria. Results indicate that I. ricinus habitat suitability is determined by higher temperature and normalized difference vegetation index (NDVI) values, lower temperature during the driest months, and a higher percentage of artificial and forest areas. The performance of the model was improved when extracting the environmental variables for a 100-m radius buffer around the sampling points and when considering the climatic conditions of the 2 years previous to the sampling date. Chlamydiales bacteria were favored by a lower percentage of artificial surfaces, drier conditions, high precipitation during the coldest months, and short distances to wetlands. From 2009 to 2018, we observed an extension of areas suitable to ticks and Chlamydiales, associated with a shift toward higher altitude. The importance of considering spatiotemporal variations in the environmental conditions for obtaining better prediction was also demonstrated.IMPORTANCEIxodes ricinus is the vector of pathogens including the agent of Lyme disease, the tick-borne encephalitis virus, and the less well-known Chlamydiales bacteria, which are responsible for certain respiratory infections. In this study, we identified the environmental factors influencing the presence of I. ricinus and Chlamydiales in Switzerland and generated maps of their distribution from 2009 to 2018. We found an important expansion of suitable areas for both the tick and the bacteria during the last decade. Results also provided the environmental factors that determine the presence of Chlamydiales within ticks. Distribution maps as generated here are expected to bring valuable information for decision makers in controlling tick-borne diseases in Switzerland and establishing prevention campaigns. The methodological framework presented could be used to predict the distribution and spread of other host-pathogen pairs to identify environmental factors driving their distribution and to develop control or prevention strategies accordingly.

The role of edaphic factors on plant species richness and diversity along altitudinal gradients in the Brazilian semi-arid region

Unlike well-known global patterns of plant species richness along altitudinal gradients, in the mountainous areas of the Brazilian Caatinga, species richness and diversity reach their maxima near mountain tops. The causes of this unusual pattern are not well understood, and in particular the role of edaphic factors on plant community assembly along these gradients has not been investigated. Our goal was to assess the role of edaphic factors (fertility and soil texture) on plant community composition and structure on two mountains of the Brazilian semi-arid region. In 71 plots (Bodocongó site, twenty-one 200-m2 plots, 401–680 m asl; Arara site, fifty 100-m2 plots, 487–660 m asl) we recorded 3114 individuals representing 61 plant species; in addition, at each plot we collected composite soil samples from 0–20 cm depth. Significant altitude-related changes were observed both for community structure and composition, and edaphic variables. A canonical correspondence analysis allowed the distinction of two groups of plots according to species abundances, indicating a preferential habitat distribution of species depending both on altitude and soil variables. Although soil fertility was lowest at the highest altitudes, these areas had high richness and diversity. Conversely, the more fertile foothills were characterized by the dominance of generalist pioneer species. Despite the relatively short altitudinal range that characterizes the studied mountains, this study elucidates the role of edaphic factors on the floristic composition and species richness patterns on the mountains of the Brazilian semi-arid region.

Prediction of the Suitable Area of the Chinese White Pines (Pinus subsect. Strobus) under Climate Changes and Implications for Their Conservation

White pines (Pinus subsect. Strobus) play important roles in forest ecosystems in the Northern Hemisphere. Species of this group are narrowly distributed or endangered in China. In this study, we used a species distribution model (SDM) to project and predict the distribution patterns of the 12 species of Chinese white pine under a variety of paleoclimatic and future climate change scenarios based on 39 high-resolution environmental variables and 1459 distribution records. We also computed the centroid shift, range expansion/contraction, and suitability change of the current distribution area to assess the potential risk to each species in the future. The modeling results revealed that the suitable habitat of each species is consistent with but slightly larger than its actual distribution range and that temperature, precipitation, and UV radiation are important determining factors for the distribution of different white pine species. The results indicate that the Last Glacial Maximum (LGM) greatly affected the current distribution of the Chinese white pine species. Additionally, it was predicted that under the future climate change scenarios, there will be a reduction in the area of habitats suitable for P. armandii, P. morrisonicola, and P. mastersiana. Furthermore, some of the current distribution sites of P. armandii, P. kwangtungensis, P. mastersiana, P. morrisonicola, P. sibirica, and P. wallichiana were predicted to become more unsuitable under these scenarios. These results indicate that some Chinese white pine species, such as P. armandii, P. morrisonicola, and P. mastersiana, may have a very high risk of population shrinkage in the future. Overall, this study provided relevant data for the long-term conservation (both in situ and ex situ) and sustainable management of Chinese white pine species.

Diversity patterns of reef fish along the Brazilian tropical coast

Causal mechanisms for broad-scale reef fish diversity patterns are poorly understood and current knowledge is limited to trends of species richness. This work compared the effects of ecological drivers on components of fish diversity across reefs spanning over 2.000 km of the tropical Brazilian coastline. A quarter of communities' diversity is accountable to common and dominant species, while remaining species are rare. Low-latitude sites were more diverse in rare species. Communities along the coast share common and dominant species, which display high densities across all reefs, but differ in rare species that show abundance peaks in particular reef morphotypes. The disproportionate distribution of rare species reveals a higher vulnerability of these communities to impacts and stochastic density fluctuations. Uneven conservation efforts directed to these morphotypes pose a threat to the maintenance of a paramount component of the reef fish diversity represented by rare species.