Taxonomic Variation Research Articles

Phosphorus Release and Regeneration Following Laboratory Lysis of Bacterial Cells.

The availability of phosphorus limits primary production in large regions of the oceans, and marine microbes use a variety of strategies to overcome this limitation. One strategy is the production of alkaline phosphatase (APase), which allows hydrolysis of larger dissolved organic phosphorus (DOP) compounds in the periplasm or at the cell surface for transport of orthophosphate into the cell. Cell lysis, driven by grazing and viral infection, releases phosphorus-containing cell components, along with active enzymes that could persist after lysis. The importance of this continued enzymatic activity for orthophosphate regeneration is unknown. We used three model bacteria – Escherichia coli K-12 MG1655, Synechococcus sp. WH7803, and Prochlorococcus sp. MED4 – to assess the impact of continued APase activity after cell lysis, via lysozyme treatment, on orthophosphate regeneration. Direct release of orthophosphate scaled with cell size and was reduced under phosphate-starved conditions where APase activity continued for days after lysis. All lysate incubations showed post-lysis orthophosphate generation suggesting phosphatases other than APase maintain activity. Rates of DOP hydrolysis and orthophosphate remineralization varied post-lysis among strains. Escherichia coli K-12 MG1655 rates of remineralization were 0.6 and 1.2 amol cell–1hr–1 under deplete and replete conditions; Synechococcus WH7803 lysates ranged from 0.04 up to 0.3 amol cell–1hr–1 during phosphorus deplete and replete conditions, respectively, while in Prochlorococcus MED4 lysates, rates were stable at 0.001 amol cell–1hr–1 in both conditions. The range of rates of hydrolysis and regeneration underscores the taxonomic and biochemical variability in the process of nutrient regeneration and further highlights the complexity of quantitatively resolving the major fluxes within the microbial loop.

Microhabitat features determine the tadpole diversity in mountainous streams

The study on the mechanism driving the spatial patterns of biological diversity along elevational gradients is a main focus in ecology, biogeography, and conservation biology. Based on the intraspecific variability of tadpole communities in 18 mountainous streams, the present study quantified the spatial patterns of taxonomic and functional diversity, and the environmental factors underlying the process of spatial distribution and diversity. First, our results illustrated that both elevation and microhabitat features (e.g., water pH, dissolve oxygen, current velocity, chlorophyll a, and ammonium nitrogen) determined tadpole community compositions. Second, the richness of functional entities showed a hump-shape response to the change of elevation. However, no significant relationships were detected between other diversity indices at both taxonomic and functional levels and site elevation. Finally, microhabitat environmental variables were the primary drivers of the taxonomic variation and functional diversity in tadpole communities. However, the relative contribution to the variation of specific diversity indices differed among microhabitat environmental variables. Our results supported the claim that the assembly of montane communities is determined by both spatial processes and environmental filtering. Importantly, tadpole taxonomic and functional diversities were strongly determined by microhabitat features in mountainous streams, providing evidence that microhabitat should be a priority in this study of tadpole diversity conservation. This study suggests that tadpole diversity should be considered in the long-time monitoring of species conservation, as the tadpole is part of the life history in amphibians.

Valley-scale hydrogeomorphology drives river fish assemblage variation in Mongolia.

River hydrogeomorphology is a major driver shaping biodiversity and community composition. Here, we examine how hydrogeomorphic heterogeneity expressed by Functional Process Zones (FPZs) in river networks is associated with fish assemblage variation. We examined this association in two distinct ecoregions in Mongolia expected to display different gradients of river network hydrogeomorphic heterogeneity. We delineated FPZs by extracting valley‐scale hydrogeomorphic variables at 10 km sample intervals in forest steppe (FS) and in grassland (G) river networks. We sampled fish assemblages and examined variation associated with changes in gradients of hydrogeomorphology as expressed by the FPZs. Thus, we examined assemblage variation as patterns of occurrence‐ and abundance‐based beta diversities for the taxonomic composition of assemblages and as functional beta diversity. Overall, we delineated 5 and 6 FPZs in river networks of the FS and G, respectively. Eight fish species were found in the FS river network and seventeen in the G, four of them common to both ecoregions. Functional richness was correspondingly higher in the G river network. Variation in the taxonomic composition of assemblages was driven by species turnover and was only significant in the G river network. Abundance‐based taxonomic variation was significant in river networks of both ecoregions, while the functional beta diversity results were inconclusive. We show that valley‐scale hydrogeomorphology is a significant driver of variation in fish assemblages at a macrosystem scale. Both changes in the composition of fish assemblages and the carrying capacity of the river network were driven by valley‐scale hydrogeomorphic variables. River network hydrogeomorphology as accounted for in the study has, therefore, the potential to inform macrosystem scale community ecology research and conservation efforts.

The temperature sensitivity of soil: microbial biodiversity, growth, and carbon mineralization.

Microorganisms drive soil carbon mineralization and changes in their activity with increased temperature could feedback to climate change. Variation in microbial biodiversity and the temperature sensitivities (Q10) of individual taxa may explain differences in the Q10 of soil respiration, a possibility not previously examined due to methodological limitations. Here, we show phylogenetic and taxonomic variation in the Q10 of growth (5-35 °C) among soil bacteria from four sites, one from each of Arctic, boreal, temperate, and tropical biomes. Differences in the temperature sensitivities of taxa and the taxonomic composition of communities determined community-assembled bacterial growth Q10, which was strongly predictive of soil respiration Q10 within and across biomes. Our results suggest community-assembled traits of microbial taxa may enable enhanced prediction of carbon cycling feedbacks to climate change in ecosystems across the globe.

Rare Earth Element in Bivalves' Soft Tissues of French Metropolitan Coasts: Spatial and Temporal Distribution.

Rare earth elements (REE) are becoming an environmental pollutant of emerging concern, linked to their use in various anthropic processes. Because REE bioconcentrate in marine organisms throughout their food webs, a better understanding of biogeochemical processes leading to REE concentrations found in coastal species is necessary. This study was designed to assess REEs concentrations in various common bivalves from the French coastline to identify possible geographic, taxonomic, or temporal variations of concentrations. Based on the French Mussel Watch program, three species of bivalves (oyster Crassostrea gigas and mussels Mytilus edulis and Mytilus galloprovincialis) were collected all along the French metropolitan coast and soft tissues were analyzed forREEconcentrations. Results have shown higher REE concentrations in bivalve soft tissues near estuaries without taxonomic nor national geographic differences. The highest levels have been observed in the Gironde estuary with total REE concentrations (∑REE) in oysters up to 10.94µgg-1 d.w. The REE distribution pattern in both mussel species described a particle-like (inverse V-shape) pattern, whereas C. gigas REE distribution pattern changes from a particle-like to a dissolved-like pattern with a heavy REE (HREE) enrichment. However, no environmental parameter could be linked to these pattern changes. Finally, neither Gd anomalies nor an evolution of REE concentrations over a 30-year period have been detected in bivalves' soft tissues.

Responses of cyanobacterial aggregate microbial communities to algal blooms

Freshwater lakes are threatened by harmful cyanobacterial blooms, whose basic unit is Cyanobacterial Aggregate (CA). CA-attached bacteria play a significant role through different blooming stages with substantial variation of their taxonomic structure. However, little is known about their functional variations and functional links with cyanobacteria due to the lack of reference genomes. In this longitudinal study, we collected 16 CA samples from Lake Taihu, one of China's largest freshwater lakes, from April 2015 to February 2016, and sequenced their V4 region of 16S rRNA genes, full metagenomes (MG), and metatranscriptomes (MT). The analysis of these data revealed the dynamics of microbial taxonomic and functional structure in CAs, influenced by both external environmental factors and internal metabolism. 55 OTUs, 456 genes, and 37 transcripts showed significantly differential abundance across the early, middle, and late blooming stages (ANOVA test, P < 0.05). Total nitrogen and total phosphorus were proved to be the most important environmental drivers of microbial taxonomic and functional variations in CAs (Mantel's r > 0.25, P < 0.05). We constructed 161 high-quality metagenome-assembled genomes (MAGs), out of which 22 were cyanobacterial strains with diverse energy pathways, transporters and prokaryotic defense systems. Based on these MAGs, we constructed a cyanobacteria-bacteria co-nitrogen-pathway and a cyanobacteria-bacteria co-phosphorus-pathway, by which we demonstrated how nitrogen and phosphorus influence the dynamics of the microbial structure to a certain extent by affecting these co-pathways. Overall, these results characterized the taxonomic, functional, and transcriptional variations of microbes in CAs through different blooming stages. Genome assembly and metabolic analysis of cyanobacteria and their attached bacteria suggested that the material exchange and signal transduction do, indeed, exist among them. Our understanding of the underlying molecular pathways for cyanobacterial blooms could lead to the control of blooms by interventional strategies to disrupt critical microbes' expression.

Taxonomic, seasonal and spatial variation in the amino acid profile of freshwater macroinvertebrates

Macroinvertebrates play a key role in aquatic food webs, with amino acids (AA) playing an important role in determining their nutritional value to higher consumers. This study aimed to determine whether AA profile varies among four macroinvertebrate taxa, spatially and seasonally (summer/winter). The freshwater prawn, Macrobrachium australiense; freshwater shrimp, Paratya australiensis; freshwater snail, Physa sp. and caddisfly, Triplectides sp. were collected from seven sites along the Murray–Darling Basin, Australia. Sampling was conducted during summer 2015 (October–December), winter 2016 (May–June) and summer 2016 (October–December). AA profiles were found to be significantly different among the four taxa, with the highest total amino acid content found in decapods (M. australiense and P. australiensis). Based on the total essential AA content from our study, decapods had higher nutritional value compared to Physa. Seasonal variations in AA profiles of decapods were observed, with an increased proportion of the non-essential amino acid glycine and decreased proportion of different essential AAs found in individuals collected during winter compared to summer. No seasonal variation in the AA profiles of Physa sp. or Triplectides sp. was shown. Spatial variation in the AA profile of macroinvertebrates was only recorded in P. australiense during winter 2016. These findings expand the current understanding of the AA profile of freshwater macroinvertebrates showing that AA profiles are taxa specific and vary seasonally and spatially depending on taxa.

Soil microbiome of different-aged stages of self-restoration of ecosystems on the mining heaps of limestone quarry (Elizavetino, Leningrad region)

Abstract Soil microbiome plays an important role in soil forming process as well as soil functioning. This is especially relevant for initial stages of soil regeneration after strong anthropogenic impact (i.e., in quarrying complexes). The study of soil microbiome in such areas is crucial for both understanding the forces driving soil formation and optimization of the reclamation techniques. This study is aimed to investigate the soil microbiome of different ages of soil formation on the heaps of limestone mines in conditions of boreal climate of North-West of Russia. Soil microbiome analysis was performed using high-throughput sequencing. Soils of the investigated sites were predominantly Rhendzic Leptosols. The initial set (2 years) of OTUs in the entire period of soil formation remains unchanged, accumulating more than 98% of the total microbiome in each time point. Analysis of beta-diversity (weighted and unweighted) demonstrated a clear differentiation of microbiomes of all time points, which suggests that underlying taxonomic structure variations can be attributed to variation of the minor taxa set composition. The most significant differences occur in Proteobacteria, Chloroflexi, Acidobacteria, and Actinobacteria, but majority of these phyla have different sets of OTUs demonstrating opposite trends. Generally time positively correlate with microbiome of carbonate soils in all cases of benchmark and newly formed soils is familiar because of the uniform zonal environmental conditions in geochemically specific landscape of Izhora upland.

Bacterial associations in the healthy human gut microbiome across populations

In a microbial community, associations between constituent members play an important role in determining the overall structure and function of the community. The human gut microbiome is believed to play an integral role in host health and disease. To understand the nature of bacterial associations at the species level in healthy human gut microbiomes, we analyzed previously published collections of whole-genome shotgun sequence data, totaling over 1.6 Tbp, generated from 606 fecal samples obtained from four different healthy human populations. Using a Random Forest Classifier, we identified 202 signature bacterial species that were prevalent in these populations and whose relative abundances could be used to accurately distinguish between the populations. Bacterial association networks were constructed with these signature species using an approach based on the graphical lasso. Network analysis revealed conserved bacterial associations across populations and a dominance of positive associations over negative associations, with this dominance being driven by associations between species that are closely related either taxonomically or functionally. Bacterial species that form network modules, and species that constitute hubs and bottlenecks, were also identified. Functional analysis using protein families suggests that much of the taxonomic variation across human populations does not foment substantial functional or structural differences.

Integrating morphology and metagenomics to understand taxonomic variability of Amphisorus (Foraminifera, Miliolida) from Western Australia and Indonesia.

Foraminifera are a group of mostly marine protists with high taxonomic diversity. Species identification is often complex, as both morphological and molecular approaches can be challenging due to a lack of unique characters and reference sequences. An integrative approach combining state of the art morphological and molecular tools is therefore promising. In this study, we analysed large benthic Foraminifera of the genus Amphisorus from Western Australia and Indonesia. Based on previous findings on high morphological variability observed in the Soritidae and the discontinuous distribution of Amphisorus along the coast of western Australia, we expected to find multiple morphologically and genetically unique Amphisorus types. In order to gain detailed insights into the diversity of Amphisorus, we applied micro CT scanning and shotgun metagenomic sequencing. We identified four distinct morphotypes of Amphisorus, two each in Australia and Indonesia, and showed that each morphotype is a distinct genotype. Furthermore, metagenomics revealed the presence of three dinoflagellate symbiont clades. The most common symbiont was Fugacium Fr5, and we could show that its genotypes were mostly specific to Amphisorus morphotypes. Finally, we assembled the microbial taxa associated with the two Western Australian morphotypes, and analysed their microbial community composition. Even though each Amphisorus morphotype harboured distinct bacterial communities, sampling location had a stronger influence on bacterial community composition, and we infer that the prokaryotic community is primarily shaped by the microhabitat rather than host identity. The integrated approach combining analyses of host morphology and genetics, dinoflagellate symbionts, and associated microbes leads to the conclusion that we identified distinct, yet undescribed taxa of Amphisorus. We argue that the combination of morphological and molecular methods provides unprecedented insights into the diversity of foraminifera, which paves the way for a deeper understanding of their biodiversity, and facilitates future taxonomic and ecological work.

Сезонные состояния фитообрастания берегозащитного гидротехнического сооружения (бухта Круглая, Черное море)

The species composition, ecological and taxonomic structure, quantitative characteristics and variability of phyto-fouling of the coastal hydrotechnical structure (Kruglaya Bay, Sevastopol) in spring, summer and autumn were studied. The taxonomic composition of fouling is represented by 45 species of 29 genera, 19 families, 12 orders, 4 classes of the divisions Chlorophyta, Ochrophyta and Rhodophyta. The taxonomic leaders of the community are Rhodophyta, Cladophorales, Ceramiales, Ulvaceae, Cladophoraceae, Ceramiaceae, Ulva, Cladophora, Ceramium, ecological — marine, leading, annual and oligosaprobic species. The fouling is dominated by species with a high and medium frequency of occurrence. Most of the proportions of taxa and ecological groups are most resistant. The taxonomic diversity of the entire phyto-growth, its Rhodophyta, constant flora nucleus, minor species and some ecogroups, the occurrence of species, phytomass, the degree of community discreteness and the qualitative composition of its production dominants and subdominants are subject to seasonal fluctuations. Each season, the variability of the species composition corresponds to the norm for biological objects, the degree of variability of the phytomass is higher.

Blood Bacterial 16S rRNA Gene Alterations in Women with Polycystic Ovary Syndrome

Background: Evidence proved the association between gut microbiome dysbiosis and polycystic ovary syndrome (PCOS) in metabolic defect, reproductive ability and hyperandrogenism. However, alterations of the blood microbiome of PCOS remained unknown. In this case-control study, we explored the blood microbiome profile of PCOS. Methods: Blood bacterial DNA of 24 PCOS patients and 24 healthy controls were obtained and investigated by 16S rRNA Gene Sequencing using the MiSeq technology. α and β diversity were used to analyze within-sample biodiversity and similarity of one group to another, respectively. Linear discriminant analysis effect size (LEfSe) was calculated to determine biomarkers between groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional prediction was performed at genera level. Findings: α diversity of blood microbiome revealed a significant decrease in women with PCOS, and a major separation in β diversity was observed between groups by weighted UniFac technique. PCOS group demonstrated a significant decrease in the proportion of sequences in Proteobacteria, Firmicutes and Bacteroidetes, and a significant richer abundance in Actinobacteria . Cladogram demonstrated microbiome differences of the two groups at various phylogenic levels. Meanwhile, LDA presented a significant decrease in Burkholderiaceae, Lachnospiraceae, Bacteroidaceae, Ruminococcaceae and S24-7, and a significant increase in Nocardioidaceae and Oxalobacteraceae in PCOS group. KEGG analysis exhibited 14 main pathways with significant differences between two groups at a genera level. Interpretation: Our findings demonstrated a significant lower α diversity, different β diversity and significant taxonomic variations in blood microbiome in PCOS patients compared with healthy controls. Funding: Funding: This work was supported by the Clinical Research Award of the First Affiliated Hospital of Xi’an Jiaotong University, China (XJTU1AF-2018-017, XJTU1AF-CRF-2019-002), the Natural Science Basic Research Program of Shaanxi (2018JM7073, 2017ZDJC-11), the Key Research and Development Program of Shaanxi (2017ZDXM-SF-068, 2019QYPY-138), the Innovation Capability Support Program of Shaanxi (2017XT-026, 2018XT-002), and the Medical Research Project of Xi’an Social Development Guidance Plan (2017117SF/YX011-3). Declaration of Interest: The authors declare no conflict of interest. Ethical Approval: This study was conducted in accordance with the ethical standards of the Declaration of Helsinki. The study was approved by the Institutional Review Board of the First Affiliated Hospital of Xi’an Jiao Tong University (IRB No. XJTU1AF2018LSK139) and was registered in Chinese Clinical Trial Registry (ChiCTR-TRC-1800020018).

Associations of Dietary Patterns With the Gut Microbiota in Older, Community-Dwelling Men

We investigated associations of dietary patterns with composition and diversity of the gut bacterial microbiota in 517 community-dwelling older men (mean age 84.3 y) who were participants in the Osteoporotic Fractures in Men (MrOS) study. Eligible participants provided a stool sample and completed a food frequency questionnaire at the MrOS Visit 4 in 2014-2016. Dietary patterns were derived by factor analysis. 16S rRNA target gene sequencing was performed. Linear regression and PERMANOVA considered variation in alpha and beta-diversity by dietary pattern, and metagenomeSeq assessed taxonomic variation by dietary pattern. In multivariable-adjusted models, greater adherence to the Western pattern was positively associated certain taxa, including Alistipes, Desulfovibrio, Dorea, Eubacterium, and Ruminococcus, while greater adherence to the prudent pattern was positively associated with certain taxa, including Faecalibacterium, Lachnospira, and Paraprevotella. Dietary patterns were not associated with measures of alpha diversity; beta diversity measures were significantly associated with both Western and prudent patterns.

Protein sequence comparison of human and non-human primate tooth proteomes

In the context of human evolution, the study of proteins may overcome the limitation of the high degradation of ancient DNA over time to provide biomolecular information useful for the phylogenetic reconstruction of hominid taxa. In this study, we used a shotgun proteomics approach to compare the tooth proteomes of extant human and non-human primates (gorilla, chimpanzee, orangutan and baboon) in order to search for a panel of peptides able to discriminate between taxa and further help reconstructing the evolutionary relationships of fossil primates. Among the 25 proteins shared by the five genera datasets, we found a combination of peptides with sequence variations allowing to differentiate the hominid taxa in the proteins AHSG, AMBN, APOA1, BGN, C9, COL11A2, COL22A1, COL3A1, DSPP, F2, LUM, OMD, PCOLCE and SERPINA1. The phylogenetic tree confirms the placement of the samples in the appropriate genus branches. Altogether, the results provide experimental evidence that a shotgun proteomics approach on dental tissue has the potential to detect taxonomic variation, which is promising for future investigations of uncharacterized and/or fossil hominid/hominin specimens. SignificanceA shotgun proteomics approach on human and non-human primate teeth allowed to identify peptides with taxonomic interest, highlighting the potential for future studies on hominid fossils.

Diversity of gut microbiomes in marine fishes is shaped by host-related factors.

Microorganisms in the gastrointestinal tract of animals play vital roles in food digestion, homeostasis and immune response regulation. Globally, there are 33,700 fish species, representing almost half of all vertebrate diversity and a wide range of physiologies, ecologies and life histories. To investigate gut microbiomes with high coverage, we performed 16S rRNA gene amplicon sequencing with 115 samples of 20 common marine fish species. The fish gut microbiome is a remarkably simple community with low microbial diversity (a maximum of 300 amplicon sequence variants only) and has up to 70% of unknown species in some fish species. The gut microbial community structure was significantly shaped by the combined influence of host‐associated factors, including the fish taxon (p < .001, R2 = 0.16, ω 2 = 0.04), feeding habit (p < .001, R2 = 0.06, ω 2 = 0.02) and trophic level (p < .01, R2 = 0.04, ω 2 = 0.01), although the influence was subtle with a small effect size. The core gut microbiomes of different feeding habits were also previously discovered in animal‐associated and corresponding habitat samples. Certain energy metabolism pathways were enriched in herbivore/omnivore and zooplanktivore/zoobenthivore fishes, whereas lipid metabolism and glycan metabolism were enriched in zoobenthivore/piscivore fishes. Moreover, substantial taxonomic variability was found between the gut microbiomes of fish and animals, indicated by their low degree of shared microbiota. The data and observations reported herein pave the way for further investigations on the co‐evolution of fish gut microbiomes and their hosts, the physiological functions of gut microorganisms and the development of probiotics for improving the nutrition and health of aquaculture fish species.

Integrative taxonomic and geographic variation analyses in Cyrtodactylus aequalis (Squamata: Gekkonidae) from southern Myanmar (Burma): one species, two different stories

The historical accuracy of building taxonomies is improved when they are based on phylogenetic inference (i.e., the resultant classifications are less apt to misrepresent evolutionary history). In fact, taxonomies inferred from statistically significant diagnostic morphological characters in the absence of phylogenetic considerations, can contain non-monophyletic lineages. This is especially true at the species level where small amounts of gene flow may not preclude the evolution of localized adaptions in different geographic areas while underpinning the paraphyletic nature of each population with respect to the other. We illustrate this point by examining genetic and morphological variation among three putatively allopatric populations of the granite-dwelling Bent-toed Gecko Cyrtodactylus aequalis from hilly regions in southeastern Myanmar. In the absence of molecular phylogenetic inference, a compelling argument for three morphologically diagnosable species could be marshaled. However, when basing the morphological analyses of geographic variation on a molecular phylogeny, there is a more compelling argument that only one species should be recognized. We are cognizant of the fact however, that when dealing with rare species or specimens for which no molecular data are possible, judicious morphological analyses are the only option—and the desired option given the current worldwide biodiversity crisis.

Do seasonal dynamics influence traits and composition of macrobenthic assemblages of Sundarbans Estuarine System, India?

The present study investigates the influence of seasonal dynamics on macrobenthic assemblages in four seasons of 2017–2018 from the central sector of Indian Sundarbans which is under the constant threat of climate change. Besides taxonomic analysis, a trait-based approach has also been applied to assess the change in their ecosystem functioning. The maximum species density (11675 ± 11883.31 ind. m−2) was observed during the spring season which declines considerably in the monsoon season (5875 ± 6224.08 ind. m−2). A total of 95 macrobenthic taxa were recorded from Sundarbans and they were dominated by families like Capitellidae, Donacidae, Magelonidae, Nereididae, Paraonidae and Spionidae. Overall, polychaetes have shown higher taxonomic and functional variation than other groups. Opportunistic polychaete species have shown a prominent compositional shift during post-monsoon seasons. Both the univariate and multivariate analyses have shown a significant relation between macrobenthic composition and environmental parameters. SIMPER has depicted that environmental parameters made the station 4 unique for several types of molluscs like Acteocina estriata, Stenothyra deltae and Meretrix meretrix during spring. Trait percentages also showed a seasonal succession pattern and among the trait categories, burrowers and deposit feeders dominated the estuary. A gradual increase in suspension feeders in spring has been noticed. RLQ approach with fourth-corner analysis was used to unravel the relationship between traits and environmental parameters. Hence, the present study provided a comprehensive idea about the species composition along with their trait categories from such a dynamic habitat. That could be the first stepping stone for a long term monitoring of macrobenthic assemblages from this largest delta on earth.

Extrapair paternity in two populations of the socially monogamous Thorn-tailed Rayadito Aphrastura spinicauda (Passeriformes: Furnariidae).

Studies on extrapair paternity (EPP) are key to understanding the ecological and evolutionary drivers of variation in avian mating strategies, but information is currently lacking for most tropical and subtropical taxa. We describe the occurrence of EPP in two populations of a South American socially monogamous bird, the Thorn‐tailed Rayadito, based on data from 266 broods and 895 offspring that were sampled during six breeding seasons in north‐central and southern Chile. In the northern population, 21% of the broods contained at least one extrapair young and 14% of all offspring were sired by an extrapair male, while in the southern population, we detected extrapair offspring (EPO) in 14% of the broods, and 6% of all offspring were EPO. Variation in the frequency of EPP could stem from population differences in the duration of the breeding season or the density of breeding individuals. Other factors such as differences in breeding synchrony and variation in food availability need to be evaluated. More reports on EPP rates are necessary to determine the patterns of taxonomic and geographic variation in mating strategies in Neotropical birds, and to better understand the differences in ecological dynamics between northern and southern hemisphere populations.

Foliar C/N stoichiometry in urban forest trees on a global scale

Foliar C/N stoichiometry is an indicator of geochemical cycling in forest ecosystems, but the driving changes for its response to urbanization at the wide scale is not clear. In this study, data on tree-leaf C and N stoichiometry were collected in papers from across 105 tree species from 82 genera and 46 families. The foliar C/N of urban forest trees varied among different climate zones and tree taxonomic variation and tended to be higher in trees of urban forests near the equator and in eastern regions, mainly driven by lowered foliar N concentration. Neither the foliar C concentration nor foliar C/N for trees of urban forests was statistically higher than those of rural forests. For variation by taxonomic classification, C4 species Amaranthus retroflexus and Chenopodium ambrosoides (Amaranthaceae) had lower foliar C/N than did other species and families. Myrsine guianensis (Primulaceae) and Myconia fallax (Asteraceae) had the highest foliar C/N. Therefore, urbanization has not caused a significant response in forest trees for foliar C/N. The change in foliar N concentration was globally the main force driving of the differences in foliar C/N for most tree species in urban forests. More work is needed on foliar C/N in trees at cities in polar regions and the Southern Hemisphere.

A sting affair: A global quantitative exploration of bee, wasp and ant hosts of velvet ants.

The vast majority of species of velvet ants (Hymenoptera: Aculeata: Mutillidae) are ectoparasitoids of immature stages of other aculeate Hymenoptera (bees, wasps and ants). Due to their cryptic, furtive behaviour at the host nesting sites, however, even basic information on their biology, like host use diversity, is still unknown for entire subfamilies, and the known information, scattered in over two centuries of published studies, is potentially hiding tendencies to host specialization across velvet ant lineages. In this review, based on 305 host associations spanning 132 species in 49 genera and 10 main lineages (tribes/subfamilies), we explored patterns of host use in velvet ants. Overall, 15 families and 29 subfamilies of Aculeata are listed as hosts of mutillids, with a strong predominance of Apoidea (bees and apoid wasps: 19 subfamilies and 82.3% of host records). A series of bipartite networks, multivariate analyses and calculations of different indices suggested possible patterns of specialization. Host taxonomic spectrum (number of subfamilies) of velvet ants was very variable and explained by variation in the number of host records. Instead, we found a great variation of network-based host specialization degree and host taxonomic distinctness that did not depend on the number of host records. Differences in host use patterns seemed apparent across mutillid tribes/subfamilies, among genera within several tribes/subfamilies, and to lesser extent within genera. Taxonomic host use variation seemed not dependent on phylogeny. Instead, it was likely driven by the exploitation of hosts with different ecological traits (nest type, larval diet and sociality). Thus, taxonomically more generalist lineages may use hosts that essentially share the same ecological profile. Interestingly, closely related mutillid lineages often show contrasting combinations of host ecological traits, particularly sociality and larval diet, with a more common preference for ground-nesting hosts across most lineages. This review may serve as a basis to test hypotheses for host use evolution in this fascinating family of parasitoids.