Unlocking fruit dimensions: Quantification of functional traits driving plant–frugivore interactions

Trait matching, the phenomenon where ecological interactions are mediated by compatibility, constitutes a cornerstone of frugivore-fruit interaction network dynamics. Given that biotic interactions have long been hypothesized to be more intense or specialized in the tropics, the intensity of trait matching patterns might likewise exhibit a latitudinal gradient in frugivory networks, yet this remains unverified. Here, we established a dataset encompassing 200 avian frugivorous networks to explore the relationships between the body mass and gape size of frugivore birds and fruit traits (size and color) on a global scale. Our results indicated that frugivore traits were closely associated with fruit traits regardless of the climate, demonstrating a biotic match between the two counterparts. We detected a significant decrease in frugivore-fruit trait matching toward the tropics, which challenges prevailing concepts considering the high biodiversity therein. Our structural equation modeling clarified that latitude and temperature exert an indirect influence on trait matching by affecting gape size and fruit traits. These discoveries emphasize the impact of the latitudinal gradient of temperature in driving the observed patterns of trait matching. The weaker trait matching in tropical regions may suggest more complex interactions therein and also highlights the potential for altered network structures amid global climate change.

Despite their claimed low intraspecific variability, plant reproductive traits are less frequently used in functional ecology. Here we focused on underrepresented plant organs, i.e. flowers and fruits, by comparing their traits with well-established leaf traits. We evaluated 16 functional traits (six floral, six fruit, and four leaf traits) in a randomly selected group of woody species under comparable environmental conditions. We aimed to assess interspecific and intraspecimen variability and explore the potential of the proposed flower and fruit traits for ecological research. Traits related to the dry mass of flowers and fruits exhibited the highest interspecific variability, while carbon content traits in flowers and leaves had the lowest. At a specimen level, specific leaf area revealed the highest variation. Carbon content traits for all organs demonstrated the least intraspecimen variability, with flower carbon content being the least variable. Our study revealed connections between the newly proposed traits and widely recognized functional traits, uncovering intriguing links between the established traits and the floral and fruit traits upon which we focused. This complements the already well-recognized variability in plant form and function with additional insights into reproductive processes.

Loss of animal species and functional diversity can degrade ecosystem functions and services in plant–animal mutualistic networks, but their relative effects have rarely been previously examined in natural communities. Contrary to previously published theoretical results, under natural conditions, changes in pollinator functional niches caused by species and functional diversity losses are dynamic and often unpredictable. The lack of studies on natural networks limits our ability to predict future effects of decreasing pollinator diversity on wild and cultivated plants. We quantitatively evaluated the relative effects of pollinator species and functional diversity loss on plant–pollinator trait matching and pollination success across 40 spatiotemporally variable coastal networks. We found that low pollinator functional diversity (low abundance of long‐tongued pollinators) reduced community‐level plant functional specialization and trait matching between flowers and pollinators by reducing functional floral‐niche partitioning among pollinators. In contrast, pollinator species diversity did not influence community‐level trait matching. Furthermore, decreasing community‐level trait matching had a negative effect on community‐level plant pollination success, regardless of flower morphology. The present study demonstrated that pollinator functional diversity loss, rather than species diversity loss, was the main factor contributing to pollination functional loss in the plant–pollinator networks studied. We also demonstrated the importance of assessing functional aspects of plant–pollinator networks to evaluate community‐level pollination functional loss under global pollinator decline. Read the free Plain Language Summary for this article on the Journal blog.

Defaunation of large-bodied animals threatens essential ecosystem functions, such as seed dispersal. However, the consequences of this human-induced downsizing of animal communities for plant-frugivore trait matching-the alignment between frugivory-related plant traits (e.g., fruit size) and frugivore traits (e.g., body mass)-remain unquantified at macroecological scales. Here, we examine how human disturbance and environmental conditions influence trait matching in tropical plant-frugivore networks. We compiled fruit size data for 1927 plant species from primary sources, along with body mass and dietary information for 1120 frugivorous animal species (birds, mammals and reptiles), and integrated these with 12,708 plant-frugivore interactions recorded across 102 networks. Using fourth-corner analyses and structural equation models (SEMs), we quantified how human disturbance and environmental conditions directly and indirectly affected trait matching strength (fruit-size-to-body-mass correlation) across networks. SEMs revealed that human disturbance weakened trait matching by reducing the range of frugivore body masses within networks, whereas wet and productive environments promoted a higher proportion of fruit in frugivore diets, leading to stronger trait matching. Our results demonstrate that human disturbance weakens plant-frugivore trait matching through the downsizing of animal communities, thereby providing a quantitative assessment of the decoupling of coevolved relationships between fruiting plants and their animal seed dispersers.

To evaluate gene effects and heritability of fruit and flower characters in melon, three experiments were performed. In the first experiment, 48 genotypes of different melon groups were planted to choose the monoecious melon. To investigate the sex modification regarding fruit traits, seven parents, including a monoecious type and andromonoecious types, crossed in a full diallel scheme to obtain all possible combinations. Evaluation amongst all genotypes revealed one Cantaloupensis and all Flexuosus genotypes with monoecious flowers. Floral and fruit characters of F1 hybrids obtained from the diallel cross, were recorded. All hybrids that have been crossed with the monoecious parent revealed the monosexual progenies. Most of the floral characters with high GCA/SCA values remarked the additive gene effect. There were also cytoplasmic effects on flower and fruit traits. The significant GCA /SCA estimates observed for fruit traits such as yield, fruit length, fruit length to width, flesh thickness referred to the importance of additive gene effects. It could be demonstrated that classic hybridization holds great potential in controlling flowering habit and yield‐related fruit traits.

Data from functional trait databases have been increasingly used to address questions related to plant diversity and trait-environment relationships. However, such databases provide intraspecific data that combine individual records obtained from distinct populations at different sites and, hence, environmental conditions. This prevents distinguishing sources of variation (e.g., genetic-based variation vs. phenotypic plasticity), a necessary condition to test for adaptive processes and other determinants of plant phenotypic diversity. Consequently, individual traits measured under common growing conditions and encompassing within-species variation across the occupied geographic range have the potential to leverage trait databases with valuable data for functional and evolutionary ecology. Here, we recorded 16 functional traits and leaf hyperspectral reflectance (NIRS) data for 721 widely distributed Arabidopsis thaliana natural accessions grown in a common garden experiment. These data records, together with meteorological variables obtained during the experiment, were assembled to create the AraDiv dataset. AraDiv is a comprehensive dataset of A. thaliana’s intraspecific variability that can be explored to address questions at the interface of genetics and ecology.

Context Seagrasses form an important habitat that provides diverse ecosystem services essential for both the environment and people. In tropical Queensland, Australia, these meadows hold significant economic and cultural value, serving as nurseries for marine species and sustaining dugongs and green turtles. The biomass and size of tropical seagrass meadows in Queensland varies considerably and are influenced by various factors, both biotic and abiotic. Aims Functional trait-based approaches can improve the estimation of seagrass-meadow resilience and services provision by describing the relationship between environment and individual performance. To support these approaches, we provide a seagrass functional-trait database focusing on resilience and function provision for tropical Queensland. Methods We employed a combination of literature reviews, database searches, botanical information, and structured expert elicitation to target 17 functional traits across 13 seagrass species in tropical Queensland. Key results We developed a traits database to inform functional trait-based approaches to assessing seagrass-meadow resilience and dynamics. The outputs included trait information for approximately 78% of the targeted traits (of 221 unique trait–seagrass combinations). Conclusions With current information on functional traits, we can improve the estimation of resilience and ecosystem services for tropical Queensland seagrass species. We have also highlighted trait data gaps and areas for further research. Implications We have provided examples of applying this database within the tropical Queensland context, with the potential to facilitate regional comparative studies. Our database complements existing plant-trait databases and serves as a valuable resource for future trait-based seagrass research in tropical Queensland.

Corrigendum.

Fruits are a major food resource for wildlifes and have evolved different traits which attract specific frugivores and facilitate seed dispersal. This study examines the quantity of the frequency of fruit tree species, distribution amongst fruit traits and estimates the potential availability of the fruit resource for frugivores in a 16-ha permanent forest plot at Doi Suthep–Pui, Thailand. The similarity amongst traits for fleshy fruited species was explored using Principal Component Analysis (PCA). Fleshy fruited species comprised 122 of 208 tree species >2 cm diameter at breast height (DBH) recorded in the permanent plot. Amongst fleshy fruited species, small fruits (length <20 mm) were most common (63.16% of species) while large fruits were rare (4.1%). Black was the most common fruit colour (43.4%). Principal Component Analysis of fruit traits explained 57% of total variance on the first three axes, and allowed identification of three species groups. Litsea martabanica and Persea gamblei are the greatest density and represented the major PCA group; black, small-sized and thin husk indehiscent fruits. These fruiting trees scattered throughout the permanent plot and were of good regeneration status. Indicating fleshy fruit can be a food resource for frugivores especially small-sized fruit. Furthermore, large-fruited species such as Madhuca floribunda is low density but important to preserve for food resource of large frugivores. This finding is very important not only for forest protection policy but also for wildlife conservation as food resources.

Microbial diversity, ecological networks and functional traits associated to materials used in drinking water distribution systems

Chapter Five - Impacts of Climate Change on Soil Microbial Communities and Their Functioning

Biocrust microbiomes influence ecosystem structure and function in the Mu Us Sandland, northwest China

Drought is a major factor limiting plant growth. Plants cope with stress via morphophysiological responses. Rhizosphere‐related bacteria, fungi and other microorganisms can help plants cope with drought via various mechanisms. We conducted a pot experiment on Cyperus esculentus wherein we subjected it to various drought levels and analyzed the functional traits of its aboveground and belowground organs. High‐throughput sequencing was used to study the structure and diversity of the microbial community in the rhizosphere. Drought stress substantially lowered the densities of the leaves, stems, roots and seeds relative to the untreated control. Drought stress inhibited the growth and reduced the yield of C. esculentus. The leaves and seeds have higher water content and are more sensitive to drought stress than the roots. With the aggravation of drought stress, the plant height of C. esculentus decreased significantly, the root:shoot ratio increased and the specific leaf weight had no significant difference. Change in shoot height was the most evident response of C. esculentus to drought stress. Plants under drought stress reduced their leaf area and assumed a specific leaf weight to maintain photosynthetic performance. Rhizosphere fungi were more sensitive to drought stress than rhizosphere bacteria. Drought stress increased the relative abundances of Bacteroidetes, Verrucomicrobia, Patescibacteria, Actinobacteria and Nitrospirae. Drought‐stressed C. esculentus maintained their photosynthetic performance by reducing shoot height and leaf area while assuming a stable specific leaf weight. Drought stress exerted a significantly stronger negative impact on rhizosphere fungi than rhizosphere bacteria. The results clarified the response strategies of functional traits and rhizosphere microorganisms of C. esculentus to drought stress.

Due to the environmental conditions presented in arid zones, it is expected to have a high influence of deterministic processes over the community assemblages. Symbiotic interactions with microorganisms could increase colonization and survival of plants in difficult conditions, independent of the plants physiological and morphological characteristics. In this context, the microbial communities associated to plants that inhabit these types of areas can be a good model to understand the community assembly processes. We investigated the influence of stochastic and deterministic processes in the assemblage of rhizosphere microbial communities of Agave lechuguilla and bulk soil on the Cuatro Cienegas Basin, a site known for its oligotrophic conditions. We hypothesize that rhizospheric microbial communities of A. lechuguilla differ from those of bulk soil as they differ in physicochemical properties of soil and biotic interactions, including not only the plant, but also their microbial co-occurrence networks, it is expected that microbial species usually critical for plant growth and health are more common in the rhizosphere, whereas in the bulk soil microbial species related to the resistance to abiotic stress are more abundant. In order to confirm this hypothesis, 16S rRNA gene was sequenced by Illumina from rhizospheric and bulk soil samples in two seasons, also the physicochemical properties of the soil were determined. Our results showed differences in bacterial diversity, community composition, potential functions, and interaction networks between the rhizosphere samples and the ones from bulk soil. Although community structure arises from a complex interplay between deterministic and stochastic forces, our results suggest that A. lechuguilla recruits specific rhizospheric microbes with functional traits that benefits the plant through growth promotion and nutrition. This selection follows principally a deterministic process that shapes the rhizospheric microbial communities, directed by the plant modifications around the roots but also subjected to the influence of other environmental variables, such as seasonality and soil properties. Interestingly, keystone taxa in the interactions networks, not necessarily belong to the most abundant taxonomic groups, but they have an important role by their functional traits and keeping the connections on the community network.

Ecological theories suggest that higher plant genetic diversity can increase productivity in natural ecosystems. So far, varietal mixtures, that is, the cultivation of different genotypes within a field, have shown contrasting results, notably for grain yield where both positive and negative mixing effects have been reported. Such discrepancy between ecological theories and agronomical applications calls for a better understanding of plant–plant interactions in crops. Using durum wheat Triticum turgidum ssp. durum as a model species, we investigated the effect of functional trait composition on productivity and grain quality of varietal mixtures by growing 179 highly diverse genotypes in pure stands and 197 two‐way mixtures in field conditions. We quantified the agronomic performance of the mixtures relative to their components grown in pure stands on two variables related to productivity, vegetative biomass yield and grain yield, and one variable related to grain quality, grain protein content. We then analysed the relationship between the relative performance of the mixtures and their functional composition that we characterized with trait means and trait differences on 19 above‐ and below‐ground traits. We found that biomass and grain yield increased by 4% overall in mixtures relative to single varieties, but that mixing effects were non‐significant for grain protein content. The combined effects of trait means and trait differences explained 12%, 17% and 22% of the variability of relative grain yield, biomass yield and grain protein content, respectively, with different traits affecting productivity and grain quality. Clustering varieties into functional groups allowed us to identify the most beneficial associations for multifaceted agronomic performance. Synthesis and applications. Functional traits explained a significant part of the relative agronomic performance of mixtures compared to monocultures (12%–22%, depending on the yield component). They can thus serve as a basis to identify groups of varieties whose combinations are expected to generate positive mixing effects, especially for productivity, and without compromising grain quality. Selection could then target convergence between groups for some traits and divergence between groups for other traits using empirically derived relationships between functional traits and agronomic performance as a guideline.