Phylogenetic Dimensions Research Articles

A landscape‐level analysis of bird taxonomic, functional and phylogenetic β‐diversity in habitat island systems

AbstractAimHow β‐diversity patterns are shaped by landscape‐level processes remains unclear across habitat island systems. Here we assessed landscape‐level bird β‐diversity in habitat island systems and aimed to (1) evaluate the relative contribution of turnover (βSIM) and nestedness‐resultant (βSNE) components to multisite β‐diversity (βSOR) from taxonomic, functional and phylogenetic dimensions; (2) examine the influence of climate factors and system characteristics in shaping landscape‐level patterns of β‐diversity measures; and (3) study how β‐diversity patterns of bird communities vary with the spatial extents of island systems.LocationGlobal.TaxonBirds.MethodsWe compiled bird data in 22 habitat island systems from literature and classified these island systems into small and large spatial scales. We partitioned βSOR into βSIM and βSNE from three dimensions for each system and calculated standardized functional and phylogenetic β‐diversity measures. We assessed the effects of climate factors and system characteristics on observed and standardized β‐diversity measures by multiple linear models for both small and large systems.ResultsWe found that the dominant role of βSIM to βSOR in habitat island systems was pervasive. However, the best explanatory variables were not consistent across systems, which depended on the β‐diversity components, diversity dimensions and spatial extent of habitat island systems. In general, climate factors acted as the main drivers of bird communities across small and large systems, whereas system characteristics played minor roles.Main conclusionsSpatial turnover dominated overall bird β‐diversity in most habitat island systems. Our results imply the roles of niche‐based assembly processes through the interplay among differential functional traits and phylogenetic distances of species, climate factors and system characteristics as well as spatial extent in driving bird communities across multiple habitat island systems at a landscape level. This study offers a better understanding of the processes underlying macroecological patterns of isolated biological communities across habitat island systems.

Extracting phylogenetic dimensions of coevolution reveals hidden functional signals

Despite the structural and functional information contained in the statistical coupling between pairs of residues in a protein, coevolution associated with function is often obscured by artifactual signals such as genetic drift, which shapes a protein’s phylogenetic history and gives rise to concurrent variation between protein sequences that is not driven by selection for function. Here, we introduce a background model for phylogenetic contributions of statistical coupling that separates the coevolution signal due to inter-clade and intra-clade sequence comparisons and demonstrate that coevolution can be measured on multiple phylogenetic timescales within a single protein. Our method, nested coevolution (NC), can be applied as an extension to any coevolution metric. We use NC to demonstrate that poorly conserved residues can nonetheless have important roles in protein function. Moreover, NC improved the structural-contact predictions of several coevolution-based methods, particularly in subsampled alignments with fewer sequences. NC also lowered the noise in detecting functional sectors of collectively coevolving residues. Sectors of coevolving residues identified after application of NC were more spatially compact and phylogenetically distinct from the rest of the protein, and strongly enriched for mutations that disrupt protein activity. Thus, our conceptualization of the phylogenetic separation of coevolution provides the potential to further elucidate relationships among protein evolution, function, and genetic diseases.

Taxonomic, functional and phylogenetic bird diversity response to coffee farming intensity along an elevational gradient in Costa Rica

The expansion of the agricultural frontier in the species-rich tropical regions of the world has generated conflicts between the need to secure food production and the conservation of biodiversity. As natural areas give way to farmlands, the future of sensitive taxa may depend on how intensively the crops are cultivated. In order to better understand the response of avian diversity to cultivation intensity in tropical farmlands, analyses of species richness are increasingly being complemented with information about the birds’ functional roles and evolutionary history. In this study, we analysed the association of several features of vegetation composition and structure, as indicators of cultivation intensity in coffee farms in Costa Rica, on the taxonomic, functional and phylogenetic dimensions of avian biodiversity at the local scale across an approximately 2000 m elevational gradient. Bird detections and vegetation measurements were conducted at 120 randomly selected circular plots of 25 m radius, across 51 coffee farms. Using regression modelling and multi-model inference, we related six vegetation features to five biodiversity metrics in this system and evaluated whether the results differed among elevational zones. The most influential vegetation feature was the number of trees with a diameter-at-breast-height larger than 30 cm, promoting higher richness, functional redundancy and phylogenetic structure of avian species. Shade from canopy cover and the number of non-coffee crops increased species and phylogenetic richness, respectively. The effect of individual vegetation features on particular biodiversity metrics varied across elevation, possibly due to the idiosyncratic response of each dimension to the elevation gradient or because of local ecological processes. We conclude that vegetation features related to cultivation intensity have effects on avian diversity, but that these effects differ among biodiversity metrics and are sensitive to the environmental context. Consequently, targeted conservation management should be based on more comprehensive studies that include more than one biodiversity dimensions as well as variation in relevant environmental context. In general, our results suggest that, when designing conservation strategies for birds in coffee-dominated landscapes, there is likely no “one-size-fits-all” strategy.

Towards a phylogenetic ecology of plant pests and pathogens.

Plant-pathogens and insect pests, hereafter pests, play an important role in structuring ecological communities, yet both native and introduced pests impose significant pressure on wild and managed systems, and pose a threat to food security. Global changes in climate and land use, and transportation of plants and pests around the globe are likely to further increase the range, frequency and severity of pest outbreaks in the future. Thus, there is a critical need to expand on current ecological theory to address these challenges. Here, we outline a phylogenetic framework for the study of plant and pest interactions. In plants, a growing body of work has suggested that evolutionary relatedness, phylogeny, strongly structures plant-pest associations-from pest host breadths and impacts, to their establishment and spread in new regions. Understanding the phylogenetic dimensions of plant-pest associations will help to inform models of invasive species spread, disease and pest risk in crops, and emerging pest outbreaks in native plant communities-which will have important implications for protecting food security and biodiversity into the future. This article is part of the theme issue 'Infectious disease macroecology: parasite diversity and dynamics across the globe'.

Patterns and drivers determining phyllostomid bat diversity in land-bridge islands off the south-east coast of Brazil

AbstractFew studies that apply the theory of island biogeography have considered the functional and phylogenetic dimensions of diversity. However, the joint use of the three diversity dimensions, i.e. taxonomic, functional and phylogenetic, can help us to gain a better understanding of the mechanisms underlying ecological and evolutionary processes. Here, we compare phyllostomid bat assemblages between five land-bridge islands off the south-east coast of Brazil and compare these islands with three sites on the mainland. For this, we have estimated the three dimensions of α- and β-diversity, nestedness and community indexes based on mean trait values for the islands and the mainland. The mainland showed higher species richness and taxonomic, functional and phylogenetic diversity. In addition, only species richness and phylogenetic diversity were positively related to island area. Taxonomically and functionally, the poorest assemblages (minor islands) were subgroups of the richer assemblages (mainland and larger islands). Taken together, our results show that bat assemblages of smaller islands tend to be more sensitive to changes in species richness than those of larger islands, with the larger islands working as a ‘source’ of species for small islands. These results demonstrate the high conservation value of the larger islands, which has direct consequences for local population dynamics of phyllostomid bats.

Forest area predicts all dimensions of small mammal and lizard diversity in Amazonian insular forest fragments

ContextAlthough hydropower development is one of the primary drivers of habitat loss and insular fragmentation, its impacts on species identity and their functional and phylogenetic roles have often been overlooked.ObjectivesHere we use an integrative approach, considering taxonomic, functional and phylogenetic dimensions at multiple scales, to understand the processes underlying species (dis)assembly of two taxa exhibiting relatively low dispersal ability: small mammals and lizards.MethodsWe surveyed 26 islands within the Balbina Hydroelectric Reservoir, and adjacent continuous forest, in Central Amazonia. Each dimension of diversity was related to spatial and habitat variables. We also examined functional composition using community-weighted mean trait values, and community redundancy using functional uniqueness. β-diversity was partitioned into their richness (βrich) and replacement (βrepl) components.ResultsFunctional and phylogenetic α-diversities of both taxa mirrored the taxonomic dimension, all of which increased with forest area. Individual small mammal (body mass and matrix tolerance), and lizard traits (body length, heliothermic mode and habitat type) were also predicted by forest area. For both groups, functional uniqueness decreased with forest area, and all dimensions of β-diversity were predominantly partitioned in βrich.ConclusionsThe environmental filter created by forest area resulted in the low conservation value associated with small forest islands, only occupied by a small set of species comprised by generalist lizards and matrix-tolerant small mammals. On the other side, large forest sites ensured ecosystem resilience to disturbance. To maintain ecosystem integrity, creating myriad small islands over large expanses of floodwaters should be avoided in future hydropower development.

Stochasticity overrides deterministic processes in structuring macroinvertebrate communities in a plateau aquatic system

AbstractDeterministic and stochastic processes are two major factors shaping community dynamics, but their relative importance remains unknown for many aquatic systems, including those in the high‐elevation Qinghai–Tibet Plateau. Here, we explored the causes of multidimensional beta diversity patterns (i.e., taxonomic, functional, and phylogenetic) of a macroinvertebrate metacommunity in this large aquatic system by using multiple approaches (i.e., null models, phylogenetic signal testing, and ordination‐based approaches). To obtain insights into community assembly mechanisms, we also analyzed beta diversity in two deconstructed sub‐metacommunities (e.g., different tributaries and the main lake body). We found that most functional traits showed significant phylogenetic signals, indicating that the functional traits were profoundly influenced by evolutionary history. The null models showed randomness of functional and phylogenetic beta diversities for the whole basin and its tributaries, confirming the importance of stochasticity over deterministic processes in controlling community structure. However, both phylogenetic and functional community structures were clustered in the Qinghai Lake, probably reflecting the importance of environmental filtering. Ordination‐based approaches also revealed that both environmental factors and spatial processes accounted for variation in taxonomic, functional, and phylogenetic beta diversity. More specifically, environmental filtering was more important than spatial processes for the functional dimension, but the opposite was true for the taxonomic and phylogenetic dimensions. The paleogeographic history of the Qinghai Lake basin may have contributed substantially to the prevalence of stochastic processes. Overall, this study provides a better understanding of ecological patterns and assembly mechanisms of macroinvertebrate communities across this poorly known high‐elevation aquatic system that is highly sensitive to climate warming.

Effects of land‐use change on avian taxonomic, functional and phylogenetic diversity in a tropical montane rainforest

AbstractAimAlthough land use change is a leading cause of biodiversity loss worldwide, there is scant information on the extent to which it has affected the structure and composition of bird communities in the Afrotropical region. This study aimed to quantify the effects of habitat transformation on taxonomic, functional and phylogenetic diversity in Afrotropical bird communities.LocationNyungwe landscape, a montane rainforest with adjoining farmland in south‐west Rwanda.MethodsData on bird occurrence, abundance and functional traits were collected in 2017/18 using point counts. We also collected data on habitat and morphological traits for all bird species recorded. We quantified bird diversity using a range of metrics, including the inverse Simpson index, functional dispersion and the standardized effect size of mean nearest taxon distance.ResultsIn comparison with primary forest areas, even low levels of land use change altered species composition and reduced species diversity. Although overall functional diversity and phylogenetic diversity were similar across land use types, we found a significant contraction of trophic and locomotory trait structures of bird communities in restored areas and cultivated areas, respectively. Soil moisture, elevation and lower vegetation height were major factors influencing taxonomic, functional and phylogenetic dimensions of bird communities, although their effects varied across these dimensions.Main conclusionsThe sensitivity of forest species to minor habitat disturbance emphasizes the value of conserving primary vegetation. Long‐term conservation of bird communities in Afromontane ecosystems requires halting wide‐scale destruction of primary forest, promoting vegetation heterogeneity in the ecological restoration of degraded habitats and adopting wildlife‐friendly agricultural practices. Our results suggest that monitoring and conservation in these landscapes can be refined using taxonomic, functional and phylogenetic diversity metrics to provide complementary information about the current and likely future impacts of land use change.

Taxonomic, functional, and phylogenetic beta diversity in the Inner Mongolia grassland

Beta diversity, which measures the variation in community composition along environmental gradients, has great significance for biodiversity conservation and nature reserve construction. Biodiversity usually includes taxonomic, functional, and phylogenetic dimensions. However, few studies have considered these three dimensions of beta diversity simultaneously in the grassland. Thus, based on 194 sites in the Inner Mongolia grassland, we calculated taxonomic, functional, and phylogenetic beta diversity and further explored the relative importance of environmental filtering and dispersal limitation on beta diversity patterns. The results showed that the taxonomic and phylogenetic beta diversity mainly consisted of the turnover component, but functional beta diversity mainly consisted of the nestedness component. Dispersal limitation dominantly influenced taxonomic and functional beta diversity, while environmental filtering dominantly influenced phylogenetic beta diversity. According to the inequivalence of three dimensions of diversity, we highlight that it is necessary to conduct comprehensive research based on taxonomic, functional and phylogenetic diversity for better biodiversity conservation.

Mammals on mountainsides revisited: Trait‐based tests of assembly reveal the importance of abiotic filters

AbstractAimMountains provide uniquely informative systems for examining how biodiversity is distributed and identifying the causes of those patterns. Elevational patterns of species richness are well‐documented for many taxa but comparatively few studies have investigated patterns in multiple dimensions of biodiversity along mountainsides, which can reveal the underlying processes at play. Here, we use trait‐based diversity patterns to determine the role of abiotic filters and competition in the assembly of communities of small mammals across elevation and evaluate the surrogacy of taxonomic, functional, and phylogenetic dimensions of diversity.LocationGreat Basin ecoregion, western North America.TaxonRodents and shrews.MethodsThe elevational distributions of 34 species were determined from comprehensive field surveys conducted in three arid, temperate mountain ranges. Elevation–diversity relationships and community assembly processes were inferred from phylogenetic (PD) and functional diversity (FD) patterns of mean pairwise and mean nearest‐neighbor distances while accounting for differences in species richness. FD indices were calculated separately for traits related to either abiotic filtering (β‐niche traits) or biotic interactions (α‐niche traits) to test explicit predictions of the role of each across elevation.ResultsTrait‐based tests of processes indicated that abiotic filtering tied to a strong aridity gradient drives the assembly of both low‐ and high‐elevation communities. Support for competition was not consistent with theoretical expectations under the stress‐dominance hypothesis, species interactions‐abiotic stress hypothesis, or guild assembly rule. Mid‐elevation peaks in species richness contrasted with overall FD and PD, which generally increased with elevation. PD and total FD were correlated on two of three mountains.Main conclusionsThe functional diversity of small mammal communities in these arid, temperate mountains is most consistent with abiotic filters, whereas support for competition is weak. Decomposing FD into traits related to separate assembly processes and examining ecoregional variation in diversity were critical for uncovering the generality of mechanisms. Divergent patterns among dimensions revealed species richness to be a poor surrogate for PD and FD across elevation and reflect the effect of biogeographic and evolutionary history. This first analysis of elevational multidimensional diversity gradients for temperate mammals provides a versatile framework for future comparative studies.

Unraveling the drivers of plant taxonomic and phylogenetic β-diversity in a human-modified tropical dry forest

Biodiversity maintenance in human-modified landscapes largely depends on spatial variations in species composition (β-diversity), but the impact of human disturbance on β-diversity remains poorly understood. We examined how taxonomic and phylogenetic β-diversity of woody plant communities in the Brazilian Caatinga dry forest respond to two emerging threats—chronic anthropogenic disturbance and water scarcity. We separately assessed diversity metrics that give a disproportionate weight to rare species, and metrics weighted by dominant species. We recorded a total of 5118 individuals from 104 species across 19 0.1-ha plots into a 21,430-ha human-modified landscape exposed to chronic disturbances and a high variation in climatic water deficit. At the landscape scale, β-diversity was higher when considering rare species than when focusing on dominant species, especially for the phylogenetic dimension of β-diversity. Water deficit was the primary driver of plant taxonomic and phylogenetic β-diversity, followed by the number of cattle and inter-site isolation; however, rare species seem to depend more strongly on these factors than the dominant ones. Therefore, preserving as much forest as possible, including areas exposed to different disturbance level and climate variables, is critical to prevent the loss of rare species and maintain the compositional differentiation of biotic assemblages. Such forest cover should be maintained in a large number of forest patches scattered through the landscape to preserve biologically and functionally distinct components of this ecosystem, avoid landscape-scale biotic homogenization, and thus favor its ecological resilience.

Low spatial congruence between temporal functional β‐diversity and temporal taxonomic and phylogenetic β‐diversity in British avifauna

AbstractAssessing spatial and temporal patterns of biodiversity change is essential to understand how communities vary over time and confront to environmental changes for the resilience of ecosystem functioning. We use data from two bird atlases of Britain collected during the breeding periods 1988–1991 and 2008–2011 to measure temporal β‐diversity of taxonomic, functional and phylogenetic dimensions and examine the relationship and the level of congruence of the three dimensions of temporal β‐diversity and their respective partitioned components (turnover‐nestedness). Temporal β‐diversity, turnover and nestedness patterns were highly congruent for the taxonomic and phylogenetic dimension, although these dimensions were weakly associated with the functional dimension. We found higher levels of temporal changes for the taxonomic (mean Jaccard β‐diversity 0.27) and phylogenetic (mean Jaccard β‐diversity 0.21) dimensions than for the functional dimension (mean Jaccard β‐diversity 0.09), implying that despite the changes in species composition the functional composition of the communities remained less affected. For taxonomic and phylogenetic dimensions, turnover contributed more than nestedness to shaping β‐diversity, while for functional β‐diversity the two components contributed similarly. Communities at higher altitudes were also more functionally similar in 20 years but with more changes in taxonomic and phylogenetic diversity possibly due to environmental filtering. We hypothesize that the low congruence might be due to species with extreme trait values persisting throughout time and retaining the volume of functional space and thus contributing to the low temporal change of functional diversity despite the high levels of change in species composition, perhaps an indication of functional “stability.”

Sucessional trajetories of bird assemblages in amazonian secondary forests: Perspectives from complementary biodiversity dimensions

Secondary forests occupy extensive areas in tropical regions, providing an opportunity to investigate their relevance to biodiversity restoration. However, determining the conservation value of secondary forests and evaluating their successional trajectories depends on how biodiversity is measured. Here, we explore different biodiversity dimensions to understand how bird assemblages recover from forest disturbance caused by small scale farmers in the Amazon. We sampled bird species through standard visual and auditory censuses in 24 small plots of 1-hectare distributed in a paired design of old growth forests and secondary forests from different age categories (early, middle and late succession). We used 12 biodiversity metrics to explore the taxonomic, functional, and phylogenetic dimensions of bird diversity. Total species richness and evenness was similar between secondary and old growth forests. In contrast, the number of passerine species and disturbance-vulnerable species were higher in the controls of old growth forests compared to secondary forests. The relative abundance of birds with distinct functional traits consistently differed between the secondary forests of different age categories and their old growth forest counterparts. Functional evenness and divergence increased with canopy height and basal area through forest regeneration. In contrast, bird phylogenetic diversity in secondary forests was higher compared to those found in old growth forests while accounting for forest types and age categories of secondary forests. Bird species tolerant to disturbances partially compensate the loss of avian taxonomic and phylogenetic diversity during the conversion of undisturbed forests to agricultural fields. Changes in functional evenness and functional divergence suggest that resources used by birds are altered along the secondary succession and that the niche complementarity among species is reduced in more intensively managed sites. Ecological succession can be highly complex in terms of taxa identity, their functional roles and evolutionary history. Therefore, measurements that explore distinct biodiversity dimensions are fundamental to understanding how species are organized in assemblages across time and space.

A multifaceted approach to analyzing taxonomic, functional, and phylogenetic β diversity.

Ecological literature offers a myriad of methods for quantifying β diversity. One such method is determining BDtotal (BD), which, unlike other methods, can be decomposed into meaningful components that indicate how unique a sampling unit is regarding its composition (local contribution) and how unique a species is regarding its occurrence in the community (species contribution). Despite this advantage, the original formulation of the BD metric only assesses taxonomic variation and neglects other important dimensions of biodiversity. We expanded the original formulation of BD to capture variation in the functional and phylogenetic dimensions of community data by computing two new metrics-BDFun and BDPhy -as well as their respective components that represent the local and species contribution. We tested the statistical performance of these new metrics for capturing variation in functional and phylogenetic composition through simulated communities and illustrated the potential use of these new metrics by analyzing β diversity of stream fish communities. Our results demonstrated that BDPhy and BDFun have acceptable type I error and great power to detect the effect of deep evolutionary relationships and attributes mediating patterns of β diversity. The empirical example illustrated how BDPhy and BDFun reveal complementary aspects of β diversity relative to the original BD metric. These new metrics can be used to identify local communities that are of conservation importance because they represent unique functional, phylogenetic, and taxonomic compositions. We conclude that BDPhy and BDFun are important tools for providing complementary information in the investigation of the structure of biological communities.

Influence of habitat on the phylogenetic structure of Robinia pseudoacacia forests in the eastern Loess Plateau, China

Robinia pseudoacacia forests are an important component of plantations in the Loess Plateau, China. These forest communities with abundant understory plants have become interesting for ecologists and conservationists. However, most studies on species diversity focus on species richness, while few focus on the phylogenetic dimension of plant communities, especially the influence of habitat on phylogeny. In this study, we explored the species richness, phylogenetic diversity and phylogenetic structure of understory plant communities at different site types in the Caijiachuan watershed of Shanxi, China. Our findings indicated that the floristic composition in this area was variable and differed significantly among different habitats. Moreover, the introduction of R. pseudoacacia forests enhanced the heterogeneity of understory environments and provided migration opportunities for species, which played an important role in maintaining and increasing biodiversity. As expected, species richness was closely correlated with phylogenetic diversity, but species-rich communities did not always have the same high level of phylogenetic diversity. We also found that the highest values of them occurred on semi-sunny and semi-shady downhill slopes respectively, and the phylogenetic structure of these two sites was overdispersed. We suggest that these sites are key protected communities, as they may maximize the evolutionary potential of plant communities to respond to future environmental changes. In addition, our data indicated that light conditions have a significant impact on understory plant communities, which is further intensified by soil moisture constraints. Thus, forest managers should provide suitable environmental conditions for the invasion and settlement of understory plants through appropriate management measures, such as canopy pruning and thinning.

Climate warming moderates the impacts of introduced sportfish on multiple dimensions of prey biodiversity.

Human-assisted introductions of exotic species are a leading cause of anthropogenic change in biodiversity; however, context dependencies and interactions with co-occurring stressors impede our ability to predict their ecological impacts. The legacy of historical sportfish stocking in mountainous regions of western North America creates a unique, natural quasiexperiment to investigate factors moderating invasion impacts on native communities across broad geographic and environmental gradients. Here we synthesize fish stocking records and zooplankton relative abundance for 685 mountain lakes and ponds in the Cascade and Canadian Rocky Mountain Ranges, to reveal the effects of predatory sportfish introduction on multiple taxonomic, functional and phylogenetic dimensions of prey biodiversity. We demonstrate an innovative analytical approach, combining exploratory random forest machine learning with confirmatory multigroup analysis using multivariate partial least-squares structural equation models, to generate and test hypotheses concerning environmental moderation of stocking impacts. We discovered distinct effects of stocking across different dimensions of diversity, including negligible (nonsignificant) impacts on local taxonomic richness (i.e. alpha diversity) and trophic structure, in contrast to significant declines in compositional uniqueness (i.e. beta diversity) and body size. Furthermore, we found that stocking impacts were moderated by cross-scale interactions with climate and climate-related land-cover variables (e.g. factors linked to treeline position and glaciers). Interactions with physical morphometric and lithological factors were generally of lesser importance, though catchment slope and habitat size constraints were relevant in certain dimensions. Finally, applying space-for-time substitution, a strong antagonistic (i.e. dampening) interaction between sportfish predation and warmer temperatures suggests redundancy of their size-selective effects, meaning that warming will lessen the consequences of introductions in the future and stocked lakes may be less impacted by subsequent warming. While both stressors drive biotic homogenization, our results have important implications for fisheries managers weighing the costs/benefits of stocking-or removing established non-native populations-under a rapidly changing climate.

Multiple dimensions of dietary diversity in large mammalian herbivores

Theory predicts that trophic specialization (i.e. low dietary diversity) should make consumer populations sensitive to environmental disturbances. Yet diagnosing specialization is complicated both by the difficulty of precisely quantifying diet composition and by definitional ambiguity:what makes a diet 'diverse'? We sought to characterize the relationship between taxonomic dietary diversity (TDD) and phylogenetic dietary diversity (PDD) in a species-rich community of large mammalian herbivores in asemi-arid East African savanna. We hypothesized that TDD and PDD would be positively correlated within and among species, because taxonomically diverse diets are likely to include plants from many lineages. By using DNA metabarcoding to analyse 1,281 faecal samples collected across multiple seasons, we compiled high-resolution diet profiles for 25 sympatric large-herbivore species. For each of these populations, we calculated TDD and PDD with reference to a DNA reference library for local plants. Contrary to our hypothesis, measures of TDD and PDD were either uncorrelated or negatively correlated with each other. Thus, these metrics reflect distinct dimensions of dietary specialization both within and among species. In general, grazers and ruminants exhibited greater TDD, but lower PDD, than did browsers and non-ruminants. We found significant seasonal variation in TDD and/or PDD for all but four species (Grevy's zebra, buffalo, elephant, Grant's gazelle); however, the relationship between TDD and PDD was consistent across seasons for all but one of the 12 best-sampled species (plains zebra). Our results show that taxonomic generalists can be phylogenetic specialists, and vice versa. These two dimensions of dietary diversity suggest contrasting implications for efforts to predict how consumers will respond to climate change and other environmental perturbations. For example, populations with low TDD may be sensitive to phylogenetically 'random' losses of food species, whereas populations with low PDD may be comparatively more sensitive to environmental changes that disadvantage entire plant lineages-and populations with low dietary diversity in both taxonomic and phylogenetic dimensions may be most vulnerable of all.

Yeast Volatomes Differentially Affect Larval Feeding in an Insect Herbivore.

Yeasts form mutualistic interactions with insects. Hallmarks of this interaction include provision of essential nutrients, while insects facilitate yeast dispersal and growth on plant substrates. A phylogenetically ancient chemical dialogue coordinates this interaction, where the vocabulary, the volatile chemicals that mediate the insect response, remains largely unknown. Here, we used gas chromatography-mass spectrometry, followed by hierarchical cluster and orthogonal partial least-squares discriminant analyses, to profile the volatomes of six Metschnikowia spp., Cryptococcus nemorosus, and brewer's yeast (Saccharomyces cerevisiae). The yeasts, which are all found in association with insects feeding on foliage or fruit, emit characteristic, species-specific volatile blends that reflect the phylogenetic context. Species specificity of these volatome profiles aligned with differential feeding of cotton leafworm (Spodoptera littoralis) larvae on these yeasts. Bioactivity correlates with yeast ecology; phylloplane species elicited a stronger response than fruit yeasts, and larval discrimination may provide a mechanism for establishment of insect-yeast associations. The yeast volatomes contained a suite of insect attractants known from plant and especially floral headspace, including (Z)-hexenyl acetate, ethyl (2E,4Z)-deca-2,4-dienoate (pear ester), (3E)-4,8-dimethylnona-1,3,7-triene (DMNT), linalool, α-terpineol, β-myrcene, or (E,E)-α-farnesene. A wide overlap of yeast and plant volatiles, notably floral scents, further emphasizes the prominent role of yeasts in plant-microbe-insect relationships, including pollination. The knowledge of insect-yeast interactions can be readily brought to practical application, as live yeasts or yeast metabolites mediating insect attraction provide an ample toolbox for the development of sustainable insect management.IMPORTANCE Yeasts interface insect herbivores with their food plants. Communication depends on volatile metabolites, and decoding this chemical dialogue is key to understanding the ecology of insect-yeast interactions. This study explores the volatomes of eight yeast species which have been isolated from foliage, from flowers or fruit, and from plant-feeding insects. These yeasts each release a rich bouquet of volatile metabolites, including a suite of known insect attractants from plant and floral scent. This overlap underlines the phylogenetic dimension of insect-yeast associations, which according to the fossil record long predate the appearance of flowering plants. Volatome composition is characteristic for each species, aligns with yeast taxonomy, and is further reflected by a differential behavioral response of cotton leafworm larvae, which naturally feed on foliage of a wide spectrum of broad-leaved plants. Larval discrimination may establish and maintain associations with yeasts and is also a substrate for designing sustainable insect management techniques.

Testing Darwin’s naturalization conundrum based on taxonomic, phylogenetic and functional dimensions of vascular plant diversity

Testing Darwin’s naturalization conundrum based on taxonomic, phylogenetic and functional dimensions of vascular plant diversity

Untangling the assembly of macrophyte metacommunities by means of taxonomic, functional and phylogenetic beta diversity patterns

Metacommunity ecology has broadened considerably with the recognition that measuring beta diversity beyond the purely taxonomic viewpoint may improve our understanding of the dispersal- and niche-based mechanisms across biological communities. In that perspective, we applied a novel multidimensional approach including taxonomic, functional and phylogenetic data to enhance our basic understanding of macrophyte metacommunity dynamics. For each beta diversity metric, we calculated the mean overall value and tested whether the mean value was different from that expected by chance using null models. We also employed evolutionary and spatially constrained models to first identify the degree to which the studied functional traits showed a phylogenetic signal, and then to estimate the relative importance of spatial and environmental effects on metacommunity structure. We first found that most individual ponds were inhabited by species that were merely random draws from the taxonomic and phylogenetic species pool available in the study region. Contrary to our expectations, not all measured traits were conserved along the phylogeny. We also showed that trait and phylogenetic dimensions strongly increased the amount of variation in beta diversity that can be explained by degree of environmental filtering and dispersal limitation. This suggests that accounting for functional traits and phylogeny in metacommunity ecology helps to explain idiosyncratic patterns of variation in macrophyte species distribution. Importantly, phylogenetic and functional analyses identified the influence of underlying mechanisms that would otherwise be missed in an analysis of taxonomic turnover. Together, these results let us conclude that macrophyte species have labile functional traits adapted to dispersal-based processes and some evolutionary trade-offs that drive community assembly via species sorting. Overall, our exploration of different facets of beta diversity showed how functional and phylogenetic information may be used with species-level data to test community assembly hypotheses that are more ecologically meaningful than assessments of environmental patterns based on the purely taxonomic viewpoint.