Unraveling subcellular functional traits: Adaptive insights into chloroplast ultrastructure in nonmodel species.

This essay discusses how the ultrastructural changes in chloroplasts, particularly the mechanisms of thylakoid membrane unstacking, help maintain the photosynthetic performance of photosystem II (PSII) under stress conditions. This phenomenon may facilitate the repair of damaged PSII by providing access to the repair machinery. It is argued that this PSII repair mechanism accelerates PSII recovery, optimizing photosynthetic processes in stressed plants. Although some studies demonstrate the relationship between thylakoid membrane unstacking in stress conditions, these studies were developed with model species under controlled conditions. Thus, this essay serves as a validation tool for these previous studies, because it demonstrates that the relationships between ultrastructural changes in chloroplasts and the functioning of PSII are essential acclimative strategies for nonmodel plants to survive the constant edaphoclimatic changes of natural environments. Understanding these subcellular dynamics can significantly inform biologists about the plastic potential of plants, especially in heterogeneous environments. An integrated approach in future studies is necessary, highlighting the importance of exploring plant functional traits at multiple scales, because subcellular characteristics have great potential to understand plant acclimatization.

Variation in bovine milk stability according to lactational stage and genetic group.

We address the hypothesis that at early and late lactation milk presents low ethanol stability due to high acidity and ionic calcium values. Our aim was to evaluate the functional traits of milk (milk ethanol stability: MES, acidity and ionic calcium: iCa) according to lactation stage in different genetic groups. Raw milk samples were collected from Jersey (n = 271), Holstein (n = 248) and Jersey × Holstein crossbred cows (n = 82), raised on five commercial farms located in the state of Paraná, Brazil. Milk composition, somatic cell count (SCC), milk urea nitrogen (MUN), MES, pH, acidity and iCa were determined. Days in milk (DIM) were categorized into four classes: 1-60, 61-150, 151-305 and over 305 DIM. Data were submitted to analysis of variance. Fixed and random effects were incorporated into the model, in a repeated measures in time arrangement using the mixed models methodology. Significant interactions between DIM class and genetic groups were detected. The comparison between each combination of genetic group and DIM class showed that at the beginning of lactation, Holsteins produced milk with higher MES than Jersey and crossbreds. At 105-305 DIM Holstein milk presented higher MES than Jersey, while beyond 305 DIM Holstein milk showed higher MES than crossbred cows. At the beginning of lactation acidity was higher in Holstein milk and crossbreds compared with Jersey, while acidity was lower in Holstein milk compared with Jersey and crossbreds in the other lactation stages. Ionic calcium was highest after lactation peak for Holstein, but did not vary between lactation stages for Jersey and crossbreds. Functional characteristics of bovine raw milk such as MES, iCa and acidity varied between lactation stages in a distinct manner according to genetic groups. Early and end lactation stages are challenging in terms of low stability, especially for Jersey and crossbreds.

Lithium ore tailings harm the vegetative development, photosynthetic activity, and nutrition of tree species.

Lithium (Li) exploitation promotes socioeconomic advances but may result in harmful environmental impacts. Thus, species selection for recovering environments degraded by Li mining is essential. We investigated the tolerance and early growth of four tree species to Li ore tailings (LOT), Enterolobium contortisiliquum and Handroanthus impetiginosus with wide geographic distribution and Hymenaea courbaril and H. stigonocarpa with restricted geographic distribution. The plants grew in LOT and soil for 255 days to evaluate photosynthesis, growth, and mineral nutrition. LOT negatively affected species growth, reducing the length of stems, roots, and biomass through structural and nutritional impoverishment. LOT favored the accumulation of Mg and decreased the absorption of K. The species presented a reduction in potential quantum efficiency and the chlorophyll index (b and total). E. contortisiliquum was the least tolerant species to LOT, and H. courbaril and H. stigonocarpa maintained their mass production in LOT, indicating greater tolerance to tailings. Furthermore, H. courbaril presented a translocation factor > 1 for Li and Mn, indicating the potential for phytoextraction of these metals. Our results offer first-time insights into the impacts of LOT on the early development of tree species with different geographic distribution ranges. This study may help in the tree species selection with a phytoremediation role, aiming at the recovery of areas affected by Li's mining activity.

The distribution of seaweed forms and foundational assumptions in seaweed biology.

Seaweeds are the most phylogenetically diverse group of multicellular organisms and rank foremost among marine keystone species. Due to their taxonomic diversity and functional importance, previous studies have classified seaweeds into functional groups based on qualitative or semi-quantitative traits, such as seaweed form, anatomy, and thickness. Despite the widespread use of seaweed functional groups from basic marine ecology to coastal monitoring, it is not known how accurate such morphology-based proposals are in grouping seaweeds by their form. To address this uncertainty at the foundations of seaweed biology, we surveyed and gathered all available data on seaweed forms using PRISMA protocols. We used the surface area to volume ratio (SA:V), a quantitative and universal measure of seaweed form, to assess the distribution and diversity of seaweed morphology across 99 species from three phyla. We show that seaweed surface area to volume ratio values span 3.64 orders of magnitude and follow a continuous and exponential distribution, without any significant gaps or clusters. We also tested current functional group schemes based on morphology and anatomy and showed that only 30% to 38% of their groups showed any significant pairwise differences in morphology. Our results challenge the basis of the current functional group approach in seaweed biology and suggest that a trait-based framework based on quantitative and continuous measures of seaweed form could provide a simpler and more accurate alternative to functionally assess seaweed ecology and physiology, as well as its implications for coastal ecosystem management.

Long-term trends in the functional structure of estuarine fish assemblages in a subtropical estuary and its relationships with local environmental variability, man-made changes, and climatic drivers.

Climate and anthropogenic impacts are prevalent in marine and estuarine ecosystems. Rapid environmental changes have altered biological diversity and the ecological services associated with ecosystems around the world. The consequences of these impacts on estuarine ecosystems are worrying, given that estuaries are essential habitats for maintaining the diversity of species functions, as they act as sources for larger ecosystems through the recruitment and replacement of species. Through long-term standardized monitoring (1996-2019), we evaluated the temporal variability of the functional structure of fish species in a subtropical estuary using Principal Component Analysis (PCA), and their relationship with environmental, climatic, and anthropogenic variables using Generalized Additive Models (GAM). We investigate the hypothesis that natural disturbances associated with El Niño events and anthropogenic ones related with changes in the estuary morphology will lead to a decrease in the diversity of functions of the fish assemblage in the Patos Lagoon Estuary in south Brazil (32°S). Our findings suggest an overall downward trend in the fish functional structure, especially in the second half (2006-2019) of the time series, which seems to be associated with a combination of abiotic effects (salinity and temperature), global climate phenomena (ENSO phases) and anthropogenic impacts (changes in the morphology of the estuarine mouth and its connection with the sea). These findings rise concern considering the current climate change scenario, where phenomena such as El Niño may become more frequent and intense. Therefore, the evidence from this study suggests that extreme natural climatic events in synergy with anthropogenic disturbances may imply biodiversity losses over time and, consequently, loss of ecosystem processes in a subtropical estuary.

Leaf functional traits and ecological niche of Fagus grandifolia and Oreomunnea mexicana in natural forests and plantings as a proxy of climate change.

PREMISE: Functional traits reflect species' responses to environmental variation and the breadth of their ecological niches. Fagus grandifolia and Oreomunnea mexicana have restricted distribution in upper montane cloud forests (1700-2000 m a.s.l.) in Mexico. These species were introduced into plantings at lower elevations (1200-1600 m a.s.l.) that have climates predicted for montane forests in 2050 and 2070. The aim was to relate morphological leaf traits to the ecological niche structure of each species. METHODS: Leaf functional traits (leaf area, specific leaf area [SLA], thickness, and toughness) were analyzed in forests and plantings. Atmospheric circulation models and representative concentration pathways (RCPs: 2.6, 4.5, 8.5) were used to assess future climate conditions. Trait-niche relationships were analyzed by measuring the Mahalanobis distance (MD) from the forests and the plantings to the ecological niche centroid (ENC). RESULTS: For both species, leaf area and SLA were higher and toughness lower in plantings at lower elevation relative to those in higher-elevation forests, and thickness was similar. Leaf traits varied with distance from sites to the ENC. Forests and plantings have different environmental locations regarding the ENC, but forests are closer (MD 0.34-0.58) than plantings (MD 0.50-0.70) for both species. CONCLUSIONS: Elevation as a proxy for expected future climate conditions influenced the functional traits of both species, and trait patterns related to the structure of their ecological niches were consistent. The use of distances to the ENC is a promising approach to explore variability in species' functional traits and phenotypic responses in optimal versus marginal environmental conditions.

Effect of intraspecific seed trait variation on the germination of eight tropical dry forest species.

Functional traits can have intraspecific and interspecific variations essential in the structure and dynamics of natural communities. These traits may have implications in the germination and seedling establishment phases in seeds. The objective of this study was to evaluate the effect of variations in mass, volume, and nutrient content (C, N, and P) on the germination of eight species representative of the tropical dry forest (TDF). Our results showed that seed size, both in terms of mass and volume, did not predict germination rates or percentages, nor were they related to nutrient content. In contrast, N content was the most important trait in the germination phase. Larger seeds did not germinate more or faster, but they could offer better resistance against desiccation, since they had higher C/N ratios in their tissues, a characteristic of orthodox seeds. The species A. guachapele, B. arborea, H. crepitans, and V. tortuosa presented a high biological potential in terms of their regeneration capacity, particularly, because the characteristics of their seeds, as well as the nutrient content, revealed consistent implications in their reproductive success, promoting high germination percentages in less time. In general, the results obtained in this study provide basic knowledge for future research, offering starting points for further exploration of species-specific adaptations and how they may be affected by the environment.

Shifts in plant functional groups along an aridity gradient in a tropical dry forest.

Increasing aridity associated with climate change may lead to the crossing of critical ecosystem thresholds in drylands, compromising ecosystem services for millions of people. In this context, finding tools to detect at early stages the effects of increasing aridity on ecosystems is extremely urgent to avoid irreversible damage. Here, we assess shifts in plant community functional structure along a spatial aridity gradient in tropical dryland (Brazilian Caatinga), to select the most appropriate plant functional groups as ecological indicators likely useful to predict temporal ecosystem trajectories in response to aridity. We identified seven plant functional groups based on 13 functional traits associated with plant establishment, defense, regeneration, and dispersal, whose relative abundances changed, linearly and non-linearly, with increasing aridity, showing either increasing or decreasing trends. Of particular importance is the increase in abundance of plants with high chemical defense and Crassulacean Acid Metabolism (CAM) photosynthetic pathway, with increasing aridity. We propose the use of these functional groups as early warning indicators to detect aridity impacts on these dryland ecosystems and shifts in ecosystem functioning. This information can also be used in the elaboration of mitigation and ecological restoration measures to prevent and revert current and future climate change impacts on tropical dry forests.

Interdecadal changes in ichthyofauna in a tropical bay with high anthropogenic influences: functional stability despite turnover predominance.

Functional characteristics of species are of great importance for understanding their roles in ecosystems and can be used to detect long-term chances in the environment. We evaluated temporal changes (1983-1985 and 2017-2019) in taxonomic and functional indices of the fish fauna in shallow areas of a tropical bay heavily impacted by anthropogenic activities in recent decades. The hypothesis that functional indices change over time as a result of environmental degradation was tested. Our results showed a significant decrease in species richness and abundance over time, and in functional richness, while others functional diversity indices (divergency, evenness, and originality) remained stable. Thirteen functional groups were detected, some of which contained only one species, raising concerns about the loss of ecosystem functions due to ongoing changes. We also observed an increase in beta diversity over time, which may be the result of a decrease in local richness without leading to regional extinctions. Turnover was the most important process in structuring the fish fauna at the evaluated time scale. The relative stability of the functional structure and the higher levels of turnover seem to be related to the dominance of functional groups, within which species replace each other according to their responses to environmental filters that select for specific functional traits. Incorporating functional diversity indices and beta diversity variations in the fish community helped to enhance the existing information about this coastal system by offering improved estimates of biological diversity through diverse approaches. The predominance of turnover identified in the preset study suggests a dynamic and fluctuating species composition within the habitat. In this sense, habitat preservation should prioritize the protection of diverse habitats to accommodate a broad spectrum of species.

The functional traits of host fish can act as good predictors for parasite composition in a neotropical floodplain.

Parasite diversity can be influenced by the interaction of environmental factors and host traits, but understanding which traits can be decisive for the establishment of the parasite may provide subsidies for a better understanding of the host-parasite relationship. In this study, we investigated whether functional traits, diet, and host phylogeny can predict the similarity of the endoparasite composition of a fish assemblage in a Brazilian floodplain. Of the three evaluated components, the host's diet was the factor that showed the greatest influence on the composition and similarity of endoparasites, demonstrating the highest value of the explanation. The functional traits and phylogeny, despite presenting significant values (unique effect and global effect), showed low explainability in the composition of the endoparasites. When analyzing the joint effects, all components showed significant influence. Hosts that live in the same environment that are phylogenetically related and have a similar ecology have a certain degree of homogeneity in their parasite assemblages and, because they are endoparasites (which are acquired trophically along the chain), diet is the main driver of parasite richness and similarity. Overall, host traits can be one of the main determinants of parasite composition, so studies that address the functional traits of the host provide a representation of local diversity and define the possible patterns of these parasite communities.

Geographic range size and species morphology determines the organization of sponge host-guest interaction networks across tropical coral reefs.

Sponges are widely spread organisms in the tropical reefs of the American Northwest-Atlantic Ocean, they structure ecosystems and provide services such as shelter, protection from predators, and food sources to a wide diversity of both vertebrates and invertebrates species. The high diversity of sponge-associated fauna can generate complex networks of species interactions over small and large spatial-temporal gradients. One way to start uncovering the organization of the sponge host-guest complex networks is to understand how the accumulated geographic area, the sponge morphology and, sponge taxonomy contributes to the connectivity of sponge species within such networks. This study is a meta-analysis based on previous sponge host-guest literature obtained in 65 scientific publications, yielding a total of 745 host-guest interactions between sponges and their associated fauna across the Caribbean Sea and the Gulf of Mexico. We analyzed the sponge species contribution to network organization in the Northwest Tropical Atlantic coral reefs by using the combination of seven complementary species-level descriptors and related this importance with three main traits, sponge-accumulated geographic area, functional sponge morphology, and sponges' taxonomy bias. In general, we observed that sponges with a widespread distribution and a higher accumulated geographic area had a greater network structural contribution. Similarly, we also found that Cup-like and Massive functional morphologies trend to be shapes with a greater contribution to the interaction network organization compared to the Erect and Crust-like morphos. Lastly, we did not detect a taxonomy bias between interaction network organization and sponges' orders. These results highlight the importance of a specific combination of sponge traits to promote the diversity of association between reef sponges and their guest species.

Wood density is related to aboveground biomass and productivity along a successional gradient in upper Andean tropical forests.

Wood density (WD) is a key functional trait related to ecological strategies and ecosystem carbon dynamics. Despite its importance, there is a considerable lack of information on WD in tropical Andean forests, particularly regarding its relationship with forest succession and ecosystem carbon cycling. Here, we quantified WD in 86 upper Andean tree and shrub species in central Colombia, with the aim of determining how WD changes with forest succession and how it is related to productivity. We hypothesized that WD will increase with succession because early successional forests will be colonized by acquisitive species, which typically have low WD, while the shaded understory of older forests should favor higher WD. We measured WD in 481 individuals from 27 shrub and 59 tree species, and quantified aboveground biomass (AGB), canopy height, net primary production (NPP) and species composition and abundance in 14, 400-m2, permanent plots. Mean WD was 0.513 ± 0.114 (g/cm3), with a range between 0.068 and 0.718 (g/cm3). Shrubs had, on average, higher WD (0.552 ± 0.095 g/cm3) than trees (0.488 ± 0.104 g/cm3). Community weighted mean WD (CWMwd) decreased with succession (measured as mean canopy height, AGB, and basal area); CWMwd also decreased with aboveground NPP and stem growth. In contrast, the percentage of NPP attributed to litter and the percent of shrubs in plots increased with CWMwd. Thus, our hypothesis was not supported because early successional forests had higher CWMwd than late successional forests. This was related to a high proportion of shrubs (with high WD) early in succession, which could be a consequence of: 1) a low seed availability of trees due to intense land use in the landscape and/or 2) harsh abiotic conditions early in succession that filter out trees. Forest with high CWMwd had a high %NPP attributed to litter because they were dominated by shrubs, which gain little biomass in their trunks. Our findings highlight the links between WD, succession and carbon cycling (biomass and productivity) in this biodiversity hotspot. Thus, WD is an important trait that can be used to understand upper Andean forest recovery and improve forest restoration and management practices.

Similar seed preferences explain trophic ecology of functionally distinct, but co-occurring and closely related harvester ants.

To understand how food resource use and partitioning by closely related species allows local coexistence, it is key to determine whether a species' diet reflects food availability or food preferences. Here, we analysed the diets, seed selection, and seed preferences of three closely related harvester ants: Messor barbarus, M. bouvieri, and M. capitatus. Sympatric within a Mediterranean shrubland, these species differ in foraging behaviour and worker polymorphism. For 2 years, we studied the ants' diets and seed selection patterns as well as the local availability of seeds. Additionally, we performed a seed-choice experiment using a paired comparison design, offering the ants seeds from eight native plant species. The three ant species had the same general diet, which was primarily granivorous. Although they all consumed a wide variety of seeds, they mostly selected seeds from a small subset of plant species. Despite their morphological and behavioural differences, the ants displayed similar seed preferences that were highly consistent with their diets and seed selection patterns. Our results support the idea that the trophic ecology of these three harvester ants is driven by similar seed preferences rather than by their morphological and behavioural differences. Seed diversity and abundance were high near the ants' nests, suggesting that seed availability is not limiting and could in fact favour local species coexistence.

Divergence in functional traits in seven species of neotropical palms of different forest strata.

Functional traits are morphological and physiological characteristics that determine growth, reproduction, and survival strategies. The leaf economics spectrum proposes two opposing life history strategies: species with an "acquisitive" strategy grow fast and exploit high-resource environments, while species with a "conservative" strategy emphasize survival and slow growth under low resource conditions. We analyzed intra and interspecific variation in nine functional traits related to biomass allocation and tissue quality in seven Neotropical palm species from understory and canopy strata. We expected that the level of resources of a stratum that a species typically exploits would determine the dominance of either the exploitative or conservative strategy, as well as degree of divergence in functional traits between species. If this is correct, then canopy species will show an acquisitive strategy emphasizing traits targeting a larger size, whereas understory species will show a conservative strategy with traits promoting efficient biomass allocation and survival in the shade. Two principal components (57.22% of the variation) separated palm species into: (a) canopy species whose traits were congruent with the acquisitive strategy and emphasized large size (i.e., diameter, height, carbon content, and leaf area), and (b) understory species whose traits were associated with efficient biomass allocation (i.e., dry mass fraction -DMF- and tissue density). As we unravel the variation in functional traits in palms, which make up a substantial proportion of the tropical flora, we gain a deeper understanding of how plants adapt to environmental gradients.

Functional diversity in an Andean subpáramo affected by wildfire in Colombia.

Recently, the Andean subpáramo in Colombia has experienced severe wildfires, but little is known about the functional composition of recovering or not after a wildfire. Therefore, we examined the functional community composition subpáramo affected by fire in 2016. We documented how functional traits changed 31 months after the disturbance and compared them with an unburned site. We sampled from one to two years after the fire every four months, then registered all recruits in 16 5 × 5m plots. New individuals were classified into strategy functional groups based on the traits of persistence and dispersal. The first group was stem type and regeneration mechanism (seedling and resprout), and the second was fruit type and dispersal mode. We investigated the degree to which functional diversity changes plant communities over time (woody and non-woody), and we compared it with an unburned site. The most relevant results showed that resprouts and seed regenerated increased post-fire time and significant differences between sampling periods. The anemochory is the most relevant dispersal mode that indicates the community capacity to colonize the new gaps opened by the fire rapidly. We discuss how wildfire appears to be a triggering factor for persistence and dispersal strategy groups in subpáramo burned given their characteristics of tolerance to stress. For this reason, a greater functional divergence between the ecosystems studied post-fire recovery has been related to higher levels of biodiversity at the landscape scale due to the high degree of endemism and significant differences in species composition between páramos.

Variation in fruit and seed dimensions is better explained by dispersal system than by leaf size in a tropical rainforest.

PREMISE: Variation in fruit and seed traits could originate from selection pressures exerted by frugivores or other ecological factors (adaptive hypotheses) and developmental constraints (by-product hypotheses) or chance. METHODS: We evaluated fruit and leaf traits for nearly 850 plant species from a rainforest in Tinigua Park, Colombia. Through a series of linear regressions controlling for the phylogenetic signal of the traits (minimum N = 542), we tested (1) whether the allometry between seed width and length depends on seed dispersal system (Mazer and Wheelwright's adaptive hypothesis of allometry for species dispersed in the guts of animals = endozoochory) and (2) whether fruit length is associated with leaf length (i.e., Herrera's by-product hypothesis derived from the assumption that both organs develop from homologous structures). RESULTS: We found a strong negative allometric association between seed width and length for seeds of endozoochorous species, as expected; but also, for anemochorous species. We found a positive relationship between fruit and leaf length, but this relationship was not evident for zoochorous species. Fruit size was highly correlated with seed size. CONCLUSIONS: The allometry between seed length and width varied among dispersal systems, supporting that fruit and seed morphology has been modified by interactions with frugivores and by the possibility to rotate for some wind dispersed species. We found some support for the hypothesis on developmental constraints because fruit and leaf size were positively correlated, but the predictive power of the relationship was low (10-15%).

PREMISA: La variación en los rasgos de frutos y semillas de las plantas podría tener su origen en las presiones de selección ejercidas por los frugívoros u otros factores ecológicos (hipótesis adaptativas), así como en limitaciones del desarrollo (hipótesis de subproductos) o en el azar. MÉTODOS: Nosotros evaluamos rasgos de frutos y hojas en cerca de 850 especies de plantas de un bosque húmedo tropical en el Parque Nacional Natural Tinigua, Colombia. Usando una serie de regresiones lineales que controlan por la señal filogenética de dichos rasgos (mínimo N = 542), nosotros probamos (1) si la alometría entre el ancho y largo de la semilla depende del sistema de dispersión de la semilla (i.e., hipótesis adaptativa de Mazer y Wheelwright; en la que se espera una alometría negativa para especies dispersadas por endozoocoria) y (2) si el largo del fruto está asociado con el largo de la hoja (i.e., la hipótesis del subproducto de Herrera derivada de la suposición de que ambos órganos se desarrollan a partir de estructuras homólogas). RESULTADOS: Nosotros encontramos una fuerte asociación alométrica negativa entre el ancho y el largo de las semillas para las semillas de las especies endozoócoras, como era de esperar; pero también, para las especies anemócoras. Nosotros también hallamos una relación positiva entre el largo del fruto y de la hoja, pero esta relación no fue evidente para las especies endozoócoras. Detectamos que el tamaño del fruto esta altamente correlacionado con el tamaño de la semilla. CONCLUSIONES: La alometría entre el largo y el ancho de la semilla varió entre sistemas de dispersión, lo que sugiere que la morfología de frutos y semillas ha sido moldeada por interacciones con frugívoros en el caso de las semillas endozoócoras y por la posibilidad de rotar para algunas especies dispersadas por el viento. Aunque el poder predictivo de la relación entre el tamaño del fruto y de la hoja fue bajo (10-15%), nosotros encontramos un apoyo moderado a la hipótesis sobre las limitaciones del desarrollo, ya que el tamaño del fruto y de la hoja estaban correlacionados positivamente.

Environmental heterogeneity of a tropical river-to-sea continuum and its relationship with structure and phytoplankton dynamics - Lençóis Maranhenses National Park.

ß-diversity and functional traits of phytoplankton indicators associated with environmental heterogeneity were investigated as environmental quality descriptors in coastal (CS), estuarine (ES), and limnetic (LS) sectors in a tropical river-to-sea ecosystem. Results showed that environmental heterogeneity was marked by spatial differences, contributing to biological heterogeneity. Sporadic and recurrent blooms were associated with environmental spatiotemporal variations and reflected a reduction in ES α-diversity. Salinity acted as an environmental filter that governed the structure and dynamics of the community. The spatial heterogeneity and high turnover of phytoplankton resulted in reliable bioindicators selection. Colonial, bloom-forming and harmful species were associated with highly suspended particulate matter (SPM) because these species are better adapted to these conditions. Species small in size were associated with high concentrations of silicate and chlorophyll-a in the ES because of the occurrence of diatom recurrent blooms. Most flagellates indicators genera have bloom-forming potential. Integrating morphofunctional with taxonomic approaches enabled detailed observations of environmental filters, supporting the selection of priority species and areas for introducing biodiversity monitoring programs and conservation in tropical ecosystems.

Macroecotoxicological approaches to emerging patterns of microplastic bioaccumulation in crabs from estuarine and marine environments.

Despite the increasing plastic discharge into the environment, few articles have dealt with the macroecological implications of microplastics (MPs) bioaccumulation on organisms. We performed a meta-analysis of MPs accumulation in true crabs and pseudocrabs worldwide and made use of macroecotoxicological approaches to know if: I) functional traits influence the bioaccumulation of MPs in the tissues of crabs; II) there is a latitudinal pattern of MPs bioaccumulation; III) there are tissues that can accumulate more MPs; IV) crabs can sort particles according to size, color, shape and type. Our results showed that functional traits influence the accumulation of MPs. Smaller crabs in size and weight and with shorter lifespans tended to exhibit more plastic particles. According to the environment, estuarine crabs from the intertidal and muddy substrates held more MPs. Also, burrowers exhibited significantly more particles in the tissues than omnivorous crabs. Besides, we recorded that crabs from low latitudes tended to exhibit more plastic particles, probably because of the mangroves' location that acts as traps for MPs. Non-human-consumed crabs accumulated significantly more MPs than human-consumed ones. Considering the tissues, gills were prone to accumulate more debris than the digestive tract, but without significant differences. Finally, colorless fibers of 1-5 mm of PA, PP and PET were the predominant characteristics of MPs, suggesting that crabs accumulated denser types but did not sort plastic according to color. These results indicate that functional traits might influence the accumulation of MPs and that there are coastal regions and geographical areas where crabs tend to accumulate more MPs. Analyzing MPs accumulation patterns with macroecological tools can generate information to identify the most affected species and define priorities for monitoring and implementing actions toward reducing plastic use globally.

Anatomical functional traits and hydraulic vulnerability of trees in different water conditions in southern Amazonia.

PREMISE: Understanding tree species' responses to drought is critical for predicting the future of tropical forests, especially in regions where the climate is changing rapidly. METHODS: We compared anatomical and functional traits of the dominant tree species of two tropical forests in southern Amazonia, one on deep, well-drained soils (cerradão [CD]) and one in a riparian environment (gallery forest [GF]), to examine potential anatomical indicators of resistance or vulnerability to drought. RESULTS: Leaves of CD species generally had a thicker cuticle, upper epidermis, and mesophyll than those of GF species, traits that are indicative of adaptation to water deficit. In the GF, the theoretical hydraulic conductivity of the stems was significantly higher, indicating lower investment in drought resistance. The anatomical functional traits of CD species indicate a greater potential for surviving water restriction compared to the GF. Even so, it is possible that CD species could also be affected by extreme climate changes due to the more water-limited environment. CONCLUSIONS: In addition to the marked anatomical and functional differences between these phytophysiognomies, tree diversity within each is associated with a large range of hydraulic morphofunctional niches. Our results suggest the strong potential for floristic and functional compositional shifts under continued climate change, especially in the GF.

Tropical shrubs living in an extreme environment show convergent ecological strategies but divergent ecophysiological strategies.

BACKGROUND AND AIMS: Trait-based frameworks assess plant survival strategies using different approaches. Some frameworks use functional traits to assign species to a priori defined ecological strategies. Others use functional traits as the central element of a species ecophysiological strategy. We compared these two approaches by asking: (1) what is the primary ecological strategy of three dominant co-occurring shrub species from inselbergs based on the CSR scheme, and (2) what main functional traits characterize the ecophysiological strategy of the species based on their use of carbon, water and light? METHODS: We conducted our study on a Colombian inselberg. In this extreme environment with multiple stressors (high temperatures and low resource availability), we expected all species to be stress tolerant (S in the CSR scheme) and have similar ecophysiological strategies. We measured 22 anatomical, morphological and physiological leaf traits. KEY RESULTS: The three species have convergent ecological strategies as measured by CSR (S, Acanthella sprucei; and S/CS, Mandevilla lancifolia and Tabebuia orinocensis) yet divergent resource-use strategies as measured by their functional traits. A. sprucei has the most conservative carbon use, risky water use and a shade-tolerant strategy. M. lancifolia has acquisitive carbon use, safe water use and a shade-tolerant strategy. T. orinocensis has intermediate carbon use, safe water use and a light-demanding strategy. Additionally, stomatal traits that are easy to measure are valuable to describe resource-use strategies because they are highly correlated with two physiological functions that are hard to measure: stomatal conductance and maximum photosynthesis per unit mass. CONCLUSIONS: The two approaches provide complementary information on species strategies. Plant species can co-occur in extreme environments, such as inselbergs, because they exhibit convergent primary ecological strategies but divergent ecophysiological strategies, allowing them to use limiting resources differently.