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Insect herbivory can be an important selective pressure and contribute substantially to local plant richness. As herbivory is the result of numerous ecological and evolutionary processes, such as complex insect population dynamics and evolution of plant antiherbivore defenses, it has been difficult to predict variation in herbivory across meaningful spatial scales. In the present work, we characterize patterns of herbivory on plants in a species‐rich and abundant tropical genus (Piper) across forests spanning 44° of latitude in the Neotropics. We modeled the effects of geography, climate, resource availability, andPiperspecies richness on the median, dispersion, and skew of generalist and specialist herbivory. By examining these multiple components of the distribution of herbivory, we were able to determine factors that increase biologically meaningful herbivory at the upper ends of the distribution (indicated by skew and dispersion). We observed a roughly twofold increase in median herbivory in humid relative to seasonal forests, which aligns with the hypothesis that precipitation seasonality plays a critical role in shaping interaction diversity within tropical ecosystems. Site level variables such as latitude, seasonality, and maximumPiperrichness explained the positive skew in herbivory at the local scale (plot level) better for assemblages ofPipercongeners than for a single species. Predictors that varied between local communities, such as resource availability and diversity, best explained the distribution of herbivory within sites, dampening broad patterns across latitude and climate and demonstrating why generalizations about gradients in herbivory have been elusive. The estimated population means, dispersion, and skew of herbivory responded differently to abiotic and biotic factors, illustrating the need for careful studies to explore distributions of herbivory and their effects on forest diversity.

Tikal, a major city of the ancient Maya world, has been the focus of archaeological research for over a century, yet the interactions between the Maya and the surrounding Neotropical forests remain largely enigmatic. This study aimed to help fill that void by using a powerful new technology, environmental DNA analysis, that enabled us to characterize the site core vegetation growing in association with the artificial reservoirs that provided the city water supply. Because the area has no permanent water sources, such as lakes or rivers, these reservoirs were key to the survival of the city, especially during the population expansion of the Classic period (250–850 CE). In the absence of specific evidence, the nature of the vegetation surrounding the reservoirs has been the subject of scientific hypotheses and artistic renderings for decades. To address these hypotheses we captured homologous sequences of vascular plant DNA extracted from reservoir sediments by using a targeted enrichment approach involving 120-bp genetic probes. Our samples encompassed the time before, during and after the occupation of Tikal (1000 BCE–900 CE). Results indicate that the banks of the ancient reservoirs were primarily fringed with native tropical forest vegetation rather than domesticated species during the Maya occupation.

Foundational hypotheses addressing plant–insect codiversification and plant defense theory typically assume a macroevolutionary pattern whereby closely related plants have similar chemical profiles. However, numerous studies have documented variation in the degree of phytochemical trait lability, raising the possibility that phytochemical evolution is more nuanced than initially assumed. We utilize proton nuclear magnetic resonance (¹H NMR) data, chemical classification, and double digest restriction-site associated DNA sequencing (ddRADseq) to resolve evolutionary relationships and characterize the evolution of secondary chemistry in the Neotropical plant clade Radula (Piper; Piperaceae). Sequencing data substantially improved phylogenetic resolution relative to past studies, and spectroscopic characterization revealed the presence of 35 metabolite classes. Metabolite classes displayed phylogenetic signal, whereas the crude¹H NMR spectra featured little evidence of phylogenetic signal in multivariate tests of chemical resonances. Evolutionary correlations were detected in two pairs of compound classes (flavonoids with chalcones;p-alkenyl phenols with kavalactones), where the gain or loss of a class was dependent on the other’s state. Overall, the evolution of secondary chemistry in Radula is characterized by strong phylogenetic signal of traditional compound classes and weak phylogenetic signal of specialized chemical motifs, consistent with both classic evolutionary hypotheses and recent examinations of phytochemical evolution in young lineages.

Natural history studies documenting spatial and temporal variation of species assemblages and their interactions are critical for understanding biodiversity and community ecology. We characterized caterpillar–parasitoid assemblages on shrubs in the genusPiperacross remnants of semi‐evergreen forest in the Yucatán Península during the rainy and rainy–dry seasons. We collected caterpillars feeding onPiperleaves and reared them to adults or parasitoids to: (i) describe tritrophic interactions betweenPiper, caterpillars, and parasitoids, (ii) compare empirical metanetworks among sites and seasons, and (iii) investigate patterns in species and interaction turnover across spatial and temporal scales to understand the contribution of species composition and interaction rewiring to overall interaction turnover. We found sixPiperspecies supporting 79 species of caterpillars, which in turn hosted 20 species of parasitoids. In total, there were 116 realized trophic interactions. Species and interactions exhibited substantial turnover at temporal and spatial scales. Total interaction turnover was more pronounced across seasons in all sites (>93%), than it was between sites (<91%). We also found that interaction rewiring contributed more to overall interaction turnover than species turnover. The spatial and temporal variation in metanetworks documented here contribute to understanding fine‐scale temporal and spatial turnover in tropical species and interactions and raise important questions about the lability of consumer specialization and the short‐term effects of interaction rewiring on the stability of biotic communities. Our results highlight the importance of tropical food web studies that are based on natural history using consistent field methods to document bi‐ and tripartite interactions.

Abstract in Spanish is available with online material.

Species richness in tropical forests is correlated with other dimensions of diversity, including the diversity of plant–herbivore interactions and the phytochemical diversity that influences those interactions. Understanding the complexity of plant chemistry and the importance of phytochemical diversity for plant–insect interactions and overall forest richness has been enhanced significantly by the application of metabolomics to natural systems. The present work used proton nuclear magnetic resonance spectroscopy (¹H‐NMR) profiling of crude leaf extracts to study phytochemical similarity and diversity amongPiperplants growing naturally in the Atlantic Rainforest of Brazil. Spectral profile similarity and chemical diversity were quantified to examine the relationship between metrics of phytochemical diversity, specialist and generalist herbivory, and understory plant richness. Herbivory increased with understory species richness, while generalist herbivory increased and specialist herbivory decreased with the diversity ofPiperleaf material available. Specialist herbivory increased when conspecific host plants were more spectroscopically dissimilar. Spectral similarity was lower among individuals of common species, and they were also more spectrally diverse, indicating phytochemical diversity is beneficial to plants. Canopy openness and soil nutrients also influenced chemistry and herbivory. The complex relationships uncovered in this study add information to our growing understanding of the importance of phytochemical diversity for plant–insect interactions and tropical plant species richness.