Taxonomic Distinctness Research Articles

Elymus multiramosus (Poaceae), a new species from the north-western Qinghai-Tibetan Plateau, China

A new species from China, Elymus multiramosus Y.C. Zhang, sp. nov. is described and illustrated herein, based on morphological characters and molecular phylogenetic analysis. The taxonomic descriptions of E. multiramosus and the comparison with related species are presented. The taxonomic distinctiveness of this new species was inferred by Maximum Likelihood (ML) analysis and Bayesian phylogenetic analysis, based on the complete chloroplast genome sequence. It is assigned to the Elymus section and bears similarity to Elymus nutans Griseb. However, it can be easily distinguished from other species by its compound spike, in contrast to the simple spike inflorescence typical of those species. The compound spike is characterised by rhachillas that are extended at the base of the main axis, giving rise to 3–6 mini-spike-like branches. Notably, these branches significantly increase in length from the top towards the bottom of the compound spike. In the molecular phylogeny, Elymus multiramosus from Qinghai, north-western China, is phylogenetically positioned as a distinct lineage. The lineage comprising Elymus sinosubmuticus from Sichuan, east of the Tibetan Plateau and Elymus nutans from the Himalayas forms a sister group to Elymus multiramosus, suggesting that these three species share a common ancestor that is distinct from the lineage leading to Elymus atratus from Gansu, north of the Tibetan Plateau.

Species loss and decline in taxonomic diversity of macroalgae in the Gulf of Trieste (Northern Adriatic sea) over the last six decades

Assessing historical changes in marine biodiversity at regional or local scales is often challenging due to insufficient long-term data for most marine organisms. Yet, these assessments are crucial to understanding potential long-term variation in the species pool in response to complex and interacting local and global environmental changes. Here, we performed a comprehensive review of scientific and grey literature, archival records and floristic data spanning over the last two centuries to reconstruct an updated and revised taxonomic dataset of macroalgae in the Gulf of Trieste (Northern Adriatic Sea), one of the most exposed to human-driven pressures and climatically vulnerable regions in the Mediterranean Sea. The subset of data from 1960 to present, encompassing nearly all available records, was used to assess the contribution of species replacement and gain/loss to temporal β-diversity and to test for changes in the taxonomic distinctness of the species pool over the past six decades.We identified 68 species that have never been recorded again since 1990, indicating their likely local extinction. The major change, however, was due to species replacement and to a reduction in the taxonomic breadth of macroalgal diversity, as highlighted by a significant decrease in the Average Taxonomic Distinctness of the species pool, especially along the Italian coast. The loss of species has mainly affected habitat-formers (e.g., Cystoseira sensu lato) and species with Atlantic/Circumboreal and Mediterranean affinities, which were replaced by turf-formers and species with Pantropical/Cosmopolitan/IndoPacific affinities. While multiple human impacts (e.g., coastal artificialisation, unbalanced N/P ratios) might have contributed to the ongoing change in macroalgal diversity, the observed decline of cold-affinity species in favour of warm-affinity species pointed out a critical role of exacerbating climatic changes. Our study demonstrated that historical reconstructions of species records coupled with effective indicators for the analysis of presence/absence data can help quantify long-term biodiversity changes and provide valuable insights into their possible causes.

Ecological and taxonomic dissimilarity in species and higher taxa of reptiles in western Mexico.

Reptiles are one of the most diverse groups of vertebrates in the world that are distributed in almost all ecosystems. Many of these studies have focused on exploring their diversity patterns across different environments; and recent studies on reptile alpha and beta diversity have incorporated a multifaceted approach into their analysis to have more comprehensive evaluations. This study presents an assessment of the taxonomic diversity of reptile patterns using methods that incorporate the assessment of higher taxa. Likewise, the taxonomic dissimilarities between reptile communities in the physiographic regions of the state of Jalisco were analyzed. Evaluations for the groups of snakes and lizards independently are presented. We use the taxonomic distinctiveness index that assesses the complexity of the taxonomic structure of communities through hierarchical classification above the species level to measure the relationships between taxa. The dissimilarity of the taxonomic structure in each community was also analyzed. Beta diversity partitions were performed to identify the contribution of turnover and the differences in richness. We determined that alpha diversity of species and higher taxa maintain different patterns, indicating that Jalisco presents regions with overrepresentation of reptile families and genera, as well as regions with an opposite trend. The representation of higher taxa is higher in the lizard group, although in terms of species richness snakes are the most prominent group. The turnover is the most important component at species and higher taxa, with similar values for lizards and snakes. The findings presented show that incorporating phylogenetic information about species through taxonomic relationships provides complementary information that species diversity per se, especially at the level of alpha diversity.

Taxonomic diversity of terrestrial vertebrates in west-central Mexico: Conservation from a multi-taxa perspective.

Multi-taxa approaches are increasingly used because they describe complementary aspects of ecosystem dynamics from a community ecology perspective. In west-central Mexico, the complex biogeography and topography have created an environment where temperate and tropical forests converge, resulting in great biological diversity. Within this region, the Sierra de Quila Natural Protected Area (SQPA) offers an important example for understanding ecological community dynamics. We analyze the taxonomic diversity of terrestrial vertebrates in the SQPA by incorporating taxonomic levels associated with species. We evaluated the taxonomic diversity with i) an average taxonomic distinctiveness analysis (alpha diversity) and ii) an analysis of taxonomic dissimilarity and partitioning of turnover and differences in richness components (beta diversity). Tropical forests boast the highest taxonomic diversity of amphibians, reptiles, and birds, while temperate gallery forests exhibit lower values. Our results showed that terrestrial vertebrate alpha and beta diversity patterns respond mainly to contrasting vegetation types (tropical vs. temperate). Regarding beta diversity, the multi-vegetation type analysis showed the highest values for reptiles, followed by amphibians, birds, and mammals. Turnover had the highest contribution to beta diversity, while differences in richness were relevant for amphibians and reptiles, which could be related to their low mobility and sensitivity to environmental conditions. Despite the local scale, the SQPA presented high beta diversity, reflecting historical ecological processes in taxonomic composition derived from contrasting environments and constraints imposed on species. Evaluating taxonomic structure from a multi-taxa perspective is essential for conservation efforts because it allows the spatial recognition of biological assemblages as a first step for local interventions.

Historical insights, current challenges: tracking marine biodiversity in an urban harbor ecosystem in the face of climate change

The Boston Harbor Islands is the only coastal drumlin archipelago in the USA, featuring a distinctive and uncommon geological intertidal habitat known as mixed coarse substrate, which supports a range of coastal species and ecological processes. Recently designated as one of America’s 11 most endangered historic places due to climate change impacts, coastal adaptation and restoration efforts are crucial to their preservation. Such efforts can benefit from historic and current knowledge of endemic and emergent biodiversity. To investigate broad trends in coastal biodiversity, we compiled an inventory of marine coastal macroalgae, macroinvertebrates, fish, mammals, and shorebirds observed in the harbor since 1861. Records span 159 years, consisting of 451 unique taxa from 19 phyla. Analysis of average taxonomic distinctness (AvTD) revealed increases in diversity towards the end of the twentieth and early twenty-first century, likely associated with improved water quality (dissolved oxygen; AvTD > 85, p = 0.01) due to harbor restoration in the 1980s. Macroinvertebrates comprised 50% of the records, making this the most diverse taxonomic group in the time series. A significant increase of non-indigenous species, primarily macroinvertebrates and macroalgae, was observed over the last 20 years near human infrastructure and across multiple islands, a consequence of global change and characteristic of most urban harbors. The mixed coarse intertidal habitat, which makes up > 70% of Boston Harbor’s inner islands and supports high macroinvertebrate and macroalgal diversity (47% of species records), is not routinely monitored; our findings serve as a foundational resource for climate adaptation projects and decision-making.

Morphological diversity and taxonomic implications of seedling structures in selected species of Fabaceae from Karachi (Pakistan)

Seedling morphology is a valuable tool for plant identification and classification, particularly in early growth stages. This study investigates the morphological characters of seedlings from randomly selected taxa within the Fabaceae family, focusing on cotyledons, first two leaves, and subsequent leaves to support taxonomic differentiation. Not all subfamilies within Fabaceae are fully represented in this study. Seedlings from 14 randomly selected taxa were analyzed using morphological traits such as cotyledon shape, phyllotaxy, leaf shape, and venation patterns. An artificial key was constructed, and three dendrograms were developed based on cotyledon morphology, first two leaves, and subsequent leaves to illustrate taxonomic relationships. Statistical analyses were employed to assess clustering patterns among the taxa. The artificial key categorized the taxa into subfamilies within Fabaceae, including Caesalpinoideae, Mimosoideae, and Papilionoideae, based on cotyledon shape and leaf morphology. Dendrogram analysis revealed distinct clustering patterns, grouping species according to key morphological features. Not all subfamilies of Fabaceae were covered, but the analysis provided clear separation among the species studied. The morphological traits observed were consistent with previous taxonomic findings and offered a reliable basis for classification. The morphological features of seedlings, especially cotyledons and eophylls, serve as reliable taxonomic markers for identifying and classifying species within Fabaceae. Although the study does not encompass all subfamilies, the randomly selected taxa demonstrated clear taxonomic distinctions. Dendrograms combined with artificial keys provided a useful framework for classification. Further studies should expand the scope to include more taxa, covering all subfamilies of Fabaceae. Integrating molecular and other taxonomic tools such as anatomy, cytology, and chemistry can enhance the precision of classification frameworks and provide deeper insights into the evolutionary relationships within the family.

Fish Species Assemblages and Diversity in Water Body Infested by Alien Species

Human is one of the mediators for non-native species invasion, especially in the aquatic ecosystem. Aquaculture and sport fishing activities are the main reasons for non-native fish introduction, especially in man-made habitats. In the present study, we determined the fish community between the invaded as opposed to pristine ecosystems in north Terengganu, Malaysia. The primary data was collected using hook and line, hand-held push net, cast net and gills net while secondary data were also utilised from published and unpublished data. The fish general information including functional traits and prey-predator relationship were obtained from literature and reliable online resources. The data were used to construct hypothetical diagrams and analyzed using taxonomic distinctness index. The fish community between the two habitats differ significantly in which the non-native fish invaded habitat has much lesser fish species richness than that of the pristine habitat. Taxonomic diversity between the two habitats also was markedly different. The non-native Cichla ocellaris added predation pressure to fish community in the lacustrine habitat as the apex predator and were proven to feed on the native fish fauna in the lake. We discuss the community structure in both habitats and explore the further impact of invasion by this invasive alien species on the native fish species. We conclude that the presence of Cichla ocellaris amplify pressure to native fish community in the man-made lake.

Drivers of Pinus halepensis Plant Community Structure across a Post-Fire Chronosequence

The Pinus halepensis (Aleppo pine) forests prevailing in the western part of the Mediterranean Basin are amongst the most severely affected by fire due to their inherent flammability. Our understanding of the environmental factors driving post-fire community dynamics is currently limited by the lack of time-series data at temporal scales. In this present study, we analyzed a chronosequence of Greek Aleppo pine forests spanning a post-fire period of 65 years. Our goal is to explore the role of post-fire age, altitude, exposure, slope level, parent-rock material, rock cover, and cover of evergreen sclerophyllous shrubs (maquis) on plant assemblage diversity (species richness and Menhinick’s diversity index) and composition. Post-fire age had a significant effect on taxonomic distinctness and community turnover but not on species richness. Taxonomic distinctness increased with post-fire age due to a higher prevalence of the families Fabaceae, Asteraceae, and Poaceae during the early post-fire period. Maquis cover was significantly associated with Menhinick’s diversity index, taxonomic distinctness, and community turnover. Exposure and slope influenced only Menhinick’s diversity index. The turnover in species composition was primarily driven by the geographical proximity of the forests and secondarily by post-fire age and the maquis cover. This highlights the importance of the initial floristic composition in the process of autosuccession after a fire in Mediterranean-climate ecosystems.

Taxonomic Diversity and Interannual Variation of Fish in the Lagoon of Meiji Reef (Mischief Reef), South China Sea.

Coral reef fish are important groups of coral reefs, which have great economic and ecological value. Meiji Reef is a representative tropical semi-enclosed atoll in the South China Sea, with rich fish resources. Based on the data from hand-fishing, line-fishing, and gillnet surveys of fish in Meiji Reef from 1998 to 2018, this study summarized the fish species list of Meiji Reef and analyzed the species composition, inclusion index at the taxonomic level (TINCL), genus-family diversity index (G-F index), average taxonomic distinctness index (Δ+), and variation in taxonomic distinctness (Λ+) and their changes. The results revealed that from 1998 to 2018, there were 166 reef-dwelling fish species on Meiji Reef, belonging to 69 genera, 33 families, and 11 orders, of which 128 species were from 20 families of Perciformes, accounting for 77.10% of the total cataloged species. Regarding the dependence of fish on coral reefs, there were 155 reef-dependent species or resident species (accounting for 93.37%) and 11 reef-independent species or wandering species (accounting for 6.63%). The TINCL of the order, families, and genus of fish in Meiji Reef were very high. The genus diversity index (G index), family diversity index (F index), and G-F index of fish in Meiji Reef were very high, and the G index of fish in Meiji Reef in 1998-1999 was higher than that in 2016-2018. The Δ+ and Λ+ values of fish in Meiji Reef from 1998 to 2018 were 56.1 and 148.5, respectively. Compared with 1998-1999, Δ+ and Λ+ of fish increased during 2016-2018, reflecting that the relatives of fish in Meiji Reef became further distant, and the uniformity of taxonomic relationships among species decreased. The research findings indicated that fish exhibited a high taxonomic diversity in Meiji Reef; however, it also revealed significant fluctuations in the fish diversity of Meiji Reef over an extended period, emphasizing the urgent need for timely protection measures. This investigation significantly contributes to our comprehension of the intricate dynamics governing fish species within Meiji Reef and holds broader implications for biodiversity conservation in tropical marine ecosystems.

Unraveling Evolutionary Dynamics: Comparative Analysis of Chloroplast Genome of Cleomella serrulata from Leaf Extracts

Cleomella serrulata is a native flowering plant found in North America. Even though this plant is of ecological and native medicinal importance, very little is known about the genomic makeup of Cleomella and the Cleomaceae family at large. Here, we report the complete chloroplast genome of Cleomella serrulata and provide an evolutionary comparison to other chloroplast genomes from Cleomaceae and closely related families. This study not only confirms the taxonomic placement of Cleomella as a distinct genus, but also provides phylogenetic insights that imply potential adaptive strategies and evolutionary mechanisms driving the genomic diversity of the Cleomella genus. Whole-genome-based and ANI comparisons indicate that the Cleomella species form a distinct clade that is about equidistant from the other Cleomaceae genera as it is from the genera from the nearby Capparaceae and Brassicaceae. This is the first complete chloroplast-based phylogenetic comparison of Cleomella species to other related genera and helps refine the complex taxonomic distinctions of Cleomaceae.

Consumers’ categorizations of dairy products and plant-based milk, yogurt, and cheese alternatives

Plant-based dairy alternatives have many benefits in terms of sustainability, animal welfare, and health, but they can only be successful in the market if consumers perceive them as suitable substitutes for conventional dairy. Consumers' expectations for new products are strongly influenced by the food categories into which they place these products. The present study aims to reveal consumers' categorizations of plant-based dairy products to gain insights into their potential as dairy substitutes. In a free sorting task, 100 participants from the German-speaking part of Switzerland sorted a variety of plant-based and conventional animal-based dairy products into groups, indicating their spontaneous similarity perceptions. Additionally, we assessed the participants' characteristics and attitudes toward plant-based dairy products to test potential differences in categorization strategies among consumer groups. Multidimensional scaling and cluster analysis showed that consumers' mental representations of plant-based dairy and conventional animal-based dairy were clearly separated across a wide range of product types. This pattern was even observed among consumers who ate less meat, had higher exposure to vegan dietary styles, and had less negative attitudes toward dairy alternatives. The results suggest that taxonomic distinctions based on plant or animal origin dominate consumers' perceptions and are likely to hinder the substitution of dairy with plant-based dairy. Nevertheless, they also imply that plant-based products that manage to emphasize shared goals and functional properties akin to conventional dairy products are more likely to form a common goal–derived category in consumers’ minds and thus have better prospects as substitutes.

Phenotypic variation and genetic diversity in European Alnus species

Abstract The recent taxonomic distinction between the European common alder species Alnus glutinosa and A. lusitanica strengthens the need for studies on phenotypic and genetic variation. Understanding such variations requires the use of populations encompassing the total latitudinal distribution and environmental envelope of the distribution range of A. glutinosa and A. lusitanica. This study aims to describe the genetic diversity and assess the phenology, morphology, physiology and biochemistry of alder seedlings from populations reaching out to the latitudinal extremes of both species. We grew 1579 2-year-old seedlings from seven A. glutinosa and six A. lusitanica populations in a common garden in Oeiras, Portugal. By using simple sequence repeat markers, two genetically distinct groups in A. glutinosa and three in A. lusitanica were identified. The species presented marked morphological and biochemical differences. The southern populations of A. lusitanica showed higher genetic diversity than A. glutinosa populations. Significant associations between four alleles from three loci, and one morphological and three biochemical traits were detected in several genetic groups from both alder species. Traits from southern populations of A. lusitanica were associated with low water availability. Inter-specific trait variation and association of traits with molecular markers suggest that A. lusitanica might have an adaptive advantage if subjected to drought and heat stressors. This study strengthens the recent taxonomical differentiation between the two species and emphasizes the need for preserving southern A. lusitanica populations and their genetic diversity in Mediterranean riparian corridors.

Antibacterial activity and biosynthetic potential of Streptomyces sp. PBR19, isolated from forest rhizosphere soil of Assam.

An Actinomycetia isolate, designated as PBR19, was derived from the rhizosphere soil of Pobitora Wildlife Sanctuary (PWS), Assam, India. The isolate, identified as Streptomyces sp., shares a sequence similarity of 93.96% with its nearest type strain, Streptomyces atrovirens. This finding indicates the potential classification of PBR19 as a new taxon within the Actinomycetota phylum. PBR19 displayed notable antibacterial action against some ESKAPE pathogens. The ethyl acetate extract of PBR19 (EtAc-PBR19) showed the lowest minimum inhibitory concentration (MIC) of ≥ 0.195µg/mL against Acinetobacter baumannii ATCC BAA-1705. A lower MIC indicates higher potency against the tested pathogen. Scanning electron microscope (SEM) findings revealed significant changes in the cytoplasmic membrane structure of the pathogen. This suggests that the antibacterial activity may be linked to the disruption of the microbial membrane. The predominant chemical compound detected in the EtAc-PBR19 was identified as phenol, 3,5-bis(1,1-dimethylethyl), comprising 48.59% of the area percentage. Additionally, PBR19 was found to contain the type II polyketide synthases (PKS type II) gene associated with antibiotic synthesis. The predicted gene product of PKSII was identified as the macrolide antibiotic Megalomicin A. The taxonomic distinctiveness, potent antibacterial effects, and the presence of a gene associated with antibiotic synthesis suggest that PBR19 could be a valuable candidate for further exploration in drug development and synthetic biology. The study contributes to the broader understanding of microbial diversity and the potential for discovering bioactive compounds in less-explored environments.

Population genetics and phylogeography of Trachylepis sulcata (Peters, 1867) and T. ansorgii (Boulenger, 1907) in south-western Africa

ABSTRACT Ansorge’s Rock Skink Trachylepis ansorgii (Boulenger, 1907) is an Angolan taxon, the taxonomic distinctiveness and geographic distribution of which are poorly understood. It is closely related to the widespread Western Rock Skink T. sulcata (Peters, 1867) from Namibia and South Africa, but heretofore a lack of samples has prevented a comprehensive assessment of T. ansorgii in a molecular phylogenetic context. We combine new genetic sampling from south-western Angola, including topotypical material of T. ansorgii, with published sequences from South Africa and Namibia to identify population structure, phylogenetic relationships, and divergence dates within this species complex. A multi-locus dataset of three nuclear and two mitochondrial loci recovered significant population structuring with a centre of diversity in south-western Angola and northern Namibia. Mitochondrial data recovered seven clades representing distinct geographic populations, while the nuclear data supported either two or three deeper groupings. Mito-nuclear discordance was observed with respect to the geographic boundary between T. ansorgii and T. sulcata. The nuclear data support a break along the western Kunene River (the political boundary between Angola and Namibia), while the mitochondrial data support this break ∼250 km to the north in south-western Angola. A time-calibrated BEAST phylogeny found the deepest species-level divergence to have occurred in the late Miocene/early Pliocene (∼6 mya), potentially related to the formation of the Kunene River. Our results support the recognition of both taxa at the species level, and add further evidence that south-western Angola is a centre of reptile diversity.

Phytoplankton distribution pattern and its implication for the establishment of land-based ballast water treatment technology and test facility in tropical waters

The present study was carried out to investigate the phytoplankton distribution in tropical waters and its implication for establishing land-based ballast water treatment technology and test facility (BWTT-TF) as per the International Maritime Organization (IMO) guidelines. Samples were collected from the Swarnamukhi estuary (SE) and coastal locations on the east and west coast of India. The maximum phytoplankton density in the size group of ≥10 and < 50 μm was recorded as 3002 cells/mL in estuarine waters and 172 cells/mL in coastal waters. Among the phytoplankton, Bacillariophyta and Pyrrophyta were observed at all locations, whereas Ochrophyta and Chlorophyta were found only at specific locations or during specific periods. According to IMO guidelines, the minimum required number of species (5) was observed at all the locations, but the minimum number of phyla (3) was not found at some locations. The IMO minimum required phytoplankton density (>1000 cells/mL) was observed only during the bloom period, whereas it was about 5–50 times lower during other periods. Taxonomic distinctness indices were used to examine the diversity beyond the conventional species count. The study found that the Buckingham Canal and Swarnamuki River upstream among the SE locations, and coastal stations of Pamanji and Tirunelveli among the coastal locations, are suitable sites to establish land-based BWTT-TF. Since the results indicate that achieving the IMO specified size group of ≥10 and < 50 μm density in tropical waters was possible only during the bloom period, culturing phytoplankton surrogates and concentrating naturally available phytoplankton are recommended as alternate methods for establishing land-based ballast water treatment technology and test facilities.

SEM and LM insights: Spore morphology and its taxonomic significance in Sino Himalayan, Malesian, and European elements of Pteridaceae.

The Pteridaceae family, known for its taxonomic complexity, presents challenges in identification due to high variability among its species. This study investigates the spore morphology employing both SEM and LM techniques in 10 Pteridaceae taxa phytogeographicaly Sino-Himalayan, Malesian, and European elements in Pakistan. The taxa include Adiantum capillus-veneris, A. incisum, A. venustum, Aleuritopteris bicolor, Oeosporangium nitidulum, O. pteridioides, Onychium cryptogrammoides, O. vermae, Pteris cretica, and P. vittata. The objective is to assess their taxonomic relevance and develop a spore-based taxonomic key. Findings indicate differences in spore shape, sizes, exospore thickness, and in surface ornamentation highlighting the potential for taxonomic differentiation. Spores are trilete, and notable differences are observed in the dimension of spores in both distal and proximal sides. Equatorial dimensions vary between 35 and 50 μm, while the polar diameter ranges from 29 to 50 μm. SEM revealed different spore ornamentation types that show several useful characteristics establishing valuable taxonomic variations. The studied Adiantum taxa feature a perispore with tubercules and a micro-granulose surface. The spores of examined Oeosporangium and Aleuritopteris taxa shows cristate sculptures with variable ornamentations. Both species of Onychium have tuberculate-pleated tubercles with sinuous folds on both distal and proximal sides. The surface ornamentation among examined Pteris taxa show variability. PCA analysis indicated that spore quantitative data identified distinct groups, underscoring taxonomic significance. Nevertheless, there was variation observed in surface ornamentation and spore shape, indicating the potential for discrimination among taxa. RESEARCH HIGHLIGHTS: Spore morphology of 10 Pteridaceae taxa has been investigated through LM and SEM. Investigated species shows differences in spore shape, sizes, exospore thickness, and in surface ornamentation. Ornamentation on the perispore provides several valuable characteristics, establishing useful taxonomic distinctions. Spore morphological analysis is effective at the generic level, with minor distinctions discernible at the species level.

Taxonomic distinctness and diversity patterns of a polychaete (Annelida) community on the continental shelf of the Southern Gulf of Mexico.

The spatial patterns of taxonomic diversity of annelid polychaete species from the continental shelf in the Southern Gulf of Mexico were examined in this study. We used taxonomic distinctness and its spatial variations to explore the diversity patterns and how they change between Southern Gulf of Mexico regions. In addition, using taxonomic distinctness as a dissimilarity measure and Ward's Clustering, we characterized three distinct faunal assemblages. We also investigated patterns of richness, taxonomic distinctness, and distance decay of similarity between sampling stations as a ß-diversity measure. Finally, we examined the spatial relationships between polychaete assemblages and environmental variables to test the relative importance of spatial and environmental components in annelid polychaete community structure from the Southern Gulf of Mexico. We used a combination of eigenvector-based multivariate analyses (dbMEMs) and distance-based redundancy analysis (dbRDA) to quantify the relative importance of these explanatory variables on the spatial variations of taxonomic distinctness. The significance level of spatial and environmental components to the distribution of polychaete species showed that the combined effect of spatial processes and sediment characteristics explained a higher percentage of the variance than those parameters could alone.

Century-long recovery of mycorrhizal interactions in European beech forests after mining

Abstract Background and aims Ecological restoration strategies are emerging globally to counteract biodiversity loss and ecosystem degradation. However, restored ecosystems may not reach undisturbed biodiversity and functionality. One reason of this limited success may be a focus on short-term recovery of diversity, composition, or isolated functions. These simplified metrics may underestimate the real time ecosystems need to recover. Thus, studies of more complex metrics, like biotic interactions, at larger timescales, are essential to understand ecosystem recovery. Methods Using molecular identification, we assessed the recovery of the interactions between ectomycorrhizal (EcM) fungi and European beech (Fagus sylvatica L.) in two opencast iron mines in use since the fourteenth century and abandoned over 107 and 148 years. Results Species richness, species diversity, Basidiomycota/Ascomycota abundance ratio and taxonomic distinctness of EcM fungi recovered to undisturbed values, whereas species composition was still different. Certain fungal functional traits (i.e. exploration and sporocarp types) also reached undisturbed values. Differences in soil pH and NH4+ affected the composition of the EcM communities associated with beech, suggesting that mining caused a long-term impact in soil biogeochemistry, that directly impacted beech-EcM interactions. Conclusion Mycorrhizal interactions require more than 150 years to recover following mining. Contrary to the rapid recovery response provided by simple metrics like species richness, recovery metrics with more ecological information, like the identity of plant-EcM interactions, may be still capturing signals of incomplete recovery.

Drivers of Macroinvertebrate Communities in Mediterranean Rivers: A Mesohabitat Approach

We investigated the relationship between benthic macroinvertebrate community attributes (richness, abundance, biodiversity, and climate-specific and resistance forms) and the physical characteristics of distinct mesohabitats (hydromorphological unit types) discretized into fast (e.g., riffles or rapids) and slow (e.g., pools or glides) flow types in four Mediterranean rivers of Spain. Key attributes of hydromorphological units, including length, width, depth, shade, substrate composition, embeddedness, abundance of aquatic vegetation, and density of woody debris, were considered. Through a comprehensive suite of multivariate analyses, we unraveled taxonomic and habitat distinctions among rivers and hydromorphological unit types, with a notable influence of spatial proximity (greater similarity within the same river basin). In slow hydromorphological units, aquatic vegetation, depth, and abundance of coarse substrate emerged as pivotal factors shaping macroinvertebrate assemblages, whereas in fast-flowing units, vegetation, substrate embeddedness, and density of woody debris were the most important. Contrary to the remaining community attributes, the studied resistance forms (absent, eggs, cocoons, and cells against desiccation and diapause) exhibited uniformity across rivers despite observed variations in macroinvertebrate communities, underscoring regional functional analogies in biological and ecological mechanisms within the investigated Mediterranean river basins. This study contributes valuable insights for anticipating the repercussions of ongoing climate change, particularly in regions where fast-flowing hydromorphological units are more susceptible to depletion during drought periods.

Thirty years of change: Assessing the dynamics of fish communities in Daya Bay, a semi-enclosed coastal ecosystem of the South China sea

Daya Bay is a semi-enclosed bay in the South China Sea which is a coastal ecosystem with significant ecological and economic value that is subjected to a variety of anthropogenic disturbances. However, long-term variation in fish community structure in this Bay remains uncertain. In this study, we aimed to explore the changing characteristics of fish species composition and community structure in Daya Bay during the past 30 years using data from 1989 to 2021 from bottom trawl surveys and historical literature data. As of now, a total of 544 species of fish have been identified in the Bay, belonging to 24 orders and 125 families. The structure of the fish community in the bay has changed over time. Firstly, there has been a clear decrease in the number of species and biomass of large fish. Secondly, the number of fish constituent orders and families has decreased. Moreover, both the average taxonomic distinctness and variation in taxonomic distinctness decreased from 1989 to 2021. Thirdly, there is low similarity among fishes at different time phases and distinct changes in the composition of dominant species. Present results indicate that the fish community structure in Daya Bay has tended to reflect a decline in diversity, shifts in composition, and shrinking of fish body size in the past 30 years. This study improves our understanding of fish species composition and its drivers over time in Daya Bay, providing important knowledge to support the protection and restoration of this ecosystem and the important ecosystem services it provides.