Dissimilar Models Research Articles

Microstructured induced band pattern in Love wave propagation for novel nondestructive testing (NDT) procedures

We propose a new approach for assessing microstructural properties of materials via nondestructive testing (NDT). This approach lies on the observation that, accounting for the microstructure within the materials, reveals a nonclassical band propagation pattern for Love waves. Precisely this propagation structure may be directly related to the internal microstructure. To illustrate this, propagation of Love waves is first investigated within the linear theory of couple stress materials with micro-inertia. Proving wave existence by the argument principle provides a closed-form condition for propagation to occur. This connection defines propagation bands, whose limits correspond to the situation when Love waves move with the same speed as bulk waves in the underlying half-space (internal resonance). This condition is closely related to the layer-to-substrate microstructure and it may be used to assess either of the two. Furthermore, we show that the frequency equation is a three-term combination of antiplane Rayleigh and Rayleigh–Lamb functions (in a free and in a free/clamped plate). Consequently, investigation of any extra observable, such as Rayleigh waves, reduces the risk of multiple solutions at the signal processing stage. We finally consider the limit as either the half-space or the layer becomes classical elastic. We show that this unseemly bonding of dissimilar models, sometimes adopted in the literature, usually leads to inconsistencies.

Responses of different facets of aquatic plant diversity along environmental gradients in Mediterranean streams: Results from rivers of Greece

Aquatic and riparian plants play a crucial role in the functioning of riverine ecosystems. Hence, analyzing multiple facets of plant diversity could be extremely useful for assessing the ecological integrity of lotic ecosystems. The main objective of this study was to investigate the response of multiple facets of aquatic plant diversity, such as species richness, taxonomic distinctness and compositional dissimilarity, to environmental factors (i.e. nutrient pollution and hydromorphological alteration) in 72 stream reaches of mainland Greece.We employed Generalized Additive Models to identify the variables with the highest influence and examine the response of species richness and taxonomic distinctness to environmental gradients. The relationship between compositional dissimilarity and the environment was examined with Generalized Dissimilarity Modelling. Our results supported our hypothesis that human disturbances play a considerable role in shaping macrophyte assemblages. In particular, phosphates and hydromorphological modification were significant predictors of species richness, whereas taxonomic distinctness was unaffected by indicators of anthropogenic stress but it was influenced mostly by elevation, water temperature and pH. Concerning the compositional dissimilarity, geographic distance, elevation, temperature and total inorganic nitrogen were the most important environmental parameters. Our findings suggest that human stressors, such as hydromorphological modification and nutrient enrichment, affect the plant species richness at stream reach scale, but when considering community composition or taxonomic distinctness, environmental factors associated with the natural variability (e.g. elevation, temperature and geographic distance) are of higher importance. Overall, our results emphasize the advantage of examining multiple aspects of diversity when designing conservation schemes and management plans for riparian areas.

Deep ConvNet: Non-Random Weight Initialization for Repeatable Determinism, Examined with FSGM.

A repeatable and deterministic non-random weight initialization method in convolutional layers of neural networks examined with the Fast Gradient Sign Method (FSGM). Using the FSGM approach as a technique to measure the initialization effect with controlled distortions in transferred learning, varying the dataset numerical similarity. The focus is on convolutional layers with induced earlier learning through the use of striped forms for image classification. Which provided a higher performing accuracy in the first epoch, with improvements of between 3–5% in a well known benchmark model, and also ~10% in a color image dataset (MTARSI2), using a dissimilar model architecture. The proposed method is robust to limit optimization approaches like Glorot/Xavier and He initialization. Arguably the approach is within a new category of weight initialization methods, as a number sequence substitution of random numbers, without a tether to the dataset. When examined under the FGSM approach with transferred learning, the proposed method when used with higher distortions (numerically dissimilar datasets), is less compromised against the original cross-validation dataset, at ~31% accuracy instead of ~9%. This is an indication of higher retention of the original fitting in transferred learning.

Understanding the local drivers of beta‐diversity patterns under climate change: The case of seaweed communities in Galicia, North West of the Iberian Peninsula

AbstractAimTo understand spatial‐temporal changes (beta‐diversity) in coastal communities and their drivers in the context of climate change. Coastal ecosystems are extremely exposed and dynamic, where changes in seaweed assemblages have been associated with changing water temperatures. However, at local scale, the effects of changes in the upwelling events and related stressors seek further exploration.LocationGalicia rías, North West of the Iberian Peninsula.MethodsUsing data collected in 42 sampling localities in Galicia rias and over two time periods (1998 and 2014), we analysed changes in the seaweed community's composition through time and space. We calculated the temporal beta‐diversity index and spatial beta‐diversity as the pairwise composition differences between sampling localities. We use generalized dissimilarity models, to identify local environmental drivers of spatial and temporal beta‐diversity.ResultsWe found a significant change in seaweed communities of Galicia rias, between 1998 and 2014 (temporal beta‐diversity). They were mostly related to species loss rather than to species replacement. The dissimilarity among localities (spatial beta‐diversity) was significantly higher in 2014 than in 1998. Nitrate concentration was consistently predicted as the main driver of both temporal and spatial beta‐diversity patterns.Main conclusionsUnlike other studies in marine ecosystems, our results suggest that observed changes in the structure of perennial seaweed assemblages in Galicia Rias might lead to a local biotic heterogenization, indirectly linked to climate change through changes in nutrients availability and the upwelling intensity. Changes in Galicia seaweed communities call scientific attention to the importance of local stressors in climate change studies.

Seasonal patterns of taxonomic and functional beta diversity in submerged macrophytes at a fine scale.

Spatiotemporal variation in community composition is of considerable interest in ecology. However, few studies have focused on seasonal variation patterns in taxonomic and functional community composition at the fine scale. As such, we conducted seasonal high‐density sampling of the submerged macrophyte community in Hongshan Bay of Erhai Lake in China and used the generalized dissimilarity model (GDM) to evaluate the effects of environmental factors and geographic distance on taxonomic and functional beta diversity as well as corresponding turnover and nestedness components. At the fine scale, taxonomic turnover and nestedness as well as functional turnover and nestedness showed comparable contributions to corresponding taxonomic and functional beta diversity, with different importance across seasons. All taxonomic and functional dissimilarity metrics showed seasonal variation. Of note, taxonomic beta diversity was highest in summer and lowest in winter, while functional beta diversity showed the opposite pattern. Taxonomic and functional turnover showed similar change patterns as taxonomic and functional beta diversity. Taxonomic nestedness was low in summer and high in winter. Functional nestedness was also lower in summer. These results suggest that under extreme environmental conditions, both turnover and nestedness can exist at the fine scale and seasonal community composition patterns in submerged macrophytes should be considered. Future investigations on community assembly mechanisms should pay greater attention to long‐term dynamic characteristics and functional information.

Buffer zones maximize invertebrate conservation in a Biosphere Reserve

Recent declines in invertebrates are linked to anthropogenic global change drivers thus land use planning that considers invertebrate conservation is necessary. Although most animals are invertebrates, conservation initiatives largely ignore these groups in part because of a paucity of studies addressing their diversity patterns. Biosphere Reserves provide an holistic approach to conservation planning. Here we explore the covariates that underlie beetle and spider diversity across the largest Biosphere Reserve in South Africa and use this model to predict compositional turnover across the reserve using Generalized Dissimilarity Modelling (GDM). We then use these patterns to assess the proportion of the ecological environments, scaled using beetle and spider assemblages, that is included in either core or buffer zones. The GDM model explained 53% of the variation in observed compositional turnover. Important local-scale drivers of turnover were leaf litter and organic content of the soil, while broad-scale co-variables were isothermality and mean diurnal range. Buffer zones increased conservation coverage by between 50 and 100%, depending on the planning scenario involved and complimented regional conservation plans. However, local conservation practices rarely reflect that of regional planning exercises, and initiatives should focus on monitoring compliance that considers both landscape and local processes. Conservation efforts should not only focus on core areas in Biosphere Reserves. Managing buffer zones must receive similar if not more attention due to the larger anthropogenic footprint.

Amphibian diversity in the Amazonian floating meadows: a Hanski core‐satellite species system

The Amazon catchment is the largest river basin on earth, and up to 30% of its waters flow across floodplains. In its open waters, floating plants known as floating meadows abound. They can act as vectors of dispersal for their associated fauna and, therefore, can be important for the spatial structure of communities. Here, we focus on amphibian diversity in the Amazonian floating meadows over large spatial scales. We recorded 50 amphibian species over 57 sites, covering around 7000 km along river courses. Using multi‐site generalised dissimilarity modelling of zeta diversity, we tested Hanski's core‐satellite hypothesis and identified the existence of two functional groups of species operating under different ecological processes in the floating meadows. ‘Core' species are associated with floating meadows, while ‘satellite' species are associated with adjacent environments, being only occasional or accidental occupants of the floating vegetation. At large scales, amphibian diversity in floating meadows is mostly determined by stochastic (i.e. random/neutral) processes, whereas at regional scales, climate and deterministic (i.e. niche‐based) processes are central drivers. Compared with the turnover of ‘core' species, the turnover of ‘satellite' species increases much faster with distances and is also controlled by a wider range of climatic features. Distance is not a limiting factor for ‘core' species, suggesting that they have a stronger dispersal ability even over large distances. This is probably related to the existence of passive long‐distance dispersal of individuals along rivers via vegetation rafts. In this sense, Amazonian rivers can facilitate dispersal, and this effect should be stronger for species associated with riverine habitats such as floating meadows.

The influence of climate and palaeoclimate on distributions of global conifer clades depends on geographical range size

AbstractAimWe investigate how plant distributions are shaped by current and palaeoclimate regimes. We specifically use global conifer biodiversity to test if palaeoclimatic signatures are stronger in range‐restricted taxa relative to widespread taxa.LocationGlobal.TaxonConiferales.MethodsWe combine global geographical occurrences for 606 conifer species and 69 conifer genera with climate information (modern day and palaeoclimate) to examine the predictors of current conifer distribution. We test how climate predicts the richness of range‐restricted taxa and influences turnover of widespread taxa using generalized dissimilarity models and a zeta diversity framework. We also construct ensemble distribution models to test if palaeoclimates differentially influence the current distribution of range‐restricted versus widespread taxa.ResultsGeneralized dissimilarity models suggest that palaeoclimatic variation is associated with richness differences among small‐range species and genera; specifically, most occur in areas with little temporal climatic variation. Turnover among more widespread taxa, in contrast, is more strongly related to broad modern and palaeoclimatic temperature gradients. Ensemble distribution models also suggest that palaeoclimatic variation contributes more to the current range of genera with restricted ranges.Main conclusionsThe most widespread conifers broadly follow past and current temperature gradients, leading to latitudinal sorting of genera based on their physiological adaptations. Range‐restricted species and genera, however, preferentially occur in climatically stable regions where they contribute to richness hotspots. History, rather than current climate patterns, likely exerts a disproportionate influence on global richness patterns in the group.

Modeling of Microlicieae (Melastomataceae) species composition provides insights into the evolution of campo rupestre vegetation on eastern Brazilian mountaintops

The Cadeia do Espinhaço (also referred to as “Espinhaço Range”) is a mountain range that extends for more than 1,200 km from northern Bahia to southern Minas Gerais in eastern Brazil. Mountains in the Cadeia do Espinhaço usually have impoverished soils and complex micro-habitats, where outstanding levels of endemism are found. Pleistocene glaciations are often considered as relevant events that shaped communities and favored speciation in this region. We used the statistical techniques of Species Composition Interpolation and Generalized Dissimilarity Modeling to analyze beta-diversity patterns across the Cadeia do Espinhaço, delimit floristic units, identify geo-climatic predictors of species composition, and estimate changes in communities during the Last Glacial Maximum and Mid-Holocene. We used as our study group the Microlicieae, a species-rich tribe of Melastomataceae with remarkable endemism in campo rupestre, the dominant vegetation type on mountaintops of the Espinhaço Range. Two breaks in species composition and three floristic regions (Southern Espinhaço, Septentrional Espinhaço, and Chapada Diamantina) were recognized for the study area. The floristic regions differed from each other in climate and matched geologic sections of the Cadeia do Espinhaço. Climatic predictors related to climate explained beta-diversity patterns better than geography. During the Last Glacial Maximum and Mid-Holocene, the Southern Espinhaço suffered less severe changes in species composition than the Septentrional Espinhaço and the Chapada Diamantina.

Contrasting patterns of phylogenetic turnover in amphibians and reptiles are driven by environment and geography in Neotropical savannas

AbstractAimCross‐taxonomic congruence in biodiversity patterns is key to understanding the main drivers of community structure, for biogeographical regionalization and to guide conservation. We aim to map the patterns of phylogenetic turnover and disentangle the geographical and environmental factors that drive the phylogenetic composition of distinct faunal assemblages.LocationThe Cerrado savannas of South America.TaxaReptiles and amphibians.MethodsWe measured the proportion of phylogenetic branches shared among sites (i.e. phylogenetic turnover) using presence‐absence matrices for all species in the Cerrado and for endemics only, including only well‐sampled localities from previously compiled inventories. We then tested whether phylogenetic turnover is different from null expectations based on taxonomic turnover. We used generalized dissimilarity modelling (GDM) to test whether geography, topography, soil or climate best explain phylogenetic turnover. Finally, we mapped the observed and the GDM‐predicted clustering of phylogenetic turnover to assess geographical congruence between reptiles and amphibians.ResultsFor all reptiles, geographical distance is the most important factor explaining phylogenetic turnover, whereas for endemic reptiles and amphibians, in general, a set of climatic variables and relief roughness are more important. We did not find any significant correlation between the phylogenetic turnover of reptiles and amphibians, as evidenced by non‐congruent phylogenetic clustering and by different responses to geographical and environmental gradients.Main conclusionsThe different relationships of phylogenetic turnover of reptiles and amphibians to geographical and environmental distances have ultimately shaped the phylogenetic regionalization of these two groups. This incongruence indicates the differential importance of niche filtering, dispersal limitation and the influence of neighbouring biomes in the regionalization of different groups of organisms. Therefore, diversity patterns of one group should ideally not be used as a surrogate to map general patterns or to understand the drivers of diversity of other co‐occurring groups. Thus, conservation efforts need to be designed and implemented for each organismal group.

Association of putatively adaptive genetic variation with climatic variables differs between a parasite and its host.

Parasitism is a pervasive phenomenon in nature with the relationship between species driving evolution in both parasite and host. Due to their host‐dependent lifestyle, parasites may adapt to the abiotic environment in ways that differ from their hosts or from free‐living relatives; yet rarely has this been assessed. Here, we test two competing hypotheses related to whether putatively adaptive genetic variation in a specialist mistletoe associates with the same, or different, climatic variables as its host species. We sampled 11 populations of the specialist mistletoe Amyema gibberula var. tatei (n = 154) and 10 populations of its associated host Hakea recurva subsp. recurva (n = 160). Reduced‐representation sequencing was used to obtain genome‐wide markers and putatively adaptive variation detected using genome scan methods. Climate associations were identified using generalized dissimilarity modelling, and these were mapped geographically to visualize the spatial patterns of genetic composition. Our results supported the hypothesis of parasites and host species responding differently to climatic variables. Temperature was relatively more important in predicting allelic turnover in the specialist mistletoe while precipitation was more important for the host. This suggests that parasitic plants and host species may respond differently to selective pressures, potentially as a result of differing nutrient acquisition strategies. Specifically, mistletoes acquire water from hosts (rather than the abiotic environment), which may provide a buffer to precipitation as a selective pressure. This work deepens and complements the physiological and other ecological studies of adaptation and provides a window into the evolutionary processes that underlie previously observed phenomena. Applying these methods to a comparative study in a host–parasite system has also highlighted factors that affect the study of selection pressure on nonmodel organisms, such as differing adaptation rates and lack of reference genomes.

Forest management can mitigate negative impacts of climate and land-use change on plant biodiversity: Insights from the Republic of Korea

Over the past century, the decline in biodiversity due to climate change and habitat loss has become unprecedentedly serious. Multiple drivers, including climate change, land-use/cover change, and qualitative change in habitat need to be considered in an integrated approach, which has rarely been taken, to create an effective conservation strategy. The purpose of this study is to quantitatively evaluate and map the combined impacts of those multiple drivers on biodiversity in the Republic of Korea (ROK). To this end, biodiversity persistence (BP) was simulated by employing generalized dissimilarity modeling with estimates of habitat conditions. Habitat Condition Index was newly developed based on national survey datasets to represent the changes in habitat quality according to the land cover changes and forest management, especially after the ROK's National Reforestation Programme. The changes in habitat conditions were simulated for a period ranging from the 1960s to the 2010s; additionally, future (2050s) spatial scenarios were constructed. By focusing on the changes in forest habitat quality along with climate and land use, this study quantitatively and spatially analyzed the changes in BP over time and presented the effects of reforestation and forest management. The results revealed that continuous forest management had a positive impact on BP by offsetting the negative effects of past urbanization. Improvements in forest habitat quality also can effectively reduce the negative impacts of climate change. This quantitative analysis of successful forest restoration in Korea proved that economic development and urbanization could be in parallel with biodiversity enhancement. Nevertheless, current forest management practices were found to be insufficient in fully offsetting the decline in future BP caused by climate change. This indicates that there is a need for additional measures along with mitigation of climate change to maintain the current biodiversity level.

The ecological impact of pest-induced tree dieback on insect biodiversity in Yunnan pine plantations, China

China has recently announced a reform of forestry policy, with a major goal being to transform from plantation to heterogeneous forests, which have higher resistance to pests and disease and house more biodiversity. One driver of reform is increased intensity and frequency of pest-induced tree-dieback events. To inform management, we ask what effects these events have on insect biodiversity in Pinus yunnanensis monocultures in Yunnan province, the province with one of the highest proportions of forest cover in China. We sampled aerial arthropods (mostly insect) biodiversity along gradients of Pinus yunnanensis dieback severity using Malaise traps and used metabarcoding to characterise the insect community. We used MS-GDM (‘multi-site generalized dissimilarity modelling of zeta diversity’), zeta-decline analysis, and iNEXT (‘Interpolation and extrapolation for species diversity’) to assess community change as functions of forest-structure covariates. Metabarcoding of Malaise-trapped insects reveals that bark-beetle induced forest dieback does not result in detectable differences in species diversity but does result in compositional change, with the biggest turnover occurring between 0% and infested-0%-open-canopy forests and 20%-infested-20%-open-canopy forests. Zeta-decline analysis found that the insect community in low-infestation forests is characterized by a stochastic assembly, while in high-infestation forests, the community structure is consistent with niche assembly. Our results thus suggest that bark-beetle dieback mimics natural forest-gap dynamics, consistent with the interpretation of bark beetles as a keystone species in European conifer forests, where it has been proposed that forest heterogeneity can be created efficiently by allowing natural disturbances, including bark-beetle outbreaks, to proceed naturally, without being mitigated by deadwood removal and dense replanting. In Yunnan’s situation, and given predicted increases in bark-beetle dieback severity and frequency, this strategy should probably be supplemented with anthropogenic treatments, such as deadwood enhancement and planting of multiple tree species, to accelerate the succession of plantations into heterogeneous forests.

All Populations Matter: Conservation Genomics of Australia’s Iconic Purple Wattle, Acacia purpureopetala

Maximising genetic diversity in conservation efforts can help to increase the chances of survival of a species amidst the turbulence of the anthropogenic age. Here, we define the distribution and extent of genomic diversity across the range of the iconic but threatened Acacia purpureopetala, a beautiful sprawling shrub with mauve flowers, restricted to a few disjunct populations in far north Queensland, Australia. Seed production is poor and germination sporadic, but the species occurs in abundance at some field sites. While several thousands of SNP markers were recovered, comparable to other Acacia species, very low levels of heterozygosity and allelic variation suggested inbreeding. Limited dispersal most likely contributed towards the high levels of divergence amongst field sites and, using a generalised dissimilarity modelling framework amongst environmental, spatial and floristic data, spatial distance was found to be the strongest factor explaining the current distribution of genetic diversity. We illustrate how population genomic data can be utilised to design a collecting strategy for a germplasm conservation collection that optimises genetic diversity. For this species, inclusion of all field sites will capture maximum genetic diversity for both in situ and ex situ conservation. Assisted cross pollination, within and between field sites and genetically structured groups, is recommended to enhance heterozygosity particularly at the most disjunct sites and further fragmentation should be discouraged to avoid loss of genetic connectivity.

What is the role of topographic heterogeneity and climate on the distribution and conservation of vascular epiphytes in the Brazilian Atlantic Forest?

Mapping diversity patterns is important to clarify its causes and is essential information for conservation policies. We map the distribution of vascular epiphytes from the Southern block of the Brazilian Atlantic Forest (SBAF) to understand the main factors responsible for the richness and species turnover, as well as to generate information for the conservation of this functional group. We gathered a data set of vascular epiphytes, mapping the richness and weighted endemism using cells of 0.5° × 0.5°, and performed two Generalized Dissimilarity Models (GDM) using a filter of 18 and 54 species in cells of 5 km × 5 km to evaluate the species turnover and correlation with the climatic and topographic factors. We found four sites presenting both a high richness and endemism. A gradient of richness and species turnover between the coastal and inland regions was confirmed, as well as between the lowlands and the mountainous regions. The main predictors obtained from GDM were geographic distance, cloud cover, and temperature seasonality. The topographic heterogeneity and the resulting climate changes are responsible to enhance the richness and species turnover of vascular epiphytes in the SBAF. It is important to conserve the coastal areas and the mountainous gradients due to the high richness and strong species turnover, but also the inland areas since their composition is quite distinct from previous environments.

Identifying the Drivers of Spatial Taxonomic and Functional Beta-Diversity of British Breeding Birds

Spatial variation in community composition may be driven by a variety of processes, including environmental filtering and dispersal limitation. While work has been conducted on the relative importance of these processes on various taxa and at varying resolutions, tests using high-resolution empirical data across large spatial extents are sparse. Here, we use a dataset on the presence/absence of breeding bird species collected at the 10 km × 10 km scale across the whole of Britain. Pairwise spatial taxonomic and functional beta diversity, and the constituent components of each (turnover and nestedness/richness loss or gain), were calculated alongside two other measures of functional change (mean nearest taxon distance and mean pairwise distance). Predictor variables included climate and land use measures, as well as a measure of elevation, human influence, and habitat diversity. Generalized dissimilarity modeling was used to analyze the contribution of each predictor variable to variation in the different beta diversity metrics. Overall, we found that there was a moderate and unique proportion of the variance explained by geographical distance per se, which could highlight the role of dispersal limitation in community dissimilarity. Climate, land use, and human influence all also contributed to the observed patterns, but a large proportion of the explained variance in beta diversity was shared between these variables and geographical distance. However, both taxonomic nestedness and functional nestedness were uniquely predicted by a combination of land use, human influence, elevation, and climate variables, indicating a key role for environmental filtering. These findings may have important conservation implications in the face of a warming climate and future land use change.

Quantitative and Qualitative Sex Modulations in the Brain Anatomy of Autism

BackgroundSex-based neurobiological heterogeneity in autism is poorly understood. Research is disproportionately biased to males, leading to an unwarranted presumption that autism neurobiology is the same across sexes. Previous neuroimaging studies using amalgamated multicenter datasets to increase autistic female samples are characterized by large statistical noise. MethodsWe used a better-powered dataset of 1183 scans of 839 individuals—299 (467 scans) autistic males, 74 (102 scans) autistic females, 240 (334 scans) control males, and 226 (280 scans) control females—to test two whole-brain models of overall/global sex modulations on autism neuroanatomy, by summary measures computed across the brain: the local magnitude model, in which the same brain regions/circuitries are involved across sexes but effect sizes are larger in females, indicating quantitative sex modulation; and spatial dissimilarity model, in which the neuroanatomy differs spatially between sexes, indicating qualitative sex modulation. The male and female autism groups were matched on age, IQ, and autism symptoms. Autism brain features were defined by comparisons with same-sex control individuals. ResultsAcross five metrics (cortical thickness, surface area, volume, mean absolute curvature, and subcortical volume), we found no evidence supporting the local magnitude model. We found indicators supporting the spatial dissimilarity model on cortical mean absolute curvature and subcortical volume, but not on other metrics. ConclusionsThe overall/global autism neuroanatomy in females and males does not simply differ quantitatively in the same brain regions/circuitries. They may differ qualitatively in spatial involvement in cortical curvature and subcortical volume. The neuroanatomy of autism may be partly sex specific. Sex stratification to inform autism preclinical/clinical research is needed to identify sex-informed neurodevelopmental targets.

Post‐glacial determinants of regional species pools in alpine grasslands

AbstractAimAlpine habitats support unique biodiversity confined to high‐elevation areas in the current interglacial. Plant diversity in these habitats may respond to area, environment, connectivity and isolation, yet these factors have been rarely evaluated in concert. Here we investigate major determinants of regional species pools in alpine grasslands, and the responses of their constituent species groups.LocationEuropean mountains below 50° N.Time periodBetween 1928 and 2019.Major taxa studiedVascular plants.MethodsWe compiled species pools from alpine grasslands in 23 regions, including 794 alpine species and 2,094 non‐alpines. We used species–area relationships to test the influence of the extent of alpine areas on regional richness, and mixed‐effects models to compare the effects of 12 spatial and environmental predictors. Variation in species composition was addressed by generalized dissimilarity models and by a coefficient of dispersal direction to assess historical links among regions.ResultsPool sizes were partially explained by current alpine areas, but the other predictors largely contributed to regional differences. The number of alpine species was influenced by area, calcareous bedrock, topographic heterogeneity and regional isolation, while non‐alpines responded better to connectivity and climate. Regional dissimilarity of alpine species was explained by isolation and precipitation, but non‐alpines only responded to isolation. Past dispersal routes were correlated with latitude, with alpine species showing stronger connections among regions.Main conclusionsBesides area effects, edaphic, topographic and spatio‐temporal determinants are important to understand the organization of regional species pools in alpine habitats. The number of alpine species is especially linked to refugia and isolation, but their composition is explained by past dispersal and post‐glacial environmental filtering, while non‐alpines are generally influenced by regional floras. New research on the dynamics of alpine biodiversity should contextualize the determinants of regional species pools and the responses of species with different ecological profiles.

Zooplankton taxonomic and functional structure is determined by macrophytes and fish predation in a Neotropical river

Habitat structure and predation are major factors that influence the distribution of zooplankton species and functional traits. Here, we analyzed how the structure provided by macrophytes (richness, Shannon’s diversity, and biomass) and potential predation by small-bodied fishes (richness and abundance) determine the richness of species and functional traits of zooplankton, as well as the spatial dissimilarity (beta-diversity) of species and traits. Zooplankton, fish, and macrophytes were simultaneously sampled across a gradient of 30 multi-species macrophyte beds. We assessed spatial patterns of zooplankton under taxonomic and functional approaches, using linear regression models, Generalized Dissimilarity Models, a Structural Equation Model, and a Fourth-Corner Analysis. Zooplankton taxonomic beta-diversity was most represented by the turnover component and zooplankton functional beta-diversity by nestedness. Zooplankton taxonomic richness and taxonomic beta-diversity were positively related to macrophyte biomass, richness, and Shannon’s diversity, whereas zooplankton functional richness and functional beta-diversity were positively related to fish richness and abundance. Macrophyte biomass and diversity oppositely influenced fish structure, which had influence on zooplankton structure. Macrophytes also negatively influenced the zooplankton traits such as body size, reproduction type, habitat, lifespan, and predatory escape response and positively influenced the trait feeding type. Fish were negatively related to the trait body size. The spatial structure generated by macrophyte beds and fish community determined the distribution of zooplankton species and functional traits.

Metabarcoding reveals landscape drivers of beetle community composition approximately 50 years after timber harvesting

Landscape conservation planning in managed forests requires information on the relative importance of different aspects of mature forests. Regeneration forest sites with greater access to source populations for re-establishment of biodiversity are expected to have greater similarity in species composition to unharvested mature areas, i.e., when sites are in close proximity to mature forest (forest influence), and/or have a high percentage of mature forest in the surrounding landscape (landscape context). We investigated how recovery of ground-active beetle biodiversity in the mid-late successional stage (40–58 years) of previously harvested regeneration forests is affected by forest influence, landscape context, and other characteristics of the surrounding landscape. We used DNA metabarcoding to characterise beetle communities in 12 mature forest sites and 64 regeneration forest sites. Generalized dissimilarity modelling (GDM), constrained redundancy analysis, and ordinations evaluated the contribution of predictors (i.e., bioclimate, landscape configuration, regeneration age, spatial position and topography) to beetle composition. Beetle composition was significantly different between different forest ages and landscape context classes. GDM of all predictors explained 34.1% of total variance in beetle community turnover. While the geographic locations of sites accounted for most (75.1%) of composite ecological gradients, the beetle community is subtly influenced by the effects of landscape context (1.8%), forest influence (1.2%) and other variables relating to landscape configuration (collectively 5.2%). Long-term conservation of local biodiversity in managed forests requires maintaining a certain amount of mature forest, but their importance as beetle source populations declines as the regeneration forests mature.