Explore the vast range of titles available.

Productivity and environmental stress are major drivers of multiple biodiversity facets and faunal community structure. Little is known on their interacting effects on early community assembly processes in the deep sea (>200 m), the largest environment on Earth. However, at hydrothermal vents productivity correlates, at least partially, with environmental stress. Here, we studied the colonization of rock substrata deployed along a deep-sea hydrothermal vent gradient at four sites with and without direct influence of vent fluids at 1,700-m depth in the Lucky Strike vent field (Mid-Atlantic Ridge [MAR]). We examined in detail the composition of faunal communities (>20 μm) established after 2 yr and evaluated species and functional patterns. We expected the stressful hydrothermal activity to (1) limit functional diversity and (2) filter for traits clustering functionally similar species. However, our observations did not support our hypotheses. On the contrary, our results show that hydrothermal activity enhanced functional diversity. Moreover, despite high species diversity, environmental conditions at surrounding sites appear to filter for specific traits, thereby reducing functional richness. In fact, diversity in ecological functions may relax the effect of competition, allowing several species to coexist in high densities in the reduced space of the highly productive vent habitats under direct fluid emissions. We suggest that the high productivity at fluid-influenced sites supports higher functional diversity and traits that are more energetically expensive. The presence of exclusive species and functional entities led to a high turnover between surrounding sites. As a result, some of these sites contributed more than expected to the total species and functional b diversities. The observed faunal overlap and energy links (exported productivity) suggest that rather than operating as separate entities, habitats with and without influence of hydrothermal fluids may be considered as interconnected entities. Low functional richness and environmental filtering suggest that surrounding areas, with their very heterogeneous species and functional assemblages, may be especially vulnerable to environmental changes related to natural and anthropogenic impacts, including deep-sea mining.

β‐diversity is effective for measuring the degree of compositional variation among communities and can be decomposed into local (LCBD) and species (SCBD) contributions to β‐diversity. Previous studies on β‐diversity have mostly been limited to the taxonomic level; relatively few studies have been conducted on functional diversity and its two components based on species functional traits, which have seriously hindered the potential application of β‐diversity in conservation biology. In addition, increasing anthropogenic disturbance has led to uncertainties in the β‐diversity of fish communities in stream ecosystems. In this study, we explored the relationships between multidimensional β‐diversity of fish communities and regional landscape factors, local environmental factors, community metrics, and species functional traits to reveal the main drivers of β‐diversity in headwater streams of the Xin'an River, China. LCBD and SCBD values were calculated based on species abundance and functional traits, that is, local and species contribution to taxonomic (TLCBD and TSCBD, respectively) and functional (FLCBD and FSCBD, respectively) β‐diversity. The results showed that LCBD and SCBD values were affected by biological and environmental factors. Among biological drivers, TLCBD values were positively related to species abundance. FLCBD values were positively related to species abundance, functional originality, specialization, and dispersion, that is, sampling sites with greater ecological uniqueness at the taxonomic level also had greater ecological uniqueness at the functional level. Among environmental drivers, TLCBD and FLCBD values were negatively related to water temperature, substrate coarseness, and agricultural and urban land use, that is, anthropogenic land use and local environmental changes reduce the ecological uniqueness of fish communities in the studied streams. For SCBD, both TSCBD and FSCBD values were affected by species abundance, occupancy, and niche position. We suggest that consideration of SCBD as part of a conservation approach needs to be coupled with species abundance and occupancy, which will help to prioritize areas for conservation and restoration in the study region. Our results revealed differences in the spatial distribution patterns of β‐diversity and its drivers, indicating the importance of the decomposition of β‐diversity into local (LCBD) and species (SCBD) contributions to β‐diversity. The conversion of natural landscapes into artificial landscapes around streams has decreased the ecological uniqueness (TLCBD) of fish communities in the headwater stream of the Xin'an River, China. Our study suggests that conservation efforts should consider both LCBD and SCBD in contexts and emphasize the importance of protecting headwater streams.

1. The successional dynamics of forests—from canopy openings to regeneration, maturation, and decay—influence the amount and heterogeneity of resources available for forest-dwelling organisms. Conservation has largely focused only on selected stages of forest succession (e.g., late-seral stages). However, to develop comprehensive conservation strategies and to understand the impact of forest management on biodiversity, a quantitative understanding of how different trophic groups vary over the course of succession is needed. 2. We classified mixed mountain forests in Central Europe into nine successional stages using airborne LiDAR. We analysed α- and β-diversity of six trophic groups encompassing approximately 3,000 species from three kingdoms. We quantified the effect of successional stage on the number of species with and without controlling for species abundances and tested whether the data fit the more-individuals hypothesis or the habitat heterogeneity hypothesis. Furthermore, we analysed the similarity of assemblages along successional development. 3. The abundance of producers, first-order consumers, and saprotrophic species showed a U-shaped response to forest succession. The number of species of producer and consumer groups generally followed this U-shaped pattern. In contrast to our expectation, the number of saprotrophic species did not change along succession. When we controlled for the effect of abundance, the number of producer and saproxylic beetle species increased linearly with forest succession, whereas the U-shaped response of the number of consumer species persisted. The analysis of assemblages indicated a large contribution of succession-mediated β-diversity to regional γ-diversity. 4. Synthesis and applications. Depending on the species group, our data supported both the more-individuals hypothesis and the habitat heterogeneity hypothesis. Our results highlight the strong influence of forest succession on biodiversity and underline the importance of controlling for successional dynamics when assessing successional stages with highest diversity (early and late successional stages) are currently strongly underrepresented in the forests of Central Europe. We thus recommend that conservation strategies aim at a more balanced representation of all successional stages.

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.

While more and more studies are exploring the application of remote sensing in assessing biodiversity for different ecosystems, most consider biodiversity at one point in time. Using several remote-sensing-based metrics, we asked how well remote sensing can detect biodiversity (both α- and β-diversity) in a prairie grassland across time using airborne hyperspectral data collected in two successive years (2017 and 2018) and at different periods in the growing season (2018). The ability to detect biodiversity using “spectral diversity” and “spectral species” types indeed varied significantly over a 2-yr timespan. Toward the end of the growing season in 2018, the relationship between field- and remote-sensing-based α- and β-diversity weakened compared to data collected from the same season in the previous year. This contrasting pattern between the two years was likely influenced by prescribed fire, altered weather, and the resulting shifting species composition and phenology. These findings indicate that direct detection of α- and β-diversity in grasslands should be multi-temporal when possible and should consider the effect of disturbances, climate variables, and phenology. We demonstrate an essential role for airborne platforms in developing a global biodiversity monitoring system involving forthcoming space-borne hyperspectral sensors.

1. Anthropogenic environmental changes are known to affect the Earth's ecosystems. However, how these changes influence assembly trajectories of the impacted communities remains a largely open question. 2. In this study, we investigated the effect of elevated nitrogen (N) deposition and increased precipitation on plant taxonomic and phylogenetic β-diversity in a 9-year field experiment in the temperate semi-arid steppe of Inner Mongolia, China. 3. We found that both N and water addition significantly increased taxonomic β-diversity, whereas N, not water, addition significantly increased phylogenetic β-diversity. After the differences in local species diversity were controlled using null models, the standard effect size of taxonomic β-diversity still increased with both N and water addition, whereas water, not N, addition, significantly reduced the standard effect size of phylogenetic β-diversity. The increased phylogenetic convergence observed in the water addition treatment was associated with colonizing species in each water addition plot being more closely related to species in other replicate plots of the same treatment. Species colonization in this treatment was found to be trait-based, with leaf nitrogen concentration being the key functional trait. 4. Synthesis. Our analyses demonstrate that anthropogenic environmental changes may affect the assembly trajectories of plant communities at both taxonomic and phylogenetic scales. Our results also suggest that while stochastic processes may cause communities to diverge in species composition, deterministic process could still drive communities to converge in phylogenetic community structure.

Aim The mechanisms underlying the maintenance of biodiversity remain to be elucidated. Taxonomic diversity alone remains an unresolved issue, especially in terms of the mechanisms of species co‐existence. We hypothesized that phylogenetic information could help to elucidate the mechanism of community assembly and the services and functions of ecosystems. The aim of this study was to explore the mechanisms driving floral diversity in subtropical forests and evaluate the relative effects of these mechanisms on diversity variation, by combining taxonomic and phylogenetic information. Location We examined 35 1‐ha tree stem‐mapped plots across eight national nature reserves in Guangxi Zhuang Autonomous Region, China. Taxon Trees. Methods We quantified the taxonomic and phylogenetic β‐diversity between each pair of plots using the (abundance‐based) Rao's quadratic entropy and the (incidence‐based) Sørensen dissimilarity indices. Using a null model approach, we compared the observed β‐diversity with the expected diversity at random and calculated the standard effect size of the observed β‐diversity deviation. Furthermore, we used distance‐based redundancy analysis (dbRDA) to partition the variations in taxonomic and phylogenetic observed β‐diversity and β‐deviation into four parts to assess the environmental and spatial effects. Results The taxonomic β‐deviation was related to and higher than the phylogenetic β‐deviation (r = .74). This indicated that the species turnover between pairwise plots was mainly the turnover of closely related species. Higher taxonomic and phylogenetic β‐deviation were mainly concentrated in the pairwise karst and nonkarst forest plots, indicating that the species in karst forests and nonkarst forests were predominantly from distantly related clades. A large proportions of the variation in taxonomic and phylogenetic β‐deviation were explained by the joint effect of environmental and spatial variables, while the contribution of environmental variables was greater than that of spatial variables, probably owing to the influence of the sampling scale dependence, integrality of sampling size and species pool, and the unique climatic and geomorphic characteristics. Main conclusions Our study highlights the importance of phylogeny in biodiversity research. The incorporation of taxonomic and phylogenetic information provides a perspective to explore potential underlying mechanisms that have shaped species assemblages and phylogenetic patterns in biodiversity hotspots. Our study suggested that the species turnover between pairwise plots was mainly the turnover of closely related species from the same or similar clades, and environmental variables could be expected to be better predictors of taxonomic and phylogenetic β‐diversity than spatial variables in subtropical forests. Furthermore, it revealed a large dissimilarity in the composition of species from distantly related clades in karst communities compared to that of neighboring nonkarst forest communities. Finally, our study emphasized the importance of understanding community assembly mechanisms from the perspective of a combination of taxonomic and phylogenetic β‐diversity.

Ecological drift can override the effects of deterministic niche selection on small populations and drive the assembly of some ecological communities. We tested this hypothesis with a unique data set sampled identically in 200 streams in two regions (tropical Brazil and boreal Finland) that differ in macroinvertebrate community size by fivefold. Null models allowed us to estimate the magnitude to which β-diversity deviates from the expectation under a random assembly process while taking differences in richness and relative abundance into account, i.e., β-deviation. We found that both abundance- and incidence-based β-diversity was negatively related to community size only in Brazil. Also, β-diversity of small tropical communities was closer to stochastic expectations compared with b-diversity of large communities. We suggest that ecological drift may drive variation in some small communities by changing the expected outcome of niche selection, increasing the chances of species with low abundance and narrow distribution to occur in some communities. Habitat destruction, overexploitation, pollution, and reductions in connectivity have been reducing the size of biological communities. These environmental pressures might make smaller communities more vulnerable to novel conditions and render community dynamics more unpredictable. Incorporation of community size into ecological models should provide conceptual and applied insights into a better understanding of the processes driving biodiversity.

1. In 2003, 24 presence–absence β-diversity metrics were reviewed and a number of trade-offs and redundancies identified. We present a parallel investigation into the performance of abundance-based metrics of β-diversity. 2. β-diversity is a multi-faceted concept, central to spatial ecology. There are multiple metrics available to quantify it: the choice of metric is an important decision. 3. We test 16 conceptual properties and two sampling properties of a β-diversity metric: metrics should be 1) independent of α-diversity and 2) cumulative along a gradient of species turnover. Similarity should be 3) probabilistic when assemblages are independently and identically distributed. Metrics should have 4) a minimum of zero and increase monotonically with the degree of 5) species turnover, 6) decoupling of species ranks and 7) evenness differences. However, complete species turnover should always generate greater values of β than extreme 8) rank shifts or 9) evenness differences. Metrics should 10) have a fixed upper limit, 11) symmetry (βA,B = βB,A), 12) double-zero asymmetry for double absences and double presences and 13) not decrease in a series of nested assemblages. Additionally, metrics should be independent of 14) species replication 15) the units of abundance and 16) differences in total abundance between sampling units. When samples are used to infer β-diversity, metrics should be 1) independent of sample sizes and 2) independent of unequal sample sizes. We test 29 metrics for these properties and five 'personality' properties. 4. Thirteen metrics were outperformed or equalled across all conceptual and sampling properties. Differences in sensitivity to species' abundance lead to a performance trade-off between sample size bias and the ability to detect turnover among rare species. In general, abundance-based metrics are substantially less biased in the face of undersampling, although the presence–absence metric, βsim, performed well overall. Only βBaselga R turn, βBaselga B-C turn and βsim measured purely species turnover and were independent of nestedness. Among the other metrics, sensitivity to nestedness varied >4-fold. 5. Our results indicate large amounts of redundancy among existing β-diversity metrics, whilst the estimation of unseen shared and unshared species is lacking and should be addressed in the design of new abundance-based metrics.

Aim The two additive components of β‐diversity, namely turnover and nestedness, reflect the two basic mechanisms underlying the overall change in species identities across the landscape, the replacement of species or their loss, respectively. Analogously, functional turnover and nestedness express the replacement or loss of functional traits associated with variations in community composition. However, the extent to which patterns of compositional and functional nestedness and turnover may overlap, or diverge, is still uncertain in marine environments. Here, patterns of turnover and nestedness were quantified in marine benthic assemblages in order to assess their relative contribution to spatial patterns of compositional and functional ‐diversity. Location Mediterranean Sea, NE Ionian Sea, Ionian Archipelago. Methods In this study, we investigated patterns of dissimilarity in species and functional trait composition in subtidal macrobenthic assemblages from Mediterranean islands in order to quantify compositional and functional β‐diversity among islands, determine the relative contributions of turnover and nestedness, and compare β‐diversity patterns occurring in shallow and deeper reefs. Results We found a complex relationship between functional and compositional β‐diversity at varying depth. At 5 m, species and functional trait dissimilarity largely overlapped, with turnover being the dominant component in both cases. At 15 m, compositional β‐diversity was mostly due to turnover, with a negligible contribution of nestedness, whereas the opposite occurred for functional β‐diversity. Partitioning β‐diversity components revealed this discrepancy and the presence of functional hotspots, which would remain unnoticed analysing the overall compositional and functional β‐diversity. Main conclusions Our findings may have profound implications for the optimization of conservation planning, stressing the need for assessing habitat‐dependent idiosyncrasies in components of functional and compositional β‐diversity for a more comprehensive picture of possible protection scenarios that, besides structure, may also allow preserving the functioning of marine communities.