Tropical Species Research Articles

Gut microbes of a high-value marine fish, Snubnose Pompano (Trachinotus blochii) are resilient to therapeutic dosing of oxytetracycline.

Trachinotus blochii is a high-value tropical mariculture species. The present study evaluated the gut microbial impact of therapeutic exposure (80mg/day/kg biomass for 10 days) to oxytetracycline, the most common aquaculture antibiotic in T. blochii. The cultivable counts, α-diversity measures of taxonomic and functional metagenomics, microbial dysbiosis (MD) index, and microbial taxon abundances showed the resilience of gut microbiota at 16-26 days of treatment. A significant reduction in bacterial abundance, diversity measures, Firmicutes and Actinobacteria and an increase in γ-Proteobacteria was recorded on the 6th and 11th day of treatment. The increased metagenomic stress signatures, decreased beneficial bacterial abundances, decreased abundance of microbial pathways on energy metabolism, and MD index indicated short-term transient stress during the initial days of therapeutic withdrawal, warranting health management measures. Therapeutic exposure reduced the abundance of fish pathogens, including Vibrio spp., kanamycin and ampicillin-resistant bacteria. Strikingly, oxytetracycline treatment did not increase tetracycline-resistant bacterial counts and the predicted abundance of tetracycline resistance encoding genes in the gut, illustrating that therapeutic application would not pose a risk in the context of antimicrobial resistance in short term. Altogether, the present study provides a foundation for oxytetracycline treatment to develop suitable risk minimization tactics in sustainable aquaculture.

Study of the Pyrolysis of Ayous and Kambala Co-Products: Kinetic Modeling of the Two Species

A kinetic model based on the two-stage semi-global multi-reaction model of Grioui was developed using the TG and DTG curves for the by-products of Kambala and Ayous. These two tropical species are widely used in the Republic of Congo. The TG and DTG curves were obtained through thermogravimetry at five different heating rates (3, 7, 10, and 20 K/min) up to a final temperature of 800 °C under a nitrogen atmosphere. The thermal decomposition of both species started at similar temperatures, but the profiles exhibited notable differences. Kambala showed a distinct profile with two peaks at approximately 500 °C and 700 °C, which upon further investigation were found to correspond to ash decomposition. Additionally, the shoulder present in Ayous between 250 °C and 300 °C, attributed to hemicelluloses degradation, was absent in the DTG curves for Kambala. The kinetic model for Ayous was formulated in three steps, while the model for Kambala consisted of four steps. Both models accurately predicted the thermal degradation of the wood species, and the resulting kinetic parameters aligned with those reported in the literature.

Evaluation of the anticancer properties of the phytochemicals present in <em>Annona muricata</em>

Cancer is a complex disease characterized by the unrestrained proliferation and dissemination of abnormal cells. The issue continues to be a notable public health concern on a global scale, with millions of new cases and fatalities being reported annually. Despite significant advances in cancer treatment, it remains a major challenge due to the high cost and toxicity of current therapies. Phytochemicals naturally found in plants are crucial resources for developing novel drugs and potential cancer therapies. The clinical efficacy of these anti-cancer agents has been demonstrated against diverse neoplastic cell lines. Additional investigation in this field can result in improved cancer therapies. Among many other plants effective against cancer, this literature review explores the anti-cancer properties of Annona muricata, a plant commonly known as soursop, which is a tropical plant species native to Central and South America, the Caribbean, and West Africa known for its edible fruit which has some medicinal merits, but also some toxicological effects. Annona muricata has been traditionally used for medicinal purposes, including cancer treatment. Acetogenins, alkaloids, phenolic compounds, and other active compounds are only a few of the phytochemicals that this review cites as being present in A. muricata. The review also looks into A. muricata’s biological abilities to fight lung, liver, prostate, colon, pancreas, and breast cancers. The toxicity of A. muricata and possible adverse effects are also covered in the review. The review also looks at the usage of nanoparticles with A. muricata as a cancer treatment. Overall, this literature review provides valuable insights into the potential anti-cancer properties of A. muricata and its potential as a therapeutic agent in cancer treatment.

Effects of cold stress on the blood-brain barrier in Plectropomus leopardus

BackgroundThe leopard coral grouper (Plectropomus leopardus) is a commercially valuable tropical marine fish species known to be sensitive to low temperatures. A comprehensive understanding of the molecular mechanisms governing its response to acute cold stress is of great importance. However, there is a relative scarcity of fundamental research on low-temperature tolerance in the leopard coral grouper.MethodsIn this study, a cooling and rewarming experiment was conducted on 6-month-old leopard coral groupers. Within 24 h, we decreased the ambient temperature from 25 °C to 13 °C and subsequently allowed it to naturally return to 25 °C. During this process, a comprehensive investigation of serum hormone levels, enzyme activity, and brain transcriptome analysis was performed.ResultsP. leopardus displayed a noticeable adaptive response to the initial temperature decrease by temporarily reducing its life activities. Our transcriptome analysis revealed that the differentially expressed genes (DEGs) were primarily concentrated in crucial pathways including the blood-brain barrier (BBB), inflammatory response, and coagulation cascade. In situ hybridization of claudin 15a (cldn15a), a key gene for BBB maintaining, further confirmed that exposure to low temperatures led to the disruption of the blood-brain barrier and stimulated a pronounced inflammatory reaction within the brain. Upon rewarming, there was a recovery of BBB integrity accompanied by the persistence of inflammation within the brain tissue.ConclusionsOur study reveals the complex interactions between blood-brain barrier function, inflammation, and recovery in P. leopardus during short-term temperature drops and rewarming. These findings provide valuable insights into the physiological responses of this species under cold stress conditions.

Above and belowground functional trait response to biochar addition in seedlings of six tropical dry forest tree species

Above and belowground functional trait response to biochar addition in seedlings of six tropical dry forest tree species

Hyperoxia does not improve the acute upper thermal tolerance of a tropical marine fish (Lutjanus apodus).

Fish can experience hyperoxia in shallow environments due to photosynthetic activity and this has been suggested to provide them with a metabolic refuge during acute warming. However, this hypothesis has never been tested on a tropical marine species. Thus, we fitted 29°C-acclimated wild schoolmaster snapper (Lutjanus apodus; a species known to experience diel hyperoxia in mangrove creeks and coastal waters) with Transonic® flow probes and exposed them to an acute increase in temperature (at 1°Ch-1) in respirometers under normoxia and hyperoxia (150% air saturation), until their critical thermal maximum (CTmax). The CTmax of both groups was ∼39°C, and no differences in maximum cardiac function were recorded as the fish were warmed. However, temperature-induced factorial aerobic scope was significantly greater in fish tested under hyperoxia. These data suggest that hyperoxia will not protect coastal tropical fish species during marine heat waves, despite its effects on metabolic scope/capacity.

Temporal dynamics of the bacterial community structure and functions associated with marine sponges collected off Karah Island, Terengganu, Malaysia

The marine sponge microbiome has been investigated for decades, yet its temporal fluctuation/stability is poorly understood. This study aimed to describe the seasonal dynamics of the bacterial composition and predicted functions associated with two tropical marine sponge species (Aaptos suberitoides and Xestospongia testudinaria) collected off Karah Island, Malaysia, in the three seasons (dry season, pre- and post-monsoon season) using 16S rRNA gene amplicon sequencing and Functional Annotation of Prokaryotic Taxa (FAPROTAX). The bacterial taxonomic structures demonstrated divergences among A. suberitoides, X. testudinaria, and seawater, regardless of seasons. Chloroflexi, Proteobacteria, Cyanobacteria, Actinobacteriota, and Acidobacteriota comprised the core bacterial communities in two marine sponge species throughout the seasons, however, there were differences in bacterial composition between the two marine sponges. In addition, A. suberitoides was enriched with Dadabacteria, Spirochaetota, and Bdellovibrionota, whereas X. testudinaria abundantly harbored Poribacteria, PAUC34f, and Anck6. At the genus level, SAR202 clade and Candidatus Synechococcus spongiarum group dominated marine sponge samples throughout the year. Several genera, such as SAR202 clade, Candidatus Synechococcus spongiarum group, and Entotheonellaceae, were discovered only in marine sponge samples. Spirochaeta and Dadabacteriales displayed higher relative abundances in A. suberitoides, while Poribacteria and PAUC34f were more abundant in X. testudinaria. SAR202 clade was positively correlated with dissolved oxygen (DO), pH, phosphate, and ammonia in A. suberitoides. Likewise, Candidatus Synechococcus spongiarum group was negatively correlated with salinity and nitrate in X. testudinaria. Predicted functions by FAPROTAX annotated the phototrophic-related functions in both marine sponges, which might be attributed to a sponge-specific taxon Candidatus Synechococcus spongiarum group. The functions “predatory or exoparasitic” and “fermentation” were highly detected in A. suberitoides, which might be related to the bacterial genera Bdellovibrio and Spirochaeta, respectively. This study guides a deep understanding of the bacterial community structures associated with tropical marine sponges and their temporal behavior.

Canopy structure and herbage intake rate of three tropical forage grasses cultivated as pure or mixed stands

Context Using forage grass species with complementary growth and resource-use strategies to enhance forage plant diversity in pastures may be an alternative to traditional monocultures in tropical regions. Aims This study aimed to determine whether a mixture of three perennial tropical forage grasses (Andropogon gayanus cv. Planaltina, Panicum maximum cv. Massai, and Brachiaria brizantha cv. BRS Piatã) could be an alternative to enhance herbage intake rates relative to their respective monocultures. Methods The treatments corresponded to three perennial tropical forage grasses cultivated as monocultures and as a mixture composed of all three species. Defoliation management corresponded to a pre-cutting height of 35 cm and post-cutting height of 17.5 cm. Key results The botanical composition of the mixture was dynamic throughout the experimental period, with variations in the proportion of species across seasons. The upper half of the canopy predominantly comprised leaves for all treatments. The canopy structure of the mixture allowed for greater herbage intake rates than monocultures during winter/early spring. Andropogon gambagrass showed lower herbage intake rates than the other treatments. Conclusions The findings of this study indicate that it is possible to combine tropical forage grass species without compromising canopy structure and grazing animal responses, compared with single-species grass pastures. Implications The selection of forage species for mixed pastures should consider their phenological cycle, growth, and resource-use strategies to achieve temporal complementarity and provide an optimal grazing environment for animals throughout the year.

HSP90 Enhances Mitophagy to Improve the Resistance of Car-Diomyocytes to Heat Stress in Wenchang Chickens.

Heat shock protein 90 (HSP90) is recognized for its protective effects against heat stress damage; however, the specific functions and underlying molecular mechanisms of HSP90 in heat-stressed cardiomyocytes remain largely unexplored, particularly in tropical species. In our study, Wenchang chickens (WCCs) were classified into two groups: the heat stress survival (HSS) group and the heat stress death (HSD) group, based on their survival following exposure to heat stress. Heat stress resulted in significant cardiomyocyte damage, mitochondrial dysfunction, and apoptosis in the HSD group, while the damage was less pronounced in the HSS group. We further validated these findings in primary cardiomyocytes derived from Wenchang chickens (PCWs). Additionally, heat stress was found to upregulate Pink1/Parkin-mediated mitophagy, which was accompanied by an increase in HSP90 expression in both cardiomyocytes and PCWs. Our results demonstrated that HSP90 overexpression enhances PINK1/Parkin-mediated mitophagy, ultimately inhibiting apoptosis and oxidative stress in heat-stressed PCWs. However, the application of Geldanamycin (GA) reversed these effects. Notably, we discovered that HSP90 interacts with Beclin-1 through mitochondrial translocation and directly regulates mitophagy levels in PCWs. In summary, we have elucidated a novel role for HSP90 and mitophagy in regulating heat stress-induced acute cardiomyocyte injury.

Too many spines, or an integrative foundation of the Echiniscus spinulosus morphogroup (Heterotardigrada: Echiniscidae)

AbstractHistorical taxonomic bias has started to be effectively removed in tardigrade taxonomy in the last two decades by the application of modern statistical, genetic and morphological tools. Many of the “old” tardigrade taxa have been redefined, and their succinct original diagnoses—refined, finally resulting in making them properly identifiable and less enigmatic. At the same time, many of the “old” species were synonymised and perished in the taxonomic wastebasket. Herein, we address the species distinction between Echiniscus spiniger Richters, 1904 and Echiniscus spinulosus (Doyère, 1840) by means of integrative analyses of 11 European populations collected in the Mediterranean, the Carpathians and the Baltic Sea islands of Öland and Gotland, covering the southern distribution zone and northernmost known localities within trustworthy geographic range of these species. We disclose that, as previously hypothesised, E. spiniger is conspecific with E. spinulosus, and synonymised accordingly. We deliver morphological evidence supporting the triphyly of the morphogroup, with all tropical and subtropical species truly lacking intracuticular pillars, whereas the Palaearctic lineage corresponding solely to E. spinulosus and Afrotropical lineage represented by E. belloporus Gąsiorek and Kristensen, 2018—occasionally exhibiting pillars in some specimens. A synopsis and key to all representatives of the E. spinulosus morphogroup are provided, pinpointing to some problems that must be taken into consideration during identification and solved in the future.

Effect of three pretreatments on germination and nursery growth of Erythrophleum ivorense a. Chev, Aa little-known timber species in Cote d'Ivoire

Erythrophleum ivorense (A. chev), commonly known as Tali, is a tropical timber species found in savannah and forest zones. It is used for a wide range of purposes. The aim of this study is to contribute to the improvement of seed germination and seedling growth of Erythrophleum ivorense in nurseries by developing effective pre-treatment methods that will lead to a rapid lifting of seed dormancy. To achieve this, four pre-treatments were applied to Erythrophleum ivorense seeds. These were the control with no pretreatment (T0), soaking the seeds in ordinary water for 48 h (T1) and soaking the seeds in 95% dilute sulfuric acid for 20 min (T2). Germination and growth data were taken and statistically tested. The best germination rate was recorded when the seeds were soaked in 95% sulfuric acid for 20 min, with a value of 86%, while the lowest rate was obtained when the seeds were soaked in ordinary water for 48 h (10%). The analyses also showed that the different pre-treatments had a significant effect on growth parameters. Growth in height, diameter and number of leaves was greater in seedlings whose seeds had been treated with 95% dilute sulfuric acid for 20 min, with respective values of (19.19±4.13b; 14.55±0.43b; 6.51±1.75b). Pre-treatment with 95% dilute sulfuric acid for 20 min could be proposed for nursery propagation of Erythrophleum ivorense for long-term conservation. However, it should be used with precaution.

In thermotolerance tests of tropical tree leaves, the chlorophyll fluorescence parameter Fv/Fm measured soon after heat exposure is not a reliable predictor of tissue necrosis.

Tropical rainforests are hot and may be particularly sensitive to ongoing anthropogenic global warming. This has led to increased interest in the thermotolerance of tropical trees. Thermotolerance of leaves of two tropical tree species, Terminalia catappa and Coccoloba uvifera, was determined by exposing leaf samples to 15-min heat treatments, followed by measurements of potential photosystem II quantum yield (dark-adapted value of variable/maximum chlorophyll a fluorescence, Fv/Fm) after 24 h and 14 days, and visible damage (necrosis) after 14 days. T50 (24 h), the temperature at which Fv/Fm declined by 50% 24 h after heat treatments, was associated with only ~10% leaf area damage in C. uvifera and no damage in T. catappa. In neither species was leaf necrosis observed at T5 (24 h), the temperature at which Fv/Fm declined by 5%. In both species, temperatures significantly higher than T50 (24 h) were required for 50% leaf area necrosis to occur. T50 (14 days) was a better proxy of visible leaf damage than T50 (24 h). The relationship between heat-induced Fv/Fm decline and tissue necrosis varies among species. In species surveys of leaf thermal tolerances, calibration of the Fv/Fm assay against the necrosis test is recommended for each species under investigation. Fv/Fm measurements soon after heat exposure do not reliably predict irreversible heat damage and may thus not be suitable to model and predict the thermostability of tropical forest trees.

Sapindaceae fruits: A comprehensive overview on phytochemicals, nutraceuticals and health benefits application

The article delves into the intricate realm of the Sapindaceae family, shedding light on the many phytomedicinal advantages that these fruits offer. This family boasts an array of economically significant fruits, including Litchi (Litchi chinensis), Rambutan (Nephelium lappaceum), Longan (Dimocarpus longan), Guarana (Paullinia cupana), Ackee (Blighia sapida) and Soapberry (Sapindus saponaria), each of which has its own set of medicinal characteristics. The Sapindaceae family, also known as the soapberry family, comprises numerous tropical and subtropical plant species known for their phytochemical properties and potential health benefits. Despite the well-known medicinal properties of Sapindaceae fruits, there is a lack of a comprehensive compilation that combines knowledge about their important components, nutritional value, traditional value and medicinal properties. This review aims to address this gap by providing assessments of the medicinal potential of Sapindaceae fruits and their prospects as food products. The study focuses on the chemicals, nutrients and medicinal properties of Sapindaceae fruits, excluding studies lacking therapeutic relevance. Findings show that Sapindaceae fruits contain bioactive compounds such as saponins, flavonoids and phenolic acids, which are antioxidants, anti-inflammatory, anti-cancer, anti-viral, anti-obesity and anti-diabetic. In addition, these fruits are rich in essential nutrients, including vitamins, minerals and dietary fiber, which supports their use as functional foods and vitamins. The review suggests future research on sustainable uptake and development of nutrients from Sapindaceae, which could increase their use in healthcare and potentially lead to the development of cost-effective pharmaceutical products for consumers and the agricultural sector.

Decadal changes in value of dried sea cucumbers (bêche-de-mer) in Hong Kong markets

Sea cucumbers in their dried form, bêche-de-mer or trepang, have been in high demand for four decades, causing relentless exploitation pressure on fisheries. Key aspects unknown are the temporal trends in prices of different species and potential impacts of external factors. We recorded prices and measured dried specimens of 20 sea cucumber species in 38 retail shops in Hong Kong in 2022 and compared prices obtained for 15 of these species in the same market in 2011 and/or 2016. Two temperate-water species (Apostichopus japonicus and A. nigripunctatus) were the most valuable but declined slightly in price over the 11-year period. All of the tropical species rose in price. Holothuria lessoni emerged as the most valuable tropical species (average: USD$503) and was scarce in the marketplace. Two Indo-Pacific species recently enlisted on CITES Appendix II, H. nobilis and H. whitmaei, were also seldom found in the marketplace and their value had risen greater than inflationary expectations. Also rare in the marketplace was the high-valued Isostichopus badionotus. Larger specimens of A. japonicus and H. scabra demanded exponentially higher prices than small individuals, with implications for fisheries and aquaculture. Significant aquaculture production for both of these species does not appear to have greatly quelled market demand. Despite potential disruptions during the COVID pandemic, overall demand for bêche-de-mer remains strong. The increases in retail prices for certain over-exploited species, potentially exacerbated by trade restrictions from CITES listings, beckons careful resource monitoring by fishery managers and continuing opportunities for aquaculture programs.

Coastal fisheries adaptations to increasing climate change exposure in Japan

Abstract Climate change‐driven ocean warming is altering the geographic ranges of species, leading to a poleward shift of tropical species into temperate regions (tropicalisation). This threatens the native marine community assemblages by changing the availability of traditional marine resources, thus impacting the livelihood and well‐being of coastal fisheries. Fishers' individual responses are expected to transition from remaining to coping and from adapting to transforming as climate change exposure increases, yet empirical evidence is limited. The existing strong thermal gradient along the western coast of Shikoku (Japan), an area experiencing tropicalisation, provides a unique opportunity to analyse how regions facing different climate change exposure levels (North: low, Centre: medium and South: high) affect fishers' responses in relation to their adaptive capacity. Data from 92 face‐to‐face interviews with small‐scale fishers from 25 locations revealed that the largest proportion of coping and adaptive responses is in the Central region, while remaining responses predominated in the Northern and Southern regions. Results from a multinomial logistic model indicate that the exposure level is a good predictor for coping and adaptive responses but not for transformative ones. This possibly reflects the fact that these fishers might have exited coastal fisheries prior to our study as suggested by the strong fisher population decrease in the communities from the Southern region over the last three decades. This study provides novel empirical evidence on how climate change exposure influences fishers' responses to past and current climate change impacts, highlighting the intricate interplay between exposure level and individual adaptive capacity. Read the free Plain Language Summary for this article on the Journal blog.

Genetic Diversity and Population Structure of Cacao (Theobroma cacao L.) Germplasm from Sierra Leone and Togo Based on KASP–SNP Genotyping

Cacao (Theobroma cacao L.) is a tropical tree species belonging to the Malvaceae, which originated in the lowland rainforests of the Amazon. It is a major agricultural commodity, which contributes towards the Gross Domestic Product of West African countries, where it accounts for about 70% of the world’s production. Understanding the genetic diversity of genetic resources in a country, especially for an introduced crop such as cacao, is crucial to their management and effective utilization. However, very little is known about the genetic structure of the cacao germplasm from Sierra Leone and Togo based on molecular information. We assembled cacao germplasm accessions (235 from Sierra Leone and 141 from Togo) from different seed gardens and farmers’ fields across the cacao-producing states/regions of these countries for genetic diversity and population structure studies based on single nucleotide polymorphism (SNP) markers using 20 highly informative and reproducible KASP–SNPs markers. Genetic diversity among these accessions was assessed with three complementary clustering methods, including model-based population structure, discriminant analysis of principal components (DAPC), and phylogenetic trees. STRUCTURE and DAPC exhibited some consistency in the allocation of accessions into subpopulations or groups, although some discrepancies in their groupings were noted. Hierarchical clustering analysis grouped all the individuals into two major groups, as well as several sub-clusters. We also conducted a network analysis to elucidate genetic relationships among cacao accessions from Sierra Leone and Togo. Analysis of molecular variance (AMOVA) revealed high genetic diversity (86%) within accessions. A high rate of mislabeling/duplicate genotype names was revealed in both countries, which may be attributed to errors from the sources of introduction, labeling errors, and lost labels. This preliminary study demonstrates the use of KASP–SNPs for fingerprinting that can help identify duplicate/mislabeled accessions and provide strong evidence for improving accuracy and efficiency in cacao germplasm management as well as the distribution of correct materials to farmers.

Clustering of tropical species through multivariate analysis of the bonding properties of edge-glued panels (EGP)

Tropical woods have high added value, and the use of waste for panel production is an initiative to add more value to this material, typically consisting of various species. The use of raw materials from tropical solid wood waste in the Amazon region contributes to the reduction of carbon emissions associated with the burning of this material. In this context, this study aimed to cluster species based on the bonding properties of Amazonian woods by applying multivariate analysis. The apparent density 12% and strength of finger joint and edge-glued joints of Cedrela odorata, Enterolobium schomburgkii, Erisma uncinatum and Qualea paraensis was evaluated which were joined in homogeneous and hybrid configurations with the adhesives PVA and EPI, as spreading rate of 180 g/m2. The treatments were compared by multivariate analysis of variance and discriminant analysis. The discrimination of species and combinations based on wood density (low, medium, and high) revealed that this is the most important characteristic for grouping different species that make up tropical hardwood waste for the production of EGP panels. In practice, the separation of species into groups according to wood densities can contribute to a better definition of the indications for use of edge glued panels of each density class, and assertive targeting for applications according to the strength ranges required. In the static bending, parallel tensile and shear tests all species and their combinations met the minimum requirements normative, indicating the approval of species and combinations studied for the production of EGP panels.

Integrating datasets from herbarium specimens and images to treat a Neotropical myrtle species complex.

Herbaria are the most important source of information for plant taxonomic work. Resources and technologies available today, such as digitised collections and herbarium DNA sequencing, can help accelerate taxonomic decisions in challenging plant groups. Here we employ an integrative methodology relying exclusively on herbarium specimens to investigate species boundaries in the Neotropical Myrcia neoobscura complex (Myrtaceae). We collected morphometric data from high-resolution images of herbarium sheets and analysed it using hierarchical clustering. We posteriorly tested the obtained morpho-groups with phylogenomics using the Angiosperms353 probe kit. We also gathered phenological and geographic information from specimen labels and built phenological histograms and ecological niche models to investigate ecological differences amongst taxa. Current circumscriptions of Myrcia arenaria, Myrcia neoglabra and Myrcia neoregeliana are confirmed in this study. Conversely, the four pieces of evidence together support Calyptranthes langsdorffii var. grandiflora, Marlierea regeliana var. parviflora and Marlierea warmingiana as separate from Myrcia marliereana, Myrcia neoriedeliana and Myrcia neoobscura, respectively, contrary to arrangements proposed by previous authors. Integrated analyses also support separation between Myrcia excoriata and two similar, undescribed taxa. Our data reveal the need for major changes in the systematics of the group, with recognition of 12 species. The successful delivery of our study aims was possible due to obtaining robust, high-quality data from museum specimens. We emphasise the importance of maintaining botanical collections physically and digitally available for taxonomic work and advocate their use to accelerate holistic taxonomic solutions of tropical species complexes. This is urgent, given the paucity of funds for fieldwork and unprecedented rates of habitat loss in the tropics.

Shifting trait coordination along a soil‐moisture‐nutrient gradient in tropical forests

Abstract Soil nutrients and water availability are strong drivers of tropical tree species distribution across scales. However, the physiological mechanisms underlying environmental filtering along these gradients remain incompletely understood. Previous studies mostly focused on univariate variation in structural traits, but a more integrative approach combining multiple physiological traits is needed to fully portray species functional strategies. We measured nine leaf functional traits related to trees' resource capture and hydraulic strategies for 552 individuals belonging to 21 tropical tree species across an environmental gradient in Amazonian forests. Our sampling included generalist and specialist species from terra firme (TF) and seasonally flooded (SF) forests. We tested the influence of the topographic wetness index, a proxy for soil moisture and nutrient gradients, on each trait separately and on the trait integration through multivariate indices computed from the eigenvalues of a principal component analysis on the traits of the species. Finally, we evaluated intraspecific trait variability (ITV) for generalists and specialists by calculating the coefficient of variation for each trait. Results showed that (1) the environment had a greater influence on trait syndromes than single trait variation. Moreover, (2) SF specialist species expressed a stronger leaf trait coordination than TF specialist species. Furthermore, (3) the ability of generalist species to occupy a broader range of environments was not reflected by a larger ITV than specialist species but by the capacity to change trait coordination across environments. Our work highlights the need to investigate functional strategies as multidimensional syndromes in physiological trait space to fully understand and predict species distribution along environmental gradients. Read the free Plain Language Summary for this article on the Journal blog.

Evidence for a Miocene pulse of diversification of the tropical American clade of the Brazil nut family (Lecythidaceae)

ABSTRACT The tropical American species of the Brazil nut family, Lecythidaceae, are abundant in the tree flora, with some economically important species. Yet, the phylogenetic relationships and pace of diversification within this family are understudied. Here, we used shotgun sequencing data for 86 of the 228 currently accepted species in the exclusively tropical American subfamily Lecythidoideae in a phylogenomic context. For each sampled species, we built the full plastid DNA sequence, and also extracted nuclear DNA for 571 regions using the new bioinformatics pipeline REFMAKER, which we used to produce a time-calibrated phylogenetic hypothesis. Our analysis shows that phylogenetic inference from plastid and nuclear DNA alignments resulted in different topologies. The nuclear DNA topology strongly suggests that genus Lecythis should be split into at least four genera. Samples of the genus Eschweilera formed a monophyletic group, with the exception of one sampled species (Eschweilera amazoniciformis S.A.Mori). The Bertholletia clade, which contains the majority of the Lecythidoideae species, and all Lecythis and Eschweilera species, started diversifying around 27.5 Ma, with an accelerated rate of diversification starting in the middle Miocene (c. 12 Ma). The clade sister to Bertholletia (including Corythophora, Eschweilera, and Corrugata, Chartacea and Poiteaui clades) includes at least 124 species and it has diversified less than 10 Ma. This time frame of diversification coincides with major changes in tropical American landscapes and climate associated with the Andean uplift.