Omer Nevo

Arboreal camera trapping is an emerging remote sensing tool for building plant-frugivore interaction networks with enormous potential to provide new insights into seed dispersal as an eco-evolutionary process. Interaction data derived from camera trap videos broadly falls into two categories: visitation–indicating the presence of an animal in a tree–and intake–indicating true fruit consumption. These linked approximations of seed dispersal may or may not provide distinct sets of information, shaping our understanding of network dynamics, yet the extent to which emergent network structure depends on variable choice is unknown. To address this gap, we deployed camera traps in the canopy of 21 plant species in the Costa Rican tropical dry forest, an endangered biome with sparse community-wide plant-frugivore interaction data. Our objectives were: 1) Quantify plant-frugivore network structure in the tropical dry forest via network, group, and species-level metrics; and 2) Compare metrics between visitation and intake networks. We find strong structural patterns of low connectance, low nestedness, high modularity, and low niche overlap that differ significantly from null expectations in the same direction in both networks. The visitation network exhibited significantly greater modularity & species degree than the intake network, while the intake network exhibited significantly greater plant niche overlap than the visitation network. These findings suggest that the likelihood of consuming fruit on camera differs across species, which may have downstream consequences on other emerging metric estimations. Researchers seeking to build quantitative plant-frugivore networks should therefore consider visitation and intake variables in concert when relying on camera trap data. This work provides foundational plant-frugivore interaction data for a critically endangered biome and enhances our understanding of camera trapping as a remote sensing tool in frugivory and seed dispersal research.

Fleshy fruits have evolved diverse traits to attract seed dispersers in response to frugivore behavior and sensory capacities. Fruit scent has been suggested to signal ripeness and nutritional quality, yet the volatile components involved and the information they convey remain poorly understood. It is unknown which information is encoded in fruit scent, whether plants actively synthesize these signals, and thus whether scent constitutes an evolved communication system shaping seed-dispersal interactions. Aliphatic esters, chemicals whose odor is often described as “fruity,” are abundant in some ripe fruits, especially those dispersed by animals which tend to rely on their sense of smell for fruit selection. Moreover, they have been argued to be associated with sugar content, potentially rendering them an honest signal and hence a hotspot of animal-plant chemical communication. We investigated whether aliphatic esters indicate fruit quality honestly and represent an adaptive trait shaped by disperser identity. Using 13 fig species ( Ficus spp.; Moraceae) in Madagascar, we quantified seed dispersal by multiple animals using a quantitative ecological network. We then quantified chemical signals and nutritional rewards using thermal desorption gas chromatography-mass spectrometry (TD-GCMS) and high-performance liquid chromatography (HPLC), and used genome-guided transcriptome assembly to identify the candidate genes responsible for ester signaling. Our results show that (a) aliphatic esters occur more frequently in species dispersed primarily by olfactory-oriented mammals than in those dispersed by visually oriented birds; (b) ester abundance correlates positively with soluble sugar across species only in mammal-dispersed species, indicating an honest signal that is activated only when ecologically relevant; and (c) putative AAT gene revealing elevated expression associated with the increased abundance of aliphatic esters, sugars in single mammal-dispersed taxon. Together, these findings support the hypothesis that fruits have evolved to utilize the biochemical link between esters (signals) and sugars (rewards) to provide honest signals to seed dispersers. Significance Statement: Fruit–frugivore communication is a critical component of ecological systems as it allows animals to find and identify ripe fruit, thus facilitating seed dispersal, plant reproduction, forest regeneration, and animal community maintenance. Chemical communication via fruit scent remains underexplored, particularly regarding the information encoded, active signal synthesis, and adaptive significance. Using a model system of wild figs from Madagascar, our study suggests that fruits have evolved to utilize aliphatic esters, a group of chemicals commonly described as “fruity” by human observers, to signal sugar levels to seed-dispersing animals. In species that rely on lemurs, which tend to rely strongly on their sense of smell, ester levels were higher than in bird-dispersed species, where visual signals are more prominent. Further, in lemur-dispersed species ester levels were correlated with sugar, indicating that they are reliably signaling fruit quality. Linking these patterns to elevated expression of the gene mediating ester biosynthesis, we also identify a molecular mechanism potentially under selection. These findings establish fruit scent as an adaptive communication system and reveal how plant chemicals evolve under mammalian selection.

Pollination and seed dispersal by animals are key drivers of terrestrial biodiversity and ecosystem functioning. Effective mutualistic interactions rely heavily on temporal and functional- trait matching between plants and animals. While global warming is known to induce shifts in plant traits, the extent and direction in which higher temperatures may systematically alter flower and fruit traits across species in natural habitats remains poorly understood. Using elevation as a proxy for temperature across natural populations, we conducted a meta-analysis evaluating 21 quantitative functional traits (15 floral, 6 fruit) across 82 studies and 161 species. Standardized mixed-effects linear regression models revealed widespread, systemic responses to elevational temperature gradients in both reproductive structures. In flowers, higher temperatures were systematically associated with changes in petal and sepal width and length (and hence morphology), longevity, nectar volume, number of flowers, and inflorescence length. In fruits, elevation was associated with changes in vitamin C content, crop size, weight and width. Taken together, these results demonstrate that warming temperatures exert widespread, multi-axis effects on the morphology, availability, timing, and nutritional quality of both flowers and fleshy fruits. Given that flower and fruit traits are developmentally linked and co-determine animal visitor dynamics, these temperature-driven phenotypic shifts are likely to propagate cascading disruptions throughout plant–pollinator and plant–frugivore interaction networks under continued climate change.

Plant–frugivore mutualisms are shaped by suites of fruit traits that evolve in tandem with the preferences of seed dispersers, a concept encapsulated by the dispersal syndrome hypothesis. While morphological characteristics (e.g., size, color, firmness) have been extensively studied, the nutritional dimension, and particularly sugar profiles, remains comparatively understudied. This is despite its role as a primary reward influencing frugivore foraging decisions and despite the fact that these are the primary attractants driving animal feeding and ultimately seed dispersal. Here, we investigated the evolutionary and ecological drivers of sugar profile diversity in the ripe fruits of 15 animal-dispersed wild fig (Ficus) species. We sampled 1019 ripe fruit samples of 50 individual trees at 4 different field sites in Madagascar. Fruits were oven-dried and analyzed using High‑Performance Liquid Chromatography to quantify the abundances of sugars. We addressed three questions: (Q1) Are sugar-composition profiles species-specific? (Q2) Is the sugar profile phylogenetically conserved? (Q3) Do sugar profiles covary with other fruit traits in ways that support dispersal syndromes? Our results demonstrate fig species exhibit certain distinct sugar profiles, alongside substantial intraspecific variability; we did not find a phylogenetic signal in sugar profiles, suggesting that sugar profiles are not strongly constrained by shared ancestry but have likely diverged under ecological selection; and sugar profiles covary significantly with other fruit traits. Species with smaller fruits, different/multiple coloration, and mixed aromatic profiles rich in terpene and ester exhibited elevated sucrose concentrations, whereas larger, more conspicuous, and ester-rich fruits tended to contain higher fructose levels. Together, these findings lend support for the dispersal syndrome hypothesis by demonstrating that sugar profile, like other non-sugar traits, such as morphology, has evolved in association with frugivore preferences.

Fleshy fruits attract animals to ingest fruit, swallow the seeds, and release them in the landscape, thus facilitating seed dispersal and plant regeneration. Attraction of animal dispersers is achieved via attractants such as color or scent, and rewards like sugars, lipids, and micronutrients. In addition to these attractants and rewards, a plethora of fruit and seed functional traits, including size, hardness, and chemistry, can affect the accessibility and attractiveness of fruits to seed‐dispersing animals. These functional traits form the interface between animals and fruits and, through trait matching, act as filters in dispersal networks. Yet, despite their critical roles in shaping seed dispersal networks, many fruit traits are not quantified in a standardized fashion, if they are quantified at all. As such, the existing databases of fruit traits used for syntheses lack many functional dimensions. We review the latest developments in fruit trait analysis, focusing on traits relevant for plant–frugivore interactions (i.e., morphology, color, chemistry), as well as some of their drivers (DNA, RNA, and microbial communities). We provide an overview of many existing methods, their advantages and disadvantages, and their application in field conditions.

Seed dispersal by animals is critical to both animal and plant ecology. Among species, fruits show a tremendous diversity of traits such as colour, scent, texture and size. Recent studies demonstrated a significant degree of variation in fruit traits within species as well. This often-overlooked variation may play a critical role in animal–plant interactions as they can inform fruit selection and be the basis for the evolution of interspecific variation. Yet data on the role of intraspecific variation on animal behaviour are rare. We combine behavioural and fruit trait data to test whether sensory ecology is driven by: (H1) intraspecific variation in fruit traits; and/or (H2) traits that are correlated with fruit quality. Our overarching hypothesis is that variation within a species will lead to differential deployment of senses across species. We collected sensory behaviour of wild red-bellied lemurs and quantified intraspecific variation in the traits of six consumed fruit species. We found support for both: the use of olfaction was significantly associated with both intraspecific variation in fruit scent and its association with sugar content. This underscores the significance of intraspecific variation in plant traits to animal sensory ecology, as well as their potential implications for fruit trait evolution.

By dispersing seeds, animals provide ecological functions critical for the ecology, evolution, and conservation of plants. We review quantitative and empirical approaches and emerging technologies to quantify processes and patterns of animal‐mediated seed dispersal (zoochory) across its phases: from predispersal to postdispersal. In addition, we consider approaches to studying seed disperser behaviors and plant traits, both of which influence all dispersal phases of animal‐mediated dispersal. Finally, we discuss how we can use quantitative and empirical approaches to integrate across seed dispersal phases and address data gaps to improve our mechanistic understanding of zoochory and its consequences for ecology and conservation. To move towards generalization and predictability in seed dispersal ecology, we recommend the development of standardized protocols that can be widely implemented across systems with simultaneous and iterative development of theory and quantitative models. As approaches in studying animal‐mediated seed dispersal continue to advance, exciting opportunities present themselves to increase our understanding of seed dispersal ecology.

Leaf metabolites are important drivers of biotic interactions. Leaf metabolic profiles are changing over ontogeny and in response to biotic and abiotic conditions. Additionally, plant species diversity can influence leaf metabolomes. However, it is rarely considered how changes in leaf metabolomes might affect the leaf litter volatiles, which mediate interactions with the decomposer community. We designed an optimized and validated solid-phase microextraction (SPME) method coupled with a gas chromatography-mass spectrometry (GC-MS) analysis to analyze liter volatile organic compound (VOC) emissions. This method was applied to test the hypothesis that sessile oak ( Quercus petrea ) leaf litter VOC profiles are influenced by surrounding tree diversity. The results showed that plot diversity significantly affected oak litter VOC profiles by increasing the emissions of fatty acids. Tree diversity marginally modulated terpenoid emissions. Particularly, the emission rates of (-)-β-bourbonene and (E)-β-caryophyllene decreased with increasing species diversity. Also, ethanol emissions, likely due to microbial activity, decreased with increasing tree diversity. By detecting diversity- and C: N-related changes in terpenoids, and diversity effects on fatty acids and ethanol emissions of Q. petraea leaf litter, we provide new insights into how biodiversity shapes litter chemistry and potentially restructures decomposer interactions.

Premise: Plants produce a tremendous variety of secondary compounds that are crucial to interspecific and intraspecific interactions and for adaptation to environmental changes. This chemical diversity has been attributed to multiple factors, including interactions with herbivores or pollinators, tissue‐specific needs, and evolutionary constraints. The interplay between a vast array of factors driving plant chemodiversity remains unclear, mainly because most studies have focused on a single organ—mostly leaves—or, when comparing different organs, have been limited to single taxa. Thus, the relationship between functional and phylogenetic factors remains unresolved. We use a model system of Ficus from Madagascar to examine the extent to which phytochemical diversity is shaped by tissue‐specific function and the degree to which phylogenetic relatedness explains variation in fruit and leaf chemodiversity.Methods: We applied an untargeted metabolomics approach to unripe fruits (the syconium, a hollow structure containing numerous small flowers) and leaves from eight species of wild figs (Ficus spp.) sampled in a tropical rainforest in Madagascar. We characterized their chemical profiles using ultra‐performance liquid chromatography–mass spectrometry and reconstructed their phylogeny using six genetic markers to understand the patterns of chemodiversity.Results: Fruit and leaf metabolomes were more similar to the same organ in other species than to the other organs within the same species. There was a significant but moderate phylogenetic correlation in fruit and leaf chemodiversity.Conclusions: Although phylogenetic relatedness influences plant chemodiversity in Malagasy figs, functional convergence of tissue‐specific metabolites may be a major evolutionary driver.

Ground foraging among volant frugivores is an underappreciated aspect of behavioral flexibility. Here we report the first evidence of fruit bats feeding on fallen fruit, captured by camera traps in a Costa Rican tropical dry forest. These observations provide insight into the flexibility and mechanisms of coexistence among frugivores.