Biology subjects

Galimberti, A.

Publications and source records attributed to Galimberti, A..

11 recordsLinked to original sources

bioRxiv2023

E-PoSa: a novel and effective tool for sampling pollen directly from flowers

O_LIPollinator insects are declining worldwide also due to the alteration of their diet with severe implications on their health status. Pollinators diet relies mainly on flower rewards (i.e., pollen and nectar) and a precise characterization of their chemical composition is crucial in defining pollinators nutritional ecology. In this context, the pollen represents a challenging source to investigate, especially due to operative challenges during collection operations and to the small amounts produced per flower. C_LIO_LIHere, we designed and tested a novel, easy-to-assemble tool for pollen sampling: E-PoSa (Electronic Pollen Sampler), based on the use of a portable vacuum cleaner. We compared it with some of the most used sampling methods for pollen (i.e., anthers sieving and sampling of the whole anthers) by looking at the differences in their quantitative recovery and nutritional profile. Its applicability in ecological studies was also corroborated by an assessment of its recovery rate obtained from a panel of wildflowers species in an operational environment. C_LIO_LIThe data obtained showed a significantly higher pollen recovery capacity of E-PoSa compared to the conventional sieving approach and the success in retrieving enough pollen to conduct phytochemical analyses from a broad range of flower morphologies in the field. Our results also demonstrated that high purity pollen can be collected with E-PoSa and that the device does not introduce any significant variation in the nutritional analysis compared to the conventional sieving. C_LIO_LIThis new sampling approach represents a cheap and easy-to-assemble tool encouraging its future use not only in the field of pollen nutrition but also in a wide variety of other contexts related to pollination ecology. Acknowledging the potential influences of the sampling techniques and moving towards shared standardized field protocols will advance the comprehension of species interactions and foraging patterns of pollinators and their nutritional needs. C_LI

ecology↗

bioRxiv2022

Mimicking orchids lure bees from afar with exaggerated ultraviolet signals

O_LIFlowers have many sensory traits to appeal to pollinators, including ultraviolet (UV) absorbing markings, which are well known for attracting bees at close proximity (e.g. < 1 m). While striking UV signals have been thought to attract pollinators also at greater distances of meters, how the signals impact the plant pollination success over distance remains unknown. Here we report the case of the Australian orchid Diuris brumalis, a non-rewarding species, pollinated by bees via mimicry of rewarding pea plant Daviesia decurrens. When distant from the pea plant, Diuris brumalis was hypothesized to enhance pollinator attraction by exaggerately mimicking the floral ultraviolet (UV) reflecting patterns of its model. C_LIO_LIBy experimentally modulating floral UV reflectance with a UV screening solution, we quantified the orchid pollination success at variable distance from the model plants. C_LIO_LIWe demonstrate that the deceptive orchid Diuris brumalis attracts bee pollinators by emphasizing the visual stimuli, which mimic the floral UV signalling of the rewarding model D. decurrens. Moreover, the exaggerated UV reflectance of D. brumalis flowers impacted pollinators visitation at an optimal distance from D. decurrens, and the effect decreased when orchids were too close or too far away from the model. C_LIO_LIOur findings show that salient UV flower signalling plays a functional role in visual floral mimicry, likely exploiting perceptual gaps in bee neural coding, and mediates the plant pollination success at much greater spatial scales than previously expected. C_LI

ecology↗

bioRxiv2022

Dealing with the promise of metabarcoding in mega-event biomonitoring: EXPO2015 unedited data

As human activities on our planet persist, causing widespread and irreversible environmental degradation, the need to biomonitor ecosystems has never been more pressing. These circumstances have required a renewal in monitoring techniques, encouraged by necessity to develop more rapid and accurate tools which will support timely observations of ecosystem structure and function. The World Exposition (from now EXPO2015) hosted in Milan from May to October 2015 was a global event that could be categorized as a mega-event, which can be defined as an acute environmental stressor, possibly generating biodiversity alteration and disturbance. During the six months of EXPO2015, exhibitors from more than 135 countries and 22 million visitors insisted on a 1.1 million square meters area. Faced with such a massive event, we explore the potential of DNA metabarcoding using three molecular markers to improve the understanding of anthropogenic impacts in the area, both considering air and water monitoring. Furthermore, we explore the effectiveness of the taxonomy assignment phase considering different taxonomic levels of analysis and the use of data mining approaches to predict sample origin. Unless the degree of taxa identification still remains open, our results showed that DNA metabarcoding is a powerful genomic-based tool to monitor biodiversity at the microscale, allowing us to capture exact fingerprints of specific event sites and to explore in a comprehensive manner the eukaryotic community alteration. With this work, we aim to disentangle and overcome the crucial issues related to the generalization of DNA metabarcoding in order to support future applications.

molecular biology↗

bioRxiv2021

Phylogeography of Lanius senator reveals conflicts between alpha taxonomy, subspecies ranges and genetics.

Implementing the effort in understanding biogeographic distribution patterns and taxonomic limits within animal groups is crucial for addressing several challenges of modern zoology. Although avian phylogeography has been deeply investigated within Western Palearctic, several families, such as shrikes, still display complicated or neglected biogeographic patterns both between and within species, thus requiring further investigations. The Woodchat Shrike (Lanius senator) is a long-distance migratory species that exhibits three morphologically well-recognizable subspecies, whose boundaries have never been molecularly investigated. Here, we aimed to define the phylogeographic structure of Lanius senator throughout its breeding range and assess the genetic coherence with the phenotypically described subspecies. We assembled a collection of 34 samples mainly from breeding populations of each subspecies and analyzed them at four mtDNA and two nuDNA markers. We did not find a clear phylogenetic structure with nuclear Ornithine Decarboxylase (ODC) and myoglobin intron 2 (MYO), while all the four mtDNA loci (i.e., ND2, COI, cytb and Control Region) highlighted two main haplogroups, one including both the nominate subspecies L. s. senator and L. s. badius and the second consistent with L. s. niloticus only from the easternmost part of the range. Surprisingly, individuals phenotypically assigned to L. s. niloticus from Israel were genetically assigned to the senator/badius haplogroup. Moreover, genetic distances showed intermediate values between inter-intraspecies diversity usually found in Passerines. We estimated a divergence time among the two haplogroups around 800 kya (549 - 1.259 kya HPD). Our findings showed a mismatch in subspecies assignment using morphology and genetic information and a marked differentiation between the eastern L.s. niloticus and all the other L. senator populations.

zoology↗

bioRxiv2021

City climate and landscape structure shape pollinators, nectar and transported pollen along a gradient of urbanization

O_LIUrbanization gradients influence both landscape and climate and provide opportunity for understanding how species, especially plants and pollinators, respond to artificially driven environmental transitions. C_LIO_LIHere, we investigated several aspects of pollination along an urbanization gradient in landscape and climate. We quantified wild hoverfly and bee abundances with trapping, standing crop of nectar with spectrophotometer, and the pollen transported by flower-visitors with DNA-metabarcoding, in 40 independent sites from seminatural to built-up areas in Northern Italy. C_LIO_LILinear and nonlinear relationships were detected along the urbanization gradient. Pollinator abundances increased until 22% of impervious surface, dropping by 34% after that, and it also decreased with green patch distance and urban park size. Thus, suburban landscapes host more pollinators than highly cemented or seminatural areas. Moreover, pollinators diminished by up to 45% in areas with low temperature seasonality: urbanized areas likely posing thermic stress. Furthermore, the sugar mass available in nectar increased by 91% with impervious cover, indicating that city nectars were less consumed or flowers more productive. Furthermore, the species richness of pollen decreased by 32% in highly urbanized areas, and with a high incidence of exotic plants, hinting for anthropized plant communities. C_LIO_LISynthesis and applications. Urbanization influences pollinator abundances, nectar resources and transported pollen. Pollinators are negatively affected by a thermally harsh climate in highly urbanized areas with isolated green areas and large parks. Suburban landscapes demonstrated the highest pollinator presence. In the city core, flowers contained more nectary sugar, while pollinators collected pollen from a small number of plants, mainly exotic. These findings highlight the influence of urban landscape structure and climate on pollinators and plants, showing that cities are heterogenous realities. Patterns from this study will serve as basis for pollinator-friendly planning and management of urban landscapes. C_LI

ecology↗

bioRxiv2021

Harnessing the power of metabarcoding in the ecological interpretation of plant-pollinator DNA data: strategies and consequences of reads filtering

DNA metabarcoding approaches to analyse complex mixtures of pollen has become the standard in pollination biology, especially in the light of recent threats affecting pollination. In spite of the increasing adoption of High Throughput Sequencing (HTS) approaches, these studies generate huge numbers of raw reads, some of which might be associated to false positives or infrequently recorded species with potentially little biological information. If these reads are not discarded (i.e. pruned), they can lead to changes in the ecological findings and lead to biased conclusions. In this study we reviewed 42 papers in the recent pollen DNA metabarcoding literature and focused on the type of pruning applied. We also tested whether the different types of those cut off threshold may leave a mark on the DNA metabarcoding data. To do so, we compared for the first time community composition, species richness and networks of species interactions (i.e. Connectace, Modularity, Connectivity and Shannon entropy) associated with the most relevant ways of treating HTS outputs: no cut (no reads filtering), or cutting levels obtained as proportional 1% of sample total reads, or as fixed amount of 100 reads, or from ROC (Receiver operator characteristic). Results clearly indicated that pruning type shapes species composition and that to apply or not a threshold dramatically impacts ecological indices, potentially increasing the risk of misinterpreting DNA metabarcoding data under an ecological point of view. Given the high methodological heterogeneity from the revised literature, we discuss in what conditions filtering types may be more appropriate, and also recommend to biologically justify the pruning threshold when analysing DNA metabarcoding raw reads, and to develop shared approaches to make future studies more comparable.

ecology↗

bioRxiv2021

EFFECTS OF LAND-USE INTENSIFICATION AND ENVIRONMENTAL STRESSORS ON INTRASPECIFIC FUNCTIONAL TRAITS VARIABILITY IN BUMBLEBEES

The way urbanization shapes the intraspecific variation of pollinator functional traits is little understood. However, this topic is relevant for investigating ecosystem services and pollinator health. Here, we studied how urbanization affects the functional traits of workers in two bumblebee species (Bombus terrestris and B. pascuorum) sampled in 37 sites along a gradient of urbanization in North Italy (an area of 1800 km2 including the metropolitan context of Milan and other surrounding capital districts). Namely, we investigated the role played by land-use composition, configuration, temperature, flower resource abundance, and air pollutants on the variation of traits related to flight performance (i.e., body size, wing shape and size fluctuating asymmetry). These traits are relevant because they are commonly used as indicators of stress during insect development. The functional traits of the two bumblebees responded idiosyncratically to urbanization. Urban temperatures were associated with smaller wing sizes in B. pascuorum and with more accentuated fluctuating asymmetry of wing size in B. terrestris. Moreover, flower abundance correlated with bigger wings in B. terrestris and with less asymmetric wing sizes in B. pascuorum. Other traits did not vary significantly and other urban variables played minor effects. These patterns highlight that environmental stressors linked to urbanization negatively impact traits related to flight performance and development stability of these species with possible consequences on the pollination service they provide. Overall, this study found species-specific variation patterns in syntopic taxa, expanding our understanding about the effects of anthropic disturbance in shaping relevant functional traits of pollinator model species.

ecology↗

bioRxiv2020

Italian Odonates in the Pandora's Box: A Comprehensive DNA Barcoding Inventory Shows Taxonomic Warnings at the Holarctic Scale

The Odonata are considered among the most endangered freshwater faunal taxa. Their DNA-based monitoring relies on validated reference datasets that are often lacking or do not cover important biogeographical centres of diversification. This study presents the results of a DNA barcoding campaign on Odonata, based on the standard 658 bp 5 end region of the mitochondrial COI gene, involving the collection of 812 specimens (409 of which barcoded) from peninsular Italy and its main islands (328 localities), belonging to all the 88 species (31 Zygoptera and 57 Anisoptera) known from the country. Additional BOLD and GenBank data from Holarctic samples expanded the dataset to 1294 DNA barcodes. A multi-approach species delimitation analysis involving two distance (OT and ABGD) and four tree-based (PTP, MPTP, GMYC, bGMYC) methods were used to explore these data. Of the 88 investigated morphospecies, 75 (85%) unequivocally corresponded to distinct Molecular Operational Units, whereas the remaining ones were classified as warnings (i.e., showing a mismatch between morphospecies assignment and DNA-based species delimitation). These results are in contrast with other DNA barcoding studies on Odonata showing up to 95% of identification success. The species causing warnings were grouped in three categories depending on if they showed low, high, or mixed genetic divergence patterns. The analysis of haplotype networks revealed unexpected intraspecific complexity at the Italian, Palearctic, and Holarctic scale, possibly indicating the occurrence of cryptic species. Overall, this study provides new insights into the taxonomy of odonates and a valuable basis for future DNA and eDNA-based monitoring studies.

zoology↗

bioRxiv2020

Tasting the differences: microbiota analysis of different insect-based novel food

Traceability, quality and safety of edible insects are important both for the producers and the consumers. Today, alongside the burst of edible insects in western countries, we are facing a gap of knowledge of insect microbiota associated with the microbial ecosystems of insect-based products. Recent studies suggest that the insect microbiota can vary between insect species and that can be shaped by additional factors, such as rearing conditions. Also, the production processes of raw materials (i.e. insect flour) into final food products can affect the insect microbiota too. This has consequences for the evaluation of food safety and food traceability. In this context, High-Throughput DNA Sequencing (HTS) techniques can give insight into the carryover of insect microbiota into final food products. In this study, we investigated the microbiota composition of insect-based commercial food products, applying HTS techniques coupled with bioinformatic analysis. The aim of this work was to analyse the microbiota variability of different categories of insect-based products made of A. domesticus (house cricket), T. molitor (mealworm beetle), and A. diaperinus (lesser mealworm or litter beetle), including commercial raw materials and processed food items, purchased via e-commerce from different companies. Our data revealed that samples cluster per insect species based on microbiota profile and preliminary results suggested that a small number of prevalent bacteria formed a "core microbiota" characterizing the products depending on the insect, suggesting that a resident microbiota is conserved. This microbial signature can be recognized despite the different food processing levels, rearing conditions selling companies. We showed that differences exist when comparing raw vs processed food made of the same insect, or similar products produced by different companies as well, laying the groundwork for further analyses. These results support the application of HTS analysis for studying the composition of processed insect food in a wider perspective, for food traceability and food quality control.

microbiology↗

bioRxiv2019

Novel Universal Primers For Metabarcoding eDNA Surveys Of Marine Mammals And Other Marine Vertebrates

Metabarcoding studies using environmental DNA (eDNA) and high throughput sequencing (HTS) are rapidly becoming an important tool for assessing and monitoring marine biodiversity, detecting invasive species, and supporting basic ecological research. Several barcode loci targeting teleost fish and elasmobranchs have previously been developed, but to date primer sets focusing on other marine megafauna, such as marine mammals have received less attention. Similarly, there have been few attempts to identify potentially universal barcode loci which may be informative across multiple marine vertebrate Orders. Here we describe the design and validation of four new sets of primers targeting hypervariable regions of the vertebrate mitochondrial 12S and 16S rRNA genes, which have conserved priming sites across virtually all cetaceans, pinnipeds, elasmobranchs, boney fish, sea turtles and birds, and amplify fragments with consistently high levels of taxonomically diagnostic sequence variation. In silico validation using the OBITOOLS software showed our new barcode loci outperformed most existing vertebrate barcode loci for taxon detection and resolution. We also evaluated sequence diversity and taxonomic resolution of the new barcode loci in 680 complete marine mammal mitochondrial genomes demonstrating that they are effective at resolving amplicons for most taxa to the species level. Finally, we evaluated the performance of the primer sets with eDNA samples from aquarium communities with known species composition. These new primers will potentially allow surveys of complete marine vertebrate communities in single HTS metabarcoding assessments, simplifying workflows, reducing costs, and increasing accessibility to a wider range of investigators.

ecology↗

bioRxiv2019

Does a strong reduction of colony workforce affect the foraging strategy of a social pollinator?

The way pollinators gather resources may play a key role for buffering their population declines. Social pollinators like bumblebees could adjust their foraging after significant workforce reductions to keep provisions to the colony optimal, especially in terms of pollen quality, diversity, and quantity. To test what effects a workforce reduction causes on the foraging for pollen, colonies of the bumblebee Bombus terrestris were experimentally manipulated in field by removing half the number of workers. The pollen pellets of the workers were taxonomically identified with DNA metabarcoding, a ROC approach was used to filter out underrepresented OTUs, and video cameras and network analyses were employed to investigate foraging strategies and behaviour. The results suggested that the plant diversity in the pollen pellets was high but plant identity and pollen quantity traits were influenced mainly by plant phenology. During the experiment, although the treated colonies increased foraging effort in relation to control nests, only minor changes in the diet breadth and in the other node-level and network-level indices were observed after workforce removal. Therefore, a consistency in the bumblebees feeding strategies emerges despite the lowered workforce, which questions the ability of social pollinators to adjust their foraging in the field.

ecology↗