The phylogenetic and functional diversity of regional breeding bird assemblages is reduced and constricted through urbanization

Aim

Urbanization broadly affects the phylogenetic and functional diversity of natural communities through a variety of processes including habitat loss and the introduction of non‐native species. Due to the challenge of acquiring direct measurements, these effects have been studied primarily using “space‐for‐time” substitution where spatial urbanization gradients are used to infer the consequences of urbanization occurring across time. The ability of alternative sampling designs to replicate the findings derived using space‐for‐time substitution has not been tested.

Location

Global.

Methods

We contrasted the phylogenetic and functional diversity of breeding bird assemblages in 58 cities worldwide with the corresponding regional breeding bird assemblages estimated using geographic range maps.

Results

Compared to regional assemblages, urban assemblages contained lower phylogenetic diversity, lower phylogenetic beta diversity, a reduction in the least evolutionary distinct species and the loss of the most evolutionarily distinct species. We found no evidence that these effects were related to the presence of non‐native species. Urban assemblages contained fewer aquatic species and fewer aquatic foraging species. The distribution of body size and range size narrowed for urban assemblages with the loss of species at both tails of the distribution, especially large bodied and broadly distributed species. Urban assemblages contained a greater proportion of species classified as passerines, doves or pigeons; species identified as granivores; species that forage within vegetation or in the air; and species with more generalized associations with foraging strata.

Main conclusions

Urbanization is associated with the overall reduction and constriction of phylogenetic and functional diversity, results that largely replicate those generated using space‐for‐time substitution, increasing our confidence in the quality of the combined inferences. When direct measurements are unavailable, our findings emphasize the value of developing independent sampling methods that broaden and reinforce our understanding of the ecological implications of urbanization.

     

Deconstructing the dimensions of alpha diversity in squamate reptiles (Reptilia: Squamata) across the Americas

Aim

Our aim is to document the dimensions of current squamate reptile biodiversity in the Americas by integrating taxonomic, phylogenetic and functional data, and assessing how this may vary across phylogenetic scales. We also explore the potential underlying mechanisms that may be responsible for the observed geographical diversity patterns.

Location

The Americas.

Time period

Present.

Major taxa

Squamate reptiles.

Methods

We used published data on the distribution, phylogeny, and body size of squamate reptiles to document the current dimensions of their alpha diversity in the Americas. We overlapped species ranges to estimate taxonomic diversity (TD) and calculated phylogenetic diversity (PD) using mean pairwise phylogenetic distance (MPD), speciation rate (DivRate) and Faith's phylogenetic index (PD). We estimated functional diversity (FD) as trait dispersion in the multivariate space using body size and leg development data. We implemented a deconstructive macroecological approach to understand how spatial mismatches between the three facets of diversity vary across phylogenetic scales, and the potential eco-evolutionary mechanisms driving these patterns across space.

Results

We found a strong latitudinal gradient of TD with a large accumulation in tropical regions. PD and FD patterns were largely similar likely due to the high phylogenetic signal in the traits used, and higher values tended to be concentrated in harsh and/or heterogeneous environments. We found differences between major clades within Squamata that display contrasting geographical patterns. Several regions across the continent shared the same spatial mismatches between dimensions across clades, suggesting that similar eco-evolutionary processes are shaping these regional reptile assemblages. However, we also found evidence that non-mutually exclusive processes can operate differently across clades.

Main conclusions

The deconstructive approach implemented here is based on a solid macroecological framework. We can extend this to other taxonomic groups to establish whether there are particularities about how different eco-evolutionary mechanisms shape biodiversity facets in a spatially explicit context.     

Functional and phylogenetic structure of forest and savanna bird assemblages across spatial scales

Ecological and evolutionary mechanisms that drive community assembly vary in space and time. However, little is known about how such mechanisms act in contrasting habitats. Here, we estimated the functional and phylogenetic structure of forest and savanna bird assemblages across different spatial scales to understand: 1) the mechanisms that govern the structure of assemblages in these habitats; 2) the relationship between phylogenetic and functional structure; and 3) the influence of species richness on the functional and phylogenetic structure of assemblages. We used a null model where forest and savanna bird species were allowed to occur in the same null assemblages and other where species were separated based on their habitats. According to the first null model, forest bird assemblages were functionally and phylogenetically clustered at all spatial scales, whereas savanna bird assemblages generally showed random functional and phylogenetic structure. These results can be explained by the low dispersal rate of forest species across of the patchy habitats and the widespread distribution of savanna species. However, in the second null model, both forest and savanna bird assemblages showed random functional and phylogenetic structure at regional and local scales. This suggests that trait‐based assembly might not play an important role in both habitats and across different spatial scales. In addition, the phylogenetic and functional structure of assemblages were not correlated, evidencing that caution is necessary when using phylogenetic relationships as a surrogate to functional distances among species. Finally, the relationships between species richness and functional and phylogenetic structure indicated that an increase in the number of species can promote both clustering and overdispersion, depending on the studied habitat and scale. Our study shows that integrating different types of habitat, spatial scales and biodiversity components in a single framework can shed light on the mechanisms that determine the community assembly.     

Australian Tropical and Subtropical Rain Forest Community Assembly: Phylogeny,Functional Biogeography,and Environmental Gradients

To compare community assemblage patterns in tropical northeastern and subtropical central eastern Australia across selected gradients and scales, we tested the relationship of species traits with phylogenetic structure, and niche breadth. We considered phylogenetic relationships across current‐day species in assemblages in relation to rain forest species pool sizes, and trait values along gradients including elevation and latitude. Trait values were quantified across scales for seed size, leaf area, wood density and maximum height at maturity for 1137 species and 596 assemblages using trait gradient analysis (TGA). Local assemblages of subtropical species had narrower trait ranges, and higher niche breadth values than corresponding assemblages of tropical species. Leaf size and seed size increased at low latitudes, and community phylogenetic structure was most strongly correlated with seed traits in the subtropics, reflecting dispersal and re‐colonization processes. Elevation accounted for little of the variance in community phylogenetic structure or trait variation across local and regional scales. Stable moist forest areas retained many species from ancestral rain forest lineages across a range of temporally conserved habitats; species within assemblages were less related; and rain forest assemblages had higher functional diversity, but lower niche breadth. This suggests that on average, assemblages of species in stable areas had greater trait variation and narrower distributions. Historic and recent rain forest contraction and re‐expansion can result in recolonized areas that are dominated by species that are more related (phylogenetically) than by chance, have smaller, widely dispersed seeds, and greater niche breadth (broader distributions).     

Environmental variation is a major predictor of global trait turnover in mammals

Aim

To evaluate how environment and evolutionary history interact to influence global patterns of mammal trait diversity (a combination of 14 morphological and life‐history traits).

Location

The global terrestrial environment.

Taxon

Terrestrial mammals.

Methods

We calculated patterns of spatial turnover for mammalian traits and phylogenetic lineages using the mean nearest taxon distance. We then used a variance partitioning approach to establish the relative contribution of trait conservatism, ecological adaptation and clade specific ecological preferences on global trait turnover.

Results

We provide a global scale analysis of trait turnover across mammalian terrestrial assemblages, which demonstrates that phylogenetic turnover by itself does not predict trait turnover better than random expectations. Conversely, trait turnover is consistently more strongly associated with environmental variation than predicted by our null models. The influence of clade‐specific ecological preferences, reflected by the shared component of phylogenetic turnover and environmental variation, was considerably higher than expectations. Although global patterns of trait turnover are dependent on the trait under consideration, there is a consistent association between trait turnover and environmental predictive variables, regardless of the trait considered.

Main conclusions

Our results suggest that changes in phylogenetic composition are not always coupled with changes in trait composition on a global scale and that environmental conditions are strongly associated with patterns of trait composition across species assemblages, both within and across phylogenetic clades.     

Phylogenetic community patterns suggest Central Indian tropical dry forests are structured by montane climate refuges

Aim

We used an eco-phylogenetic approach to investigate the diversity and assembly patterns of tropical dry forests (TDFs) in Central India. We aimed at informing conservation and restoration practices in these anthropogenically disturbed forests by identifying potential habitats of conservation significance and elements of regional biodiversity most vulnerable to human impact and climate change.

Location

Tropical dry forests of Madhya Pradesh, Central India.

Methods

We analysed the species richness, stem density, basal area and phylogenetic structure (standardized effect size of MNTD, MPD, PD and community evolutionary distinctiveness cED) of 117 tree species assemblages distributed across a ~230 to ~940 m elevational gradient. We examined how these community measures and taxonomic (Sørensen) and phylogenetic (UniFrac) beta diversity varied with elevation, precipitation, temperature and climatic stress.

Results

Species richness, phylogenetic diversity, stem density and basal area were positively correlated with elevation, with high-elevation plots exhibiting cooler temperatures, higher precipitation and lower stress. High-elevation assemblages also trended towards greater phylogenetic dispersion, which diminished at lower elevations and in drier, more stressful plots. Phylogenetic turnover was observed across the elevation gradient, and species evolutionary distinctiveness increased at lower elevations and under harsher abiotic conditions.

Main Conclusions

Harsher abiotic conditions at low elevations may act as a selective filter on plant lineages, leading to phylogenetically clustered low-diversity assemblages. These assemblages contained more evolutionarily distinct species that may contribute disproportionately to biodiversity. Conversely, milder abiotic conditions at high elevations may serve as refuges for drought-sensitive species, resulting in more diverse assemblages. Conservation practices that prioritize both high- and low-elevation habitats could promote the persistence of evolutionarily distinct species and areas of high biodiversity within the Central Indian landscape. Establishing connectivity between these habitats may provide a range of climatic conditions for species to retreat to or persist within as climates change.     

Bioindicators of edge effects within Atlantic Forest remnants: Conservation implications in a threatened biodiversity hotspot

Aim

Deforestation of the Atlantic Forest of eastern Paraguay has been recent but extensive, resulting in a fragmented landscape highly influenced by forest edges. We examined edge effects on multiple dimensions of small mammalian diversity.

Location

Forest fragments of eastern Paraguayan Atlantic Forest.

Methods

We trapped small mammal species at different distances from the forest edge (DTE) in reserves and estimated multiple dimensions of diversity per site. Similarity analysis identified species clusters that best described the patterns of diversity across reserves. Multivariate ordination and linear mixed models were used to determine the influence of DTE on various dimensions of small mammal diversity.

Results

There was an increase in richness and abundance along a DTE gradient, and remnants with higher edge:area ratios showed higher richness and abundance, independent of remnant size. Species at edges were generalists, open-habitat species or exotic species (spillover effect). We found higher phylogenetic diversity and functional richness and divergence towards forest edges. Spillover of non-forest and invasive species best explained richness, generalist forest species best explained total abundance, abundance of Hylaeamys megacephalus best explained diversity and evenness metrics and the presence of Marmosa paraguayana best explained various phylogenetic diversity models. None of the models that included megafauna or social factors were shown to be important in explaining patterns as a function of DTE.

Main Conclusions

We found strong support for a spillover effect and mixed support for complementary resource use and enhanced habitat resources associated with ecotones. Generalists characterized edge assemblages but not all generalists were equivalent. Edges showed more phylogenetically and functionally distinct assemblages than the interior of remnants. There was a conservation of functional diversity; however, open-habitat species, habitat generalists and exotic species boosted diversity near forest edges. Mechanisms governing diversity along forest edges are complex; disentangling those mechanisms necessitates the use of multiple dimensions of diversity.     

Conservation of Forest Birds: Evidence of a Shifting Baseline in Community Structure

Background

Quantifying changes in forest bird diversity is an essential task for developing effective conservation actions. When subtle changes in diversity accumulate over time, annual comparisons may offer an incomplete perspective of changes in diversity. In this case, progressive change, the comparison of changes in diversity from a baseline condition, may offer greater insight because changes in diversity are assessed over longer periods of times. Our objectives were to determine how forest bird diversity has changed over time and whether those changes were associated with forest disturbance.

Methodology/Principal Findings

We used North American Breeding Bird Survey data, a time series of Landsat images classified with respect to land cover change, and mixed-effects models to associate changes in forest bird community structure with forest disturbance, latitude, and longitude in the conterminous United States for the years 1985 to 2006. We document a significant divergence from the baseline structure for all birds of similar migratory habit and nest location, and all forest birds as a group from 1985 to 2006. Unexpectedly, decreases in progressive similarity resulted from small changes in richness (<1 species per route for the 22-year study period) and modest losses in abundance (−28.7–−10.2 individuals per route) that varied by migratory habit and nest location. Forest disturbance increased progressive similarity for Neotropical migrants, permanent residents, ground nesting, and cavity nesting species. We also documented highest progressive similarity in the eastern United States.

Conclusions/Significance

Contemporary forest bird community structure is changing rapidly over a relatively short period of time (e.g., ∼22 years). Forest disturbance and forest regeneration are primary factors associated with contemporary forest bird community structure, longitude and latitude are secondary factors, and forest loss is a tertiary factor. Importantly, these findings suggest some regions of the United States may already fall below the habitat amount threshold where fragmentation effects become important predictors of forest bird community structure.     

Environmental filters shaping angiosperm tree assembly along climatic and geographic gradients

Question

Global‐scale forest censuses provide an opportunity to understand diversification processes in woody plant communities. Based on the climatic or geographic filtering hypotheses associated with tropical niche conservatism and dispersal limitation, we analysed phylogenetic community structures across a wide range of biomes and evaluated to what extent region‐specific processes have influenced large‐scale diversity patterns of tree species communities across latitude or continent.

Location

Global.

Methods

We generated a data set of species abundances for 21,379 angiosperm woody plants in 843 plots worldwide. We calculated net relatedness index (NRI) for each plot, based on a single global species pool and regional species pools, and phylogenetic β‐diversity (PBD) between plots. Then, we explored the correlations of NRI with climatic and geographic variables, and clarified phylogenetic dissimilarity along geographic and climatic differences. We also compared these patterns for South America, Africa, the Indo‐Pacific, Australia, the Nearctic, Western Palearctic and Eastern Palearctic.

Results

NRI based on a global‐scale species pool was negatively associated with precipitation and positively associated with Quaternary temperature change. PBD was positively associated with geographic distance and precipitation difference between plots across tropical and extratropical biomes. Moreover, phylogenetic dissimilarity was smaller in extratropical regions than in regions including the tropics, although temperate forests of the Eastern Palearctic showed a greater dissimilarity within extratropical regions.

Conclusions

Our findings support predictions of the climatic and geographic filtering hypotheses. Climatic filtering (climatic harshness and paleoclimatic change) relative to tropical niche conservatism played a role in sorting species from the global species pool and shaped the large‐scale diversity patterns, such as the latitudinal gradient observed across continents. Geographic filtering associated with dispersal limitation substantially contributed to regional divergence of tropical/extratropical biomes among continents. Old, long‐standing geographic barriers and recent climatic events differently influenced evolutionary diversification of angiosperm tree communities in tropical and extratropical biomes.     

American Exceptionalism: Population Trends and Flight Initiation Distances in Birds from Three Continents

Background

All organisms may be affected by humans'' increasing impact on Earth, but there are many potential drivers of population trends and the relative importance of each remains largely unknown. The causes of spatial patterns in population trends and their relationship with animal responses to human proximity are even less known.

Methodology/Principal Finding

We investigated the relationship between population trends of 193 species of bird in North America, Australia and Europe and flight initiation distance (FID); the distance at which birds take flight when approached by a human. While there is an expected negative relationship between population trend and FID in Australia and Europe, we found the inverse relationship for North American birds; thus FID cannot be used as a universal predictor of vulnerability of birds. However, the analysis of the joint explanatory ability of multiple drivers (farmland breeding habitat, pole-most breeding latitude, migratory habit, FID) effects on population status replicated previously reported strong effects of farmland breeding habitat (an effect apparently driven mostly by European birds), as well as strong effects of FID, body size, migratory habit and continent. Farmland birds are generally declining.

Conclusions/Significance

Flight initiation distance is related to population trends in a way that differs among continents opening new research possibilities concerning the causes of geographic differences in patterns of anti-predator behavior.     

Community assembly in temperate forest birds: habitat filtering,interspecific interactions and priority effects

Recent attempts to understand the processes governing community assembly have increasingly focused on patterns of phylogenetic relatedness and functional similarity among co-existing species. Considerations of the species pool, the number and identity of functional traits and the metrics used to identify patterns have come under scrutiny as possible influences on the detection of non-random patterns. Most mechanistic explanations of community assembly based on functional and phylogenetic approaches rely on deterministic explanations, while ignoring the role of stochastic processes and historical contingency, despite the prominent historical role of both types of explanations of species coexistence. We evaluated the phylogenetic and functional structure of 20 temperate forest bird assemblages in northeastern North America. We compared three approaches for characterizing the functional structure of assemblages. Regardless of approach, assemblages were generally no different than expected by chance. In contrast, phylogenetic structures of bird assemblages were overdispersed, clumped or consistent with random assembly depending on the site. Nonetheless, we found little evidence for differences in phylogenetic structure arising as a consequence of the identity of the species pool. We identified a strong relationship between the proportion of residents and phylogenetic relatedness that was unrelated to the species richness of assemblages. Our results suggest that different assembly mechanisms may structure resident and migratory subsets of temperate breeding bird communities. Resident assemblages are likely structured by interspecific interactions and habitat filtering prior to arrival of migrants. In contrast, the composition of migrant assemblages may be a consequence of priority effects in which the presence and abundance of residents and earliest arriving species affect the ability of subsequent migrants to colonize sites. This phenomenon enhances the likelihood of multiple alternative community structures in similar environments.     

Seasonal dynamics of waterbird assembly mechanisms revealed by patterns in phylogenetic and functional diversity in a subtropical wetland

Despite growing interest in using phylogenetic and functional methods to understand community assembly, few studies have examined how these methods can be used to assess seasonal variation in assembly mechanisms among migrant species. Migration can rapidly alter the relative influence of stochastic processes, species interactions, or environmental factors in shaping communities across seasons. Here, we describe seasonal dynamics in the phylogenetic and functional diversity of waterbirds in Mai Po Wetland, a subtropical region with significant and predictable temporal variation in climate and migratory bird density. Phylogenetic α diversity varied seasonally, exhibiting a clustered structure (indicative of environmental filtering) in summer, and over‐dispersed structure (indicative of biotic filtering) in winter. Phylogenetic diversity in spring and autumn exhibited a more intermediate, random structure, consistent with stochastic arrivals and departures of migrants. Functional diversity was clustered in spring but showed over‐dispersion in the other three seasons. Phylogenetic β diversity in summer and winter assemblages was characterized by two distinct groups, while spring and autumn assemblages were mixed. Our results suggest that waterbird assemblages were primarily shaped by interspecific competition in winter, while random processes tended to shape assemblages in spring and fall. Environmental factors played a more important role in summer, during periods of high heat stress. In addition, species co‐occurrence patterns were significantly more strongly related to phylogenetic similarity in winter than in summer. Our results suggest that the relative importance of assemblage mechanisms can vary seasonally in response to changing environmental conditions, suggesting that studies attempting to infer a single dominant assembly mechanism may ignore important assembly processes. Temporal shifts in assembly mechanisms may play an important role in maintaining diversity in subtropical and temperate wetlands and perhaps also in other dynamic systems.     

Bat and bird diversity along independent gradients of latitude and tree composition in European forests

Species assemblages are shaped by local and continental-scale processes that are seldom investigated together, due to the lack of surveys along independent gradients of latitude and habitat types. Our study investigated changes in the effects of forest composition and structure on bat and bird diversity across Europe. We compared the taxonomic and functional diversity of bat and bird assemblages in 209 mature forest plots spread along gradients of forest composition and vertical structure, replicated in 6 regions spanning from the Mediterranean to the boreal biomes. Species richness and functional evenness of both bat and bird communities were affected by the interactions between latitude and forest composition and structure. Bat and bird species richness increased with broadleaved tree cover in temperate and especially in boreal regions but not in the Mediterranean where they increased with conifer abundance. Bat species richness was lower in forests with smaller trees and denser understorey only in northern regions. Bird species richness was not affected by forest structure. Bird functional evenness increased in younger and denser forests. Bat functional evenness was also influenced by interactions between latitude and understorey structure, increasing in temperate forests but decreasing in the Mediterranean. Covariation between bat and bird abundances also shifted across Europe, from negative in southern forests to positive in northern forests. Our results suggest that community assembly processes in bats and birds of European forests are predominantly driven by abundance and accessibility of feeding resources, i.e., insect prey, and their changes across both forest types and latitudes.     

Global patterns of phylogenetic relatedness of invasive flowering plants

Aim

The ability of predicting which naturalized non-native species are likely to become invasive can help manage and prevent species invasions. The goal of this study is to test whether invasive angiosperm (flowering plant) species are a phylogenetically clustered subset of naturalized species at global, continental and regional scales, and to assess the relationships of phylogenetic relatedness of invasive species with climate condition (temperature and precipitation).

Location

Global.

Time period

Current.

Taxon

Angiosperms (flowering plants).

Methods

The globe is divided into 290 regions, which are grouped into seven biogeographic (continental) regions. Two phylogenetic metrics (net relatedness index and nearest taxon index), which represent different evolutionary depths, are used to quantify phylogenetic relatedness of invasive angiosperms, with respect to different tailor-made species pools. Phylogenetic relatedness of invasive angiosperms is related to climatic variables.

Results

The global assemblage of invasive angiosperm species is a strongly phylogenetically clustered subset of the species of the entire global angiosperm flora. Most invasive angiosperm assemblages are a phylogenetically clustered subset of their respective naturalized species pools, and phylogenetic clustering reflecting shallow evolutionary history is greater than that reflecting deep evolutionary history. In general, the phylogenetic relatedness of invasive species is greater in regions with lower temperature and precipitation across the world.

Main conclusions

The finding that invasive angiosperm assemblages across the globe are, in general, phylogenetically clustered subsets of their respective naturalized species pools has significant implications in biological conservation, particularly in predicting and controlling invasive species based on phylogenetic relatedness among naturalized species.     

Global patterns and predictors of avian population density

Aim

How population density varies across animal species in the context of environmental gradients, and associated migratory strategies, remains poorly understood. The recent influx of avian trait data and population density estimates allows these patterns to be described and explored in unprecedented detail. This study aims to identify the main macroecological drivers of population density in birds.

Location

Global.

Time period

1970–2021.

Major taxa studied

Birds (Aves).

Methods

We collated a dataset of 5072 local population density estimates for 1853 species and modelled population density as a function of trait and environmental predictors in a Bayesian framework accounting for phylogenetic and spatial autocorrelation. We explored the influence of body mass, diet, primary lifestyle, mating system, nesting behaviour, territoriality, and migratory behaviour on population density, accounting for a range of environmental variables, including preferred habitat type, primary productivity, precipitation and temperature. Based on this empirical baseline, we then predicted the mean population density for 9089 species of birds and estimated global geographic patterns of bird population density.

Results

Population density was lower in species with larger body mass and higher trophic levels, and also declined in territorial species, migratory species, brood parasites and species inhabiting resource-poor habitat types (e.g., deserts). Conversely, population density increased in cooperative breeders. Environmental drivers were most influential for migratory birds, with precipitation and temperature both associated with higher population density. Overall, bird population densities were higher at lower latitudes.

Main conclusions

Our results support previous findings on the role of body mass, diet and environmental gradients, but also reveal novel species-specific drivers of avian densities related to reproduction, migration and resource-holding behaviour. Substantial fine-scale variation remains unexplained. We provide a global dataset of population density predictions for use in macroecological analyses and conservation assessments.     

Both rare and common species make unique contributions to functional diversity in an ecosystem unaffected by human activities

Aim

Rare species typically contribute more to functional diversity than common species. However, humans have altered the occupancy and abundance patterns of many species—the basis upon which we define “rarity.” Here, we use a globally unique dataset from hydrothermal vents—an untouched ecosystem—to test whether rare species over‐contribute to functional diversity.

Location

Juan de Fuca Ridge hydrothermal vent fields, Northeast Pacific Ocean.

Methods

We first conduct a comprehensive review to set up expectations for the relative contributions of rare and common species to functional diversity. We then quantify the rarity and commonness of 37 vent species with relevant trait information to assess the relationship between rarity and functional distinctiveness—a measure of the uniqueness of the traits of a species relative to traits of coexisting species. Next, we randomly assemble communities to test whether rare species over‐contribute to functional diversity in artificial assemblages ranging in species richness. Then, we test whether biotic interactions influence functional diversity contributions by comparing the observed contribution of each species to a null expectation. Finally, we identify traits driving functional distinctiveness using a distance‐based redundancy analysis.

Results

Across functional diversity metrics and species richness levels, we find that both rare and common species can contribute functional uniqueness. Some species always offer unique trait combinations, and these species host bacterial symbionts and provide habitat complexity. Moreover, we find that contributions of species to functional diversity may be influenced by biotic interactions.

Main conclusions

Our findings show that many common species make persistent, unique contributions to functional diversity. Thus, it is key to consider whether the abundance and occupancy of species have been reduced, relative to historical baselines, when interpreting the contributions of rare species to functional diversity. Our work highlights the importance of testing ecological theory in ecosystems unaffected by human activities for the conservation of biodiversity.     

The role of landscape in shaping bird community and implications for landscape management at Nanjing Lukou International Airport

Understanding the patterns of bird diversity and its driving force is necessary for bird strike prevention. In this study, we investigated the effects of landscape on phylogenetic and functional diversity of bird communities at Nanjing Lukou International Airport (NLIA). Bird identifications and counting of individuals were carried out from November 2017 to October 2019. Based on the land-cover data, the landscape was divided into four main types, including farmlands, woodlands, wetlands, and urban areas. Bird phylogenetic and functional diversity were strongly affected by landscape matrix types. Species richness and Faith's phylogenetic distance were highest in woodlands, while mean pairwise distance (MPD), mean nearest-taxon distance (MNTD), and functional dispersion (FDis) were highest in wetlands. Based on the feeding behavior, carnivorous birds had the lowest species richness but had the highest FDis, which implied that carnivorous birds occupied most niches at the NLIA. Moreover, bird assemblages exhibited phylogenetic and functional clustering in the four kinds of landscapes. A variety of landscape attributes had significant effects on species diversity, phylogenetic and functional diversity. Landscape-scale factors played an important role in the shaping of bird communities around NLIA. Our results suggest that landscape management surrounding airports can provide new approaches for policymakers to mitigate wildlife strikes.     

Metabarcoding reveals seasonal and spatial patterns of arthropod community assemblages in two contrasting habitats: Desert and oasis of the Baja California Peninsula,Mexico

Aim

Desert springs or oases are the only permanent mesic environments in highly water-limited arid regions. Oases have immense cultural, evolutionary and ecological importance for people and a high number of endemic and relic species. Nevertheless, they are also highly vulnerable ecosystems, with invasive species, overexploitation and climate change being the primary threats. We used the arthropod communities' spatiotemporal diversity and distribution patterns as a proxy to understand biodiversity dynamics in two geographically close but ecologically contrasting and highly threatened ecosystems: deserts and oases.

Location

Baja California Peninsula, Mexico.

Methods

Arthropod communities at five oases and surrounding desert scrub areas were sampled in two seasons. Using DNA metabarcoding and traditional taxonomic surveys, we tried to identify what biotic and abiotic characteristics of the habitat are important drivers of arthropod diversity and how these characteristics can change across spatial and temporal scales.

Results

Over 6200 individuals representing 23 orders were collected. In oasis samples, the community composition fluctuated more in space (i.e. among sites) than in time (i.e. seasons). Thus, seasonal changes did not affect oasis community diversity and composition, but the dissimilarity among sites increased with geographic distance. Moreover, anthropic activities negatively correlated with arthropod diversity in oases. On the other hand, the season, geography (e.g. latitude) and biotic characteristics of the habitat (e.g. sampled scrub species) significantly affected the diversity and composition of the desert arthropod communities.

Main Conclusions

Neutral dynamics (e.g. historical climatic events, dispersal limitation and spatial component) and human impact significantly influenced the biodiversity patterns of each oasis. In contrast, the habitat's seasonal variation and biotic characteristics were the most important variables influencing the diversity of the desert communities. Baja California oases harbour distinct invertebrate communities; therefore, each oasis should be conserved individually to preserve these unique assemblages.