Phylogenetic Dissimilarity Research Articles

Do closely related species interact with similar partners? Testing for phylogenetic signal in bipartite interaction networks

Whether interactions between species are conserved on evolutionary time-scales has spurred the development of both correlative and process-based approaches for testing phylogenetic signal in interspecific interactions: do closely related species interact with similar partners? Here we use simulations to test the statistical performances of the two approaches that are the most widely used in the field: Mantel tests and the Phylogenetic Bipartite Linear Model (PBLM). Mantel tests investigate the correlation between phylogenetic distances and dissimilarities in sets of interacting partners, while PBLM is a process-based approach that relies on strong assumptions about how interactions evolve. We find that PBLM often detects a phylogenetic signal when it should not. Simple Mantel tests instead have infrequent false positives and moderate statistical power; however, they often artifactually detect that closely related species interact with dissimilar partners. Partial Mantel tests, which are used to partial out the phylogenetic signal in the number of partners, actually fail at correcting for this confounding effect, and we instead recommend evaluating the significance of Mantel tests with network permutations constraining the number of partners. We also explore the ability of simple Mantel tests to analyze clade- specific phylogenetic signals. We provide general guidelines and an application on an interaction network between orchids and mycorrhizal fungi.

Estimating ancient biogeographic patterns with statistical model discrimination.

The geographic ranges in which species live is a function of many factors underlying ecological and evolutionary contingencies. Observing the geographic range of an individual species provides valuable information about these historical contingencies for a lineage, determining the distribution of many distantly related species in tandem provides information about large-scale constraints on evolutionary and ecological processes generally. We present a linear regression method that allows for the discrimination of various hypothetical biogeographical models for determining which landscape distributional pattern best matches data from the fossil record. The linear regression models used in the discrimination rely on geodesic distances between sampling sites (typically geologic formations) as the independent variable and three possible dependent variables: Dice/Sorensen similarity; Euclidean distance; and phylogenetic community dissimilarity. Both the similarity and distance measures are useful for full-community analyses without evolutionary information, whereas the phylogenetic community dissimilarity requires phylogenetic data. Importantly, the discrimination method uses linear regression residual error to provide relative measures of support for each biogeographical model tested, not absolute answers or p-values. When applied to a recently published dataset of Campanian pollen, we find evidence that supports two plant communities separated by a transitional zone of unknown size. A similar case study of ceratopsid dinosaurs using phylogenetic community dissimilarity provided no evidence of a biogeographical pattern, but this case study suffers from a lack of data to accurately discriminate and/or too much temporal mixing. Future research aiming to reconstruct the distribution of organisms across a landscape has a statistical-based method for determining what biogeographic distributional model best matches the available data.

Functionally and phylogenetically diverse boreal forests promote sapling recruitment

Sapling recruitment in established forest stands is critical to long-term ecosystem functioning but can be constrained due to competition from increased neighbourhood crowding. Tree species diversity has the potential to ameliorate negative crowding effects; however, the mechanisms underlying the relationship between diversity and sapling recruitment remain unclear. We used data from spatially mapped individual stems, which were repeatedly measured at 5-year intervals between 1986 and 2010 from 173 permanent plots in Canada. We analyzed individual sapling recruitment probabilities over 5-year census intervals as a function of neighbourhood crowding index, stand age, neighbourhood diversity from shade tolerance dissimilarity and phylogenetic dissimilarity, and their interactions. We show that sapling recruitment probability on average decreases with neighbourhood crowding but increases with stand age and neighbourhood shade tolerance and phylogenetic dissimilarities. The positive effect of shade tolerance dissimilarity was strongest in young stands, while phylogenetic dissimilarity had a positive effect only in older stands. Moreover, sapling recruitment probability in neighbourhoods with high shade tolerance and phylogenetic dissimilarities was less negatively affected by crowding than in more similar neighbourhoods. Our study highlights the mechanisms that promote sapling recruitment in diverse neighbourhoods are context-dependent, with niche complementary being more important in young stands and the feedback from pests and pathogens playing a greater role in old boreal stands. Our results provide direct evidence that neighbourhood diversity helps ameliorate the negative neighbourhood crowding effect on sapling recruitment, particularly in old-growth boreal forests. The mixtures of broadleaves and conifers increase sapling recruitment and are particularly important in the late-successional stages of boreal forests.

Loss of lateral hydrological connectivity impacts multiple facets of molluscan biodiversity in floodplain lakes

Lateral hydrological connectivity (LHC) is a key process in maintaining aquatic biodiversity in river floodplain ecosystems. However, the effects of LHC loss on aquatic biodiversity are rarely studied. Here, we evaluated, for the first time, the responses of multiple facets (i.e., taxonomic, functional and phylogenetic) of alpha and beta diversity of freshwater molluscs to the LHC loss in 23 floodplain lakes in the Yangtze River Basin in China. Our results showed that taxonomic and functional alpha diversities were all significantly higher in connected lakes (CLs) than in disconnected lakes (DLs), whereas phylogenetic alpha diversity (Δ+) was lower in CLs than in DLs. For beta diversity facets, taxonomic (Tβsor) and phylogenetic (Pβsor) dissimilarities were slightly more contributed by the turnover component or equally contributed by the turnover and nestedness-resultant components both in CLs and DLs. Instead, functional beta diversity (Fβsor), generally showing much lower values than Tβsor and Pβsor, was mainly contributed by the nestedness-resultant component (76.6–84.0%), especially in DLs. We found that only functional dissimilarities were significantly higher in DLs than CLs, indicating a high level of functional diversity loss without replacement of species possessing traits sensitive to hydrological disconnection (i.e., large body size, lamellibranch body form, filter feeding, ovoviviparity and burrowing habits). In general, lake area, hydrological connectivity, aquatic vegetation coverage and nutrient levels (TN and TP) played important roles in structuring variation in molluscan alpha and beta diversities, although the three diversity facets responded to different environmental factors. Our results suggest that loss of connectivity to the mainstem river has negative impacts on molluscan assemblages in floodplain lakes. More importantly, as taxonomic, functional and phylogenetic diversities responded somewhat differently to the loss of hydrological connectivity, all of these biodiversity facets should be better incorporated into aquatic biodiversity assessment and conservation programs in large river floodplains.

Multiple β‐diversity patterns and the underlying mechanisms across amphibian communities along a subtropical elevational gradient

AbstractAimMountain systems offer excellent opportunities to understand β‐diversity patterns and the processes driving them. However, β‐diversity patterns and the underlying mechanisms that lead to dissimilarity in mountain amphibian communities across elevational gradients remain elusive. We aimed to evaluate how amphibian communities respond to environmental gradients with elevation and to explore how different ecological mechanisms drive elevational β‐diversity.LocationA 2600‐m elevational gradient along Mount Emei in southwestern China.MethodsWe investigated elevational patterns and assembly processes of pairwise β‐diversity across three dimensions (taxonomic, phylogenetic, and functional) in turnover (i.e., species replacement) and nestedness‐resultant (i.e., species lose/gain) for amphibians. We compared multifaceted β‐diversity components and assessed the extent to which β‐diversity responded to environmental and elevational distances. We also quantified the standardized effect size of β‐diversity and its components using null models to examine the dynamics of niche‐based and neutral processes.ResultsThe turnover component dominated taxonomic β‐diversity, whereas nestedness was relatively more important for phylogenetic and functional dissimilarity. Moreover, taxonomic total dissimilarity and turnover were higher than their phylogenetic and functional analogues. Our results indicated a significant distance‐decay effect for multifaceted β‐diversity of amphibians on Mount Emei and found that effects and directions of predictors on multifaceted β‐diversity were different, with temperature seasonality, annual precipitation, and elevational distance acting as the most important factors. Comparing observed patterns with null‐model expectations, environmental filtering, and competitive exclusion may jointly drive elevational patterns of β‐diversity.Main conclusionsOur study emphasizes the importance of partitioning taxonomic, phylogenetic, and functional components of β‐diversity and community assembly when determining β‐diversity drivers. Although it is difficult to distinguish random communities from outcomes of niche‐based processes, this work highlights the potential roles of environmental filtering and competitive exclusion in controlling elevational communities and provides insights into amphibian community assembly in a biodiversity hotspot.

Deterministic assembly and anthropogenic extinctions drive convergence of island bird communities

AbstractAimWhether entire communities of organisms converge towards predictable structural properties in similar environmental conditions remains controversial. We tested for community convergence in birds by comparing the structure of oceanic archipelago assemblages with their respective regional species pools.LocationEighteen major oceanic archipelagos of volcanic origin with global distribution.Major taxa studiedTerrestrial birds.MethodsWe compiled a comprehensive database of morphological trait and phylogenetic data for 6,579 bird species, including species known to have become extinct owing to human activities. We quantified morphological and phylogenetic dissimilarity among species between pairs of archipelagos, using a modified version of the mean nearest taxon distance. We tested for convergence by estimating whether overall mean turnover among archipelagos and pairwise turnover between archipelagos were lower than expected by chance.ResultsFor all land birds, we found that turnover in body plan, body mass and phylogeny among archipelagos was significantly lower than expected. Seventeen (of 18) archipelagos showed significant body plan and phylogenetic similarity with at least one other archipelago. Similar convergent patterns of community assembly were detected in different subsamples of the data (extant species, endemics, native non‐endemics, and Passeriformes only). Convergence was more pronounced for extant species than for extant and extinct species combined.Main conclusionsConsistent convergence in phylogenetic and morphological structure among archipelagic communities arises through a combination of non‐random colonization andin situadaptation. In addition, by including data from extinct taxa, we show that community convergence both precedes and is accentuated by the anthropogenic extinction of endemic lineages. Our results highlight the potential role of non‐random extinction in generating patterns of community convergence and show that convergence existed even before anthropogenic extinctions, owing to deterministic community assembly in similar environmental settings at the global scale.

Alpha and beta phylogenetic diversities jointly reveal ant community assembly mechanisms along a tropical elevational gradient

Despite the long-standing interest in the organization of ant communities across elevational gradients, few studies have incorporated the evolutionary information to understand the historical processes that underlay such patterns. Through the evaluation of phylogenetic α and β-diversity, we analyzed the structure of leaf-litter ant communities along the Cofre de Perote mountain in Mexico and evaluated whether deterministic- (i.e., habitat filtering, interspecific competition) or stochastic-driven processes (i.e., dispersal limitation) were driving the observed patterns. Lowland and some highland sites showed phylogenetic clustering, whereas intermediate elevations and the highest site presented phylogenetic overdispersion. We infer that strong environmental constraints found at the bottom and the top elevations are favoring closely-related species to prevail at those elevations. Conversely, less stressful climatic conditions at intermediate elevations suggest interspecific interactions are more important in these environments. Total phylogenetic dissimilarity was driven by the turnover component, indicating that the turnover of ant species along the mountain is actually shifts of lineages adapted to particular locations resembling their ancestral niche. The greater phylogenetic dissimilarity between communities was related to greater temperature differences probably due to narrow thermal tolerances inherent to several ant lineages that evolved in more stable conditions. Our results suggest that the interplay between environmental filtering, interspecific competition and habitat specialization plays an important role in the assembly of leaf-litter ant communities along elevational gradients.

Altered Gut Microbiota as an Auxiliary Diagnostic Indicator for Patients With Fracture-Related Infection.

Preoperative diagnosis of fracture-related infection (FRI) is difficult for patients without obvious signs of infection. However, specific profiles of gut microbiota may be used as a potential diagnostic tool for FRI as suggested by a previous study. The fecal microbiome was compared between 20 FRI patients (FRI group), 18 fracture healed patients (FH group), and 12 healthy controls (HC group) included after collection of fecal samples and evaluation. The α and β diversity indices were used to characterize the fecal microbiome. Dysbiosis indexes were constructed based on the characteristic high-dimensional biomarkers identified in the fecal microbiota from the three groups by linear discriminant analysis and generalized linear model analysis to quantify the dysbiosis of fecal microbiota. The effectiveness of α and β diversity indices and dysbiosis indexes was assessed in distinguishing the fecal microbiome among the three groups. The influences of serum inflammatory factors on gut microbiota were also addressed. The α diversity indices were significantly different between the three groups, the highest in HC group and the lowest in FRI group (P < 0.05). The β diversity indices showed significant phylogenetic dissimilarity of gut microbiome composition among the three groups (P < 0.001). The dysbiosis indexes were significantly higher in FRI group than in FH and HC groups (P < 0.001). The area under Receiver operating characteristic curve showed the characteristics of gut microbiota and the gut microbiota was found as effective in distinguishing the three groups. The dysbiosis in the FRI patients was associated with systemic inflammatory factors. In addition, significant differences in the gut microbiota were not observed between the FRI patients versus without sinus tract or pus before operation. Since FRI patients, with or without sinus tract or pus, have a characteristic profile of gut microbiota, their gut microbiota may be used as an auxiliary diagnostic tool for suspected FRI.

Effects of neighborhood interaction on tree growth in a temperate forest following selection harvesting

Selection harvesting is a common silvicultural practice in uneven-aged natural forests. Understanding the complex response of individual trees to forest harvesting is of great importance to clearly assess how forest ecosystems respond to future management. While tree growth dynamics following forest harvesting have been well documented at the stand level, at the individual level, how neighborhood interaction affects tree growth after forest harvesting has received little attention. Based on the data from four1-ha permanent forest plots with mapped trees and different harvesting intensities in Northeastern China, the effects of neighborhood interaction on tree growth of 1,108 focal trees were analyzed four years after forest harvesting. Neighborhood interaction was quantified by several indices, considering both crowding and biological dissimilarity (based on taxonomy, phylogeny, and functional traits) between neighboring trees. Additionally, we tested whether the effects of the neighborhood interaction on tree growth might differ across harvesting intensities. Our results found that selection harvesting significantly increased tree growth and biological dissimilarity but decreased crowding at the individual tree level. Focal tree growth decreased by 12.9%, 9.7%, and 7.9% as a result of neighborhood interaction based on taxonomic, phylogenetic, and multi-trait dissimilarity, respectively. Neighborhood interaction based on maximum height appeared to be the most important determinant of tree growth among the four traits examined (i.e., leaf dry mass per area; leaf nitrogen concentration; wood density; and maximum height), and its effect was much stronger than that of the multi-trait dissimilarity index. Moreover, among the neighborhood interaction indices, increasing neighborhood crowding reduced tree growth and there was a significant negative crowding effect at medium to high harvesting intensities (40%∼60% basal area removed) on tree growth. Our study expands our understanding of the relationship between neighborhood interaction and tree growth by identifying crowding and biological dissimilarity as important neighborhood indices for post-harvest tree growth.

Associations between Gut Microbiota and Intestinal Inflammation, Permeability and Damage in Young Malawian Children

BackgroundEnvironmental enteric dysfunction (EED) is common in low- and middle-income countries and associated with childhood undernutrition. The composition of gut microbiota has been implicated in the pathogenesis of EED. Our aim was to assess the associations between gut microbiota and EED biomarkers in rural Malawian children. We hypothesized that there would be an inverse association between microbiota maturity and diversity and fecal concentrations of EED biomarkers.MethodsWe used data from fecal samples collected at 6, 18 and 30 months from 611 children who were followed up during a nutrition intervention trial. The primary time point for analysis was 18 months. Microbiota data were obtained through 16S rRNA sequencing and variables included microbiota maturity and diversity, phylogenetic dissimilarity and relative abundances of individual taxa. EED biomarkers included calprotectin (marker of inflammation), alpha-1 antitrypsin (intestinal permeability) and REG1B (intestinal damage).ResultsThere was an inverse association between microbiota maturity and diversity and fecal concentrations of all 3 EED biomarkers at 18 months (p≤0.001). The results were similar at 30 months, while at 6 months inverse associations were found only with calprotectin and alpha-1 antitrypsin concentrations. At 18 months, EED biomarkers were not associated with phylogenetic dissimilarity, but at 6 and 30 months several associations were observed. Individual taxa predicting EED biomarker concentrations at 18 months included several Bifidobacterium and Enterobacteriaceae taxa as well as potentially displaced oral taxa.ConclusionsOur findings support the hypothesis of an inverse association between microbiota maturity and diversity and EED in rural Malawian children.

The prevalence of temperature and dispersal limitation as drivers of diversity in Neotropical small mammals

AbstractThe spatial distribution of biodiversity is driven by species dispersal and their response to the environment. Therefore, diversity patterns should differ across taxonomic groups depending on differences in traits associated with dispersal, metabolism, and foraging. We compared the distribution of rodents and marsupials in the Atlantic forest and investigated how species traits direct their responses to climate, habitat loss, and habitat fragmentation. To understand the effect of historic processes associated with dispersal and environmental filters, we also tested for the association of the taxonomic, functional, and phylogenetic dissimilarities with spatial distance and differences in climate and habitat loss. We hypothesise that marsupials would be more limited by the temperature gradient than rodents, which are more cold‐tolerant and dispersal‐limited. We compiled a database of 73 sites with data on small‐mammal species occurrences and conducted multiple regression analyses to determine the influence of the environment on species richness and trait measures. Multiple regressions on distance matrices (MRM) were used to assess the relationship of species taxonomic, functional, or phylogenetic dissimilarities with geographical and environmental distances. Species with higher tail/body ratio and arboreality were found in warmer temperatures, but species richness increased mostly in areas with low precipitation and large forest fragments. Taxonomic dissimilarity was mostly associated with geographic distance and the distance‐decay relationship was steeper for taxonomic than for phylogenetic or functional dissimilarities. As predicted, temperature had a stronger effect on the trait distribution of marsupials than of rodents. However, for both groups, spatial distance was the most important predictor of species dissimilarity. These results might suggest that, at broad scales, dispersal shaped the distribution of Neotropical small‐mammal regardless of species adaptations to climatic conditions.

Influence of elevation on bioregionalisation: A case study of the Sino‐Himalayan flora

AbstractAimElevation is an important factor that influences bioregionalisation in mountainous areas, but its effects are not well known. Taking the Sino‐Himalayan flora as a case, we aimed to test the effect of elevation on bioregionalisation and provide a regionalisation scheme of the Sino‐Himalayan flora.LocationThe Sino‐Himalaya (East Himalaya, the Hengduan Mountains and the Yunnan Plateau in China).TaxonAngiosperms.MethodsWe compiled distribution data and elevation ranges of angiosperms in the Sino‐Himalaya and adjacent areas and reconstructed a species‐level phylogenetic tree of 19,313 angiosperm species. The area was divided into 398 grid cells, each 1 × 1°. Nine datasets of different elevation ranges were then used to delineate the flora of the Sino‐Himalaya and adjacent areas using the phylogenetic dissimilarity approach.ResultsA comparison of nine regionalisation schemes of the Sino‐Himalayan flora based on different elevation range datasets revealed that more than half of grid cells were allocated to more than one subregion. Most of these grid cells were located in areas with a wide range of elevation and/or at the boundaries between subregions. After revising the subregion allocations of eight shifting grid cells, we generated a phylogeny‐ and elevation‐based regionalisation scheme of three regions, comprising eight subregions, for the Sino‐Himalayan flora.Main conclusionsBy integrating phylogenetic and elevational information, the Sino‐Himalaya can be divided into three floristic regions: the Yunnan Plateau region, the Hengduan Mountains region and the East Himalaya region. Our study provides novel insights into the regionalisation of the flora and highlights the importance of incorporating elevation data in the bioregionalisation of areas with a broad elevational range.

Diverging facets of grassland ant diversity along a Mediterranean elevational gradient

1. We address associations of taxonomic diversity (TD), functional diversity (FD), and phylogenetic diversity (PD) of ant assemblages with gradients of elevation to assess whether energetic limitations or deterministic or stochastic niche‐building processes are more relevant to the assembly of communities.2. We sampled ant assemblages using pitfall traps in grassland habitats along an elevational gradient of 1712 m in the Guadarrama Mountains of Central Spain. The relationships of alpha and beta diversity metrics with soil temperature, productivity, elevation, and geographical distances were examined with generalised additive (mixed) models.3. The facets of diversity showed strong and partially coincident responses to the gradients, but the responses and the similarities among them weakened or disappeared when the effects of species richness were factored out. TD and FD changed roughly in a similar manner with elevation and productivity, but PD did not show clear responses to those factors. Taxonomic and functional richness increased with productivity and decreased with elevation. Mean pairwise functional and phylogenetic dissimilarities did not change along the gradients. Elevation and productivity gradients accounted for much of the beta TD among assemblages but only explained a moderate variation of functional traits and phylogenetic relationships, while geographical distances were more explanatory of beta PD.4. The partial redundancies among facets of diversity suggest that the spatial variation of diversity is mainly related to the sheer number of species. However, both environmental filtering and limiting similarity could be acting in concordance to reduce the number of species present in communities.

Morphological and molecular characterization of Ceratomyxa xanthopteri n. sp. (Myxosporea: Ceratomyxidae) from the marine ornamental fish Acanthurus xanthopterus Valenciennes 1835 (Acanthuridae) off Vizhinjam coast, Kerala.

A new species of Ceratomyxa infecting the gallbladder of the marine ornamental fish Acanthurus xanthopterus collected from the Vizhinjam coast of Kerala is described. The parasite exhibited a prevalence of 100%. Mature spores recovered from the gallbladder were slightly crescentic with rounded lateral extremities and possessed convex anterior and slightly concave to straight posterior margins. Spore valves two, equal, joined by a straight and prominent suture. Myxospores measured 5.5 ± 0.6 μm in length and 15.9 ± 2.3 μm in thickness. Polar capsules two, equal, spherical, positioned anteriorly on either sides of the suture, 2.3 ± 0.2 μm long and 2.2 ± 0.2 μm wide. Polar filament with four to five coils, 21.2 ± 0.6 μm when extruded. Posterior angle 173.6 ± 5.2°. Early sporogonic stages and monosporic, disporic, and multisporic plasmodial stages were spherical to irregular in shape, with or without filopodia. Histopathologic analysis revealed that spores and developing stages were attached to the gallbladder wall as well as found free in the lumen. Morphologic and morphometric comparison of the present parasite with known species of Ceratomyxa indicated significant differences. In molecular and phylogenetic analyses, the present myxosporean revealed high divergence with related forms and occupied an independent position within the Ceratomyxa clade with high nodal support. Considering the morphological, morphometric, molecular, and phylogenetic dissimilarities with the previously described species of Ceratomyxa and the differences in host and geographic locations, the present species of myxosporean is treated as new and is named Ceratomyxa xanthopteri n. sp.

Multiple diversity facets of crucial microbial groups in biological soil crusts promote soil multifunctionality

AbstractAimMicrobial diversity is one of the most important factors for maintaining the performance of multiple functions in soils (multifunctionality). However, existing studies typically consider the taxonomic richness or Shannon diversity of the entire community. We know little about the connection network of taxonomic and phylogenetic facets of diversity and their collective impact on multifunctionality. In this study, the linkages of effects of diversity within functional groups were disentangled in drylands.LocationThe central Tibetan Plateau.Time periodPresent.Major taxa studiedPhototrophs and diazotrophs (mainly cyanobacteria).MethodsGiven the carbon‐ and nitrogen‐limited nature of drylands, we conducted a high‐throughput sequencing of C/N‐fixing functional groups from biocrusts and evaluated multiple facets of diversity (i.e., richness, evenness and phylogeny‐related trait dissimilarity), together with seven crucial variables of soil functioning to calculate multifunctionality. The relationships between multifaceted diversity and abundance with individual functions and multifunctionality were validated by a set of solid statistical analyses.ResultsWe found that the integrated biodiversity index was a stronger predictor of multifunctionality than richness. The divergent performance of different facets of diversity determined the idiosyncratic effect of each functional group on soil multifunctionality. Moreover, the evaluation of functional significance at the species level gave important clues on the trade‐offs and redundancy in each functional group, explaining the distinct patterns of effects of diversity. Richness was the dominant factor for diazotrophs to maximize multifunctionality, whereas phylogenetic dissimilarity was the essential one for phototrophs.Main conclusionsOur study demonstrated that multiple facets of diversity should be considered when assessing the effects of biodiversity. In contrast to the community level, within‐functional group measures might adequately capture the features of diversity that are most correlated with soil multifunctionality. Our results provide a perspective to bridge the gap between taxonomic and trait‐based approaches for elucidating the biodiversity–ecosystem function relationship.

Abundance, not diversity, of host beetle communities determines abundance and diversity of parasitoids in deadwood.

Most parasites and parasitoids are adapted to overcome defense mechanisms of their specific hosts and hence colonize a narrow range of host species. Accordingly, an increase in host functional or phylogenetic dissimilarity is expected to increase the species diversity of parasitoids. However, the local diversity of parasitoids may be driven by the accessibility and detectability of hosts, both increasing with increasing host abundance. Yet, the relative importance of these two mechanisms remains unclear. We parallelly reared communities of saproxylic beetle as potential hosts and associated parasitoid Hymenoptera from experimentally felled trees. The dissimilarity of beetle communities was inferred from distances in seven functional traits and from their evolutionary ancestry. We tested the effect of host abundance, species richness, functional, and phylogenetic dissimilarities on the abundance, species richness, and Shannon diversity of parasitoids. Our results showed an increase of abundance, species richness, and Shannon diversity of parasitoids with increasing beetle abundance. Additionally, abundance of parasitoids increased with increasing species richness of beetles. However, functional and phylogenetic dissimilarity showed no effect on the diversity of parasitoids. Our results suggest that the local diversity of parasitoids, of ephemeral and hidden resources like saproxylic beetles, is highest when resources are abundant and thereby detectable and accessible. Hence, in some cases, resources do not need to be diverse to promote parasitoid diversity.

A taxonomic and phylogenetic perspective on plant community assembly along an elevational gradient in subtropical forests

AbstractAimsBiodiversity patterns along elevational gradients have been well documented. Yet, the variations of biodiversity patterns along elevations and their underlying mechanisms are still unclear. Integrating multiple facets of biodiversity provides novel insights into the mechanisms for driving community assembly. In this study, species abundance information was incorporated into taxonomic and phylogenetic diversity to reveal the ecological and evolutionary forces of plant community assembly along an elevational gradient in subtropical forests.MethodsWe selected 17 woody plant plots along an elevational gradient from 270 to 1470 m in eastern China’s subtropical forests. Both presence-based and abundance-based measures of angiosperm species were used to quantify taxonomic alpha diversity, phylogenetic alpha diversity, phylogenetic relatedness, as well as taxonomic and phylogenetic dissimilarity among these plots. And the relations between these measures and climatic and topographic variables were analyzed.Important FindingsFor both abundance-weighted and unweighted measures, we observed an overall increasing pattern for taxonomic alpha diversity along elevation, and distance-decay trends of taxonomic and phylogenetic similarity with increased elevational distances. However, there were disparity patterns of phylogenetic alpha diversity between abundance-weighted and unweighted measures. For phylogenetic structure, there was no significant trend along elevation. Both topographical and microclimatic variables were main drivers of diversity patterns and phylogenetic structure. Compared with unweighted measures, abundance-weighted measures were strongly related with the slope and stand basal area. Overall, our results prove that deterministic processes mediated by local species abundance imprint on plant community composition along the elevational gradient.

Bioinformatic Analysis of Genome-Predicted Bat Cathelicidins.

Bats are unique in their potential to serve as reservoir hosts for intracellular pathogens. Recently, the impact of COVID-19 has relegated bats from biomedical darkness to the frontline of public health as bats are the natural reservoir of many viruses, including SARS-Cov-2. Many bat genomes have been sequenced recently, and sequences coding for antimicrobial peptides are available in the public databases. Here we provide a structural analysis of genome-predicted bat cathelicidins as components of their innate immunity. A total of 32 unique protein sequences were retrieved from the NCBI database. Interestingly, some bat species contained more than one cathelicidin. We examined the conserved cysteines within the cathelin-like domain and the peptide portion of each sequence and revealed phylogenetic relationships and structural dissimilarities. The antibacterial, antifungal, and antiviral activity of peptides was examined using bioinformatic tools. The peptides were modeled and subjected to docking analysis with the region binding domain (RBD) region of the SARS-CoV-2 Spike protein. The appearance of multiple forms of cathelicidins verifies the complex microbial challenges encountered by these species. Learning more about antiviral defenses of bats and how they drive virus evolution will help scientists to investigate the function of antimicrobial peptides in these species.

Beta and phylogenetic diversities tell complementary stories about ecological networks biogeography.

The beta-diversity of interactions between communities does not necessarily correspond to the differences related to their species composition because interactions show greater variability than species co-occurrence. Additionally, the structure of species interaction networks can itself vary over spatial gradients, thereby adding constraints on the dissimilarity of communities in space. We used published data on the parasitism interaction between fleas and small mammals in 51 regions of the Palearctic to investigate how beta-diversity of networks and phylogenetic diversity are related. The networks could be separated in groups based on the metrics that best described the differences between them, and these groups were also geographically structured. We also found that each network beta-diversity index relates in a particular way with phylogenetically community dissimilarity, reinforcing that some of these indexes have a strong phylogenetic component. Our results clarify important aspects of the biogeography of hosts and parasites communities in Eurasia, while suggesting that networks beta-diversity and phylogenetic dissimilarity interact with the environment in different ways.

Global functional variation in alpine vegetation

AbstractQuestionsWhat are the functional trade‐offs of vascular plant species in global alpine ecosystems? How is functional variation related to vegetation zones, climatic groups and biogeographic realms? What is the relative contribution of macroclimate and evolutionary history in shaping the functional variation of alpine plant communities?LocationGlobal.MethodsWe compiled a data set of alpine vegetation with 5,532 geo‐referenced plots, 1,933 species and six plant functional traits. We used principal component analysis to quantify functional trade‐offs among species and trait probability density to assess the functional dissimilarity of alpine vegetation in different vegetation zones, climatic groups and biogeographic realms. We used multiple regression on distance matrices to model community functional dissimilarity against environmental and phylogenetic dissimilarity, controlling for geographic distance.ResultsThe first two PCA axes explained 66% of the species’ functional variation and were related to the leaf and stem economic spectra, respectively. Trait probability density was largely independent of vegetation zone and macroclimate but differed across biogeographic realms. The same pattern emerged for both species pool and community levels. The effects of environmental and phylogenetic dissimilarities on community functional dissimilarity had similar magnitude, while the effect of geographic distance was negligible.ConclusionsPlant species in alpine areas reflect the global variation of plant function, but with a predominant role of resource use strategies. Current macroclimate exerts a limited effect on alpine vegetation, mostly acting at the community level in combination with evolutionary history. Global alpine vegetation is functionally unrelated to the vegetation zones in which it is embedded, exhibiting strong functional convergence across regions.