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Nestedness is an important pattern frequently reported for species assemblages on islands or fragmented systems. However, to date, there are few studies that comprehensively investigated faunal nestedness and underlying processes in urbanized landscapes. In this study, we examined the nestedness of bird assemblages and its underlying causal mechanisms in 37 urban parks in Nanjing, China. We used the line-transect method to survey birds from April 2019 to January 2020. We used the Weighted Nestedness metric based on Overlap and Decreasing Fill (WNODF) to estimate the nestedness of bird assemblages. We applied spearman partial correlation test to examine the relationships between nestedness ranks of sites and park characteristics (area, isolation, anthropogenic noise, number of habitat types, and building index), as well as between nestedness ranks of species and their ecological traits (body size, geographic range size, clutch size, minimum area requirement, dispersal ratio, and habitat specificity). We found that bird assemblages in urban parks were significantly nested. Park area, habitat diversity, building index, habitat specificity, and minimum area requirement of birds were significantly correlated with nestedness. Therefore, the nestedness of bird assemblages was caused by selective extinction, habitat nestedness, and urbanization. However, the nestedness of bird assemblages did not result from passive sampling, selective colonization, or human disturbance. Overall, to maximize the number of species preserved in our system, conservation priority should be given to parks with large area, rich habitat diversity, and less building index. From a species perspective, we should focus on species with large area requirement and high habitat specificity for their effective conservation.

In the Arctic ecosystems, fungi are crucial for interactions between soil and plants, the cycling of nutrients, and the transport of carbon. To date, no studies have been conducted to thoroughly examine the mycobiome and its functional role in various habitats of the High Arctic region. The aim was to unravel the mycobiome in the nine habitats (i.e., soil, lichen, vascular plant, moss, freshwater, seawater, marine sediment, dung, and marine alga) in the Ny-Ålesund Region (Svalbard, High Arctic) using a high-throughput sequencing approach. A total of 10,419 ASVs were detected. Among them, 7535 ASVs were assigned to unidentified phyla, while the remaining 2884 ASVs were assigned to 11 phyla, 33 classes, 81 orders, 151 families, 278 genera, and 261 species that were known. The distribution of the mycobiome was driven by habitat specificity, indicating that habitat filtering is a crucial factor influencing the fungal assemblages at a local scale in this High Arctic region. Six growth forms and 19 fungal guilds were found. The ecological guild (e.g., lichenized, ectomycorrhizal) and growth form (e.g., yeast, thallus photosynthetic) varied significantly among various habitats. In addition, the occurrence of 31 fungal species that are considered to be potential pathogens was determined. These results will increase our understanding of fungal diversity and its functional significance in this distinctive High Arctic area and thereby establish the groundwork for prediction about how the mycobiome will alter in various environments as a result of anticipated climate change.

Little is known about the ichthyofauna from intertidal rock pools of the west coast of Africa, especially in the Gulf of Guinea. Rock pools are characteristic habitats of the intertidal zone of structurally complex rocky shores, adding important niche space to coastal fish species. In this study, rock pools of three similar rocky shores of Príncipe Island were sampled to describe the composition, abundance and distribution of fish assemblages and their relation to parameters of pool structure (volume, depth), water mass (temperature, salinity and pH) and biology (algal and coral cover, and biological species richness). A total of 18 fish species and one leptocephalus larva of unknown species, representing 13 families, were observed during sampling. In decreasing order, the five-most-abundant species were the goby Bathygobius burtoni, night sergeant Abudefduf taurus, West African rockhopper Entomacrodus cadenati, sailfin blenny Microlipophrys velifer and Biafra doctorfish Prionurus biafraensis, which together represented 81% of the total number of fish recorded during this study. The four-most-abundant species also proved to be the better adapted to the range of conditions found in rock pools. Overall, larger rock pools with minimal biological cover and higher salinity were found to support higher fish abundance and species richness. Most species individually preferred rock pools with larger volumes, but some presented a degree of habitat specificity, such as the absence or presence of biological cover. Species that were more-active swimmers preferred deeper pools.

The insects trapped in 63 plots positioned in a mixed pinewood and a marsh in Schinias, Marathon, Greece is studied relative to the anthropogenic disturbance. The last anthropogenic impact was recently intensified because of the Olympic Games in the area. One hundred and forty insect species were found that had abundances greater than two individuals in each sampling session in all plots. Seven insect community types were found using cluster analysis. The types, which corresponded to recognized habitats, re-emerged in a non-metric multidimensional scaling ordination. It was also found that insects tended to dwell in different plots, even in the same habitat. The invading P. halepensis Mill., which replaces P. pinea L., changed the entomofauna. The seven habitats had different numbers of bioindicators out of 74 insect species, not in general correlated with human impact. Three components of insect diversity were measured, and the temporal species turnover was consistently higher than the spatial one. In this sense, pine habitats were rated first in terms of overall insect diversity. In terms of biodiversity, the impact on the various biotopes was assessed utilizing the diversity–equitability index V, which indicated that the two P. halepensis-dominated habitats have negative V values together with the habitat dominated by Tamarix hampeana Nied. The conservation of P. pinea and the marsh habitats is recommended for conserving local entomofauna and stopping the progression of P. halepensis. The optimization of management strategies to meet the management goals of all elements of this degraded ecosystem seems to be crucial.

13 páginas, 8 figuras, The ventral surfaces of translucent rocks from hot desert pavements often harbor hypolithic microbial communities, which are mostly dominated by cyanobacteria. The Namib Desert fog belt supports extensive hypolithic colonization of quartz rocks, which are also colonized by lichens on their dorsal surfaces. Here, we aim to evaluate whether lichens colonize the ventral surface of the rocks (i.e., show hypolithic lifestyle) and compare the bacterial composition of these coastal hypolithic communities with those found inland. Fungal DNA barcoding and fungal and bacterial Illumina metabarcoding were combined with electron microscopy to characterize the composition and spatial structure of hypolithic communities from two (coastal and inland) areas in the Namib Desert. We report, for the first time, the structure and composition of lichen-dominated hypolithic communities found in the coastal zone of the Namib Desert with extensive epilithic lichen cover. Lichen modified areoles with inverted morphology of the genus Stellarangia (three lineages) and Buellia (two lineages) were the main components of these hypolithic communities. Some of these lineages were also found in epilithic habitats. These lichen-dominated hypolithic communities differed in structural organization and bacterial community composition from those found in inland areas. The hypolithic lichen colonization characterized here seems not to be an extension of epilithic or biological soil crust lichen growths but the result of specific sublithic microenvironmental conditions. Moisture derived from fog and dew could be the main driver of this unique colonization., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. DC acknowledges the financial support of the University of Pretoria and the National Research Foundation of South Africa. AV was supported by the project “CLU-2019–05 – IRNASA/CSIC Unit of Excellence,” funded by the Junta de Castilla y León and co-financed by the European Union (ERDF “Europe drives our growth”). This work was supported by grants CTM2015-64728-C2-2-R (MINECO/FEDER, EU) and PID2019-105469RB-C22 (MICINN).

In stratified lakes, methane-oxidizing bacteria (MOB) are strongly mitigating methane fluxes to the atmosphere by consuming methane entering the water column from the sediments. MOB communities in lakes are diverse and vertically structured, but their spatio-temporal dynamics along the water column as well as physico-chemical parameters and interactions with other bacterial species that drive the community assembly have so far not been explored in depth. Here, we present a detailed investigation of the MOB and bacterial community composition and a large set of physico-chemical parameters in a shallow, seasonally stratified, and sub-alpine lake. Four highly resolved vertical profiles were sampled in three different years and during various stages of development of the stratified water column. Non-randomly assembled MOB communities were detected in all compartments. We could identify methane and oxygen gradients and physico-chemical parameters like pH, light, available copper and iron, and total dissolved nitrogen as important drivers of the MOB community structure. In addition, MOB were well-integrated into a bacterial-environmental network. Partial redundancy analysis of the relevance network of physico-chemical variables and bacteria explained up to 84% of the MOB abundances. Spatio-temporal MOB community changes were 51% congruent with shifts in the total bacterial community and 22% of variance in MOB abundances could be explained exclusively by the bacterial community composition. Our results show that microbial interactions may play an important role in structuring the MOB community along the depth gradient of stratified lakes.

Anthropogenic land-use change causes substantial changes in local and global biodiversity. Rare and common species can differ in sensitivity to land-use change; rare species are expected to be affected more negatively. Rarity may be defined in terms of geographic range size, population density, or breadth of habitat requirements. How these 3 forms of rarity interact in determining global responses to land use is yet to be assessed. Using global data representing 912 vertebrate species, we tested for differences in responses to land use of species characterized by different types of rarity. Land-use responses were fitted using generalized linear mixed-effects models, allowing responses to vary among groups of species with different forms of rarity. Species considered rare with respect to all 3 forms of rarity showed particularly strong declines in disturbed land uses (40% of species and 30% of individuals in the most disturbed land uses). In contrast, species common both geographically and numerically and with broad habitat requirements showed strong increases (up to 90% increase in species and 40% in abundance in some land uses). Our results suggest that efforts to understand the vulnerability of species to environmental changes should account for different types of rarity where possible. Our results also have potentially important implications for ecosystem functioning, given that rare species may play unique roles within ecosystems.Efectos de la Forma de Rareza sobre las Respuestas de las Especies ante el Uso de Suelo Sykes et al. Resumen Los cambios en el uso de suelo ocasionados por el humano causan modificaciones sustanciales en la biodiversidad local y mundial. Las especies raras y comunes pueden tener diferencias en la sensibilidad ante el cambio en el uso de suelo; generalmente se espera que las especcies raras se vean afectadas de manera más negativa. La rareza puede estar definida en términos del tamaño de la extensión geográfica, la densidad poblacional o la gama de requerimientos de hábitat. La manera en que interactúan estas tres formas de rareza para determinar las respuestas mundiales ante el uso de suelo todavía no ha sido evaluada. Buscamos diferencias en las respuestas ante el uso de suelo en especies caracterizadas por diferentes tipos de rareza. Para esto usamos datos mundiales que representaron a 912 especies de vertebrados. Las respuestas ante el uso de suelo fueron ajustadas con modelos lineales y generalizados de efectos mixtos, lo que permitió que las respuestas variaran entre los grupos de especies con diferentes formas de rareza. Las especies consideradas como raras con respecto a las tres formas de rareza mostraron declinaciones particularmente fuertes en los usos de suelos perturbados (40% de las especies y 30% de los individuos en los usos de suelo más perturbados). Como contraste, las especies comunes tanto geográfica como numéricamente y con requerimientos amplios de hábitat mostraron incrementos sólidos (hasta un 90% de incremento de las especies y 40% en abundancia para algunos usos de suelo). Nuestros resultados sugieren que los esfuerzos para entender la vulnerabilidad de las especies ante los cambios ambientales deberían considerar los diferentes tipos de rareza cuando sea posible. Nuestros resultados también tienen implicaciones potencialmente importantes para el funcionamiento de los ecosistemas, dado que las especies raras pueden tener un papel único dentro del ecosistema.人类导致的土地利用变化对局部和全球生物多样性造成了重大影响。稀有种和常见种在对土地利用变化的敏感性上有所不同; 稀有种可能会遭受更多负面影响。物种的稀有性可以根据地理范围大小、种群密度和生境需求宽度三个方面来界定。然而, 这三个方面的稀有性在决定全球范围内物种响应土地利用中如何相互作用仍有待评估。我们利用全球 912 种脊椎动物的数据, 检验了不同类型的稀有种对土地利用响应的差异。其中, 物种对土地利用的响应由广义线性混合效应模型来拟合, 允许响应在不同类型稀有种的组间变化。三个方面都稀有的物种在受干扰土地利用类型中表现出急剧下降 (受干扰最严重的土地利用类型中超过 40% 的物种和 30% 的个体数量下降) 。相比之下, 在地理分布、种群数量和生境需求宽度上都属于常见种的物种则表现出大幅增长 (一些土地利用类型中物种数增长达 90%, 丰度增长达 40%) 。我们的研究结果表明, 在理解物种面对环境变化的脆弱性时, 应尽可能考虑不同类型的稀有物种。鉴于稀有种在生态系统中可能具有独特的作用, 我们的结果对生态系统功能研究也有潜在的重要意义。【翻译: 胡怡思; 审校: 聂永刚】.

Traditional approaches to the study of species persistence in fragmented landscapes generally consider a binary classification of habitat being suitable or unsuitable; however, the range of human-modified habitats within a region may offer a gradient of habitat suitability (or conservation value) for species. We identified such a gradient by comparing bird assemblages among contrasting land uses (pine plantations of different age, annual crops, clear cuts and cattle pastures) in the Upper Parana Atlantic forest. Bird assemblages and vegetation structure were characterized in an extensive area of 4400 km2 in Argentina and Paraguay during the breeding seasons of 2005–2010. Similarity of bird assemblages between anthropogenic habitats and the native forest and the proportion of forest species increased with vegetation vertical structure, while the proportion of open-area species decreased. As a consequence, mature tree plantations were the most suitable habitats for forest species and were mainly used by frugivores and bark insectivores. In contrast, open habitats were the least suitable habitat for forest species and were used primarily by insectivores. Human-created habitats that are structurally complex can be used by a subset of forest species, and may improve functional connectivity and mitigate edge effects. The conservation of large tracks of native forests, however, is critical for the long-term persistence of the entire bird assemblage, especially for native forest dependent species. Resumen Tradicionalmente los estudios sobre los efectos de la fragmentacion en las especies consideraron un clasificacion binaria de ambientes aptos vs. no aptos; sin embargo, los diferentes ambientes creados por el hombre en una region generalmente representan un gradiente de aptitud para las especies. Comparamos los ensambles de aves en usos de la tierra contrastantes (plantaciones de Pino de diferente edad, cultivos anuales, areas deforestadas y pasturas) para identificar este gradiente en el bosque Atlantico del Alto Parana. Las aves y la estructura de la vegetacion fueron caracterizadas durante el periodo 2005-2010 en un area de 4400 km2 en Argentina y Paraguay. La similitud en el ensamble de aves entre los ambientes creados por el hombre y el bosque nativo y la proporcion de especies de bosque se incremento con la estructura vertical de la vegetacion, mientras que la proporcion de especies de ambientes abiertos disminuyo. Las plantaciones forestales fueron el ambiente mas apto para las especies de bosque y fueron principalmente utilizados por frugivoros e insectivoros de troncos. Por otro lado, los ambientes abiertos fueron los menos aptos para las aves de bosque y fueron principalmente utilizados por especies insectivoras. Si bien los usos de la tierra estructuralmente complejos pueden ser utilizados por un subconjunto de especies de bosque y, en algunos casos, incrementar la conectividad funcional y mitigar el efecto borde; la conservacion de grandes remanentes de bosque nativo es de vital importancia para la conservacion del ensamble completo de aves en el largo plazo.

Habitat specificity is the most important factor affecting the regional distribution of dragonflies. Nevertheless, species with the highest specificity are not always the scarcest. Several important determinants of dragonfly density-distribution relationships were identified. Altitude preference and altitude range are significantly associated with dragonfly distribution. Some of the species that are habitat specialists but occur over a wide range of altitudes should be classified as rare but not endangered. This very simple principle is based on the assumption that habitat specialists have a very limited number of suitable biotopes. Obviously, dragonflies with a marginal distribution prefer a narrow range of altitudes (especially in terms of temperature limitation) and biotopes (effect of biogeography, marginality). Surprisingly, there is no "critical" life stage that is significantly associated with the regional distribution of dragonflies, although most species spend most time in the larval stage. Knowledge of the dispersal ability of particular species is limited, although it could significantly affect species survival and distribution.

The Unified Neutral Theory of Biodiversity has been advanced as a universal theory for species coexistence in forests worldwide, but few studies have examined its relevance to high-elevation, stressful environments. I established the Utah Forest Dynamics Plot (UFDP) in a heterogeneous subalpine forest at 3,091 m elevation on the Colorado Plateau to examine three underlying assumptions of neutral theory (functional equivalence, ecological equivalence, and habitat generality) and one prediction (the species abundance distribution). The UFDP comprises 27,845 stems ���1 cm diameter at breast height of 17 species, 10 genera, and 6 families over 13.6 ha. The neutral model was a poor fit to the observed species abundance distribution, but I did not find the alternative lognormal model to provide a better fit. Using spatial pattern analyses of tree data, topography, and soil type, I found some limited support for the neutral theory assumptions of functional and ecological equivalency, with notable exceptions. Populus tremuloides, Pinus flexilis, and Pinus longaeva were characterized by non-neutral recruitment processes, and Abies bifolia and Populus tremuloides exhibited asymmetric competitive and facilitative interactions. The assumption of habitat generality was strongly contradicted, with all ten abundant species in the UFDP having habitat preference. In this subalpine temperate forest, species diversity and community structure are influenced more by habitat heterogeneity, species differences, and niche selection, with neutral processes playing a lesser role.

Fish community data were collected to investigate the role of wetlands in supporting fish communities of protected embayments in Lake Ontario. Wetland and deeper, more open, littoral sites were sampled in five protected embayments using gill nets, fyke nets, minnow traps, and electrofishing gear during the summers of 2001 and 2002. Pooled gear data were used to analyze community composition, size frequency, and species richness. We found that even within protected embayments where community composition of both habitats is similar, wetlands support a community of fish different in species dominance and size structure than littoral embayment habitats. The abundance of young-of-year fish suggests that wetlands support fish populations by providing important nursery habitat. The similarity in fish community composition between wetland and littoral habitats indicates that wetlands remain important in supporting a subset of the embayment fish community. These results demonstrate that both wetlands and littoral areas in embayments are valuable and intensively utilized fish habitats that should receive special consideration in ecosystem management plans for the Great Lakes.

International audience; Previous surveys of population structure in the Atlantic-Mediterranean anchovy Engraulis encrasicolus L. have reported heterogeneity in morphology, allozyme frequencies, and mitochondrial-DNA haplotype frequencies at a regional scale. In particular, two stocks of anchovy have been detected in the Adriatic Sea. Here I review the available data with the aim to relate genetic variation with geography at the widest possible geographical scale, for investigating the evolutionary mechanisms underlying stock structure in anchovy. Correspondence analysis of allozyme frequencies (24 samples, 3 polymorphic loci) compiled from the literature indicated three distinct entities in the Mediterranean Sea. Open-sea or oceanic anchovy populations are genetically different from inshore-water populations within a region (Nei’s ^GST=0.035-0.067), while broadscale geographical variation is weak for each of these two habitat-specific forms (^GST =0.005-0.006). Mitochondrial-DNA haplotype frequencies also support the distinction between an inshore form and an oceanic form (^GST =0.067-0.107), with virtually no genetic differences among oceanic populations across the Gulf of Biscay, the Western Mediterranean and the Ionian Sea (^GST =-0.001). If natural selection on marker loci is unimportant, these results indicate the occurrence of two parapatric, genetically distinct, habitat-specific forms that are widely distributed throughout the Mediterranean Sea. Persistent allele- and haplotype-frequency differences between these forms indicates reproductive isolation and the presence of an E. encrasicolus species complex in the Mediterranean.

Coastal cliff-tops are specific saline environments, where only highly specialized halophytes can thrive. Limonium spp. are commonly found in these ecological conditions, many of them being considered as threatened or with an unknown conservation status. The habitat requirements of Limonium multiflorum, an apomictic halophyte endemic to western Portugal, were investigated. Results showed the species narrow habitat specificity as well as its intolerance to competition with invasive alien plants. We conclude that in situ conservation of this rare and vulnerable species emerges as a priority in order to ensure that its biodiversity is not lost., Coastal areas and other saline environments are major contributors to regional and global biodiversity patterns. In these environments, rapidly changing gradients require highly specialized plants like halophytes. In European coastal cliff-tops, rocky and sandy seashores, and saltmarshes, typical halophytes from the genus Limonium are commonly found. Among them, the aneuploid tetraploid (2n = 4x = 35, 36, 37) Limonium multiflorum, endemic to the west coast of Portugal, is an interesting case study for investigating the ecology and conservation of a halophyte agamospermic species. Although it is listed in the IUCN red list of threatened species, information on its population size or rarity, as well as its ecology, in some respects is still unknown. Field surveys in the largest known population were performed (Raso cape, Portugal) in order to determine habitat requirements and conservation status. A total of 88 quadrats were monitored, 43 of which contained at least one L. multiflorum individual. For each sampled quadrat, four abiotic and four biotic variables as well as two spatially derived variables were recorded. Principal component analysis and cluster analysis showed narrow habitat specificity for this species which appeared to be intolerant to competition with invasive alien plants. We conclude that in situ conservation in a local ‘hotspot’ of this rare and vulnerable species emerges as a priority in order to ensure that biodiversity is not lost.

Risk assessment investigates the potential impacts of chemicals on non-target organisms. To assess the risk, ecotoxicologists study the responses of a panel of species to different substance exposure. Among the different parameters used to select indicator species (i.e. focal species), their frequency of occurrence is considered as the key parameter. Although species occurrence within a given habitat is easy to determine, we argue that it does not totally reflect the dependence of a species on a given habitat or its potential exposure to chemicals. In this study, we combined the occurrence of species with their habitat-specificity to identify focal species for risk assessment in cereals. We showed that ranking species by occurrence or by habitat-specificity produced different results, with generalist species ranking high in the occurrence list, and species with specialised habitats ranking high in the abundance list. Integrating frequency and abundance of species into one single indicator (the "Indicator Value") allows us to rank species with specialised habitats as high as generalist species in the top rank species list. Although habitat-specificity is an ecologically meaningful concept, it is largely overlooked in eco-toxicological risk assessment, despite the fact that specialists are good indicators of various environmental pressures. This method could be used extensively at different scales and could contribute to studies on risk assessment issue by (re)introducing ecological and population-level concepts and opening up new trait-based approaches.