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In this study, we evaluated the efficacy of sample collection approaches and DNA metabarcoding to identify plants utilized by nectivorous bats. Samples included guano collected from beneath bat roosts and pollen-swabs from bat fur, both of which were subjected to DNA metabarcoding and visual identification of pollen (microscopy) to measure plant diversity. Our objectives were to determine whether DNA metabarcoding could detect likely food plants of nectivorous bats, whether sample types would produce different estimates of plant diversity, and to compare results of DNA metabarcoding to visual identification. Visual identification found that 99% of pollen was from Agave, which is thought to be the bats' main food source. The dominant taxon found by metabarcoding was also Agavoideae, but a broader diversity of plant species was also detected, many of which are likely 'by-catch' from the broader environment. Metabarcoding outcomes differed between sample types, likely because pollen-swabs measured the plant species visited by bats and guano samples measured all items consumed in the bat's diet, even those that were not pollen or nectar. Overall, metabarcoding is a powerful, high-throughput tool to understand bat ecology and species interactions, but careful analysis of results is necessary to derive accurate ecological conclusions.Key words: diet, diversity, DNA metabarcoding, guano, nectivorous bats.Dans ce travail, les auteurs ont évalué l'efficacité d'approches d'échantillonnage et de métacodage à barres de l'ADN pour identifier les espèces végétales exploitées par des chauves-souris nectarivores. Les échantillons incluaient du guano collecté sous des perchoirs de chauves-souris et des prélèvements de pollen provenant de la fourrure des chauves-souris, tous deux faisant l'objet de métacodage à barres de l'ADN et à l'identification visuelle du pollen (microscopie) pour mesurer la diversité des plantes. Les objectifs étaient de déterminer si le métacodage à barres pouvait détecter les sources vraisemblables de nourriture des chauves-souris nectarivores, si différents types d'échantillons produiraient différents estimés de la diversité végétale et de comparer les résultats des tests d'ADN avec l'identification visuelle. L'identification visuelle a révélé que 99 % du pollen provenait de l'agave, dont on pense qu'il s'agit de la principale source de nourriture des chauves-souris. Le taxon dominant révélé par le métacodage à barres était également les Agavoideae, mais une gamme plus large de végétaux a été détectée, dont la plupart sont vraisemblablement << capturés >> au sein de l'environnement plus large. Les résultats du métacodage à barres étaient différents selon les types d'échantillons, vraisemblablement parce que les frottis de pollen mesuraient toutes les espèces végétales visitées par les chauves-souris, tandis que les échantillons de guano mesuraient tous les items consommés par les chauves-souris, même ceux qui n'étaient pas du pollen ou du nectar. Globalement, le métacodage à barres est un outil puissant à haut débit permettant de mieux connaître l'écologie des chauves-souris et les interactions entre les espèces, mais une analyse soignée des résultats est nécessaire pour en tirer des conclusions écologiques qui soient justes. [Traduit par la Rédaction]Mots-clés : diète, diversité, métacodage à barres de l'ADN, guano, chauves-souris nectarivores., IntroductionIdentifying the diversity of food resources used by animals is critical for understanding their behavior, physiological requirements, and habitat needs, all of which are important for effective conservation. Traditionally, techniques [...]

Summary: Annual rings from 30 year old vines in a California rootstock trial were measured to determine the effects of 15 different rootstocks on Chardonnay and Cabernet Sauvignon scions. Viticultural traits measuring vegetative growth, yield, berry quality, and nutrient uptake were collected at the beginning (1995 to 1999) and end (2017 to 2020) of the lifetime of a vineyard initially planted in 1991 and removed in 2021. X-ray Computed Tomography (CT) was used to measure ring widths in 103 vines. Ring width was modeled as a function of ring number using a negative exponential model. Early and late wood ring widths, cambium width, and scion trunk radius were correlated with 27 traits. Modeling of annual ring width shows that scions alter the width of the first rings but that rootstocks alter the decay of later rings, consistently shortening ring width throughout the lifetime of the vine. Ravaz index, juice pH, photosynthetic assimilation and transpiration rates, and instantaneous water use efficiency are correlated with scion trunk radius. Ultimately, our research indicates that rootstocks modulate secondary growth over years, altering physiology and agronomic traits. Rootstocks act in similar but distinct ways from climate to modulate ring width, which borrowing techniques from dendrochronology, can be used to monitor both genetic and environmental effects in woody perennial crop species. [ABSTRACT FROM AUTHOR]

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Grapevine leaves have diverse shapes and sizes. Their shape and size is known to be influenced by genetics, vine phytosanitary status, environment, leaf and vine age, node position on the shoot, shoot order, and other factors. In order to determine the importance of grapevine leaf shape and size to canopy temperature, we examined the relationship in five seedling populations grown in a vineyard in the San Joaquin Valley, California, USA. The seedlings were individual genotypes and unreplicated. All of the populations had one parent or grandparent with compound leaves of the Vitis piasezkii type and each population had a different second parent with non-compound leaves. As expected based on published reports and our own observations in related populations, the V. piasezkii compound leaf phenotype segregated as a dominant or semi-dominant trait and the populations all showed noticeable segregation for leaf shape. We measured leaf shape using 21 homologous landmarks. We used an infrared thermometer to measure the temperature of the canopy in July and August 2018 and 2019. By recording time of sampling and temperatures, we were able to determine which vines were cooler or hotter than expected, using a linear model. We did not measure canopy architecture, photosynthesis, or water use efficiency, as the heterogeneity of individual seedling canopies is very high, and this substantially complicates these observations on unreplicated seedlings. We established a relationship between leaf size and leaf temperature: vines with larger leaves were cooler than expected. In contrast, leaf shape was not strongly correlated with variation in vine temperature. Ultimately, these findings indicate that vines with larger leaves may contribute to the reduction of overall vine canopy temperature, but further work is needed to determine if this is due to variation in leaf size, differences in the openness of the canopy, or other related traits. [ABSTRACT FROM AUTHOR]