Felipe Yon

Animal microbiomes often show phylosymbiosis, a pattern in which closely related hosts harbour more similar microbial communities than distant hosts. Yet, the processes generating this pattern remain unresolved, particularly whether phylosymbiosis requires sociality and vertical microbial transmission or can emerge through host filtering from environmental microbial pools. Bees (Anthophila) provide a powerful model to test this question because their major evolutionary radiation spans diverse life histories and contrasting microbiome transmission modes. Here, we analysed gut bacterial communities from 60 bee genera worldwide (1,989 samples), spanning all major bee families, and combined comparative phylogenetic models with host traits, bacterial phylogenies and predicted functional profiles to disentangle ecological and evolutionary drivers of phylosymbiosis. We found strong phylosymbiosis across and within bee families, with host phylogeny explaining substantial variation in gut microbiome composition despite weak effects of measured host traits. Geo-environmental context also explained considerable variation, indicating interactions between evolutionary and environmental filters. Despite extensive taxonomic and phylogenetic turnover, microbial functional divergence was weaker, suggesting convergence despite compositional differentiation. Together, these results show that microbiome composition can follow host phylogeny even under predominantly environmental acquisition and that phylosymbiosis can emerge through repeated assembly of functionally conserved communities rather than strict microbial inheritance.

Body weight is a key trait in insects, reflecting size, condition, and energetic status. It also influences their flight performance, reproduction, and ecological interactions. Yet most ecological and taxonomic studies rely on preserved rather than living individuals, despite the substantial mass loss caused by drying and other curatorial procedures. We quantified how preservation affects body mass in moths (Lepidoptera) using three complementary datasets representing major workflows: laboratory-reared Spodoptera littoralis (Boisduval, 1833), freshly collected moths from Germany, and frozen geometrid specimens from Peru. Across datasets, body weight declined markedly across developmental stages and preservation states, with only partial recovery after rehydration. In S. littoralis , females were consistently heavier than males, while egg presence did not influence female mass. By integrating results across workflows, we derived practical correction factors for estimating fresh body weight from dry specimens. These order-level approximations substantially improve the ecological value of preserved material by allowing body-mass data from museum collections to reflect the mass of living insects more accurately. Applying such corrections enhances the reliability of trait-based and comparative analyses that depend on preserved Lepidoptera.

Insects make up the majority of all animal species, with 70% occurring in the tropics ¹ , yet the impacts of warming on tropical insects remain highly uncertain ² . This stems from sparse, taxonomically biased data on thermal tolerance of tropical insects and an incomplete understanding of the underlying physiological mechanisms ³ . Here we compared environmental temperatures with field-measured upper and lower thermal tolerance limits of around 2,300 insect species along Afrotropical and Neotropical elevational gradients and identified genomic signatures of thermal tolerance across the insect tree of life. We show that thermal tolerances do not proportionally track environmental temperatures but approach an asymptote in tropical lowlands. Insects at high elevations utilize plasticity to cope with rising temperatures, whereas lowland species have limited plastic abilities. Heat tolerance showed strong differences among insect orders and families, reflected in the thermal stability of proteins, suggesting that variation in thermal tolerance is founded in the fundamental protein architecture. Up to 52% of future surface temperatures and 38% of air temperatures in the Amazonian lowlands can cause heat mortality in half of the studied community. Our data suggest a limited capacity of insects in the Earth’s most biodiverse regions to buffer future warming.

Cold waves crossing the Amazon rainforest are an extraordinary phenomenon likely to be affected by climate change. We here describe an extensive cold wave that occurred in June 2023 in Amazonian–Andean forests and compare environmental temperatures to experimentally measured thermal tolerances and their impact on lowland animal communities (insects and wild mammals). While we found strong reductions in activity abundance of all animal groups under the cold wave, tropical lowland animals showed thermal tolerance limits below the lowest environmental temperatures measured during the cold wave. While mammal activity and the biomass of most insects recovered over the next season, dung beetle biomass remained low. A quarter of all insects showed very small thermal safety margins (0.62 °C) with respect to the recorded minimum temperature of 10.5 °C, suggesting that an increased intensity of cold waves in the future could imperil cold-sensitive taxa of Amazonian animal communities.

Increasing water deficits and warming temperatures due to climate change threaten agricultural systems in the Peruvian Andes, where environmental conditions are themselves challenging. Lepidium meyenii Walpers also known as "maca" is an endemic root crop that can tolerate adverse conditions such as low temperatures and high UV radiation, but little is known about its response to drought. This study aimed to test the effect on maca germination and early seedling growth of water restriction under two maximum temperatures: 15 °C (current scenario) and 20 °C (warming scenario). Water restriction had either a direct or a temperature-dependent effect on germination and above ground seedling growth, which was greater at 15 °C. By contrast, its effects on seedlings growing at 20 °C were completely overcome by faster germination, initial growth, and biomass acquisition. The results are consistent with those from other crops and contribute to the understanding of how climate change is affecting high-mountain agriculture. El aumento de los déficits de agua y las temperaturas más cálidas debido al cambio climático amenazan los sistemas agrícolas en los Andes peruanos, donde las condiciones ambientales son desafiantes. Lepidium meyenii Walpers, también conocida como “maca”, es un cultivo de raíz endémico que puede tolerar condiciones adversas como bajas temperaturas y alta radiación ultravioleta, pero se sabe poco sobre su respuesta a la sequía. El objetivo de este estudio fue evaluar el efecto de la restricción hídrica sobre la germinación de maca y el crecimiento temprano de las plántulas en dos temperaturas máximas: 15 °C (escenario actual) y 20 °C (escenario de calentamiento). Se encontró que la restricción hídrica tuvo un efecto directo o dependiente de la temperatura sobre la germinación y el crecimiento foliar de las plántulas, que fue mayor a 15 °C. Por el contrario, sus efectos sobre las plántulas que crecieron a 20 °C fueron completamente superados por una germinación más rápida, crecimiento inicial y adquisición de biomasa. Los resultados son consistentes con los de otros cultivos y contribuyen a la comprensión de cómo el cambio climático está afectando a la agricultura de alta montaña.

Main conclusion: Nicotiana attenuata’s capacity to interact with arbuscular mycorrhizal fungi influences its intraspecific competitive ability under field and glasshouse conditions, but not its overall community productivity. Arbuscular mycorrhizal (AM) fungi can alter the nutrient status and growth of plants, and they can also affect plant–plant, plant–herbivore, and plant–pathogen interactions. These AM effects are rarely studied in populations under natural conditions due to the limitation of non-mycorrhizal controls. Here we used a genetic approach, establishing field and glasshouse communities of AM-harboring Nicotiana attenuata empty vector (EV) plants and isogenic plants silenced in calcium- and calmodulin-dependent protein kinase expression (irCCaMK), and unable to establish AM symbioses. Performance and growth were quantified in communities of the same (monocultures) or different genotypes (mixed cultures) and both field and glasshouse experiments returned similar responses. In mixed cultures, AM-harboring EV plants attained greater stalk lengths, shoot and root biomasses, clearly out-competing the AM fungal-deficient irCCaMK plants, while in monocultures, both genotypes grew similarly. Competitive ability was also reflected in reproductive traits: EV plants in mixed cultures outperformed irCCaMK plants. When grown in monocultures, the two genotypes did not differ in reproductive performance, though total leaf N and P contents were significantly lower independent of the community type. Plant productivity in terms of growth and seed production at the community level did not differ, while leaf nutrient content of phosphorus and nitrogen depended on the community type. We infer that AM symbioses drastically increase N. attenuata’s competitive ability in mixed communities resulting in increased fitness for the individuals harboring AM without a net gain for the community.

Most flowering plants depend on animal pollination for successful sexual reproduction. Floral signals such as color, shape, and odor are crucial in establishing this (often mutualistic) interaction. Plant and pollinator phenotypes can vary temporally but also spatially, thus creating mosaic-like patterns of local adaptations. Here, we investigated natural variation in floral morphology, flower volatile emission, and phenology in four accessions of a self-compatible wild tobacco, Nicotiana attenuata, to assess how these traits match the sensory perception of a known pollinator, the hawkmoth Manduca sexta. These accessions differ in floral traits and also in their habitat altitudes. Based on habitat temperatures, the accession occurring at the highest altitude (California) is less likely to be visited by M. sexta, while the others (Arizona, Utah 1, and Utah 2) are known to receive M. sexta pollinations. The accessions varied significantly in flower morphologies, volatile emissions, flower opening, and phenology, traits likely important for M. sexta perception and floral handling. In wind tunnel assays, we assessed the seed set of emasculated flowers after M. sexta visitation and of natural selfed and hand-pollinated selfed flowers. After moth visitations, plants of two accessions (Arizona and Utah 2) produced more capsules than the other two, consistent with predictions that accessions co-occurring with M. sexta would benefit more from the pollination services of this moth. We quantified flower and capsule production in four accessions in a glasshouse assay without pollinators to assess the potential for self-pollination. The two Utah accessions set significantly more seeds after pollen supplementation compared with those of autonomous selfing flowers, suggesting a greater opportunistic benefit from efficient pollinators than the other two. Moreover, emasculated flowers of the accession with the most exposed stigma (Utah 2) produced the greatest seed set after M. sexta visitation. This study reveals intraspecific variation in pollination syndromes that illuminate the potential of a plant species to adapt to local pollinator communities, changing environments, and altered pollination networks.

The highly conserved core circadian clock component TIMING OF CAB EXPRESSION1 (TOC1) contextualizes environmental stress responses in plants, for example by gating abscisic acid signaling and suppressing thermoresponsive growth. Selective interaction of TOC1 with PHYTOCHROME B under far-red–enriched light suggests a connection between circadian gating of light responses and sensitivity to ABA, an important regulator of growth and stress responses, including under drought. However, the fitness consequences of TOC1 function, particularly in the root, are poorly understood. Here, we used the desert annual, Nicotiana attenuata, to investigate the function of TOC1 in shoots and roots for maintaining fitness under drought, in both field and glasshouse experiments. Despite marked decreases in leaf water loss, TOC1-deficient lines failed to maintain fitness in response to drought stress as measured by total seed capsule production. Restoring TOC1 transcript levels in shoots via micrografting was sufficient to restore wild-type drought responses under field conditions. Microarrays identified a coexpression module in leaves strongly linking red and far-red light signaling to drought responses in a TOC1-dependent manner, but experiments with phytochrome-deficient lines revealed that the effects of TOC1 deficiency under drought cannot be attributed to changes in red/far-red light perception alone. Taken together, these results elucidate the sophisticated, tissue-dependent role of the circadian clock in maintaining fitness in the face of long-term abiotic stresses such as drought.

Flower signaling and orientation are key characteristics that determine a flower's pollinator guild. However, many flowers actively move during their daily cycle, changing both their detectability and accessibility to pollinators. The flowers of the wild tobacco Nicotiana attenuata orientate their corolla upward at sunset and downward after sunrise. Here, we investigated the effect of different flower orientations on a major pollinator of N. attenuata, the hawkmoth Manduca sexta. We found that although flower orientation influenced the flight altitude of the moth in respect to the flower, it did not alter the moth's final flower choice. These behavioral observations were consistent with the finding that orientation did not systematically change the spatial distribution of floral volatiles, which are major attractants for the moths. Moreover, hawkmoths invested the same amount of time into probing flowers at different orientations, even though they were only able to feed and gather pollen from horizontally and upward‐oriented flowers, but not from downward‐facing flowers. The orientation of the flower was hence crucial for a successful interaction between N. attenuata and its hawkmoth pollinator. Additionally, we also investigated potential adverse effects of exposing flowers at different orientations to natural daylight levels, finding that anther temperature of upward‐oriented flowers was more than 7°C higher than for downward‐oriented flowers. This increase in temperature likely caused the significantly reduced germination success that was observed for pollen grains from upward‐oriented flowers in comparison to those of downward and horizontally oriented flowers. These results highlight the importance of flower reorientation to balance pollen protection and a successful interaction of the plant with its insect pollinators by maintaining the association between flower volatiles and flower accessibility to the pollinator.